Дисертації з теми "Adsorption and ion exchange"
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1
Watkins, E. James. "Foulant adsorption onto ion exchange membranes." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/7062.
2
Leonard, Danièle. "Adsorption of bile acids by ion-exchange resins." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74309.
Анотація:
The interactions of cholestyramine with bile acids in aqueous buffer solutions were studied by in vitro adsorption experiments. Application of the Donnan theory, which is based on ion partitioning between two phases, indicates that the adsorption is an ion-exchange process--the bile acid anion displaces the chloride counter-ion of cholestyramine. Donnan considerations indicate that the bile acid in the resin phase exists in two forms, bound and unbound, but at higher Ceq the bound form is increasingly favoured. Since the concentrations of bound bile acid in the resin phase are above the critical micellar concentration, micelle-type ordering is occurring. It is also possible that the unbound bile acid in the resin phase aggregates to form "regular" micelles. The micellization promotes the partitioning of glycocholic acid into the resin phase, explaining the ability of cholestyramine to adsorb glycocholic acid significantly, in vitro.Ion-exchange resins were prepared by solid phase peptide synthesis with active sites chosen to resemble those of cholestyramine. They were produced by coupling 4-(aminomethyl)benzoic acid, 4-aminophenylacetic acid or 4-(aminomethyl)phenylacetic acid to the backbone. The ion-exchange resins were prepared both as primary amines and in the quaternized form. The cholestyramine-like sorbents were synthesized with systematic changes in the structure, to determine which structural parts of cholestyramine are involved in the adsorption process. As compared to cholestyramine, both sets of resins were remarkably ineffective in adsorbing bile acids in vitro. It was found that the nature of the backbone determines the accessibility to the active site; that the resins with the methylene group positioned between the phenyl group and the amino group have higher adsorption capacity for glycocholic acid; and that quaternization increases the adsorption capacity. The two latter observations indicate the importance of the basicity of the active site. Therefore, in cholestyramine, the backbone is such that it permits the transfer of ionic species and the quaternary ammonium group is involved in the interaction with bile acids.
Computer modelling showed that the cholestyramine pendants are close to one another and are separated by benzene rings, thus leaving too little space between them to allow a bile acid molecule to interact with the benzene rings. Therefore, the bile acids must interact with the quaternary ammonium group, leaving the bile acid molecule inside the cavity where they interact with one another to form micelles. The possible modes of interactions of bile acids with the synthesized resins are more numerous since the pendants are not as close together. (Abstract shortened by UMI.)
3
Arcanjo, Maria Rosiene Antunes. "Study on the adsorption of lactic acid by ion exchange chromatography." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13346.
Анотація:
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoCurrently the demand for renewable fuels has increased a lot. Thus, biodiesel is an alternative to oil and its derivatives, since its production is cheaper, there is a reduction in emissions, and is considered a renewable energy. Due to government incentives that drive the production of biodiesel, such fuel has been produced on a large scale. Of all the raw material used for producing biodiesel via transesterification, 10 % in mass is converted into glycerin, excess demand and absorption capacity of the current markets. In this context, it is of fundamental importance to develop alternative technologies and innovative at the same time to consume this surplus of crude glycerin. The production of lactic acid by hydrothermal conversion of glycerol is an alternative that adds significantly to the productivity of the biodiesel industry value, besides the production of an organic acid that is widely used industrially. This organic acid exists as two optical isomers, D - lactic acid and L- lactic acid. Presently, it has become an important monomer in the plastics industry, and polymerized biodegradable plastics such as poly-L- lactic acid and copolymers of lactic acid. Therefore, there is a continued interest in a more efficient process for the production of lactic acid as well as for their recovery and purification. Thus, the aim of this study was to conduct a study on the adsorption of lactic acid (derived from the conversion of glycerol resulting from biodiesel production) by ion exchange by Amberlite IRA 67 and IRA 96. Different eluents were evaluated at various concentrations in order to obtain a higher efficiency in removing lactic acid adsorbents studied. From the breakthrough curves obtained with different concentrations of lactic power (60-302 g/L) acid the adsorption isotherms were constructed at temperatures of 30 ÂC, 40 ÂC and 60 ÂC. With data from lactic acid concentration for each condition studied, became the model fit the Langmuir adsorption isotherm. Studies on the purification column fixed bed with mono-component solutions, binary mixtures and real mixture were also performed. It was concluded that the application of the proposed methodology for the purification of lactic acid in a fixed-bed column showed better results when the condition (temperature = 30 ÂC) was used in both adsorbents. As the Amberlite IRA 96, the adsorbent showed better performance in the adsorption of lactic acid.
Atualmente a procura por combustÃveis renovÃveis tem aumentado muito. Deste modo, o biodiesel surge como alternativa em relaÃÃo ao petrÃleo e seus derivados, jà que sua produÃÃo à mais barata, hà uma diminuiÃÃo na emissÃo de poluentes, e à considerada uma energia renovÃvel. Devido aos incentivos governamentais que impulsionam a produÃÃo de biodiesel, tal combustÃvel tem sido produzido em larga escala. De toda a matÃria-prima utilizada para a produÃÃo de biodiesel, atravÃs de transesterificaÃÃo, 10% em massa à convertida em glicerina, excedendo a demanda e capacidade de absorÃÃo dos mercados atuais. Neste contexto, à de fundamental importÃncia o desenvolvimento de tecnologias alternativas e ao mesmo tempo inovadoras para consumir este excedente de glicerina bruta. A produÃÃo de Ãcido lÃtico por conversÃo hidrotÃrmica do glicerol à uma alternativa que agrega um valor significativo para a produtividade da indÃstria de biodiesel, alÃm da produÃÃo de um Ãcido orgÃnico que à amplamente utilizado industrialmente. Esse Ãcido orgÃnico existe como dois isÃmeros Ãpticos, D-Ãcido lÃtico e L-Ãcido lÃtico. Atualmente, tem se tornado um importante monÃmero na indÃstria de plÃsticos, sendo polimerizado em plÃsticos biodegradÃveis, tal como poli-L-Ãcido lÃtico e seus copolÃmeros de Ãcido lÃtico. Por isso hà um interesse contÃnuo em um processo mais eficiente para a produÃÃo de Ãcido lÃtico, assim como para a sua recuperaÃÃo e purificaÃÃo. Dessa maneira, o objetivo desse trabalho foi realizar um estudo sobre a adsorÃÃo de Ãcido lÃtico (oriundo da conversÃo do glicerol resultante da produÃÃo do biodiesel) por cromatografia de troca iÃnica pelas resinas Amberlite IRA 67 e IRA 96. Foram avaliados diferentes eluentes em concentraÃÃes diversas, afim de se obter uma maior eficiÃncia na remoÃÃo de Ãcido lÃtico dos adsorventes estudados. A partir das curvas de ruptura obtidas com diferentes concentraÃÃes de alimentaÃÃo de Ãcido lÃtico (60-302 g/L) foram construÃdas as isotermas de adsorÃÃo nas temperaturas de 30ÂC, 40ÂC e 60ÂC. Com os dados de concentraÃÃo de Ãcido lÃtico para cada condiÃÃo estudada, fez-se o ajuste do modelo da isoterma de adsorÃÃo de Langmuir. Estudos sobre a purificaÃÃo em coluna de leito fixo com soluÃÃes monocomponentes, misturas binÃrias e mistura real tambÃm foram realizados. Concluiu-se que a aplicaÃÃo da metodologia proposta para purificaÃÃo do Ãcido lÃtico em coluna de leito fixo mostrou melhores resultados quando a condiÃÃo (temperatura=30ÂC) foi utilizada em ambos os adsorventes. Sendo a resina Amberlite IRA 96, o adsorvente que mostrou melhor eficiÃncia na adsorÃÃo do Ãcido lÃtico.
4
Bowley, Michael Allan. "The adsorption of colloidal material to highly porous ion-exchange resins." Master's thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/23171.
5
Löfgren, Rebecka. "Metal ion adsorption of highly mesoporous magnesium carbonate." Thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388827.
Анотація:
In this project the adsorption ability of mesoporous magnesium carbonate (MMC) for copper (Cu), cobalt (Co), chromium (Cr) and arsenic (As) was evaluated. This was done by mixing MMC and dissolved metal (of different concentrations) and measuring the concentration of the solution before and after addition of MMC with Inductively coupled plasma optical emission spectroscopy. Besides MMC, “ordinary” magnesium carbonate (MgCO_3) was evaluated for comparison. Furthermore, the MMC was characterised with various instruments before and after adsorption of the metals. The adsorption experiments established that MMC was able to adsorb large amounts of Cu, Co and As while MgCO_3 was not. Moreover, it was discovered that both materials adsorbed equally large amounts of Cr. At higher concentrations of Cu and Co the uptake capacity of MMC suddenly dropped. However, for As, it was determined that MMC reached saturation at a concentration of ~22 mg/L. An adsorption experiment of a mixture of metals of 20 mg/L of each metal could not conclude anything about the selectivity of MMC, but the experiment revealed that MMC was able to adsorb all of Cu, Co and As rapidly at this concentration. The characterisation of MMC before adsorption revealed an amorphous structure and a high porosity. The structure of MMC after adsorption of Cu went from amorphous to crystalline and after adsorption of Co and As the structure also became crystalline, but of a lower degree than after adsorption of Cu. Furthermore, it was discovered that ion exchange also occurred along with adsorption.
6
Burcher-Jones, Cody Owen. "Mineralogical and ion-exchange leaching study of a Rare Earth Element (REE) bearing ion-adsorption clay deposit." Master's thesis, Faculty of Engineering and the Built Environment, 2018. http://hdl.handle.net/11427/30161.
Анотація:
Rare earth elements (REEs), La to Lu including Y, are vital elements in manufacture of catalysts and metallurgical industries, and play a critical role in meeting future energy demands, such as through their use in permanent magnets in wind turbines. China has dominated more than 90 % of the REE market, with heavy REE (HREE) clay deposits in South China accounting for 35 % of their total REE output. This has prompted the evaluation of ion-adsorption clay (IAC) deposits in tropical regions outside China, namely Madagascar. Clay minerals such as kaolinite are part of the phyllosilicate class, containing structures of shared octahedral aluminium and tetrahedral silicon sheets. Isomorphous substitutions within the lattice leads to a charge imbalance, which accounts for negative charge on kaolinite, thus giving the ability to attract REE cations from aqueous solution to the surface of the clay particle. IAC deposits are formed from the tropical weathering of granite with REE enrichment from accessory minerals. IAC clay samples of two regolith profiles, the pedolith (A1) and saprock (A2, B and F) from northern Madagascar were collected and subjected to a suite of characterisation techniques to investigate the properties of the clay mineral. This included particle size distribution (PSD), X-ray fluorescence (XRF), X-ray diffraction (XRD), quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The geochemical leaching characteristics of the clay mineral were investigated using a sequential leaching program, targeting ion-exchangeable REE on kaolinite, halloysite, REEorganic matter and mineral phase. Ammonium sulphate leach experiments were conducted, varying the ionic strength to determine optimum leaching concentrations. Seawater is easily available at the coastal mine, therefore simulated seawater (NaCl) experiments were conducted with the addition of ammonium sulphate to improve the REE recovery. Compound leaching agents were investigated including varying magnesium / ammonium ratios in a sulphate system as well as ammonium in a varying nitrate / sulphate ratio system. The magnesium ion was investigated to correct the Mg deficiency in soils after leaching and the nitrate ion was investigated due to its high ionic permeability in kaolinite. Ion-adsorption clay leaching includes the leaching of impurities such as Al, Fe, Mg, K, Na, Ca and Mn. Ammoniumsulphate experiments with increasing amounts of ammonium acetate were conducted. Ammonium acetate acts a buffering agent to inhibit the leaching of the main impurity Al. The texture of sample A1 (5 to 6.5 m) was homogenous, with the QEMSCAN results showing Fe minerals distributed through the kaolinite, giving it a red appearance. The saprock samples A2, B and F have a heterogeneous texture due to the preservation of the primary texture. The QEMSCAN results show that this texture is composed of pure white kaolin, kaolin with red staining due to Fe minerals, tawny staining due to Al minerals and black phases containing Mn minerals. These Mn minerals show Ce deposited as the mineral cerianite, unavailable for ion-exchange. The pedolith sample was light REE (LREE) enriched but depleted in total REE (TREE = 1 503 ppm) compared with the saprock samples (TREE = 7 006 ppm on average). The saprock samples show LREE and HREE enrichment with samples A2 and F having La / Gd ratio of 17.4 and Gd / Lu ratios of 1.2. The more crystalline samples A2 and F (Hinckley index 0.40 and 0.44 respectively) are more REE enriched than the more weathered sample B (Hinckley index 0.32). The geochemical characterisation of sample A1 showed decreasing REE recovery from LREE to HREE from kaolinite whereas sample A2 showed consistent recovery across the REEs from kaolinite with both showing little Ce recovery. The best TREE recovery for samples A1 and A2 in the chloride system achieved with was NH4 + (44.3 % and 83.1 % respectively) followed by Na+ (39.5 % and 72.2 %) and Mg2+ (28.9 % and 72.1 % respectively). For sample A1 the recovery from the kaolinite fraction was 37.7 %, halloysite 5.1 %, organic 1.6 % and mineral 55.7 %. The proportion of ion-exchangeable REE is increased in sample A2 showing a recovery from the kaolinite fraction of 66.9 %, halloysite 12.7 %, organic 3.5 % and mineral 16.9 %. The results from increasing the ionic strength of ammonium sulphate shows that TREE leachant concentration increases as the concentration increases but decreases above 0.25 M. This indicates that the ammonium sulphate concentration saturates at 0.25 M and any further lixiviant increase eliminates access to the kaolinite surface. The simulated seawater experiments indicate that some addition of ammonium sulphate is beneficial as the addition of 0.05 M ammonium sulphate almost doubled the TREE leachant concentration. However excess addition of ammonium sulphate above 0.05 M had adverse effects on the leachant concentration of the LREEs. It was concluded from the compound leaching experiments that the Mg2+ ion can be used to supplement ammonium leaching with the greatest leachant concentration using a Mg2+:NH4 + ratio of 1:2 (equal charge). This ratio would produce a high REE leachant concentration while keeping Mg available for plants (flora). Compound leaching with the nitrate ion shows that the greatest REE leachant concentration was with a NO3 - :SO4 2- ratio of 2:1 (equal charge) due to increased nitrate ion permeability. The results from the addition of ammonium acetate as a buffer showed that the buffer inhibited the leaching of Al in both samples A1 and F, with the greatest inhibition at 0.05 M. The characterisation experiments illustrate the complexity of the in-situ clay deposit and further work should use this information to construct leaching models that take into account the heterogeneity of saprock samples. The leaching experiments show that compound leaching can improve REE recovery and further work should incorporate multiple lixiviants in in-situ leaching models.
7
Langford, John F. Jr. "Effects of adsorbent structure and adsorption on transport phenomena in ion-exchange chromatography." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 250 p, 2007. http://proquest.umi.com/pqdweb?did=1251904681&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
8
Dietrich, Theo Henry. "The removal of heavy metals from dilute aqueous streams by the use of ion exchange resins." Thesis, Cape Technikon, 1998. http://hdl.handle.net/20.500.11838/887.
Анотація:
Thesis (MTech (Chemical Engineering)--Cape Technikon, Cape Town, 1998Ion exchange resins are widely used to remove or concentrate heavy metals from aqueous solutions or slurries.This thesis attempts to properly evaluate the interaction between ion exchange resins and heavy metals at trace metal concentrations.The durability of the resins and their effectiveness in real slurries were also investigated. In this study, a chelating resin, as well as a cation, and anion exchange resin was contacted with aqueous solutions of heavy metals in both free and complexed form. Zinc, nickel and copper cyanide complexes were adsorbed onto the anion exchange resin, while the chelating and cation exchange resins were contacted with zinc and nickel nitrates, and cupric sulphate. All the tests were conducted in batch stirred tank reactors. All the metal cyanide complexes behaved in a similar manner when contacted with the anion exchange resins. These tests were p~rf0nned under variations in temperature, stirring speed, pH., ionic strength and . initial metal 90E~entrations. Fitting of a dual resistance model to the profiles for thetlptllk:e" of the complexes, show that both film diffusion and intraparticle diffusion rates were improved with an increase in temperature, and that film diffusion rates improved with an increase in stirring speed. A high ionic strength negatively affected equilibrium loading as well as diffusional rates.It was found that at these low concentrations, the diffusional rates improves with a decrease in the external metal concentration. A comparative study involving the chelating and cation·exchange resins were performed, during which the resins were contacted with the metals in free fonn. It was found that at high metal concentrations, the chelating resin induced a rate limiting effect, but at trace concentrations, this effect is virtually negated. Whereas the cation exchange resin exhibited little selectivity in adsorbing the metals, it was found that the chelating resin prefers the metals in the eu > Ni > Zn. The chelating resin proved to be no less durable then the cation exchange resin, and both slightly lost their ability to adsorb the metal cations as a result of the effects of an inert coarse sand slurry.Tests performed with a real ore leachate, showed the cation exchange resin to be efficient at a low pH , but also relatively non selective, since the adsorption of copper from the leachate was greatly reduced due to the presence of other heavy metals.
9
Chartrand, Zachary Guy. "The Selective Ion-Exchange Removal of Ammonia from Mining Wastewater." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37543.
Анотація:
The Canadian mining industry is a multi-billion-dollar effort and one of Canada’s largest industrial sectors, creating jobs and security across the country. Certain practices employed within the industry have led to great developments, while increasing productivity and reducing costs. One such practice is the use of nitrogen-based explosives, which have serious environmental repercussions, namely the introduction of large quantities of ammonia into the ecosystem through means of complex blends of wastewaters also containing various metals. These explosive impacted mining wastewaters (EIMWW), must be treated before being introduced into natural waterways as ammonia pose several threats to the environment including the depletion of dissolved oxygen as well as acute toxicity for fish. Newterra, a provider of modular treatment solutions for water, wastewater and groundwater, requested an assessment of the feasibility of a brine-based ion exchange (IE) system for the removal of ammonia from EIMWW, that would be simple to operate and could be deployed in remote areas. The following thesis consists of an evaluation of several IE materials, to determine the feasibility of an IE system for the treatment of real EIMWW. Potassium and calcium were determined to be the problematic ions present in the EIMWW, potentially leading to competitive adsorption issues. This was accomplished by comparing batch IE isotherms for five different IE materials; one natural zeolite (clinoptilolite), one modified clinoptilolite (Resintech SIR-600), and three synthetic resins (Purolite SSTC60, Amberlite IR120 Na and Bojie BC121 H) using both a synthetic single-solute ammonia wastewater and real EIMWW with a total ammonia nitrogen (TAN) concentration of 3.87 meq TAN/L (~70 mg/L). The three synthetic resins produced the largest reductions in capacities from the effects of competition and featured the following exchange capacities when treating EIMWW: 0.24±0.03, 0.25±0.01 and 0.22±0.001 meq TAN/g for the Purolite, Amberlite and Bojie resins respectively. These were respective reductions of 87±0.96, 86±0.80 and 87±0.03 % compared to their single-solute TAN solution capacities. The two zeolites featured higher multi-component exchange capacities; 0.32±0.04 meq TAN/g for the clinoptilolite and 0.42±0.01 meq TAN/g for the SIR-600. Furthermore, calcium was found to pose minimal competitive effects and potassium was responsible for the most capacity reduction. Batch regeneration experiments with the clinoptilolite and SIR-600 were undertaken to evaluate the long-term performance of both materials. These consisted of IE isotherms with the EIMWW followed by material regeneration with various regenerants including a 2.5 % KCl/2.5 % NaCl, a 5 % KCl, and a 2.5, 5 and 10 % NaCl solution. Ultimately, the 5 % and 10 % NaCl solutions were the only regenerants to result in an increase of capacity with the 10 % solution featuring higher capacities for both materials. After four exchange/regeneration cycles using a 10 % NaCl brine, the clinoptilolite produced the following capacities: 0.16±0.01 meq Ca2+/g, 0.39±0.06 meq K+/g and 0.34±0.02 meq TAN/g. For the same conditions the Resintech SIR-600 resulted in the following capacities: 0.12±0.01 meq Ca2+/g, 0.52±0.01 meq K+/g and 0.46±0.00 meq TAN/g. Based on the higher TAN exchange performance, column studies were performed with the Resintech SIR-600 to validate the material’s performance using a more realistic mode of operation similar to real world applications. This was accomplished by comparing the capacities of the material using both a single solute TAN wastewater as well as the EIMWW and a breakthrough concentration criterion of 0.55 meq TAN/L (~10 mg/L). The EIMWW featured breakthrough after only 50 bed volumes, comparatively to the synthetic TAN solution where breakthrough occurred after 274 bed volumes, indicating that competition played a significant role in the performance of the system.
10
Marinetti, Andrea. "Recovery of Carboxylic acids from anaerobic fermented broth through ionic exchange processes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Анотація:
The recovery of Carboxylic acids were based on two particular objective: the study of the efficiency of a cation exchange resin, used in order to reduce the pH of the actual effluent, considering it is necessary to have a low pH for the anion exchange resin to be able to adsorb the acids from the effluent, and the preliminary studies perfomerd on the anion exchange resin, at various flow rates and both mode of operation, expanded and packed bed mode, using a simulated effluent, were the carboxylic acids were represented by just acetic acid, as the target molecule.
11
Els, Ellis Raymond. "The adsorption characteristics of precious and base metals on four different ion-exchange resins." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51936.
Анотація:
Dissertation PhD--University of Stellenbosch, 2000.ENGLISH ABSTRACT: Adsorption tests were conducted with four different ion-exchange resins to determine the equilibrium adsorption of a range of precious and base metals. The adsorption characteristics were determined for synthetic single metal, as well as for multicomponent and base metal solutions. The effect of the el- concentration on the equilibrium adsorption was established for three different Hel concentrations in the above solutions. From the ion-exchange characteristics determined, a selective adsorption sequence is proposed for the separation of precious and base metals. Pure platinum, palladium and gold were dissolved in aqua regia and diluted to 2000 ppm (as metal) in 4M Hel. Ruthenium, rhodium and iridium were dissolved from pure salts in Hel. A 2000 ppm base metal solution was prepared by dissolving all the required components, including precious metals, to match an in-plant industrial basemetals solution composition. For each precious metal the equilibrium adsorption was determined for a couple of solution concentrations. Data points for adsorption curves were established by varying the amount of resin added to the test solution of a specific concentration. The equilibrium solution concentrations were determined by Iep analysis after 24 hours of exposure, using the bottle-roll technique. The experimental results obtained indicate a possible process route for the separation of precious metals with ion-exchange resin. The XAD7 resin is highly selective for gold from mixed solutions containing precious and base metals. It is also evident that, with the gold removed from the solution, the A22 resin adsorbs only palladium. IR200 resin adsorbs only the base metals from the solution. With all other precious metals removed from the solution (platinum and ruthenium must be extracted by other means), iridium can be adsorbed from the solution by IRA900 resin which is highly selective for iridium over rhodium. For all of the anion resins, XAD7, IRA900, and A22, the chloride concentration of the solution did not have a big effect on the adsorption capacity. However, the adsorption of base metals on IR200 is sensitive to chloride concentration, with a rapid reduction in adsorption at higher chloride concentrations. Statistical models were developed for the adsorption of each of the precious metals, as well as for the base metal solution. All adsorption data, obtained for a resin (typically 250 equilibrium data points), was used in the development of the model. The SPSS statistical software package was used to develop linear regression models. The interaction between all the input parameters, e.g. the interaction of gold and chloride ions, was modelled by specifying the product of the gold and the chloride concentrations as an input variable. The variables that determine the adsorption quantities were identified. High solution concentrations of the target adsorption component increase the adsorption quantity. It has been established that a higher platinum concentration increases the adsorption quantity of gold on XAD7 resin. However, the adsorption quantity is reduced at higher ruthenium concentrations. The adsorption quantity of iridium on IRA900 is reduced with increased rhodium concentration. The adsorption quantity of palladium on A22 is increased by the presence of rhodium and decreased by larger concentrations of iridium and platinum. The adsorption of base metals on IR200 is decreased at higher acid concentrations. Higher concentrations of gold in the base metal solution also decrease the adsorption quantity of base metals. The model predicted adsorption of each component compares well with the actual measured values. In batch adsorption tests the counter ion is not removed from the resin. The resin capacity for a specific ion concentration could therefore not be determined. As such, the adsorption models are only valid for the initial part of the ion-exchange process. The effect of kinetics on the adsorption was not determined.
AFRIKAANSE OPSOMMING: Adsorpsietoetse is gedoen met vier verskillende ioonuitruilharse om die ewewig adsorpsie van edelmetale en basismetale te bepaal. Die adsorpsie karakteristieke is bepaal vir sintetiese enkelmetaal-, meermetaal-, en basismetaaloplossings. Die effek van die Cl konsentrasie op die ewewigadsorpsie is bepaal vir drie soutsuurkonsentrasies in al die bogenoemde oplossings. 'n Prosesvloeidiagram vir die selektiewe adsorpsie van edelmetale en basismetale met behulp van die vier verskillende ioonuitruilharse word voorgestel. Suiwer platinum, palladium en goud is opgelos in koningswater en verdun na 2000 dpm (uitgedruk as metaal) in 4 molaar HCl. Rutenium-, rodium- en iridiumoplossings is verkry deur die oplos van suiwer edelmetaalsoute in HCl. 'n Basismetaaloplossing van 2000 dpm is voorberei deur die individuele komponente, wat die edelmetale ingesluit het, in die regte verhouding te kombineer om die samestelling van 'n industriële basismetaaloplossing te verkry. Vir elke edelmetaal is die ewewigadsorpsie bepaal vir tipies twee konsentrasies van edelmetaaloplossings. Verskillende data punte by 'n spesifieke edelmetaalkonsentrasie is bepaal deur die hoeveelheid hars wat by die toets oplossing gevoeg word te varieer. Die oplossingkonsentrasies by ewewig is bepaal deur IGP analise na 24 uur blootstelling met die roterende botteltegniek. Die resultate wat verkry is dui op 'n moontlike ioonuitruiigebaseerde proses vir die skeiding van edelmetale. Die XAD hars is selektief vir goudadsorpsie uit gemengde oplossings wat al die edelmetale, asook basismetale bevat. Dit is ook bevind dat indien goud uit die gemengde oplossing verwyder word, die A22 hars slegs palladium adsorbeer uit die oplossing. Die IR200 hars adsorbeer slegs basismetale. Wanneer al die ander edelmetale uit die oplossing verwyder is (platinum en rutenium moet met alternatiewe prosesse verwyder word) kan iridium geadsorbeer word met !RA900 hars vanuit 'n iridium- en rodium- gemengde oplossing. Vir al drie die anioonharse wat getoets is, naamlik, XAD7, !RA900 en A22, het die chloriedkonsentrasie nie 'n groot effek op die adsorpsie gehad nie. Die hoeveelheid basismetale wat op IR200 hars geadsorbeer word is egter baie sensitief vir die chloriedkonsentrasie, met 'n vinmge afname In adsorpsie by hoër chloriedkonsentrasies. Statistiese modelle is ontwikkel vir elke hars en vir elk van die edelmetale, asook die basismetaaloplossing. Al die eksperimentele data wat vir elke hars verkry is, tipies 250 ewewigspunte, is gebruik in die ontwikkeling van lineêre regressie modelle vir die primêre absorberende spesie op die hars. Hoër konsentrasies van die teiken adsorpsie komponent verhoog die adsorpsie daarvan. Hoër platinumkonsentrasies verhoog die adsorpsie van goud op XAD7, maar die teenwoordigheid van rutenium verlaag adsorpsie. Die adsorpsie van iridium op IRA900 word verlaag met hoër rodiumkonsentrasies. Die adsorpsie van palladium op A22 verhoog met die teenwoordigheid van rodium, maar neem af met hoër konsentrasies van iridium en platinum. Die adsorpsie van basismetale op IR200 neem af by hoër suurkonsentrasies. 'n Hoër goudkonsentrasie verlaag ook die adsorpsie van basismetale. Die gemodelleerde adsorpsie hoeveelhede vergelyk goed met die gemete waardes. Aangesien die uitgeruilde ioon nie verwyder word uit die toetsoplossing nie, kon die harskapasiteit vir 'n spesifieke ioonkonsentrasie nie bepaal word nie. Die modelle is derhalwe slegs getoets vir die aanvanklike deel van die ewewigsdata en die kinetika van adsorpsie is nie in ag geneem nie.
12
Selbe, Tyler J. "Applications of aluminosilicate and zincosilicate materials: aqueous phase ion exchange and gas phase adsorption." Diss., Kansas State University, 2010. http://hdl.handle.net/2097/7057.
Анотація:
Doctor of PhilosophyDepartment of Chemical Engineering
Jennifer L. Anthony
Zeolites and zeolite-like materials have well-ordered structures and pores creating varying capacities for molecules based upon size, functional groups, polarity, and intermolecular forces making the materials useful for molecular sensing as well for molecules that are considered hazardous at very low concentrations with reproducible results because of these properties. This study will identify and characterize applications for zeolite and zeolite-like materials in gas and liquid phases based upon the dominating physical and chemical properties of the materials. The properties of interest include liquid phase ion exchange capacities, selectivities, gas/vapor phase adsorption capacity, and initial adsorption uptake rate. Zincosilicates have similar framework structures to aluminosilicate zeolites; however, they have distinct advantages over traditional zeolites. Zincosilicates typically have a higher ion density, lack “cages” in their structure which leads to all the cations being accessible for ion exchange, and have the ability to form three-membered rings which lead to large void spaces in their structure. These features lead to high capture capacities for divalent heavy metal mercury ions. In this work, the potential to use zincosilicates as ion exchangers such as VPI-7, VPI-9 and VPI-10 is presented. Results have shown that zincosilicates have capture capacities greater than traditional zeolites, even greater than those that have been synthesized with functional groups intended to increase metal sorption capacities. The selectivity coefficients in a binary ion exchange system were successfully modeled using the Gibbs-Donnan selectivity model. The selectivities for the zincosilicates were Pb>Na>Hg>K>Ca. Zeolites are also able to adsorb chemical species and therefore can be used as the recognition element in sensing devices. The sorption capacity of 2-chloroethyl ethyl sulfide, dimethyl methanephosphonate, ethanol, and n-butanethiol were examined with zeolites 13X, 4A, MCM-41, VPI-7, VPI-9, and ZSM-5. The zeolites selected provided very different framework composition, countercation, and surface area features for determining the most significant properties in adsorption. Zeolite 13X had the highest equilibrium and initial uptake rate for most compounds tested, whereas the low surface area zincosilicates, VPI-7 and VPI-9, had the lowest capacity. Based on these results, a piezoelectric device with an array of zeolites can be successfully employed as a sensor.
13
Ndayambaje, Guillaume. "Sorption properties of natural zeolites for the removal of ammonium and chromium ions in aqueous solution." University of the Western Cape, 2011. http://hdl.handle.net/11394/5425.
Анотація:
>Magister Scientiae - MScThere are huge amount of natural clinoptilolite available in South Africa which can be utilised for wastewater treatment of ammonia and chromium if their characteristics are properly known. However, these deposits have not been well characterised but in this study, the untreated clinoptilolite materials were fully characterised using techniques such as SEM-EDS, HRTEM-SAED, XRD, XRF, FTIR and BET. After acid pretreatment with several extractions, the pretreated samples were again characterised using the above mentioned techniques. These pretreated materials were used for NH₄⁺ and Cr³⁺ adsorption of wastewater. The three natural South African clinoptilolite samples used in this study were from ECCA Holdings (ESC and EHC samples) and Pratley (PC sample) deposits obtained from Western Cape and KwaZulu-Natal Province respectively. This study revealed that the chemical composition and mineral phases of South African clinoptilolites vary considerably from site to site, even clinoptilolite mined from the same deposit sites. The XRD analyses showed that Pratley clinoptilolite (PC) was the most pure clinoptilolite sample (81.41 %) compared to the purity of EHC (67.88 %) and ESC (44.0 %) sample. The ECCA Holdings untreated clinoptilolite samples contained dense phases such as quartz which was not found in Pratley sample. Quartz was found to be the most dominant impurity in both ECCA Holding sample. The cation exchange capacity (CEC) of ESC, EHC and PC samples were found to be 1.23, 1.81 and 2.90 meq/g respectively and these results were compared to that of XRF analyses. The acid solutions of 0.02 and 1.0 M HCl were used to pretreat natural clinoptilolite to determine the optimum acid concentration and number of extractions required to fully replace the exchangeable cations. The pretreatment results showed that 0.02 M HCl was the optimum acid concentration for acid pretreatment of clinoptilolite samples. Between 7 and 22 extractions were required to remove Na⁺, K⁺, Ca²⁺ and Mg²⁺ without causing much dealumination of the framework. Sodium ion was found to be weakly bound cation in the clinoptilolite framework, since it could be completely exchanged by H⁺ after 7 extractions with 0.02 M HCl acid solution. Potassium ion was found to be strongly bound in the clinoptilolite framework since it could not be completely exchanged during the acid pretreatment process even after 22 extractions. The HRTEM-SAED and BET results showed that ESC, EHC and PC were all polycrystalline and microporous materials respectively. It was found that the adsorption capacity of the treated Pratley clinoptilolite sample was increased by 36 % for NH₄⁺ removal, compared to that of the untreated PC sample. The adsorption study results showed that the pretreatment of clinoptilolite samples using 150 mL volumes of 0.02 M HCl with 7 acid extractions at 25 °C for ESC pretreated and EHC pretreated. The pretreatment of PC sample at 22 extractions could remove high percentage of NH₄⁺ (98.11 %) within a short contact time of 10 min. The pretreated Pratley clinoptilolite sample was found to be the best NH₄⁺ adsorbent (98.11 % NH₄⁺ removal) compared to EHC treated (93.89 % NH₄⁺ removal) and ESC treated (75.00 % NH₄⁺ removal) clinoptilolite samples. However, acid-pretreated Pratley clinoptilolite did not sufficiently remove Cr³⁺ (16.10 %) from synthetic wastewater showing that it is not a good adsorbent for this particular metal ion removal. Despite several studies that have been conducted on clinoptilolite, no study has been carried out on the pretreatment and comparison of sorption capacity of different South African clinoptilolites for the removal of NH₄⁺ from wastewater. This study has been able improve on the acid-pretreatment procedure for clinoptilolite. This study demonstrated that it is not only the acid concentration that is important but also the number of extractions needed to remove all the exchangeable cations from the clinoptilolite framework. This study has also been able to prove that South African clinoptilolite can treated ammonia from wastewater.
14
Payne, Karl A. "Mathematical and Numerical Modeling of Hybrid Adsorption and Biological Treatment Systems for Enhanced Nitrogen Removal." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7702.
Анотація:
High nutrient loading into groundwater and surface water systems has deleterious impacts on the environment, such as eutrophication, decimation of fish populations, and oxygen depletion. Conventional onsite wastewater treatment systems (OWTS) and various waste streams with high ammonium (NH4+) concentrations present a challenge, due the inconsistent performance of environmental biotechnologies aimed at managing nutrients from these sources.
Biological nitrogen removal (BNR) is commonly used in batch or packed-bed reactor configurations for nitrogen removal from various waste streams. In recognition of the need for resource recovery, algal photobioreactors are another type of environmental biotechnology with the potential for simultaneously treating wastewater while recovering energy. However, irrespective of the technology adopted, outstanding issues remain that affect the consistent performance of environmental biotechnologies for nitrogen removal and resource recovery. In OWTS, transient loading can lead to inconsistent nitrogen removal efficiency, while the presence of high free ammonia (FA) can exert inhibitory effects on microorganisms that mediate transformation of nitrogen species as well as microalgae that utilize nitrogen. Therefore, to overcome these challenges there have been experimental studies investigating the addition of adsorption and ion exchange (IX) media that can temporarily take up specific nitrogen ions.
Bioreactors comprised of microorganisms and adsorption/IX media can attenuate transient loading as well as mitigate inhibitory effects on microorganisms and microalgae; however, the interplay between physicochemical and processes in these systems is not well understood. Therefore, the main objective of this dissertation was to develop theoretical and numerical models that elucidate the complex interactions that influence the fate of chemical species in the bioreactors.
To achieve this objective and address the issues related to improving the understanding of the underlying mechanisms occurring within the environmental biotechnologies investigated, the following three research studies were done: (i) experimental and theoretical modeling studies of an IX-assisted nitrification process for treatment of high NH4+ strength wastewater (Chapter 3), (ii) theoretical and numerical modeling of a hybrid algal photosynthesis and ion exchange (HAPIX) process for NH4+ removal and resource recovery (Chapter 4), and (iii) mathematical and numerical modeling of a mixotrophic denitrification process for nitrate (NO3-) removal under transient inflow conditions (Chapter 5).
The experimental results for the IX-assisted nitrification process showed that by amending the bioreactor with zeolite, there was a marked increase in the nitrification rate as evidenced by an increase in NO3– production from an initial concentration of 3.7 mg-N L-1 to 160 mg-N L-1. This increase is approximately an order of magnitude greater than the increase in the reactor without chabazite. Therefore, the experimental studies provided support for the hypothesis that IX enhances the nitrification process. To garner further support for the hypothesis and better understand the mechanisms in the bioreactor, a novel mathematical model was developed that mechanistically describes IX kinetics by surface diffusion coupled with a nitrification inhibition model described by the Andrews equation. The agreement between the model and data suggests that the mathematical model developed provides a theoretically sound conceptual understanding of IX-assisted nitrification.
A model based on the physics of Fickian diffusion, IX chemistry, and algal growth with co-limiting factors including NH4+, light irradiance, and temperature was developed to describe a batch reactor comprised of microalgae and zeolite. The model can reproduce the temporal history of NH4+ in the reactor as well as the growth of microalgae biomass. The mathematical model developed for the HAPIX process balances between simplicity and accuracy to provide a sound theoretical framework for mechanisms involved.
In OWTS, transient inflow conditions have an influence on the performance of environmental biotechnologies for nitrogen removal. Prior experiments have shown that for denitrification, a tire-sulfur hybrid adsorption and denitrification (T-SHAD) bioreactor consistently removes nitrogen under varying influent flow and concentration conditions. To enhance the understanding of the underlying mechanisms in the T-SHAD bioreactor, a mathematical model describing mass transport of NO3- and SO42- in the aqueous phase and mixotrophic denitrification was developed. Additionally, a numerical tool to solve the mathematical model was implemented and compared to previously conducted experiments. Results from the numerical simulations capture the trend of the experimental data showing approximately 90% NO3- -N removal under varying flow conditions. Moreover, the model describes the effluent characteristics of the process showing a transient response in correspondence the changes in fluid velocity.
The new tools developed provide new insight into the underlying mechanisms of physical, chemical, and biological processes within these bioreactors. The tools developed in this dissertation have a potential broad impact in environmental biotechnology for wastewater treatment in on-site systems, for treatment of high strength wastewater, and can be extended easily for stormwater management systems aimed at mitigating high nutrient loading to the environment.
15
Yalala, Bongani Ndhlovu. "Ion exchange resins an functional fibres :a comparative study for the treatment of brine waste water." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8342_1298358875.
Анотація:
To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80°
C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM)
Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker.
16
Papworth, Shannon P. "Evaluation of ion exchange as a pre-treatment option for coal seam gas water." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/90057/14/90057_Shannon_Papworth_Thesis.pdf.
Анотація:
The Coal Seam Gas (CSG) industry in Australia has grown significantly in recent years. During the gas extraction process, water is also recovered which is brackish in character. In order to facilitate beneficial reuse of the water, the CSG industry has primarily invested in Reverse Osmosis (RO) as the primary method for associated water desalination. However, the presence of alkaline earth ions in the water combined with the inherent alkalinity of the water may result in RO membrane scaling. Consequently, weak acid cation (WAC) synthetic ion exchange resins were investigated as a potential solution to this potential problem. It was shown that resins were indeed highly efficient at treating single and multi-component solutions of alkaline earth ions. The interaction of the ions with the resin was found to be considerably more complex that previously reported.
17
Zhao, Wen. "The Control of Water Contaminants Assisted by Natural Materials." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/7114.
Анотація:
Natural materials can be used to remove water contaminants by applying proper physical, chemical, and biological water treatment processes. This study involves using natural materials, as they are considered to be more environmentally benign and cost-effective than synthetic materials. This dissertation concentrates on monitoring five major water quality parameters—ammonia, fluoride, turbidity, pH, and fecal indicator bacteria (FIB) —in two major applications where clean water is needed. The focus is on meeting the water quality requirements for each contaminant. The overall objective of this study is to control the levels of ammonia in aquaculture wastewater, and adjust fluoride, turbidity, pH, and FIB in drinking water by using natural materials. To accomplish this objective, this dissertation study is divided into two parts. Part I is about ammonia removal in aquaculture wastewater. Zeolite was the representative natural material that was used in this study. The methodologies presented include ion exchange and chemical neutralization processes. Part II is about fluoride, turbidity, pH and fecal indicator bacteria control in drinking water. Pumice stone was used in this study. The methodologies utilized in this work include biofiltration and adsorption.
In Part I, the methods of ion exchange and chemical neutralization as a function of ammonia removal efficiency, toxicity, and daily cost were compared. All these methods were found to remove ammonia by a simple drop-off system. Chabazite, a natural zeolite, was the ion exchanger source. Similarly, we compared the effectiveness of commercialized neutralizers versus a novel neutralizer prepared for this work. The ion exchanger (chabazite) had the highest ammonia removal in freshwater, but no significant ammonia removal in seawater was observed after in-vivo trials. However, for commercial water neutralizers, the in-vivo trials showed that they are not able to control ammonia levels in either freshwater or seawater. The novel neutralizer was found to have higher ammonia removal efficiencies in both freshwater and seawater. In terms of toxicity, the AmmoSorb can be considered non-toxic. To safely use the novel neutralizer, it is recommended to control its daily dose at 1 g/L/day followed by a two-thirds volume of water change every day. A comprehensive cost analysis also showed that the novel neutralizer was the least expensive ammonia remover.
In Part II, drinking water was treated by a bench-scale biosand filter system that included different filtration technologies, biological disinfection, and adsorption. The filtration technologies analyzed in this work include Aluminum Oxide Coated Pumice (AOCP) and sand. The AOCP also works as adsorption media to remove fluoride in water. As results, the AOCP imbedded biosand filter (BSF) can efficiently control fluoride, turbidity, and pH level to meet the WHO standards. In addition, the exhausted BSF can be regenerated by recoating the pumice with additional layers of aluminum oxide. The fluoride, turbidity, pH, as well as fecal indicator bacteria levels controlled by the regenerated BSF also meet the WHO standard for about one-month operation.
The overall contribution of this research is providing new methods to treat water at an affordable cost and an easy operational procedure with potential health benefits to the specific applications that require ammonia, fluoride, turbidity, pH, and E. coli levels to be controlled.
18
Kammerer, Judith [Verfasser]. "Selective Polyphenol Recovery from By-Products of Plant Foodstuff Processing by Adsorption and Ion Exchange Technology / Judith Kammerer." Aachen : Shaker, 2011. http://d-nb.info/1071529005/34.
19
Pierini, Alessia. "Recupero di fosfati da acque reflue municipali mediante adsorbimento e scambio ionico: sintesi del materiale adsorbente e sviluppo del processo." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25454/.
Анотація:
Il fosforo (P) è una risorsa essenziale e limitata. Tuttavia, l'agricoltura moderna dipende dal fosforo per i fertilizzanti. Le acque reflue municipali (MWW) sono una fonte promettente di P e potrebbero essere utilizzate per il suo recupero a sostituzione del fosforo ottenuto da minerali. Lo scambio ionico e l'adsorbimento rappresentano uno dei processi più promettenti per il recupero del fosfato da MWW. Gli obiettivi di questo progetto sono stati i seguenti: 1. Selezionare un materiale adatto e selettivo verso gli anioni del fosforo. 2. Verificare il comportamento di esso durante cicli di adsorbimento/desorbimento. Il materiale selezionato, un Mg:Fe 3:1 Layered Double Hydroxide (LDH) calcinato, denominato Calcined Pyroaurite ha dato come risultato: un‘alta efficienza di utilizzo (83%), elevata capacità totale (258 mgP gdryresin-1), elevata resa di adsorbimento a fine prova (86%) e buona selettività verso i fosfati. Inoltre, le prestazioni del processo sono risultate stabili durante i 5 cicli di adsorbimento/desorbimento.
20
SANTOS, ELIANE E. dos. "Estudo da separacao de galio e zinco por meio de resinas trocadoras e de adsorcao de ions. Obtencao de sup67Ga para uso em medicina nuclear." reponame:Repositório Institucional do IPEN, 1995. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10426.
Анотація:
Made available in DSpace on 2014-10-09T12:38:34Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:05:19Z (GMT). No. of bitstreams: 1 06051.pdf: 3741184 bytes, checksum: a75ec12829b661a213233009e5987d2a (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
21
Liang, Juan [Verfasser]. "Theoretical and experimental study of single and binary components adsorption of proteins onto ion-exchange chromatographic media / Juan Liang." München : Verlag Dr. Hut, 2014. http://d-nb.info/1053859538/34.
22
Mabovu, Bonelwa. "Brine treatment using natural adsorbents." Thesis, University of the Western Cape, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_3665_1319180742.
Анотація:
The current study investigated application of natural adsorbents in brine treatment. Brines are hypersaline waters generated in power stations and mining industries rich in Mg2+, K+, Ca2+, Na+, SO4 2- , Cl- and traces of heavy metals, thus there is a need for these brines to be treated to recover potable water and remove problematic elements. Natural adsorbents have been successfully used in waste water treatment because of their high surface area and high adsorptive properties when they are conditioned with acid or base. The investigation of pH showed that natural adsorbents did not perform well at low pH of 4 and 6. The adsorbents were able to work efficiently at the natural pH of 8.52 of the brine solution. These results show that natural adsorbents hold great potential to remove cationic major components and selected heavy metal species from industrial brine wastewater. Heterogeneity of natural adsorbents samples, even when they have the same origin, could be a problem when wastewater treatment systems utilizing natural clinoptilolite and bentonite are planned to be developed. Therefore, it is very important to characterize the reserves fully in order to make them attractive in developing treatment technologies.
23
Drici, Nawal. "Hydroxydes doubles lamellaires, synthèse, caractérisation et propriétés." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCD007/document.
Анотація:
L’étude cinétique a permis de déterminer le temps d’équilibre atteint lors de la fixation du benzopurpurine 4B sur chaque composé, ainsi que l’ordre de la réaction et la nature du mécanisme de diffusion. Cette adsorption est favorisée par un milieu légèrement basique, et l’augmentation de la température a un effet positif sur l’amélioration des performances maximales de la fixation. L’étude des isothermes d’adsorption de ce colorant, a été établie pour déterminer l’efficacité de cette nouvelle classe d’adsorbants. Ces dernières sont de type L, et les donnés de sorption ont été traitées selon plusieurs modèles, afin de mieux comprendre le mécanisme d'adsorption du colorant sur les différents matériaux. L’analyse des résultats de l’étude thermodynamiques a montré que l’adsorption du colorant sur les différents composés est un phénomène spontané, endothermique et favorable, régie par une adsorption physique pour les matériaux CoFe-CO3/Ec, CoFe-CO3/A et MgAl-CO32- et par une adsorption physico-chimique pour les matériaux CoFe-Ac/p, CoNiFe-Ac/p , et MgAl-500. Ces résultats ont été confirmés par les analyses DRX et IR des différents matériaux avant et après adsorption. En comparant les résultats obtenus pour l’adsorption du colorant sur les différents matériaux, le composé CoNiFe-Ac/p constitue le meilleur adsorbant avec une capacité d’adsorption d’environ 593mg/g. Par conséquent, et compte tenu de l’ensemble des résultats fournis par cette étude, l’hydrolyse forcée en milieu polyol, s’avère une méthode très efficace pour l’élaboration des hydroxydes doubles lamellaire à base de métaux de transition avec une morphologie contrôlée, de taille nanométrique présentant un faible taux d’agglomération, et par conséquent une bonne dispersion de particules et un meilleur pouvoir adsorbant. Ces caractéristiques peuvent être à l’origine de l’application de ces matériaux avec succès dans l’élimination des colorants contenant dans les effluents industrielsNew layered double hydroxides (LDHs) CoFe-Ac, CoNiFe-Ac, ZnNiFe-Ac and ZnCoFe-Acwith MII/MIII molar ratio of 3, and acetate ions in the interlayer region have been preparedusing forced hydrolysis of acetate metallic salts in a polyol medium. The structure,morphology and properties of as-prepared product were investigated by X-ray Diffraction(XRD), FT-IR Spectroscopy, elemental analysis, transmission Electron Microscopy (TEM),Scanning Electron Microscopy (SEM), thermal analysis (DTA, TGA) and V-visibleSpectroscopy: showed that these nanocomposites present the typical features of hydrotalcitelikestructure, exhibit a turbostratic character and the intercalation of acetate anions into theinterlayer domain has been successfully done, giving an interlayer spacing value of 12.70,12.47, 13.64 and 14.69 Å for CoFe-Ac, CoNiFe-Ac, ZnNiFe-Ac and ZnCoFe-Acrespectively.We can note that there is some difference between the interlayer spacing for all synthesizedphases. That can be explained by the arrangement of inserted species (anions + water) indifferent orientation in the interlayer domain.57Fe Mössbauer spectrometry allows concluding the presence of Fe3+ cations which occupyoctahedral sites and confirming the absence of Fe2+ in the as-prepared compounds.In order to check the capacity of our materials synthesized in polyol medium to exchange theacetate anions inserted in their interlamellar space, anionic exchange in aqueous medium waseffected for CoFe-Ac compound as à model of synthesized LDH. All the physicochemicalmethods of analysis (DRX, IR, ATD/ATG and elemental analysis) carried out on the materialCoFe- Ac /EC (exchanged). The comparison with a lamellar phase containing oFeCO3/Asynthesized in aqueous medium, show a layered double hydroxide compound with aturbostratic disorder, and a new interlamellar distance d003 = 7.67Å which correspondsperfectly with the presence of the carbonate anions and the water molecules in the interfeuilletfield.In the second part of this study, we are interested to examine the capacities of these kinds ofmaterials for the adsorption of an anion dye benzopurpurine-4B-. The adsorption of direct red2 by CoFe-Ac, CoNiFe-Ac LDHs has been examined in order to measure the capability ofthis new organic/inorganic nanomaterial to eliminate this highly toxic azoic class of anionicdyes from wastewater. The sorption capacities of LDHs for Benzopurpurine4B are also compared with those of other adsorbents : CoFe- Ac /Ec, CoFeCO3/A (synthesized in aqueous medium), Mg-Al-CO3/A and its calcined product at 500°C “Mg-Al-500”. The quantity of dye eliminated was found to depend on contact time, pH, initial concentration of dye and heating temperature. The thermodynamic parameters ΔG°, ΔH° and ΔS° werecalculated to predict the nature of adsorption. Results suggested that the Benzopurpurine 4B adsorption on different compounds was a spontaneous and endothermic process. Adsorption kinetic data were tested using pseudo-first order, pseudo-second order, Elovitch’sequation and intra-particle diffusion models. Kinetic studies for all cases showed that the adsorption followed a pseudo-second order reaction. Studies revealed that intra-particle diffusion played an important role in the mechanism of dye adsorption by MgAl-500. Theequilibrium data were analyzed using Langmuir, Freundlich, Tempkin, Elovitch, Dubinin-Radushkevich, Redlich-Peterson and Toth isotherm models. [...] Taking these results into account, we can conclude that prepared LDHs by forced hydrolysis in a polyol medium can be used successfully in the removal of anionic dyes from aqueous solutions
24
De, Villiers Pieter Gabriel Retief. "The use of ion-exchange resins for the recovery of valuable species from slurries of sparingly soluble solids." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53181.
Анотація:
Thesis (PhD)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: The availability of vast deposits of high-grade ore bodies are rapidly becoming something of the past in the modern mining and metallurgical scenario. Apart from the lower grade content of these ore bodies, complex mineralogy are an even greater obstacle in the recovery of valuable metal species. The development of new technology to deal with these type of ore bodies is therefore critical and worth investigating, as the world's easily exploitable high grade ore deposits are decreasing. Valuable species can be recovered from sparingly soluble solids, which slightly dissociate to give traces of the valuable ions in solution, with the use of ion-exchange resins in a slurry mixture. A dissociation equilibrium exists between the dissolved ions in solution and the solid ore body. Jf the dissolved ions are removed from the solution by ion-exchange, the solid / liquid dissociation equilibrium is continually displaced. According to Le Chatelier's principle further dissolution of the sparingly soluble solid is required to restore the equilibrium concentration of the valuable species in solution. It is possible to recover valuable metal species from metal precipitates, such as metal sulphides, by contacting a slurry of the precipitate with a suitable ion-exchange resin. The resulting ion exchange reaction between the valuable metal species and counter ions creates electrolyte solutions that may facilitate the further dissolution of the metal precipitate. These counter ion electrolyte solutions may easily become significantly concentrated. This occurs in the event of a Resin-in-Leach (RIL) mixture that results in a continuous ion-exchange reaction taking place due to the continually changing electrolyte composition of the mixture, which significantly changes the activities and hence the solubility of the valuable metal species in solution. Complete dissolution and liberation of the metal precipitate can often be achieved provided that a sufficient amount of a suitable high capacity ion-exchange resin is used in a properly engineered Resin-in- Leach (RIL) circuit. The simultaneous dissolution and adsorption of various base metal precipitates were tested. Various interactions that take place in the slurry at molecular level as well as the effects of various variables on the "adsorption by dissolution process" are discussed through the development of fundamental thermodynamic models. These thermodynamic mathematical models are developed for the three phase system that exists in a Resin-in- Leach mixture, i.e. the solid ore body, the electrolyte solution and the ion-exchange resin, and can be used for possible other applications such as the recovery of rare earths from low grade ores in the minerals processing industry. A typical example of an industrial process for the recovery of rare earth species is the percolation leaching of rare earths from low-grade kaolinitic ores, which continually shifts the solid / liquid dissociation equilibrium condition. The rare earth content of these ores is usually between 0.05%and 0.3 %, which is very low by any modern industrial extraction and refining standards.
AFRIKAANSE OPSOMMING: Die beskikbaarheid van ryk mineraal ertsneerslae is spoedig besig om iets van die verlede te word in die huidige mineraalontginning en metallurgiese veredelings industrie. Afgesien van die lae graad van die huidige mineraal ertsneerslae, blyk die komplekse mineralogiese samestelling van hierdie neerslae In veel groter struikelblok te wees in die herwinning en veredeling van die edelmetale teenwoordig in hierdie ertse. Die ontwikkeling van nuwe veredelings en ekstratiewe tegnologie vir die herwinning van edel metale, vanuit hierdie lae graad mineraal ertsneerslae, word dus benodig wat verdere navorsing in hierdie gebied regverdig. Dit is wel moontlik om metaal spesies afkomstig van ertse met 'n baie lae oplosbaarheid in waterige oplossings te herwin met ioon-uitruilings harse vanweë die feit dat die metaal spesies wel teen baie lae konsentrasies in die waterige oplossings teenwoordig is. Die metaal spesies los op in die waterige oplossings volgens hulle karakteristieke oplossings termodinamika. Indien die opgeloste metaal spesies vanuit die waterige oplossing verwyder word, sal die vaste stof / vloeistof ewewigs balans weer herstel word deurdat die vaste stof verder saloplos as gevolg van Le Chatelier se beginsel. Dit is dus moontlik om metaalagtige spesies, soos metaal sulfiedes, te herwin deur 'n waterige oplossing wat die metaal erts bevat in kontak te bring met 'n ioon-uitruilings hars. Die daaropvolgende ioon-uitruilings reaksie tussen die metaalagtige spesies en die spesies teenswoordig op die ioon-uitruilingshars het tot gevolg dat die elektrolitiese samestelling van die waterige oplossing verander. Dit is die gevolg van die migrasie van spesies aanvanklik teenswoordig op die hars wat in die waterige fase eindig. Die veranderende samestelling van die waterige oplossing mag verder tot gevolg hê dat die oplosbaarheid van die metaalagtige spesie verder verhoog mag word. Die gevolg van bogenoemde reaksies is dat die waterige oplossing ionies sterk gekonsentreerd kan word soos meer en meer spesies aanvanklik teenswoordig op die hars migreer na die oplossing. Die ioniese verandering van die waterige oplossing van 'n suiwer waterige fase tot 'n ionies sterk gekonsentreerde oplossing vind plaas tydens die oplos van erste in 'n hars-inpulp (HIP) oplossing. Die nuwe ioniese aktiwiteit in die oplossing kan die oplosbaarheid van die vaste stof drasties verander. Die volledige oplossing van 'n bepaalde kwantiteit van die vaste stof kan bereik word deur die genoegsame toevoeging van 'n geskikte hars tot die waterige oplossing wat die vaste stofbevat. Die gelyktydige oplossing en absorpsie van die metaalagtige vastestowwe vanuit waterige oplossings met behulp van ioon-uitruilings harse is eksperimenteel getoets vir die doeleindes van hierdie werkstuk. Verskeie interaksies wat op molekulêre vlak in die pulp plaasvind asook die adsorpsie proses van die spesies vanuit die waterige oplossing op die harse word bespreek en gemodelleer. Wiskundige modelle wat die termodinamika van die verskillende fases wiskundig verteenwoordig is ontwikkel vanaf bestaande termodinamiese beginsels. Die drie verskillende fases wat in ag geneem is, is die waterige fase met opgeloste metaal spesies, die vaste stof fase wat as die erts in bostaande paragrawe beskryf is en die ioon-uitruilings fase wat 'n komplekse vastestof en water fase gekombineerd is. Die doel van die werkstuk is om die basis te skep vir die ontwikkeling van modelle wat gebruik kan word om die herwinning van skaars-aarde mertale vanuit lae oplosbare erstse te modelleer en beskryf. 'n Tipiese industriële voorbeeld is die herwinning van skaars-aarde metale van lae-graadse kalkagtige erste deur gebruik te maak van perkolerende logings reaksies wat geduring die vastestof / vloeistof ewewig versteur. Die konsentrasie van die skaars-aarde metale in hierde erts gesteentes kan wissel vanaf so laag as 0.05% tot 0.3% per massa. Hierdie konsentrasies is uiters laag gesien vanuit enige industriële herwinnings proses oogpunt.
25
Miriyala, Amulya. "Impact of Recirculating Nitrified Effluent on the Performance of Passive Onsite Hybrid Adsorption and Biological Treatment Systems." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7697.
Анотація:
Approximately 25% of households in the U.S. treat their wastewater onsite using conventional onsite wastewater treatment systems (OWTS). These systems typically include a septic tank or a series of septic tanks followed by a soil absorption system. They effectively remove biochemical oxygen demand (BOD), total suspended solids (TSS), fats and grease but are not designed to remove significant amounts of nitrogen. High nitrogen loading to coastal and ground waters can be dangerous to aquatic life and public health. Hence, there is a need for advanced onsite wastewater treatment systems that can effectively remove nitrogen. Making enhanced nitrogen removal for OWTS as our primary goal, a laboratory scale Hybrid Adsorption and Biological Treatment Systems (HABiTS) was developed and upon observation of its effective nitrogen removal capacity, a pilot demonstration study with two side-by-side HABiTS, one with recirculation and one without recirculation (only forward flow) were constructed and tested at the Northwest Regional Water Reclamation Facility in Hillsborough County (Florida).
HABiTS employ biological nitrogen removal and ion exchange for effective nitrogen removal. HABiTS is a two-stage process which uses nitrification for the oxidation of ammonium to nitrate and ion exchange for ammonium adsorption that helps buffer transient loading and also acts as a biofilm carrier in its stage 1 biofilter and it uses tire-sulfur hybrid adsorption denitrification (T-SHAD) in its stage 2 biofilter. These sulfur pellets help promote sulfur oxidation denitrification (SOD) and tire chips are used for nitrate adsorption during transient loading conditions, as biofilm carriers for denitrifying bacteria, and can also be used as organic carbon source to promote heterotrophic denitrification because they leach organic carbon. For this research, HABiTS without recirculation is considered as the control system and the performance of HABiTS with recirculation was tested for its ability to further enhance nitrogen removal from HABiTS.
Nitrified effluent recirculation is a common strategy employed in wastewater treatment for enhanced nitrogen removal. It is the reintroduction of semi-treated wastewater to pass through an anoxic pre-treatment chamber to achieve better quality effluent. Recirculation is said to improve and consistently remove nitrogen at any hydraulic loading rate and/or nitrogen concentration. This is because of the dilution of high BOD septic tank effluent with nitrified effluent which lowers COD:TKN ratio and also improves mass transfer of substrates in the stage 1 biofilter. Recirculation also provides some pre-denitrification in the pre-treatment chamber, thereby reducing nitrogen load on the system.
The HABiTS with recirculation (R) was run at 1:1 ratio of nitrified effluent recirculation rate to the influent flow rate for 50 days, and at 3:1 ratio for the remaining period of this research (200 days). The forward flow system (FF) was run under constant conditions throughout the research and comparisons between the two systems were made for different water quality parameters (pH, DO, conductivity, alkalinity, TSS, chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and various nitrogen species). The final effluent ammonium results showed that the system with recirculation removed consistently > 80% NH4+-N during 1:1 and 3:1 recirculation ratios whereas the forward flow system achieved 57% removal. Further, an average of 81% total inorganic nitrogen (TIN) removal from the system influent was seen in the recirculation system’s final effluent when compared to an average of 55% in forward flow system’s final effluent.
This research explains in detail, the impact of nitrified effluent recirculation on enhanced nitrogen removal in onsite systems and the results presented in this thesis proved that nitrified effluent recirculation provides promising enhanced nitrogen removal in an onsite wastewater treatment system.
26
Dibello, Genny. "Studio di processi di recupero dell'ammonio da acque reflue tramite adsorbimento: materiali e strategie innovative." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21703/.
Анотація:
Questo studio di tesi magistrale nasce dall’esigenza di contrastare il fenomeno dell’eutrofizzazione, accelerato dalla presenza di azoto ammoniacale (NH4+-N) nei fiumi e nei laghi. I processi biologici utilizzati per rimuovere l’ammonio dalle acque, ossidandolo a N2, sono ad alta intensità energetica e hanno difficoltà a raggiungere le concentrazioni di effluenti richieste inferiori a 1 mg∙L-1. Un obiettivo del recupero dell’ammonio è quello di trasformare questo nutriente in altri composti e fertilizzanti a partire da materiali di scarto, riducendo così significativamente la dipendenza dal processo Haber-Bosch per l'ottenimento di ammoniaca e urea, il quale utilizza ogni anno l’1-2 % della fornitura di energia mondiale. L’adsorbimento per scambio ionico è risultato un metodo interessante per la rimozione dell’ammonio dalle acque reflue a bassa concentrazione. Sono stati valutati diversi materiali adsorbenti tramite il confronto tra gli esperimenti riportati in letteratura, ovvero test in batch (isoterme), in continuo (breakthrough) e tramite la rielaborazione dei dati sperimentali con il modello cinetico di Thomas. Le zeoliti naturali e sintetiche, tra cui rispettivamente la Cabasite e la MesoLite, hanno mostrato le migliori proprietà come adsorbenti, ovvero buona capacità di adsorbimento ma soprattutto selettività, abbondanza, basso costo, resistenza a NaOH, resistenza meccanica e a compressione. La rigenerazione rappresenta un grande ostacolo per l’utilizzo del trattamento delle acque reflue a base di zeolite su vasta scala e in modo economicamente fattibile: alternative valide discusse sono lo stripping con membrana e la precipitazione tramite struvite. I possibili futuri candidati come materiali adsorbenti, sui quali si sta focalizzando la letteratura più recente, sono i materiali ceramici e in particolare i compositi di geopolimeri, che vantano proprietà di scambio ionico molto vicine a quelle delle zeoliti, data anche la somiglianza delle loro strutture.
27
Morali, Nihan. "Investigation Of Zinc And Lead Removal From Aqueous Solutions Using Clinoptilolite." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12606983/index.pdf.
Анотація:
Natural zeolites, especially clinoptilolite, have the ability of removing certain cations from wastewater by utilizing ion exchange and adsorption. In this study, clinoptilolite originated from Bigadiç, Balikesir deposit was investigated in its natural and conditioned form for its effectiveness in removing Zn2+ and Pb2+ ions from aqueous solutions. In addition, relevant mechanisms involved in heavy metal removal by clinoptilolite were examined in this study. Throughout this work, equilibrium and kinetic studies were performed with as-received and conditioned clinoptilolite, having particle size of 0.15 &ndash
0.80 mm. Conditioning aimed to replace exchangeable cations (Na+, K+, Ca2+, Mg2+) on clinoptilolite with a cation that is more willing to undergo ion exchange. The results of equilibrium studies revealed that clinoptilolite had different capacities for Zn2+ and Pb2+ ions. Clinoptilolite had high capacity for Pb2+ ions, whereas lower capacities were attained for Zn2+. Conditioning with concentrated NaCl solution increased the removal capacity for both metals. Maximum capacities attained were 0.14 meq/g (as-received) and 0.39 meq/g (conditioned) for Zn2+, and 0.51 meq/g (as-received) and 1.10 meq/g (conditioned) for Pb2+. Furthermore, kinetic studies performed under pH-uncontrolled and pH-controlled conditions revealed that heavy metal removal can not only be explained by ion exchange. These studies also indicated that Zn2+ ions were weakly bound to clinoptilolite structure, whereas there was a strong bonding between Pb2+ ions and clinoptilolite structure. To examine possible removal mechanisms, relationship between exchangeable ions released from clinoptilolite structure and Zn2+ and Pb2+ ions removed from aqueous solutions were investigated during equilibrium and kinetic studies. For equilibrium studies, it was observed that the higher the heavy metal equilibrium concentration, the higher is the amount of exchangeable ions released. However, the results indicated that the release of exchangeable ions were not only due to ion exchange. Examination of Si4+, the main central metal ion of clinoptilolite, during kinetic studies showed that destruction of clinoptilolite framework was partly responsible for the release of exchangeable ions. Release of Si4+ was more pronounced in Pb2+ removal studies, indicating dependency of framework destruction on the type of heavy metal species.
28
Liu, Dan. "Removal of Emerging Contaminants from Aqueous Solutions by Using Polymeric Resins." Master's thesis, Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/149804.
Анотація:
Civil EngineeringM.S.E.
The emerging contaminants (ECs) such as estrogen hormones, perfluorinated compounds (PFCs), bisphenol A (BPA) and 1, 4-dioxane have been detected in natural water bodies at a noticeable level worldwide. The presence of ECs in the aquatic environment can pose potential threats to aquatic organisms as well as human world. Ion-exchange is a highly efficient technology for the removal of heavy metal ions and natural organic materials (NOMs) due to the nature of exchanging similar charged ions. However, this technology has not been explored for removing ECs. In this study, four categories of ECs: estrogen hormones (12), perfluorinated compounds (10), bisphenol A and 1, 4-dioxane were used as model contaminants. The adsorption of each category of ECs onto various types of polymeric resins (MN100, MN200, A530E, A532E and C115) was investigated. The removal of ECs was tested under batch and column mode. The effects of pH, resin dosage, and contact time on the removal of ECs were studied in batch mode; isotherm and kinetics models were applied to fit the experimental data. Column experiments were conducted to verify the practicability of the polymeric resins. Adsorption results have shown that both MN100 and MN200 resins could efficiently remove estrogen hormones mixture (more than 95%), and bisphenol A (more than 80%) with the initial concentration of 100 ìg/L; A532E and A530E could remove perfuorinated compounds mixture (more than 99%) with the initial concentration of 100 ìg/L. As pH increased from 9 to 11, the adsorption capacity onto polymeric resins decreased dramatically for estrogen hormones such as 17á-ethinylestradiol, estriol, 17â-estradiol, 17á-estradiol, estrone, 17á-dihydroequilin and equilin as well as bisphenol A. The adsorption of estrogen hormones and bisphenol A onto MN100 and MN200 resins reached the equilibrium within 24 hours, whereas the adsorption of perfluorinated compounds onto A532E and A530E reached the equilibrium within 8 hours. It was also observed that the adsorption of PFCs largely depends on the C-C chain length. PFCs with longer chain yielded lower adsorption efficiency onto the ion-exchange resins A532E and A530E. Adding salinity decreased the first-order rate constants for the adsorption of bisphenol A onto MN100 and MN200 resins. Fixed-bed column experiment results with estrogen hormones mixtures confirmed that the polymeric resins were good candidates in the removal of estrogen hormones. Trimegestone was the first compound detected in the effluent in the column test while 17â-estradiol, 17á-estradiol were the last. 80% of the exhausted resins (MN100 and MN200) by bisphenol A were regenerated by using pure methanol as regeneration solution. Polymeric resins were not effectively removing 1, 4-dioxane from the aqueous solution.
Temple University--Theses
29
Medeiros, Fabiana Oliveira de. "Adsorção e purificação da enzima beta-galactosidade de Kluyveromyces marxianus CCT 7082 através de cromatografia de troca iônica." reponame:Repositório Institucional da FURG, 2008. http://repositorio.furg.br/handle/1/3055.
Анотація:
Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, 2008.Submitted by Caroline Silva (krol_bilhar@hotmail.com) on 2012-09-24T18:55:13Z No. of bitstreams: 1 dissertacao fabiana oliveira de medeiros.pdf: 1020636 bytes, checksum: 53a365d525d6cffb152a57bfa7d3872c (MD5)
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A beta-galactosidase é uma enzima utilizada industrialmente na hidrólise da lactose do leite gerando derivados lácteos destinados a pessoas intolerantes a este açúcar. Sua importância é salientada por sua atividade de galactosiltransferase, responsável pela síntese de galactooligosacarídeos, compostos com propriedades prebióticas. Quando produzida por leveduras do gênero Kluyveromyces, esta enzima é intracelular. Tendo em vista que as etapas de purificação, principalmente quando aplicadas a produtos intracelulares, são responsáveis por grande parte dos custos de produção, é importante estudar técnicas que possam ser aplicadas diretamente ao extrato bruto. A presente dissertação teve como principal objetivo estudar a adsorção e purificação da enzima beta-galactosidase de Kluyveromyces marxianus CCT 7082 através de cromatografia de troca iônica. A enzima foi produzida por fermentação submersa em frascos agitados a 30 °C, 180 rpm por 96 horas. Primeiramente foi avaliado o uso de diferentes relações biomassa:solvente na extração da enzima utilizando ondas ultrassônicas. Foram testadas relações de 2,62 a 50 mg.mL-1, avaliando a resposta em termos de atividade enzimática e rendimento de extração. Em seguida foi determinada a estabilidade da enzima quanto à temperatura e pH. No estudo da estabilidade à temperatura, a enzima foi incubada a -18°C, 4°C, 10°C e 25°C. A estabilidade ao pH foi avaliada para valores entre 4,6 e 8,6, nas temperaturas de 37°C, 25°C, 10°C e 4°C. A atividade residual foi acompanhada ao longo do tempo. A adsorção da enzima pela resina aniônica Q Sepharose Fast FlowTM foi estudada a 4°C e 10°C e em pH de 6,5 a 7,5, através de ensaios cinéticos em reatores agitados contendo a enzima e a resina, a 200 rpm por 360 minutos, onde foram determinados os coeficientes de partição da enzima no equilíbrio para cada condição. A capacidade de adsorção da resina, nas velocidades de alimentação da enzima de 20 cm.h-1 e 40 cm.h-1, foi determinada através da construção de curvas de ruptura em coluna de leito fixo do tipo C10/20. Na purificação da enzima foi avaliado o efeito das variáveis pH de eluição e volume necessário para o gradiente linear salino. Para isso, foi utilizado um planejamento experimental onde o pH variou de 5,5 a 7,5 enquanto que o volume para o gradiente salino variou de 10 a 30 vezes o volume de leito. Na etapa de concentração da enzima beta-galactosidase, a melhor condição foi o uso de uma suspensão celular contendo 40 mg.mL-1, a qual proporcionou uma atividade de 42 U.mL-1. A enzima foi mais estável nas temperaturas de 10°C e 4°C, para a faixa de pH de 6,6 a 8,6. A maior adsorção da enzima pela resina de troca iônica ocorreu em pH 7,5 e temperatura de 10°C, obtendo-se um coeficiente de partição de 61,2, assim como utilizando velocidade superficial de alimentação de 20 cm.h-1 expressa pelo valor de q igual a 104,4 U.mL-1. Foi possível obter e validar um modelo empírico linear para descrever o processo de purificação da enzima por cromatografia de troca iônica em termos de rendimento e fator de purificação. A melhor condição para purificação da beta galactosidase foi pH de eluição de 5,5 e volume para o gradiente linear salino igual a vinte vezes o volume de leito, obtendo-se rendimento de 85,5% e fator de purificação de 12 vezes.
The beta-galactosidase is an enzyme industrially used in the hydrolysis of milk lactose, generating dairy products destined to people intolerant to this sugar. Its importance is pointed out by its galactosiltransferase activity, responsible for galactooligosaccharide synthesis, compounds with prebiotic properties. When produced by yeasts of the Kluyveromyces gender, this enzyme is intracellular. Considering that the purification steps, mainly when applied to intracellular products, are responsible for great part of the production costs, it is important to study techniques that can be directly applied to the crude extract. The present dissertation had as the main objective to study the adsorption and purification of the beta-galactosidase enzyme of Kluyveromyces marxianus CCT 7082 through ion exchange chromatography. The enzyme was produced by fermentation submerged in agitated flasks at 30 °C, 180 rpm for 96 hours. Firstly the use of different biomass:solvent ratios (from 2.62 to 50 mg.mL-1) in the extraction of the enzyme using ultrasonic waves was evaluated. The response in terms of enzymatic activity and extraction yield was assessed. The stability of the enzyme in relation to the temperature and pH was them determined. In the study of the stability to the temperature, the enzyme was incubated at -18°C, 4°C, 10°C and 25°C. The pH stability was evaluated between 4.6 and 8.6, at temperatures of 37°C, 25°C, 10°C and 4°C. The residual activity was followed along the time. The adsorption of the enzyme for the anionic resin Q Sepharose Fast Flow TM was studied at 4°C and 10°C and in pH from 6.5 to 7.5, through kinetic assays in agitated reactors containing the enzyme and the resin, at 200 rpm for 360 minutes, where the coefficients of partition of the enzyme at equilibrium for each condition was determined. The adsorption capacity q of the resin, at flow rate of enzyme extract of 20 cm.h-1 and 40 cm.h-1 , was determined through the construction of rupture curves in fixed-bed column of type C10/20. In the purification of the enzyme the effect of the elution variables pH and the necessary volume for the linear saline gradient was evaluated. Therefore, an experimental design was use, where the pH varied from 5.5 to 7.5, while the volume for the saline gradient varied from 10 to 30 times the bed volume. In the step of concentration of the enzyme beta-galactosidase, the best condition was the use of a cellular suspension containing 40 mg.mL-1, which provided an activity of 42 U.mL-1. the enzyme was more stable in the temperatures of 10°C and 4°C, for the pH range from 6.6 to 8.6. The largest adsorption of the enzyme for the ion exchange resin happened in pH 7.5 at 10°C, yielding a partition coefficient of 61.2, similar to that obtaining using flow rate of 20 cm.h-1, expressed by value of q similar to 104.4 U.mL-1. It was possible to obtain and to validate a linear model to describe the process of purification of the enzyme by chromatography of ionic change in terms of yield and purification factor. The best condition for purification of the beta-galactosidase was elution pH of 5.5 and volume for the linear saline gradient equal to twenty times the bed volume, obtaining a yield of 85,5% and purification factor of 12 times.
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Sundman, Ola. "Cation adsorption properties of substituted kraft fibres : an experimental and thermodynamic modelling study." Doctoral thesis, Umeå universitet, Kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1891.
Анотація:
Acid/base and metal ion adsorption properties have been investigated for a range of chemically modified bleached Kraft fibre materials (pulps). The studies were performed via potentiometric titrations, Flame Atomic Absorbtion (and Emission) Spectroscopy, Inductively Coupled Plasma Optical Emission Spectroscopy and Extended X-ray Absorbtion Fine Structure measurements. As a result of a chemical modification procedure, the total concentration of acidic carboxylate groups in the fibre materials ranged between 43 and 590 μmol/g. The preferable surface potential model for modelling the ionic strength dependent acid/base properties of fibre materials with low charge densities, i.e. unmodified fully bleached Kraft fibre materials, was found to be the Basic Stern Model. For fibre materials with high total charge, ≳100 μmol/g, this model resulted in poor fits to data, and for such materials a number of Constant Capacitance Models, one at each ionic strength, must be recommended. With respect to metal ion adsorption, the results have indicated that the unspecific Donnan theory could correctly model the simultaneous adsorption of several metal ions, i.e. K+, Na+, Mg2+, Ca2+ and Cu2+, provided that the salt concentration in the fibre suspension is low. In suspensions of high salt concentration it was, however, found that this very same model strongly underestimated the adsorption of Ca2+ and Cu2+. Here, the Donnan model had to be complemented by specific ion exchange equilibria. These results were corroborated by spectroscopic evidence of specific interactions between Cu2+-ions and fibres. The spectroscopic indication of a complex formed between two fibre surface carboxylate groups and one Cu2+-ion, agree with the specific ion exchange model. It was therefore concluded that specific metal ionfibre interactions cannot be neglected, especially at high salt concentrations. The interactions occurring between the polycation GaO4Al12(OH)24(H2O)127+ and fibre materials were studied by both adsorption and spectroscopic measurements. These indicate that GaO4Al12(OH)24(H2O)127+ is surprisingly stable in fibre suspensions and that intact GaO4Al12(OH)24(H2O)127+- ions are strongly adsorbed onto the fibres. Also for this ion, specific interactions has to be considered, since the strong adsorption registered was too strong to be explained by Donnan equilibria. In the thesis, the stochiometric composition and an equilibrium constant characterising these interactions is presented.
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Buck, Rachel Lynn. "Importance of Placement Depth in Evaluating Soil Nitrogen, Phosphorus, and Sulfur Using Ion Exchange Resin Capsules in Semi-Arid, Low Fertility Soils." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4293.
Анотація:
Ion exchange resin capsules provide a possible alternative to conventional soil testing procedures. Previous studies with semi-arid, low fertility soils observed poor relationships with poorly mobile nutrients such as phosphorus (P). We propose that placement depth may improve those relationships. Our objective was to (1) determine if placement depth could improve resin capsule estimation of the bioavailability of nitrogen (N), P, and sulfur (S) and (2) to determine if resin capsules can effectively estimate S availability in semi-arid, low fertility soils. Field sites were established in Rush and Skull Valleys, Utah on loam and sandy loam soils, respectively. Fertilizer was surface applied as ammonium sulfate and triple superphosphate with six N, P and S treatments (0, 5.5, 11, 22, 44 and 88 kg ha-1 of N and P2O5 and 0, 7, 14, 28, 56 and 112 kg ha-1 of S). Thirty 4.0-m2 plots were established at each field location. Resin capsules were placed three per plot at 0–5, 5–10, and 10–15 cm deep in the soil and soil samples taken at respective depths. The capsules were removed and replaced after approximately 90 d. Final removal and soil sampling occurred approximately 240 d later. For the second study, fertilizer was surface applied as ammonium sulfate with six S treatments (0, 7, 14, 28, 56 and 112 kg ha-1 of S) with one resin capsule placed in each 4.0-m2 plot at a depth of 5 cm in the soil. Resin capsules were removed and replaced approximately every 90 d for a total of four samplings. Soil samples were taken with every resin capsules install and removal. In the first study, bicarbonate extractable P was significantly related to P application at all depths and times except the two lowest depths at the time of final sampling, and resin capsule P was only related to P application 398 days after application in the 0–5 and 5–10 cm depths. However, this is an improvement in estimates of bioavailability compared to a single placement depth. The 5–10 cm depth was the best for placement for determination of NH4-N, and resin capsules improved upon soil test estimates. For NO3-N, depth was not important, but resin capsules had a stronger relationship with N applied than the soil test 398 d after application. In addition, both resin capsules and the S soil test were related to S applied, but resin capsules were more able to pick up S cycling through the system. In the second study resin capsules and conventional soil tests were both effective in distinguishing between fertilizer rates, though only the conventional soil test was related to S applied at the last sampling (366 d after fertilizer application). Overall resin capsules were effective at reflecting application rates, and may be a good tool to estimate nutrient bioavailability. Correlation with plant uptake is required to determine if soil tests or resin capsules were a better estimate of bioavailable nutrients.
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Salih, Ali Mohammed. "The purification of industrial wastewater to remove heavy metals and investigation into the use of zeolite as a remediation tool." Thesis, University of Wolverhampton, 2018. http://hdl.handle.net/2436/621859.
Анотація:
Zeolites are well-known aluminosilicate minerals that have been widely used as adsorbents in separation, purification processes and environmental pollution control. Zeolites are used in various industrial applications due to their high cation-exchange ability, molecular sieve and cataltic properties. In order to reduce the costs of acquisition and minimise the disposal of adsorbents, both modified natural zeolite and synthetic zeolite (derived from kaolinite) were used for the purification of wastewater. The characteristic properties and applications of adsorbents are also discussed including the advantages and disadvantages of each technique. The present work involves the study of the removal of Cu2+, Fe3+, Pb2+ and Zn2+ from synthetic metal solutions using natural zeolite. Laboratory experiments were used to investigate the efficiency of adsorbents in the uptake of heavy metals from industrial wastewater. These include equilibrium tests, kinetic studies and regeneration studies. The physical and chemical characterization of the zeolites was carried out using different analytical techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X - Ray Diffraction (XRD), X - Ray Fluorescence (XRF), Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FT-IR) Spectroscopy and Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). The kinetic study indicated the suitability of the natural zeolite for the removal of Cu2+, Fe3+, Pb2+ and Zn2+ ions from synthetic wastewater. Batch experiments were used to identify the effect of parameters that affect the rate of adsorption such as the effect of adsorbent mass, effect of adsorbent particle size, effect of initial solution pH, effect of initial solution concentration, effect of agitation speed and effect of pre-treatment of adsorbent and evaluated their impact on the efficiency of the zeolite in the removal of heavy metals from industrial wastewater. The kinetic studies showed that the capacity of the adsorbents for the removal of heavy metals increased with a greater mass of absorbent, increased initial solution pH, increased agitation speed, higher solution concentration as well as the application of a pre-treatment. The results from the equilibrium studies positively demonstrated that natural zeolite can be used as an excellent adsorbent for removing heavy metals from multi-component solutions. The equilibrium experiments indicated that the capacities of natural zeolite for the uptake of heavy metals increased when the initial solution pH increased. The results indicated that the maximum removal capacities Q were 22.83, 14.92, 14.49 and 17.54 mg/g natural zeolite for copper, iron, zinc, and lead respectively. Both the Langmuir and Freundlich isotherm models were used to characterize the experimental data and to assess the adsorption behaviour of natural zeolite for copper, iron, lead and zinc. The experimental data were slightly better suited to the Langmuir isotherm than the Freundlinch isotherm. The value of the correlation coefficients r2 ranged from 0.93 to 0.99 for the Langmuir isotherm and from 0.90 to 0.99 for the Freundlich isotherm. The present work also involved the study of synthetic zeolite A, which was derived from natural kaolinite. The conversion of the raw materials into zeolitic materials was carried out in two ways: first, conventional hydrothermal synthesis and second, alkaline fusion prior to hydrothermal synthesis. The results from both routes show that zeolite A was synthesised successfully. Finally, the experiments show that both natural and synthetic zeolites can be available in commercial quantities. Synthetic zeolites are more attractive for some specific applications, while the cheapness of natural zeolite may favour its use.
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Riani, Josiane Costa. "Utilização de resinas de troca-iônica em efluentes de galvanoplastia." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-30092008-151250/.
Анотація:
A crescente industrialização acompanhada do uso de metais pesados nos processos industriais nas últimas décadas resultou num aumento da contaminação do meio ambiente, principalmente em ambientes aquáticos. Assim, sendo a água um recurso natural de suma importância para a vida, métodos de tratamento de efluentes tornam-se indispensáveis para empresas geradoras de efluentes. O objetivo desse trabalho é a utilização de um sistema de troca iônica constituído por micro-colunas de resinas catiônicas e aniônicas para adsorção de metais pesados de soluções industriais, visando à recirculação de água de lavagem de processos de galvanoplastias. As resinas utilizadas são: Amberlyst 15 WET e Amberlyst A-21; Dowex Marathon C e Dowex Marathon A; Purolite C-150 e Purolite A-850. Também se avalia a eluição dos íons metálicos nas resinas em questão. O efeito que a temperatura possui na eluição é avaliado para as resinas catiônicas, Purolite C-150 e Dowex Marathon C. A cinética e a termodinâmica de adsorção do cromo trivalente e do zinco são avaliados. A metodologia consiste em realizar experimentos de adsorção e eluição em colunas de troca-iônica e experimentos de adsorção em batelada para análise da cinética e termodinâmica dos íons presentes em solução. Os resultados mostram que a qualidade da água após a adsorção nos três sistemas propostos está de acordo com os valores permitidos pela Resolução CONAMA 357/05. Analisando os resultados da eluição nas resinas se verifica que o aumento da temperatura favorece a remoção de íons presentes nos sítios de troca da resina, com exceção do cromo trivalente. As reações de troca-iônica dos íons Cr3+ e Zn2+ seguem os modelos de reação pseudo-segunda ordem. A natureza das reações de troca-iônica do cromo trivalente nas resinas estudadas é exotérmica e a do zinco é endotérmica.The increasing industrialization carried out with the use of heavy metal in industrial processes over the last decades resulted in increasing environmental contamination, mainly in aquatic environments. Thus, as water is an extremely important natural resource for life, effluent treatment methods become essential for effluent generating companies. This work aims at using an ionic exchange system made of micro-columns of both cathionic and anionic resins for heavy metals adsorption of industrial solutions, for the recirculation of wastewater from electroplating processes. The resins used are: Amberlyst 15 WET and Amberlyst A- 21; Dowex Marathon C and Dowex Marathon A; Purolite C-150 and Purolite A-850. An evaluation of the metallic ions elution is also carried out for such resins. The effect of temperature on the elution is assessed for cathionic resins, Purolite C-150 and Dowex Marathon C. The adsorption kinetics and thermodynamics for trivalent chrome and zinc are assessed. The methodology consists of carrying out experiments of adsorption and elution in ion exchange columns and experiments of adsorption by batch for both kinetic and thermodynamic analyses of ions present in the solution. The results show that the water quality after the adsorption in all three systems proposed is in accordance with the values allowed by the CONAMA 357/05 Resolution. By analyzing the results of the elution in the resins, one can observe that the temperature increase favors the removal of ions present in resin-exchange sites, except for the trivalent chrome. The reactions of ionic exchange of Cr3+ and Zn2+ ions follow the models of pseudo-second order reaction. For the resins analyzed, the nature of ionic exchange reactions of the trivalent chrome is exothermic and of the zinc is endothermic.
34
Fields, Marilyn A. "Development of nitroguanidine wastewater treatment technologies." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/74516.
Анотація:
Nitroguanidine (NQ) is a nitramine used in many propellant formulations. The purpose of this study was to develop a method for treating nitroguanidine process wastewaters. The major wastewater contaminants were found to be nitroguanidine and guanidine nitrate (GN) (an intermediate product). Pilot tests were conducted for the removal of nitroguanidine using granulated carbon adsorption (GAC) and ion exchange for the removal of GN. The nitroguanidine concentration in demonstration plant wastewater was reduced from 15.5 mg/L to less than 1 mg/L. The carbon capacity was found to be 0.045 g NQ/g carbon. Strong acid resin was found to reduce guanidinium ion Gu⁺ concentration from 14.5 mg/L to 1 mg/L with a resin capacity of 0.13 eq Gu⁺ /L resin. No significant reduction in resin capacity for Gu⁺ was experienced after five regenerant cycles. A unique two-step regeneration was used. This included a 5% calcium nitrate solution to produce a spent regenerant that could be recycled to the production process. This was followed by regeneration with a 15% sodium chloride solution to place the resin in the sodium form. Anion exchange was used for the removal of nitrate ions.Master of Science
35
Gédéon, Antoine. "Contribution a l'etude par rmn (**(1)h et **(129)xe) des zeolithes my (m = na**(+), ni**(2+), cu**(2+) et co**(2+)) : adsorption d'eau et d'ammoniac." Paris 6, 1987. http://www.theses.fr/1987PA066390.
Анотація:
L'application de la rmn **(129)xe permet de suivre l'evolution du libre parcours moyen du xenon adsorbe utilise comme sonde en fonction de la concentration en eau d'une zeolite nay. De plus, l'adsorption de l'ammoniac sur la zeolite y modifiee par echange de cations metalliques, a montre que la rmn-**(1)h permet de suivre la reconstitution des complexes ammoniaques en fonction de la temperature de pretraitement du solide et de la concentration en nh::(3) adsorbe ou desorbe
36
Westergren, Robin. "Arsenic removal using biosorption with Chitosan : Evaluating the extraction and adsorption performance of Chitosan from shrimp shell waste." Thesis, KTH, Chemistry, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4642.
Анотація:
Nicaragua is a country in which the toxic metal contamination of freshwater resources has become an increasingly important problem in certain regions posing a threat to the environment as well as to human health. Among the metals found in the waters of Nicaragua, arsenic is one of the most problematic since its long time consumption is connected to serious health problems such as cancer and neurological disorders. The arsenic contamination of water recourses in Nicaragua is mostly attributable natural factors, even though anthropogenic activities including gold mining may be a contributing factor.
In this work the biopolymer Chitosan was studied as a potential adsorption material for the removal of arsenic from aqueous solutions for water treatment design purposes.
The Chitosan used in this study was extracted from shrimp shells with an overall yield of 40% and a deacetylation grade of 59%. The maximum adsorption capacity was determined to 20.9 mg As/g at a controlled pH of 5.5 using the Langmuir isotherm. The adsorption was found to be strongly pH dependant with a fourfold increase in adsorption capacity when pH was well under the pKa of Chitosan. The pH dependence indicates that ionic exchange was the most important mechanism. No difference in adsorption capacity with respect to the initial pH of the solution was detected in the pH range 3-7. This was attributed to the ability of Chitosan to act as a weak base in water solutions.
The arsenic was desorbed from Chitosan using NaOH, (NH4) 2SO 4 and NaCl, with a 1M NaOH solution being the most efficient displaying a concentration ratio of 1.08. The NaOH and (NH4) 2SO 4 solutions displayed a steep desorption curvature with a large fraction of the arsenic being easily desorbed. The arsenic was, however, not completely desorbed from the Chitosan implying that the adsorption capacity would decrease for the coming cycles. Being a biopolymer the Chitosan is quite easily degraded in acid and alkali solutions, which might be a limiting step for the process applicability.
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Al-Nasri, Salam Khudhair Abdullah. "Treatment of wastewater containing cobalt (Co-59) and strontium (Sr-89) as a model to remove radioactive Co-60 and Sr-90 using hierarchical structures incorporating zeolites." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/treatment-of-wastewater-containing-cobalt-co59-and-strontium-sr89-as-a-model-to-remove-radioactive-co60-and-sr90-using-hierarchical-structures-incorporating-zeolitesa(ff5cff3e-1366-4a35-9b15-0246811d6ad1).html.
Анотація:
Zeolites were used in this study to remove two types of non-radioactive ions (Cobalt-59 and Strontium-89) from wastewater. This was designed to model the use of ion-exchange technique to remove radioactive Co-60 and Sr-90 from low level wastewater from Al-Tuwaitha site. Al-Tuwaitha site is a nuclear research in Iraq was used for radio-medical and radio-chemical purposes before 1990. In this study, hierarchical microporous/macroporous structures were developed to overcome the diffusivity problem using zeolite. Diatomite and carbon were used to prepare the composite adsorbents by incorporating them with three types of zeolites (A, Y and clinoptilolite). From the XRD, SEM and EDAX measurement it was confirmed that successfully prepared of Iraqi palm tree leafs-Clinoptlolite (IPClinp) and Tamarind stones-Clinoptilolite (TSClinp) composites were obtained in this study as there is no evidence in literature of this being carried out before. The carbons were prepared successfully through the Pyrolysis method for 2h at 900°C in an inert atmosphere from two types of raw waste plant materials of Iraqi Palm Tree leafs (IP) and Tamarind stones (TS). For both types of carbons, the SEM images show organised porosities in different shapes. A third material used as a zeolite scaffold was diatomite (Celatom FW-14) a readily available natural material (dead algae).A hydrothermal treatment was used to build the hierarchical structure of zeolite onto carbon and diatomite materials, the scaffolds were seeded with nano-zeolite crystals prior to the treatment and thereafter mixed with the zeolite gel composition mixture in a stainless steel autoclave. Zeolite seeds were prepared using ball mill method to reduce the particle size of the commercial zeolite to sub-micron range for each type of zeolite. The surface area, morphology, element compositions and structure for each type of zeolite and composite material were characterised using BET method, SEM, EDAX and XRD. The amounts of each type of zeolite on the carbon composites were determined using TGA while that of the diatomite composite was determined by gravimetric analysis. The results show that each type of zeolite was successfully deposited and uniformly organised onto the surface of all support materials. All pure zeolites and composite materials were successfully tested to remove Co2+ and Sr2+ ions from aqueous solutions. It was found that the composite materials had higher ability to remove both ions relative to the pure zeolites. This increase is attributed to the deposition of zeolite (microporous) onto the macroporous structure (carbon and diatomite) which increased the flow accessibility within zeolite in the hierarchical structured composites. Comparison of the removal between the two metal ions indicates that all of the materials had higher uptake for Sr2+ than Co2+ ions. The highest adsorption capacities were realised with Tamarind Stone–ZeoliteA (TSA) in the order 120mg.gz-1and 290mg.gz-1 for Co2+ and Sr2+ ions, respectively. The effect of the experimental variables shows increasing uptake with increasing pH and initial ion concentrations while it decreased with increasing the solution temperature. The Co2+ loaded composites was subjected to vitrification process at 12000C for 2h. The encapsulated composites were leached for 90 and 120 days and no significant Co2+ was recorded in the leached solution. The results show that the composite materials can be used effectively to remove the radioactive ion of Co-60 and Sr-90 ion as they display the same chemical behaviour as Co-59 and Sr-89 studied in this work.
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Rodriguez-Gonzalez, Laura C. "Advanced Treatment Technologies for Mitigation of Nitrogen and Off-flavor Compounds in Onsite Wastewater Treatment and Recirculating Aquaculture Systems." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6941.
Анотація:
Non-point sources (NPS) of pollution are non-discernable, diffuse sources of pollution that are often difficult to localize and in turn mitigate. NPS can include stormwater runoff, agricultural/aquaculture wastes and wastes from small decentralized wastewater treatment systems, such as conventional septic systems. The mitigation of these NPS is imperative to reduce their potential detrimental effects on the water environment. This dissertation addresses novel treatment technologies for the mitigation of nutrients, particularly nitrogen, in Recirculating Aquaculture Systems (RAS) and onsite wastewater treatment systems (OWTS). The removal of trace organics limiting RAS production and water reuse were also investigated.
The first question this dissertation addressed is: Can the application of a UV-TiO2 reactor reduce the concentration of off-flavor compounds in RAS? In the UV-TiO2 reactor, spray-coated TiO2 plates were placed in an aluminum reactor and exposed to UV light. The process was applied in both a full-scale sturgeon RAS and a bench-scale RAS for the degradation of Geosmin (GSM) and 2-methylisoborneol (MIB). Improved performance on the removal of GSM and MIB was observed when the UV-TiO2 was applied as a batch reactor since it allowed for a longer treatment time without the effect of constant production of the compounds in the biological treatment processes. Treatment performance of UV-TiO2 was affected by GSM and MIB concentrations and dissolved oxygen. No harmful effects were observed on other water quality parameters when the UV-TiO2 reactor was operated as a batch or side stream process.
The second question this dissertation addressed is: Does the application of Tire-Sulfur Hybrid Adsorption Denitrification (T-SHAD) in RAS improve nutrient and off-flavor compound removal when compared to conventional heterotrophic denitrification? T-SHAD combines tire mulch as an adsorbent and sulfur oxidizing denitrification for the removal of NO3--N from the aquaculture waters. Adsorption studies showed the tire has significant adsorption capacity for the off-flavor compounds GSM and MIB but can be limited by contact time and, possibly, the presence of competing organic matter in RAS. The application of T-SHAD as an effluent polishing step in RAS with a high empty bed contact time (EBCT) of 720 min removed 96.6% of NO3--N and 69.6% of GSM. The application of T-SHAD within RAS as denitrification side treatment for NO3--N removal resulted in lower EBCT (185 min) that limited NO3--N removal to 21% and showed no significant removal of off-flavor compounds. The comparison between T-SHAD and a molasses fed heterotrophic upflow packed bed reactor (UPBR), showed no significant differences in N species concentrations as well as off-flavor compound removal. However, high production of SO42- resulted from sulfur oxidizing denitrification (SOD) processes was noted.
Hybrid Adsorption and Biological Treatment Systems (HABiTS), is composed of two biofilters in series employing ion exchange (IX) and nitrification for removal of NH4+ and tire scrap coupled with sulfur chips and oyster shells for both adsorption and SOD of NO3-. The third question addressed in this dissertation is: What IX/adsorption media best balances both ammonium removal and cost effectiveness for application in OWTS? Adsorption isotherms performed with different media materials showed that the zeolite material, clinoptilolite, was the best medium for the nitrification stage of HABiTS due to its high IX capacity for NH4+and cost. An adsorption capacity of 11.69 mg g-1 NH4+-N when in competition with other cations present in septic tank effluents was determined by the IX model fit to the data.
The cost of clinoptilolite is significantly higher than the other media materials tested. However, the high adsorption capacity would allow for low dosages that can be combined with non-adsorptive material reducing overall costs.
The fourth question this dissertation addressed is: How is the BNR process within HABiTS affected by IX? Results from side-by-side biofilter studies with HABiTS and a conventional nitrification/denitrification biofilter showed that the combined IX and nitrification in HABiTS can allow for faster startup, sustain variable loading, and achieve over 80% removal of NH4+ at a hydraulic loading rate of 0.34 m3 m-2-d-1 when compared to the conventional biofilter with 73% removal. Under lower loading rates the biological treatment was enhanced and dominated the NH4+ removal processes in both columns. The addition of a denitrification stage decreased Total Inorganic Nitrogen (TIN) by 53.54% and 40.97%, for the HABiTS treatment and the control treatment, respectively, under loading rates of 0.21 m3 m-2-d-1. Further decrease of NH4+-N loading rates results in high desorption of exchanged NH4+ in the clinoptilolite, resulting in lower TIN removal efficiencies (28.7%) when compared to the conventional control treatment (62%).
The final question addressed in this dissertation is: Does the proposed hybrid system enhance the removal of TIN in OWTS under transient loading conditions? Further studies with HABiTS and the conventional biofilter were performed to determine N removal performance on an hourly basis. It was found that the performance of HABiTS varies with daily and hourly loads, particularly when recovering from periods of very low loading to high loadings and vice versa. If recovering from low loading periods, IX is observed for HABiTS and the biofilter outperforms the conventional treatment in overall TIN removal. However, recovery from a high loading period results in release of NH4+-N stored in the clinoptilolite and increased production of NO3--N that could affect the performance of the denitrification stage.
39
Shields, Anthony J. "UNDERSTANDING AND MODELING THE SORPTION ON ANION EXCHANGE RESINS USING POLY-PARAMETER LINEAR FREE-ENERGY RELATIONSHIPS AND PHASE CONVERSION." Master's thesis, Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/217867.
Анотація:
Civil EngineeringM.S.Env.E.
Priority organic and emerging contaminants are a growing concern for drinking water treatment due to their increasing presence in the environment. This study developed a predictive model for the sorption of anionic organic contaminants from drinking water on three anion exchange resins: a strong polystyrenic (IRA-910), weak polystyrenic (IRA-96), and a strong polacrylic (A860). The model quantifies the individual mechanisms of sorption using poly-parameter linear free energy relationships (pp-LFERs) and the feasibility of phase conversion (e.g., an ideal gas phase as the reference state) for ionic species was examined. To develop the model, a training set of isotherms was obtained using aliphatic and aromatic carboxylates, phenols, anilines, nitrobenzene, and ibuprofen. These compounds were chosen as model organic contaminants in the environment. The training set and 1-3 test compounds (3-methyl-2-nitrobenzoate, phenol, and 4-nitroaniline) were accurately predicted using the created model for each resin. An understanding of the effects of resin structure on sorption interactions was also developed that focused on ionic functional groups, resin matrix, and hydrophilicity (i.e. water content). It was shown that greater sorption efficiency was achieved when electrostatic (ion exchange) and nonelectrostatic (adsorption) interactions were present together to create a synergistic addition. However, sorption on ion exchangers was poor if the pH of the system approached levels lower than the sorbate pKa. Additionally, weak base exchanges lose exchange capacity as pH levels approach resin pKa (IRA-96 pKa = 6.0). Additional contributions to the sorption mechanisms were observed by studying various electron donating/withdrawing functional groups on the contaminants. It was concluded that π-π and H-bonding interactions contributed a greater amount to the nonelectrostatic mechanisms than cavity formation forces and nonspecific forces. A comparison between the three resins showed that IRA-96 (weak base polystyrenic) had a greater removal capacity than IRA-910 (strong base polystyrenic), followed far behind by A860 (strong base polyacrylate). This is due to differences between the resins, such as the hydrophilicity, the density of the ion exchange group, and the presence of aromatic rings within the matrix structure. Although the modeling method accurately predicted the phase change from aqueous to sorbent phases, it was shown that the SPARC calculated aqueous-gas ion transfer energies were poor estimations of the transfer energy to the ideal gas phase and further study is necessary to accurately determine this value. This modeling methodology is believed to be applicable to emerging contaminants such as pharmaceuticals in water systems and helps further new water treatment technologies while developing a mechanistic understanding of electrostatic and nonelectrostatic interactions in general. This can be applied to additional separation processes such as chemical purification and chromatographic separation.
Temple University--Theses
40
Megersa, Daniel. "Evaluation of sorption behavior of two reactive filter materials using dual column laboratory investigation." Thesis, KTH, Mark- och vattenteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180281.
Анотація:
Phosphorous and nitrogen are vital elements for the well-being of biological life. Industrial discharges, waste water infiltration systems, conventional waste water collection and treatment systems, agricultural runoffs and landfill leachates had been emitting significant quantity of these nutrients into water bodies. These induced negative consequences to the environment including eutrophication of aquatic water bodies, toxicity to marine life and depletion of phosphate resources. Reactive filter technology is developed based on the need to remove and retain nutrients from waste water while improving the quality of effluents from emission sources. Reactive filter materials are used to build filter bed systems that treats domestic waste water, storm water, landfill leachates and contaminated subsurface water to the desired quality. In the past natural minerals such as zeolites and industrially produced polonite had been subject to laboratory study for the sorption of ammonium, heavy metals and phosphorous. The following paper is based on the results of experiment consisting of two columns packed with mordenite and polonite reactive materials filtering in series to reduce NH4 and PO4 content of a waste water. Septic tank effluent pre filtered using 0.45 μm filter is used as influent waste water into the dual columns. The dual column filtered a total of 24.07l s (372PV) and 23.42 ls (496PV) of the waste water. Sampling of the feed water and filtrates of both columns were done every second day with measurement of pH, conductivity and temperature. Analyzed samples confirmed that the dual column filtration resulted in re-moval efficiency of 84.39 % (PO4), 67.98 % (NH4) and -37.762.8 % (NOx). Filtration in the first (mordenite) column resulted in relatively larger proportion of the influent ammonium ion exchange than sorption of phosphate while the filtration in the second (polonite) column sorbed quite high amount of phosphorous than ammonium from effluent of the first column. Saturation of mordenite occurred faster even though there was sorption potential for few more of influent ammonium. All PO4 removal in mordenite column occurred above breakthrough condition. Polonite packed column was in a condition of a third of it’s saturation potential for PO4 removal at the end of the experiment. pH of samples was the parameter which is correlated significantly with filtration in polonite column than temperature and electrical conductivity. The performance of polonite was higher at higher pH than at lower pH. The mean concentrations of the dual column effluent were 0.77 mg-PO4/l and 11.13 mg-NH4/l. This is acceptable by the standards of environmental laws. The result of the experiment is valuable in prediction of performance and designing of real time filter bed.
41
Deboni, Taiana Maria 1986. "Desacidificação de óleo de soja por resina de troca iônica." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254989.
Анотація:
Orientador: Antonio José de Almeida MeirellesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Um método alternativo para a remoção de ácidos graxos livres presentes em óleos vegetais brutos se baseia no uso de resinas de troca iônica. Este método mostra-se adequado e vantajoso, devido às condições brandas de processamento, provável minimização das perdas de óleo neutro e a não geração de sabões. Deste modo, o objetivo deste trabalho foi estudar o processo de desacidificação de óleo de soja utilizando resina de troca iônica em meio orgânico. Para isto, realizou-se um prétratamento da resina em coluna de leito fixo utilizando isopropanol. Avaliou-se a influência deste pré-tratamento sobre a capacidade de troca iônica e sobre o teor de água no interior da resina. Curvas de ruptura foram obtidas de acordo com um delineamento composto central rotacional 22, sendo que os parâmetros avaliados foram vazão e acidez da alimentação. As respostas obtidas foram a eficiência de recuperação de soluto e eficiência de utilização de leito, ambas calculadas a partir das curvas de ruptura. No estudo, foi utilizado leito fixo com 150 mL de resina aniônica forte (Amberlyst A26 OH), sendo que a miscela de alimentação do leito foi composta por uma mistura de óleo de soja degomado com acidez original igual 2,16 % e ácido linoléico, utilizando como solvente isopropanol na proporção de 50 %. A temperatura empregada durante o processo foi de 50 °C. Também foi analisado o comportamento do teor de óleo, água e altura de leito durante a operação. Condições de temperatura e pressão foram investigadas para a evaporação do solvente. O óleo obtido foi caracterizado quanto às suas propriedades físico-químicas e então comparado ao óleo de soja degomado antes da etapa de desacidificação e ao óleo industrial desacidificado com hidróxido de sódio. Nos resultados observou-se que utilizando o pré-tratamento em coluna de leito fixo com isopropanol consegue-se diminuir o teor de água na resina, mantendo a capacidade de troca iônica que a mesma teria em meio aquoso. A eficiência de recuperação de soluto apresentou valores altos para todas as condições estudadas de vazão e acidez na alimentação. A eficiência de utilização do leito diminuiu com o aumento da vazão utilizada, mas não mostrou ser afetada pela acidez da corrente de alimentação. Também foi observado que o óleo é eliminado totalmente na corrente de saída, ocorrendo somente uma pequena adsorção no início da operação. O teor de água na corrente de saída do processo foi próximo ao teor de água gerada pela troca iônica, com a diferença de valores ocorrendo em função da quantidade de água acumulada inicialmente na estrutura da resina. Para evaporação do solvente, condições como 120 °C e 170 mmHg foram suficiente para removê-lo até a quantidade residual de (1 %) no óleo. O processo de desacidificação por troca iônica mostrou-se viável no caso do óleo de soja, diminuindo consideravelmente a acidez e ainda removendo compostos indesejáveis como fosfolipídios e peróxidos. Contudo, uma diminuição de componentes desejáveis, como os tocoferóis, também foi observada
Abstract: An alternative method for the removal of free fatty acids present in crude vegetable oils is based on the use of ion exchange resins. This method has shown to be adequate and advantageous due to its mild processing conditions, minimal loss of neutral oil and nongeneration of soaps. Thus, the objective of this work was to study the process of soybean oil deacidification using ion exchange resin in organic media. Pre-treatment of the resin was first performed in a fixed-bed column using isopropanol. The influence of pretreatment on ion exchange capacity and water content in the resin was evaluated. Breakthrough curves were obtained according to a central composite rotational design 22, where the parameters evaluated were flow and acidity of the feed stream. The responses obtained were the solute recovery efficiency and bed utilization efficiency, both calculated from the breakthrough curves. In this study, a fixed bed with 150 mL of a strong anionic resin was used (Amberlyst A26 OH), where the miscella fed to the bed was composed of a mixture of crude soybean oil with original acidity equal to 2.16% and linoleic acid, using isopropanol as a solvent at the proportion of 50%. The temperature employed during the process was 50 °C. Also analyzed was the behavior of the oil content, water and bed height during operation. Conditions of temperature and pressure were investigated for evaporation of the solvent. The oil obtained was characterized according to its physicochemical properties and then compared to the crude soybean oil before the deacidification step and industrial oil deacidified with sodium hydroxide. Results showed that when using the pre-treatment in a fixed-bed column with isopropanol it is possible to reduce the water content in the resin, maintaing the ion exchange capacity that it would have in aqueous medium. The solute recovery efficiency was high for all studied conditions of flow and acidity of the feed. Bed utilization efficiency decreased with increasing flow rate, but was not affected by the acidity of the supply stream. It was also observed that the oil is completely eliminated in the outlet stream, in which only a small amount is adsorbed at the beginning of the operation. The water content of the outlet stream was similar to the water content generated by ion exchange, with the difference in values resultant of the water initially accumulated in the resin structure. For evaporation of the solvent, conditions of 120 °C and 170 mmHg were sufficient to remove until a residual concentration (1%) in the oil. The deacidification process by ion exchange showed to be a feasible option in the case of soy oil, significantly reducing acidity and even removing undesirable compounds such as phospholipids and peroxides. However, a decrease in desirable components, such as tocopherols, was also observed feasible option in the case of soy oil, significantly reducing acidity and even removing undesirable compounds such as phospholipids and peroxides. However, a decrease in desirable components, such as tocopherols, was also observed
Mestrado
Engenharia de Alimentos
Mestre em Engenharia de Alimentos
42
Palli, Amar D. "Heteroatom removal from nonaqueous systems by sorption processes a comparative study of kinetic models." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179950186.
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Ferreira, Marcionila de Oliveira. "Purifica??o da glicerina bruta obtida a partir da transesterifica??o do ?leo de algod?o." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15767.
Анотація:
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Previous issue date: 2009-03-05Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The crude glycerine is a raw material that can be used in a wide variety of products. Even with all the impurities inherent in the process of being obtained, the crude glycerin is already in a marketable product. However, the market is much more favorable to the commercialization of purified glycerine. The glycerin is a byproduct gotten from the process of transesterification of waste oils and fats in the production of biodiesel. More recently, the deployment of the new Federal Law of Brazil, related to the implementation of energy resources, forces, from 2008, the increase of 2% biodiesel in diesel common with prospects for 5% (B5). Therefore, it is indispensable that new routes of purification as well as new markets are developed. The objective of this work was to purify, through ion exchange, the crude glycerin, obtained from the reaction of transesterification of cottonseed oil. The cottonseed oil was characterized as the fatty acid composition and physical-chemical properties. The process of ion exchange was conducted in batch. In this process were used strong cation, low anion resins and a mixed resin used to de-ionize water. The purified glycerin was characterized as the content of metals. Tests were performed with activated charcoal adsorption, and for this, it was made tests of time contact with coal as well as quantity of coal used. The time of activation, the amount of the activation solution, the contact time of the glycerol solution in resins, the amount and type of resin applied were evaluated. Considering the analysis made with activated charcoal, when the glycerin solution was treated using the resins individually it was observed that in the conditions for treatment with 10 g of resin, 5 hours of contact with each resin and 50 mL of glycerin solution, its conductivity decreased to a cationic resin, increased to the anionic resin and had a variable value with respect to resin mixed. In the treatment in series, there was a constant decrease in the conductivity of the solution of glycerin. Considering two types of treatment, in series and individually, the content of glycerol in glycerin pre-purified solution with the different resins varied from 12,46 to 29.51% (diluted solution). In analysis performed without the use of activated charcoal, the behavior of the conductivity of the solution of glycerin were similar to results for treatment with activated charcoal, both in series as individually. The solution of glycerin pre-purified had a glycerol content varying from 8.3 to 25.7% (diluted solution). In relation to pH, it had a behavior in accordance with the expected: acid for the glycerin solution treated with cationic resin, basic when the glycerin solution was treated with the anionic resin and neutral when treated with the mixed resin, independent of the kind of procedure used (with or without coal, resins individually or in series). In relation to the color of the glycerin pre-purified solution, the resin that showed the best result was the anionic (colorless), however this does not mean that the solution is more in pure glycerol. The chromatographic analysis of the solutions obtained after the passage through the resins indicated that the treatment was effective by the presence of only one component (glycerol), not considering the solvent of the analysis
A glicerina bruta ? uma mat?ria-prima que pode ser usada em uma ampla variedade de produtos. Mesmo com todas as impurezas inerentes ao processo de sua obten??o, a glicerina bruta j? se constitui em um subproduto vend?vel. Entretanto, o mercado ? muito mais favor?vel ? comercializa??o da glicerina purificada. A glicerina ? um subproduto resultante do processo de transesterifica??o de ?leos e gorduras residuais na produ??o do biodiesel. Mais recentemente, a implanta??o da nova Lei Federal do Brasil, relacionada ? aplica??o dos recursos energ?ticos, obriga, a partir de 2008, o acr?scimo de 2% de biodiesel no diesel comum com perspectivas para 5% (B5). Dessa forma, ? indispens?vel que novas rotas de purifica??o assim como novos mercados sejam desenvolvidos. O objetivo desse trabalho foi purificar, atrav?s da troca i?nica, a glicerina bruta obtida da rea??o de transesterifica??o do ?leo de algod?o. O ?leo de algod?o foi caracterizado quanto ? composi??o em ?cidos graxos e quanto ?s propriedades f?sico-qu?micas. O processo da troca i?nica foi conduzido em batelada. Foram utilizadas nesse processo as resinas cati?nica forte, ani?nica fraca e uma resina mista utilizada para deionizar ?gua. A glicerina purificada foi caracterizada quanto ao teor de metais. Foram realizados ensaios de adsor??o com carv?o ativado, e para isto, foram feitos ensaios de tempo de contato com carv?o ativado bem como quantidade de carv?o ativado utilizada. Foram avaliados: o tempo de ativa??o, a quantidade de solu??o de ativa??o, o tempo de contato da solu??o de glicerina nas resinas, a quantidade e tipo de resina aplicada. Considerando as an?lises feitas com carv?o ativado, quando a solu??o de glicerina foi tratada utilizando as resinas individualmente foi observado que, nas condi??es definidas para o tratamento com 10g de resina, 5 horas de contato com cada resina e 50 mL de solu??o de glicerina, sua condutividade diminuiu para a resina cati?nica, aumentou para a resina ani?nica e teve um valor vari?vel com rela??o a resina mista. No tratamento em s?rie, houve uma diminui??o constante da condutividade da solu??o de glicerina. Considerando os dois tipos de tratamento, em s?rie e individualmente, o teor de glicerol na solu??o de glicerina pr?-purificada com as diferentes resinas variou de 12,46 a 29,51% (solu??o dilu?da). Nas an?lises realizadas sem o uso do carv?o ativado, o comportamento da condutividade da solu??o de glicerina foi similar ao resultado para o tratamento com carv?o ativado, tanto em s?rie quanto individualmente. A solu??o de glicerina pr?-purificada teve um teor de glicerol variando de 8,3 a 25,7% (solu??o dilu?da). Com rela??o ao pH, este teve um comportamento de acordo com o esperado: ?cido para a solu??o de glicerina tratada com resina cati?nica, b?sico quando a solu??o de glicerina foi tratada com a resina ani?nica e neutro quando tratada com a resina mista, independente do tipo de procedimento utilizado (com ou sem carv?o ativado, resinas individualmente ou em s?rie). Com rela??o ? cor da solu??o de glicerina pr?-purificada, a resina que apresentou melhor resultado foi a ani?nica (incolor), no entanto isto n?o quer dizer que a solu??o estivesse mais pura em glicerol. A an?lise cromatogr?fica das solu??es obtidas ap?s a passagem pelas resinas indicou que o tratamento foi eficaz pela presen?a de somente um componente (glicerol), n?o considerando o solvente da an?lise
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SANTOS, JACINETE L. dos. "Trocadores ionicos inorganicos a base de manganes e potassio para recuperacao e remocao de metais poluentes de efluentes aquosos." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10956.
Анотація:
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:97/07964-0
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Thach, Ut Dong. "Echanges d’anions sur ionosilices : de l'élaboration des matériaux aux études physicochimiques et leurs applications en séparation et catalyse." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT239/document.
Анотація:
L'objectif de cette thèse est le développement de nouveaux échangeurs d'anions à base d’ionosilices. Différents matériaux contenant des entités ammoniums ont été synthétisés par la procédure d'hydrolyse-polycondensation à partir de précurseurs silylés d'ammonium. Ces solides, présentant différentes textures, différentes architectures ou des morphologies ont été obtenus en faisant varier des paramètres de réaction, comme par exemple la nature du tensioactif utilisé. Outre les caractérisations structurales et texturales (adsorption-désorption d’azote, DRX, MET / MEB), nous nous sommes concentrés sur les analyses plus détaillée des propriétés physico-chimiques de ces ionosilices. En particulier, elles présentent une contribution hydrophile élevée par rapport aux silices mésoporeuses classiques ou les organosilices du type PMO (Periodic Mesoporous Organosilica). En outre, ces propriétés interfaciales d’hydrophilie peuvent être modulées soit par l'utilisation de différents précurseurs d'ammonium, soit par l'incorporation par échange d'anions hydrophobes. Enfin, nous avons utilisé ces nouveaux matériaux pour la rétention d’espèces anioniques en milieu aqueux. Nos études montrent que ces ionosilices sont des échangeurs d'anions très efficaces présentant une capacité d'adsorption de Cr (VI) élevée (jusqu’à 2.5 mmol g-1). Ces matériaux possèdent également une capacité d’adsorption d’iodure élevée combinée à une bonne stabilité radiolytique pour des applications de rétention de radionucléides. Des résultats similaires ont été obtenus pour des polluants organiques anioniques tels que les principes actifs (le diclofénac, le sulindac et le p-aminosalicylate) ou des colorants (méthyl orange). Outre le grand potentiel d’application de ces matériaux dans les procédés de séparation, cette étude donne un aperçu intéressant de la morphologie des matériaux grâce à l'accessibilité presque complète des sites cationiques. Toutes ces caractéristiques font de ces matériaux des systèmes de choix pour les applications dans le traitement de l’eau polluée, le stockage à long terme des déchets radioactifs et en tant que support de catalyseurThe objective of this thesis is the development of new anion exchangers based on ionosilica materials. Various materials containing ammonium groups were synthesized by template directed hydrolysis-polycondensation reactions starting from silylated ammonium precursors. Solids displaying different textures, architectures and morphologies were obtained via the modifications of reaction parameters, such as the nature of the used surfactant. Besides the standard structural and textural characterizations (N2 adsorption, XRD, TEM / SEM), we focused on a more detailed physico-chemical analysis of these original and innovative materials. Ionosilicas show an unusually high hydrophilicity compared to classical mesoporous silica or organosilicas of the PMO-type (Periodic Mesoporous Organosilica). Furthermore, the hydrophilicity of ionosilicas can be finely tuned either by the use of various ammonium precursors or the incorporation via exchange of hydrophobic anions. Finally, we used these new anion exchangers for the removal of various anionic species in aqueous media. Our studies show that ionosilicas are highly efficient anion exchanger displaying high capacity for the adsorption of Cr (VI) (up to 2.5 mmol g-1). These materials exhibit also high capacity of iodide combined with high radiolytic stability for radionuclides uptake. Similar results were obtained for organic anionic pollutants, e.g. drugs (diclofénac, sulindac and p-aminosalicylate) and dyes (methyl orange). Besides the high potential of these materials in separation processes, this study gives interesting insights in the materials morphology through the nearly complete accessibility of the cationic sites. All these features make ionosilicas materials of choice for solid-liquid separation processes in water treatment, depollution of industrial wastewater, the nuclear fuel cycle or catalytic support
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Iglesias, Juncà Mònica. "Utilització de suports polimèrics en processos de separació de metalls valuosos. Aplicacions hidrometal.lúrgiques i analítiques." Doctoral thesis, Universitat de Girona, 2000. http://hdl.handle.net/10803/96340.
Анотація:
The present study focuses on the characterization of solid-liquid extraction techniques for the separation and preconcentration of rare-earth elements and precious metals. We developed an impregnated resin with di (2-ethylhexyl)phosphoric acid (D2EHPA) in order to separate rare-earth elementsEls treballs realitzats es centren en la caracterització de sistemes d’extracció sòlid-líquid per a la separació i preconcentració de terres rares i metalls preciosos. Amb aquest objectiu es varen avaluar diferents resines quelants, majoritàriament disponibles comercialment, per a la separació i recuperació de metalls preciosos, així com la seva aplicació a processos en columna utilitzant llits de resina fixos. També s’inclou la caracterització del procés de separació d’itri i neodimi mitjançant una resina impregnada amb dissolvent
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SORDO, FILHO GIOVANNI del. "Estudo da adsorção de íons metálicos em caulinita para água de reuso." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26394.
Анотація:
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Ben, Abda Maher. "Etude de l'adsorption spécifique des isomères de dioxine sur des matériaux microporeux pour la mesure en ligne à l'émission des sources fixes." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4309/document.
Анотація:
Les dioxines/furanes sont des polluants organiques persistants générés principalement par l’activité anthropique et spécifiquement par l’industrie lors des procédés de combustion mettant en jeux des matières organochlorées. Etant donné leur transport à large échelle dans l'environnement et leur impact sur la santé de l’homme, il est nécessaire de contrôler en temps réel, les traces de dioxines à l'émission des sources fixes. Un tel contrôle est plus particulièrement requis lors de l’incinération de déchets hétérogènes non préalablement triés. Deux types de matériaux microporeux ont été sélectionnés pour l'adsorption des dioxines au vu de leurs propriétés physico-chimiques. Il s’agit des zéolithes et les Metal-Organic Frameworks (MOF). Deux types de test d’adsorption ont été conduits, d’une part, en laboratoire en phase liquide avec la dioxine dans de l’isooctane comme solvant, et d’autre part, en phase gazeuse lors des campagnes de prélèvement sur un site d'incinération de déchets avec une matrice réelle très complexe. L'adsorption en phase liquide nous a permis de conclure sur l’efficacité des matériaux étudiés pour l’adsorption de trois congénères de dioxine de différentes tailles. Elle a ensuite été caractérisée par des techniques d'analyses spécifiques afin de remonter aux mécanismes d'adsorption. L’efficacité d’adsorption a été testée en phase gaz sur un site d'incinération de déchets ménagers avec les mêmes matériaux testés en phase liquide au laboratoire. Finalement, en se basant sur les résultats d'adsorption en phases liquide et gaz, deux pistes ont été proposées pour la conception d’un dispositif de mesure de dioxines en ligne commercialisableDioxins and furans are persistent organic pollutants generated mainly by human activity and industry during combustion processes using organochlorine substances. Due to their long-range air transport and impact on human health, it is necessary to have on-line dioxin emission monitoring at stationary source. Such a control is tipically required for incineration of no pre-sorted heterogeneous wastes.Two types of microporous materials have been selected for dioxin adsorption due to their physicochemical properties: zeolites and Metal -Organic Frameworks (MOF). Two types of adsorption tests have been established. On the one hand, dioxin adsorption tests in liquid phase in laboratory with isooctane as solvent, and on the other hand, dioxin adsorption tests in dynamic gas phase during sampling campaigns on waste incineration site with a very complex matrix.Liquid phase adsorption allowed us to conclude on the effectiveness of materials studied for dioxin adsorption. Adsorption has been after characterized by specific analysis techniques to trace adsorption mechanisms. Adsorption efficiencies were tested in gas phase on a household waste incinerator with the same materials tested in liquid phase in laboratory. Finally, taking into account liquid and gas phase results, two solutions have been proposed for a future commercialized device for on-line dioxin monitoring
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Silva, Francisco das Chagas Beserra da. "Estudo da mistura comercial dolomita-quartzo, dopada com Hg(I), Cd(II) e Cr(III), para adsor??o de H2S." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17715.
Анотація:
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Previous issue date: 2013-07-30The present work was to carry out a study on the adsorption of hydrogen sulfide (H2S) in arrays synthesized from a commercial clay mineral formed by a mixture of dolomite and quartz. To produce the ion exchange matrix were made using aqueous solutions of salts of cobalt II chloride hexahydrate (CoCl2.6H2O) II cadmium nitrate tetrahydrate (Cd (NO3)2.4H2O) I mercuric chloride (HgCl) nitrate and chromium III pentahydrate (Cr (NO3)3.5H2O). The arrays were subjected to hydrogen sulphide gas passage for one hour. To check the amount of gas adsorbed was used gravimetric process. The best result was in the adsorption matrix doped with cadmium and the solution retained for a longer time than the largest amount of H2S was the cobalt matrix. The matrix unmodified exhibited poor adsorption capacity. The characterization of the matrices were used XRD, XRF and IV. Mother with cadmium showed a high capacity in ion exchange, because the percentage of cadmium increased from 0% to 81.38% by replacing atoms of calcium and silicon which increased from 96.54% to 17.56% and 15, 72% to 0.32%, respectively, but also the best performance in adsorption of H2S adsorbing 11.89507 mg per gram of matrix
O presente trabalho teve como finalidade realizar um estudo sobre a capacidade de adsor??o de g?s sulf?drico(H2S) em matrizes sintetizadas a partir de um argilomineral comercial formado por uma mistura de dolomita e quartzo. Para produzir as matrizes foram feitas trocas i?nicas utilizando as solu??es aquosas dos sais: cloreto de cobalto II hexaidratado(CoCl2.6H2O), nitrato de c?dmio II tetraidratado (Cd(NO3)2.4H2O), cloreto de merc?rio I (HgCl) e nitrato de cromo III pentaidratado(Cr(NO3)3.5H2O). As matrizes foram submetidas a passagem de g?s sulf?drico durante uma hora. Para verificar a quantidade de g?s adsorvido foi utilizado o processo de gravimetria. O melhor resultado na adsor??o foi com a matriz dopada com a solu??o de c?dmio e a que reteve por mais tempo a maior quantidade de H2S, foi a matriz com cobalto. A matriz n?o modificada apresentou uma fraca capacidade de adsor??o. Na caracteriza??o das matrizes foram utilizadas an?lises de DRX, FRX e IV. A matriz com c?dmio apresentou uma alta capacidade na troca i?nica, pois a porcentagem de c?dmio passou de 0% para 81,38%, substituindo ?tomos de c?lcio e de sil?cio que passaram de 96,54% para 17,56% e de 15,72% para 0,32%, respectivamente, como tamb?m, o melhor desempenho na adsor??o, adsorvendo 11,89507mg de H2S por grama de matriz
50
Simões, Fernanda Borba. "Efeito da radiação micro-ondas na interação da prata com nanocristais de hidroxiapatita." Pós-Graduação em Ciência e Engenharia de Materiais, 2018. http://ri.ufs.br/jspui/handle/riufs/8013.
Анотація:
The aim of this work was to evaluate the effect of microwave heating on the
insertion of Ag+ ions in hydroxyapatite (HA) nanocrystals ion exchange. Assynthesized
HA nanocrystals obtained by the precipitation method in aqueous
medium were immersed in an Ag+-containing solution (0.1 mol L-1) and heated in a
microwave oven at 100°C/15 min under a power of 800 W. The nanocrystals were
also heated in an oil bath at 80°C/4 h. To isolate the effect of the heating sources
from the Ag+ ions, the HA nanocrystals were also heated in aqueous solution without
Ag+ ions. All the assays were characterized by wavelength dispersive X-ray
fluorescence spectroscopy, X-ray diffraction with Rietveld refinement, transmission
electron microscopy and Fourier transform infrared spectroscopy. Regardless of the
heating source, Ag+ ions reacted with HA nanocrystals resulting in the formation of
Ag3PO4 and Ag0 phases. Microwave heating was able to accelerate these reactions.
In addition, both the microwave heating and Ag+ ions clearly affected the insertion of
the HPO4
2- and CO3
2- ions into the PO4
3- and OH- sites of the HA structure. As a
consequence of these occupations, the lattice parameters, unit cell volume, crystallite
size, morphology and aspect ratio of the HA nanocrystals were affected. The
observed results indicate that microwave heating was able to alter not only
crystallographic aspects of the HA phase, but also the Ag+-doping rate of the HA
nanocrystals in aqueous solution.O objetivo desse trabalho foi avaliar o efeito do aquecimento por micro-ondas na inserção de íons Ag+ em cristais nano-estruturados de hidroxiapatita (HA) via troca-iônica em meio aquoso. Para isso, os nanocristais de HA pura, sintetizados por precipitação química em meio aquoso, foram imersos em solução aquosa contendo Ag+ (0,1 mol L-1) e aquecidos por micro-ondas (100°C/15 min) a 800 W de potência. Para fins comparativos, o mesmo procedimento foi realizado utilizando o aquecimento em banho de óleo (80°C/4 h). Para observação do efeito dos íons Ag+ em detrimento do aquecimento, os nanocristais de HA pura também foram aquecidos em água destilada, sob as duas fontes de calor. As amostras foram caracterizadas por espectroscopia de fluorescência de raios X por dispersão de comprimento de onda, difração de raios X com refinamento pelo método Rietveld, microscopia eletrônica de transmissão e espectroscopia no infravermelho por transformada de Fourier. Independentemente do tipo de aquecimento, a interação da HA com os íons Ag+ resultou na formação de Ag3PO4 e de Ag0. O aquecimento por micro-ondas foi capaz de acelerar as reações entre os íons Ag+ e a superfície da HA formando uma maior quantidade de Ag3PO4 em um menor tempo de aquecimento. Além disso, tanto o aquecimento por micro-ondas quanto a interação com os íons Ag+ afetaram visivelmente a ocupação de HPO4 2- e CO3 2- em nos sítios de PO4 3- e OH- na estrutura da HA. Como consequência dessas ocupações, os parâmetros de rede, volume da célula unitária, tamanho de cristalito, morfologia e esfericidade dos nanocristais de HA também foram afetados. Os resultados observados indicam que o aquecimento por micro-ondas foi capaz de alterar não somente os aspectos cristalográficos, mas também a taxa de dopagem dos íons Ag+ nos nanocristais de HA em meio aquoso.
São Cristóvão, SE