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1
Stocking, Kristin 1959. "Adsorption of MS-2 bacteriophage to silica". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277019.
Testo completoAbstract (sommario):
Batch and column experiments were performed to investigate the adsorption of bacteriophage MS-2 to silica at pH 5. Linear isotherm analysis of batch experiment data gave partition coefficient (KP) estimates of 270 cm³/g and 580 cm³/g for 4°C and 24°C, respectively. Breakthrough-type column experiments indicated that sorption and desorption were slow, as evidenced by a slow approach to breakthrough and tailing of the desorption limb. A non-equilibrium advection-dispersion model with all adsorption sites on the silica assumed to be kinetically controlled was used to model the column data. The model-generated parameters yielded Kp estimates 1000-fold smaller than those given by isotherm analysis and indicated that the time scale for desorption is on the order of 1-6 hours.
2
Imwer, Serge Mapan. "Adsorption of perfluorinated water contaminants on Agave sisalana activated carbon fibre". Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/867.
Testo completoAbstract (sommario):
Thesis submitted in fulfilment of the requirements for the degree
Magister Technologiae: Chemical Engineering
in the Faculty of Engineering
at the
Cape Peninsula University of Technology
2014An awareness campaign on the harmful effects of Perfluorinated compounds (PFCs), especially Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonate (PFOS) has been conducted to inform the general public about the impact of these organic compounds on hu-mans and biota. These compounds have been shown to be potential carcinogens, as indi-cated by the United States Environmental Protection Agency (USEPA) and the Organization for Economic Co-operation and Development . A major concern about these chemicals is that they have been widely used in consumer products and have been detected in food and drinking water. They have been determined to be resistant to biological degradation, owing to their unique chemical and physical properties (fluorine atoms that have substituted hydrogen atoms in their chemical structure). Owing to their characteristics of being highly soluble in water, they cannot be removed from water using ordinary purification processes. Studies have been conducted to evaluate the removal of PFOA and PFOS from water using different methods. Among these methods, it has been proved that adsorption is a suitable method with the best adsorbent identified as activated carbon (AC). AC can be found in many forms, including as a fibre. The use of AC for the removal of PCFs can be augmented with sonica-tion and electro-chemical methods for rapid absorption of these compounds. The aim of this study was to remove these contaminants using a microporous AC fibre (ACF) made from an indigenous plant, Agave sisalana, which is widely available across sub-Saharan Africa, by using electro-physico-chemical methods. ACF has the following advantages when compared with granulated and/or powdered AC: it has a slightly larger reactive surface area; small quantities can be used; it is easily handled; it retains its shape under stress, thus does not require additional filtration to remove particulate residue; and can be regenerated easily. The manufacturing process of the ACF was done in several steps: 1) harvesting of the A. sisalana leaves, stripping them to obtain wet fibre by scrapping using traditional meth-ods, 2) chemical activation using NaOH, KOH, ZnCl2 and H3PO4, employing a spraying method instead of soaking, which was followed by drying, and 3) carbonisation in a furnace at the required temperature. The use of activation reagents involved the determination of an appropriate concentration, with optimum concentrations determined as 0.54M, 0.625M, 1.59M and 0.73M for NaOH, KOH, ZnCl2 and H3PO4, respectively. Apart from the fibre acti-vation, temperature and activation time were also important parameters that were optimised. A response surface methodology was used to design a set of experiments that provided the optimum temperature and activation time. From the input variables, the Expert design soft- ware generated experimental runs (n = 13) for each fibre activation reagent used with a tem-perature range of 450°C to 933°C being assessed for carbonisation time of between 17 to 208 minutes. ACF activated with KOH (0.54 M) and characterised by micropores with the highest surface area achieved being 1285.8 m2/g in comparison with Granular activated car-bon (Ounas et al., 2009) with an average surface area range of 1000 to 1100 m2/g. This sur-face area was measured using Dubinin-Astakhov isotherm with CO2 at 273 K. The physical characteristics of the ACF were analysed using a Scanning Electron Microscope to ascertain the integrity of the fibres. PFOA and PFOS were analysed using a solid phase extraction (SPE) method fol-lowed by analysis using a liquid chromatography/tandem mass spectrometer (SPE-LC/MS/MS). The water sample volume used for extraction was 60 mL. The instrument used was an HPLC - Ultimate 3000 Dionex HPLC system and MS model - Amazon SL Ion Trap, with the following MS/MS operational conditions and ion mode: MS Interface → ESI; dry temp → 350C; nebulising pressure → 60 psi; dry gas flow → 10 L/min; ionisation mode → negative; capillary voltage → +4500V; end plate offset → −500V, while the separation col-umn was a Waters Sunfire C18, 5 μm, 4.6 × 150 mm column (supplier: Waters, Dublin, Ire-land), with an operational temperature of 30C. Initially, adsorption studies (n = 48) using sonication (20 kHz) in batch systems indi-cated efficient removal of PFOA and PFOS within 120 min, with numerous samples (n = 14) achieving complete removal for both PFOA and PFOS. The minimum removal rates ob-served were 65.55% for PFOA and 95.92% for PFOS. From the ACF samples in which high-est removal rates were achieved, a number (n = 3) of the ACF samples were selected for surface characterisation. Based on the sonication in the previous experiments, an electro-physico-chemical adsorption regime was designed, to facilitate the rapid adsorption of PFOS and PFOA from contaminated drinking water in an electrolytic cell. In these experiments, si-multaneous sonication and electrolysis were used. A comparison was made between ACF produced in this study and the commercial activated carbon. The result revealed that adsorp-tion of PFOA and PFOS on ACF was a monolayer adsorption type phenomenon and had the best fit using a Freundlich isotherm compared with the Langmuir isotherm. Adsorption of PFOA and PFOS on the commercial AC presented a multilayer adsorption type of isotherm fit with the Langmuir isotherm having the best fit compared with the Freundlich isotherm.
3
Tan, Lo 1963. "The effects of activated carbon adsorption and ozonation on trihalomethane speciation". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276953.
Testo completoAbstract (sommario):
Two surface water sources in the southwestern United States, Colorado River Water (CRW) and California State Project Water (SPW), were studied in bench-scale experiments examining two Trihalomethane (THM) precursor removal processes, activated carbon adsorption and ozone oxidation. Both source water contained bromide (Br-) ion leading to brominated THMs upon chlorination. Activated carbon removed THM precursors, as measured by dissolved organic carbon (DOC), while having little effect on bromide. The net result was an increase in the ratio of Br-/DOC and an increase in the relative abundance of brominated THMs. Ozone oxidized higher molecular weight precursor molecules into lower molecular weight by-products which were less reactive with chlorine. Moreover, ozonation transformed Br- to hypobromous acid (an "in-situ" oxidant), leading to an increase in the percentage of brominated THMs.
4
Hungate, Robert W. "Adsorption kinetics for the removal of soluble manganese by oxide- coated filter media". Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43861.
Testo completoAbstract (sommario):
This study was conducted to examine the kinetics of
manganese sorption on oxide-coated filter media. Initial
experimentation confirmed the findings of other investigators,
the Mn2+ sorption capacity of oxide-coated media
increases as solution pH increases. Further study revealed
that uptake rate kinetics could be described by first order
kinetics and also increased with increasing solution pH.
The addition of free chlorine (HOCl) to solution greatly
enhanced Mn2+ uptake rate kinetics. Later studies indicated
that the oxide coating had very little impact on the
physical properties of the media tested.
Actual data from a water treatment plant filter confirmed laboratory experimental results by showing that sorption of soluble manganese does indeed occur on oxidecoated filters. The water treatment plant data also suggested that the sorption kinetics were relatively rapid, again upholding laboratory findings.
Results from the manganese kinetics and sorption
experiments were combined to formulate a theoretical model
which would predict manganese breakthrough in a filter,
given a known set of loading parameters. Preliminary use of
the model indicated that oxide-coated filters could sorb significant quantities of soluble manganese before
detectible levels of manganese appear in the effluent.
Master of Science
5
Ambjörnsson, Linn, Katti Ewald, Kling Erika Johansson, Anna Larsson, Selenius Marie e Svedberg Elin. "Purification of arsenic contaminated water using ferrihydrite with consideration to current circumstances in Burkina Faso". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-295133.
Testo completoAbstract (sommario):
Ferrihydrite in a suspension has been studied as a solution for purification of arsenic contaminated water. Many development countries, amongst them Burkina Faso, have arsenic in their groundwater and the current methods for purification are too expensive. Measurements have shown extremely high levels of arsenic in the groundwater in several places in Burkina Faso. Since the availability of surface water is limited, the groundwater is still used as drinking water. A suspension of ferrihydrite has capacity to adsorb arsenic in water due to its chemical characteristics. Small-scale laboratory work with ferrihydrite suspensions has been performed in parallel in Uppsala, Sweden, and Ouagadougou, Burkina Faso. To purify the water with regard to the economical and practical circumstances in Burkina Faso, a column with safety filter was made out of simple materials such as plastic bottles, plastic tubes and glass wool. The contaminated water was flowing upwards through the column to prevent the filter from clogging. In Uppsala it was discovered that a 1 L ferrihydrite suspension containing 10 g ferrihydrite can adsorb 0.7 g arsenic while it was shaken and centrifuged well. In Ouagadougou it was possible, in the setup, to clean 2 L arsenic contaminated water with the concentration of 100 µg/L. The conclusions from the experiments in this project are that ferrihydrite can adsorb arsenic in contaminated water but that the setup used needs to be further evaluated and developed
6
Rathnayake, Suramya I. "Synthesis, characterisation and application of inorganic-organic clays for water purification". Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/104320/1/Rathnayake%20Mudiyanselage%20Suramya%20Indunil_Rathnayake_Thesis.pdf.
Testo completoAbstract (sommario):
This thesis reports a new remediation approach for the removal of toxic and high priority water pollutants based on the use of modified clays. Novel types of modified clays called inorganic-organic clays (IOCs) were synthesised and their structures and properties were characterised using various techniques. Adsorption behaviours and removal efficiencies of the IOCs towards both organic and inorganic water pollutants in Single and Binary Contaminants System were investigated. The work provides new insights into the structures, properties and potential environmental applications of IOCs in water remediation.
7
Park, Yu Ri. "Synthesis, characterisation and application of organic surfactants modified clays for water purification". Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/63494/1/Yu%20Ri_Park_Thesis.pdf.
Testo completoAbstract (sommario):
This thesis offered a step forward in the development of cheap and effective materials for water treatment. It described the modification of naturally abundant clay minerals with organic molecules, and used the modified clays as effective adsorbents for the removal of recalcitrant organic water pollutants. The outcome of the study greatly extended our understanding of the synthesis and characteristic properties of clay and modified clay minerals, provided optimistic evaluation of the modified clays for environmental remediation and offered potential utility for clay minerals in the industry and environment.
8
Lavinder, Steven Robert. "Evaluation of activated carbon processes for removing trihalomethane precursors from a surface water impoundment". Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45820.
Testo completoAbstract (sommario):
A pilot plant study was conducted in Newport News, Virginia to investigate the effectiveness of powdered activated carbon [PAC] and granular activated carbon [GAC], with and without preoxidation, for reducing trihalomethane [THM] precursor concentrations in Harwood's Mill Reservoir water. Preoxidation with ozone followed by GAC is referred to as the "biological activated carbonâ [BAC] process. This study showed that the GAC and BAC processes obtained the same level of organic removal; however, BAC would provide longer bed life and require less carbon than the GAC process. PAC treatment of alum coagulated water provided significantly higher TOC and THMFP removals than alum coagulation alone. The use of a preoxidant (ozone) with PAC slightly improved the organic removal efticiency. While treatment by PAC increased THMFP removals, it was not as efficient as the GAC and BAC processes. UV absorbance measured at 254 nm and TOC were found to be good surrogates for THMFP in the GAC column, but not in the BAC column.
Master of Science
9
Hyung, Hoon. "Dispersion of fullerenes in natural water and their behavior in water treatment process". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24812.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009.Committee Chair: Jae-Hong Kim; Committee Member: Joseph hughes; Committee Member: Michael Bergin; Committee Member: Seung Soon Jang; Committee Member: Vernon Snoeyink.
10
Hawley, Harmonie A. "TCE removal utilizing coupled zeolite sorption and advanced oxidation". Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0428103-150434.
Testo completo
11
Ogutverici, Abdullah. "Triclosan Removal By Nanofiltration From Surface Water". Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615617/index.pdf.
Testo completoAbstract (sommario):
Nowadays, organic pollutants occurring in surface waters have raised substantial concern in public.
Triclosan (TCS) is one of the antimicrobial agents which are utilized in both domestic and industrial
application. In this study nanofiltration (NF) of TCS in surface water was investigated. Laboratory
scale cross-flow device is operated in total recycle mode and DK-NF and DL-NF membranes were
used. Kesikköprü
Reservoir (Ankara) water was used as raw water. Effect of natural organic matter (NOM) content of raw water on TCS removal is searched through addition of humic acid (HA) into the raw water as to represent for NOM. Steady state permeate fluxes are monitored throughout the experiments to explore the flux behavior of the membranes. During the experiments, performance of the membranes is assessed by monitoring TCS, as well as other water quality parameters, such as UVA254 and total organic carbon (TOC) in the feed and permeates waters. Results obtained put forward that TCS removal by NF membrane is not as same as reported in the literature. In the literature, membrane removal efficiency is reported as above 90%. However, this study proved that this would be true if and only if one does not considers the adsorption of TCS by the system itself, in the absence of membrane. It is now clear that, because of adsorption of the TCS onto the experimental set up (feed tank, pipings etc.)
the real TCS removal efficiency of the nanofiltration is around 60-70%.
12
Sanyahumbi, Douglas. "Removal of lead from solution by the non-viable biomass of the water fern Azolla filiculoides". Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1003960.
Testo completoAbstract (sommario):
The removal of lead from aqueous solution and lead-acid battery manufacturing waste-water by the non-viable biomass of the water fern Azolla filiculoides was investigated in both batch and column reactors. The maximum lead uptake by the Azolla biomass at a pH value of approximately 5, was found to be 100 mg lead/g biomass from aqueous solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 5.6. Lead removal from aqueous solution decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. At initial lead concentrations of less than 400 mg/l, percentage lead removal was found to be over 90% of the initial lead concentration. Lead removal remained at approximately 90% between 10°C and 50°C. Biomass concentration (4-8 mg/l) had little effect on lead removal. The presence of iron (Fe) and lead, copper (Cu) and lead or all three metal ions in solution at varying ratios to each other did not appear to have any significant effect on lead removal. Percentage lead, copper and iron removal from aqueous solution was 80-95, 45-50 and 65-75% respectively for the different multiple-metal solutions studied. No break-through points were observed for lead removal from aqueous solutions in column reactors, with initial lead concentrations of less than 100 mg/l at varying flow rates of 2, 5 and 10 ml/min. This suggested that flow rate, and therefore retention time, had little effect on percentage lead removal from aqueous solution, which was more that 95%, at low initial lead concentrations (less than 100 mg/l). At initial lead concentrations of 200 mg/l or more, an increase in flow rate, which equates to a decrease in column retention time, resulted in break-through points occurring earlier in the column run. Percentage lead removal values, from lead-acid battery efiluent in column systems, of over 95% were achieved. Desorption of approximately 30% and 40% of bound lead was achieved, with 0.5 M HNO₃ in a volume of 50 ml, from two lead-acid battery. Repeated adsorption and desorption of lead by the Azalia biomass over 10 cycles did not result in any decrease in the percentage lead removal from effluent, which strongly suggested that the Azalla biomass could be re-used a number of times without deterioration in its physical integrity, or lead removal capacity. No evidence of deterioration in the Azolla biomass's physical integrity after 10 successive adsorption and desorption procedures was observed using scanning electron microscopy. The Azolla filiculoides biomass was, therefore, found to be able to effectively remove lead from aqueous solution and lead-acid battery effluent repeatedly, with no observed reduction in it's uptake capacity or physical integrity.
13
Bunhu, Tavengwa. "Preparation and evaluation of Lignocellulose-Montmorillonite nanocomposites for the adsorption of some heavy metals and organic dyes from aqueous solution". Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/535.
Testo completoAbstract (sommario):
The need to reduce the cost of adsorption technology has led scientists to explore the use of many low cost adsorbents especially those from renewable resources. Lignocellulose and montmorillonite clay have been identified as potentially low cost and efficient adsorbent materials for the removal of toxic heavy metals and organic substances from contaminated water. Montmorillonite clay has good adsorption properties and the potential for ion exchange. Lignocellulose possesses many hydroxyl, carbonyl and phenyl groups and therefore, both montmorillonite and lignocellulose are good candidates for the development of effective and low cost adsorbents in water treatment and purification. The aim of this study was to prepare composite materials based on lignocellulose and montmorillonite clay and subsequently evaluate their efficacy as adsorbents for heavy metal species and organic pollutants in aqueous solution. It was also important to assess the adsorption properties of the modified individual (uncombined) lignocellulose and montmorillonite. Lignocellulose and sodium-exchanged montmorillonite (NaMMT) clay were each separately modified with methyl methacrylate (MMA), methacrylic acid (MAA) and methacryloxypropyl trimethoxysilane (MPS) and used as adsorbents for the removal of heavy metals and dyes from aqueous solution. The lignocellulose and NaMMT were modified with MMA, MAA and MPS through free radical graft polymerisation and/or condensation reactions. NaMMT was also modified through Al-pillaring to give AlpMMT. The materials were characterised by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS) and characterisation results showed that the modification of the montmorillonite with MAA, MMA and MPS was successful. The modified lignocellulose and montmorillonite materials were evaluated for the adsorption of heavy metal ions (Cd2+ and Pb2+) from aqueous solution by the batch method. The adsorption isotherms and kinetics of both Cd2+ and Pb2+ onto the NaMMT clay, AlpMMT and lignocellulose materials are presented. The Langmuir isotherm was found to be the best fit for the adsorption of both heavy metals onto all the adsorbents. AlpMMT showed very poor uptake for heavy metals (both Cd2+ and Pb2+). PMMAgMMT, PMAAgMMT, PMAAgLig and PMPSgLig showed improved adsorption for both heavy metals. The mechanism of heavy metal adsorption onto the adsorbents was best represented by the pseudo second-order kinetic model. PMPSgLig, NaMMT and AlpMMT showed relatively high adsorption capacities for methyl orange, while the adsorption of neutral red was comparable for almost all the adsorbents. Neither the Langmuir model nor the Freundlich model was found to v adequately describe the adsorption process of dyes onto all the adsorbents. The pseudo second-order model was found to be the best fit to describe the adsorption mechanism of both dyes onto all the adsorbents. The modification of lignocellulose and montmorillonite with suitable organic groups can potentially produce highly effective and efficient adsorbents for the removal of both heavy metals and dyes from contaminated water. Novel adsorbent composite materials based on lignocellulose and montmorillonite clay (NaMMT) were also prepared and evaluated for the removal of pollutants (dyes and heavy metals) from aqueous solution. The lignocellulose-montmorillonite composites were prepared by in situ intercalative polymerisation, using methyl methacrylate, methacrylic acid and methacryloxypropyl trimethoxysilane (MPS) as coupling agents. The composite materials were characterised by FTIR, TGA, TEM and SAXS. SAXS diffractograms showed intercalated nanocomposites of PMMAgLig-NaMMT and PMAAgLig-NaMMT, whereas PMPSgLig-NaMMT showed a phase-separated composite and the same results were confirmed by TEM. The lignocellulose-montmorillonite composites were assessed for their adsorption properties for heavy metal ions (Cd2+ and Pb2+) and dyes (methyl orange and neutral red) from aqueous solution. Among these composite materials, only PMAAgLig-NaMMT showed a marked increase in the uptake of both Cd2+ and Pb2+ relative to lignocellulose and montmorillonite when used independently. The adsorption data were fitted to the Langmuir and Freundlich isotherms, as well as to the pseudo first-order and pseudo second-order kinetic models. The data were best described by the Langmuir isotherm and the pseudo second-order kinetic model. On the adsorption of dyes, only PMPSgLig-NaMMT showed enhanced adsorption of methyl orange (MetO) compared with lignocellulose and montmorillonite separately. The enhanced adsorption was attributed to the synergistic adsorption due to the presence of MPS, lignocellulose and NaMMT. Competitive adsorption studies were carried out from binary mixtures of MetO and Cd2+ or Pb2+ in aqueous solution. The adsorption process of MetO onto the composite material was found to follow the Freundlich adsorption model, while the mechanism of adsorption followed both the pseudo first-order and pseudo second-order models. This particular composite can be used for the simultaneous adsorption of both heavy metals and organic dyes from contaminated water. The adsorption of neutral red to the composite materials was comparable and the pseudo second-order kinetic model best described the adsorption mechanism.
14
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.
Testo completoAbstract (sommario):
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.
15
Silva, Evanuzia Miranda da. "Obtenção, caracterização e utilização do carvão de serragem como adsorvente para purificação de água". Universidade Federal do Tocantins, 2018. http://hdl.handle.net/11612/1058.
Testo completoAbstract (sommario):
A serragem de madeira é um produto proveniente do uso da madeira, que pode ter aproveitamento econômico, transformando-se e agregando valor a cadeia produtiva da madeira. Uma de suas aplicações pode ser a produção de carvão e bio-óleo. O carvão ativado tem um custo elevado, porém é uma opção que apresenta potencial de adsorção e remoção de cianotoxinas e matéria orgânica presentes em água de abastecimento. O objetivo deste trabalho foi analisar a qualidade do carvão de serragem e seu potencial para ser aplicado em sistema de purificação de água, através de parâmetros físico/químicos. A serragem foi caracterizada conforme sua composição química, quanto ao teor de lignina, (38%); Hemicelulose (17,8%), holocelulose (53,9%), analises elementar: Carbono (48,3%), Hidrogênio (5,09%), Nitrogênio (0,25%), Oxigênio (46,36%) e imediatas: Cinzas (0,19%), Umidade (4,52%), Material Volátil (90,39%) e carbono fixo (4,9%) para ser utilizada como matéria prima na produção de carvão em reator de leito fixo. As variáveis utilizadas para obtenção do melhor rendimento dos produtos foram: temperatura, taxa de aquecimento, tempo e vazão do gás, de acordo com o planejamento fatorial 24-1. Além da produção, a qualidade do carvão foi verificada por meio de análise imediata: Cinzas (3,42%), Umidade (2,29%), Material volátil (41,04%) e carbono fixo (53,04%). Análise elementar: Carbono (74,36%), Hidrogênio (2,96%), Nitrogênio (0,55%) e oxigênio (22,13%). As análises de microscopia eletrônica de varredura (MEV), Índice de Azul de Metileno e BET que mostraram que o carvão consiste de microporos com uma área superficial de 1,43819 m²/g evidenciando a existência e a qualidade dos poros presentes no carvão. A eficiência na remoção de matéria orgânica presente na água, foi avaliada utilizando-se filtros descendentes com o carvão obtido. Características físico-químicas e microbiológica da amostra de água foram avaliadas antes e após a filtração. Notou-se que o tempo de saturação do carvão de serragem aconteceu após 10 horas de funcionamento dos filtros, sendo que a maior eficiência na remoção de matéria orgânica ocorreu nas primeiras 3 horas.Sawdust is a product derived from the use of wood, which can be used economically, transforming and adding value to the productive chain of wood. One of its applications may be the production of coal and bio-oil. Activated carbon has a high cost, but it is an option that presents potential of adsorption and removal of cyanotoxins and organic matter present in water supply. The objective of this work was to analyze the quality of sawdust and its potential to be applied in a water purification system, through physical / chemical parameters. The sawdust was characterized according to its chemical composition, in terms of lignin content (38%); Hemicellulose (17.8%), holocellulose (53.9%), elemental analysis: Carbon (48.3%), Hydrogen (5.09%), Nitrogen (0.25%), Oxygen and immediate: Ash (0.19%), Moisture (4.52%), Volatile Material (90.39%) and fixed carbon (4.9%) to be used as raw material for coal production in bed reactor fixed. The variables used to obtain the best product yield were: temperature, heating rate, time and gas flow, according to factorial design 24-1. In addition to the production, coal quality was verified through immediate analysis: Ash (3.42%), Moisture (2,29%), Volatile material (41.04%) and fixed carbon (53.04%). Elemental analysis: Carbon (74.36%), Hydrogen (2.96%), Nitrogen (0.55%) and oxygen (22.13%). The scanning electron microscopy (SEM), Methylene Blue Index and BET analyzes showed that the coal consists of micropores with a surface area of 1.43819 m² / g evidencing the existence and the quality of the pores present in the coal. The efficiency of removal of organic matter present in the water was evaluated using downstream filters with the obtained carbon. Physical-chemical and microbiological characteristics of the water sample were evaluated before and after filtration. It was observed that the saturation time of sawdust occurred after 10 hours of filter operation, and the highest efficiency in the removal of organic matter occurred in the first 3 hours.
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Meza, Maria I. "The use of PRBs (permeable reactive barriers) for attenuation of cadmium and hexavalent chromium from industrial contaminated soil". Muncie, Ind. : Ball State University, 2009. http://cardinalscholar.bsu.edu/432.
Testo completo
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Peres, Mariana Rodrigues. "Remoção dos interferentes endócrinos 17 'alfa'-etinilestradiol, 17 'beta'-estradiol e 4-nonilfenol por adsorção em carvão ativado em pó em água de abastecimento público". [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258693.
Testo completoAbstract (sommario):
Orientador: Ricardo de Lima IsaacDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Nas últimas décadas, verifica-se um crescente interesse científico a respeito dos potenciais adversos associados à exposição humana e animal aos interferentes endócrinos. A ocorrência de interferentes endócrinos em efluente de Estação de Tratamento de Esgoto (ETE) e em águas superficiais constitui um crescente interesse científico devido à probabilidade de que esses micropoluentes não sejam removidos nos processos físico-químicos empregados em Estação de Tratamento de Água (ETA) convencional. A adsorção em carvão ativado tem sido apontada com uma opção para a remoção de interferentes endócrinos em ETA. O presente trabalho avaliou a adsorção do estrógeno natural 17?-estradiol (E2), do estrógeno sintético 17?-etinilestradiol (EE2) e do xenoestrogênio 4-nonilfenol (NP) por carvão ativado em pó (CAP) em água deionizada e água bruta do rio Atibaia. Os procedimentos analíticos empregados foram extração em fase sólida e análise por cromatografia gasosa acoplada a detector de massas (CG-EM). O modelo de Freundlich foi o que melhor representou a adsorção dos compostos nos carvões ativados usualmente aplicados nas estações de tratamento de água de Campinas-SP. Em água deionizada, a remoção mais significante dos compostos foi observada na dosagem de CAP equivalente a 15 mg/L, alcançando níveis de remoção da ordem de 95%. Os resultados obtidos nos ensaios com água bruta demonstraram que a dosagem de 10 mg/L apresenta eficiência superior a 77% na remoção dos interferentes endócrinos da água do manancial. Observou-se que o CAP com número de iodo superior a 800 mg/g apresentou, de modo geral, as melhores eficiências de remoção, favorecendo a adsorção dos compostos nos microporos do carvão. Considera-se que, embora ainda não exista legislação em vigor no Brasil que limite a presença desses micropoluentes na água de abastecimento público, recomenda-se que a adição de CAP seja realizada pelo princípio da precaução
Abstract: In the last decades, a growing scientific concern has been raised over the potential adverse effects associates to human and animal exposure to endocrine disrupting chemicals (EDC). The occurrence of these compounds in wastewater treatment plant (WWTP) effluent and surface waters has been an interesting research field due to the probability of these micropollutants to break through water treatment plant (WTP). Adsorption on activated carbon has been recognized as an option for the removal of EDC. Present paper evaluated the adsorption of the natural estrogen 17?-estradiol (E2), the synthetic estrogen 17?-ethinylestradiol (EE2) and the xenostrogen 4-nonylphenol (NP) by powdered activated carbon (PAC) in ultra-pure water and raw water from Atibaia River, at Campinas City, São Paulo State, Brazil. The analytic technique used was solid phase extraction (SPE) and gas chromatography tandem mass spectrometry (GC-MS). Freundlich's model resulted more adequate to describe the adsorption of the compounds on PAC usually applied at local WTP. In ultra-pure water it was observed more significant removal for dosages equal to 15 mg PAC/L, reaching 95% of removal. The results obtained for raw water showed that 10 mg/L PAC dosage promotes a removal of the endocrine disruptor from river water higher than 77%. It was observed that PAC with iodine number greater than 800 mg/g presented, in general, the highest removal efficiencies, supporting the adsorption of compounds in the activated carbon micropores. Although there is no current legislation in Brazil that regulates the presence of these micropollutants at water supply systems, the addition of PAC must be performed by the precautionary principle
Mestrado
Saneamento e Ambiente
Mestre em Engenharia Civil
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Santana, Pedro Manoel Araujo de. "Uso da Moringa oleifera lam. como biossorvente do cádmio em águas". Universidade Católica de Pernambuco, 2017. http://tede2.unicap.br:8080/handle/tede/934.
Testo completoAbstract (sommario):
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Industrial processes have historically been an important factor in environmental degradation. Improper disposal of industrial waste containing potentially toxic metals in water supplies is a major physical, biotic and anthropic problem. The objective of this study was to evaluate the adsorptive capacity of the ground seeds of Moringa oleifera Lam. As an alternative material to synthetic biosorbents for removal of cadmium ions in water. Before and after the treatments were carried out chemical analysis according to official methodology. The results were analyzed by ANOVA and Pearson table chart with a significance level of 5% and correlation between variables. The results showed a better performance of the alternate method, employing pitcher for removing cadmium in water treatment under the following conditions: slightly basic pH (7.11); Contact time between pitcher and water was six hours; moringa one gram per liter of water. Under these conditions there was a reduction in the concentration of 70.28% cadmium proving that the alternative methodology in addition to being inexpensive, easy to perform, helps to minimize severe impacts that metal brings to people's health and the environment.
Os processos industriais têm sido historicamente um importante fator de degradação ambiental. A disposição inadequada de resíduos industriais contendo metais potencialmente tóxicos em fontes de águas representa um grande problema físico, biótico e antrópico. O objetivo deste trabalho foi avaliar a capacidade adsortiva das sementes trituradas de Moringa oleifera Lam. como um material alternativo aos biossorventes sintéticos, para remoção de íons cádmio em águas. Antes e após os tratamentos foram realizadas determinações químicas de acordo com metodologia oficial. Os resultados foram analisados pela tabela ANOVA e o gráfico de Pearson com um nível de significância de 5 % e correlação entre as variáveis. Os resultados mostraram a melhor eficiência do método alternativo, empregando moringa, para remoção de cádmio, em tratamento de água nas seguintes condições: pH levemente básico (7,11); tempo de contato entre moringa e água de seis horas; um grama de moringa por litro de água. Nestas condições houve uma redução da concentração do cádmio de 70,28 % comprovando que a metodologia alternativa além de ser barata, de fácil execução, contribui para minimizar severos impactos que esse metal traz para a saúde das pessoas e para o ambiente.
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Manipura, Walappuly Mudiyanselage Janakasiri Aruna Shantha Bandara. "Bioprocess development for removal of nitrogenous compounds from precious metal refinery wastewater". Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1007341.
Testo completoAbstract (sommario):
Removal of nitrogenous compounds from precious metal refinery (PMR) wastewater is important in terms of avoiding eutrophication (environmental protection), metal recovery (increased overall process efficiency and value recovery) and reuse of treated water (maximum use of natural resources). Extreme pH conditions (4 to 13 depending on the wastewater stream), high chemical oxygen demand (> 10,000 mg/I), numerous metals and high concentrations of those metals (> 20 mg/l of platinum group metals) in the wastewater are the main challenges for biological removal of nitrogenous compounds from PMR wastewater. Nitrogenous compounds such as NH₄⁺-N and N0₃-N are strong metal ligands, which make it difficult to recover metals from the wastewater. Therefore, a bioprocess was developed for removal of nitrogenous compounds from carefully simulated PMR wastewater. A preliminary investigation of metal wastewater was carried out to determine its composition and physico-chemical properties, the ability to nitrify and denitrify under different pH conditions and denitrification with different carbon Source compounds and amounts. Even at pH 4, nitrification could be carried out. A suitable hydraulic retention time was found to be 72 hours. There was no significant difference between sodium acetate and sodium lactate as carbon sources for denitrification. Based on these results, a reactor comparison study was carried out using simulated PMR wastewater in three types of reactors: continuously stirred tank reactor (CSTR), packed-bed reactor (PBR) and airlift suspension reactor (ALSR). These reactors were fed with 30 mg/l of Rh bound in an NH₄⁺ based compound (Claus salt: pentaaminechlororhodium (III) dichloride). Total nitrogen removal efficiencies of > 68 % , > 79 % and > 45 % were obtained in the CSTR, PBR and ALSR, respectively. Serially connected CSTR-PBR and PBR-CSTR reactor configurations were then studied to determine the best configuration for maximum removal of nitrogenous compounds from the wastewater. The PBR-CSTR configuration gave consistent biomass retention and automatic pH control in the CSTR. Ammonium removal efficiencies > 95 % were achieved in both reactors. As poor nitrate removal was observed a toxicity study was carried out using respirometry and the half saturation inhibition coefficients for Pt, Pd, Rh and Ru were found to be 15.81, 25.00, 33.34 and 39.25 mg/l, respectively. A mathematical model was developed to describe the nitrogen removal in PMR wastewater using activated sludge model number 1 (ASMl), two step nitrification and metal toxicity. An operational protocol was developed based on the literature review, experimental work and simulation results. The optimum reactor configuration under the set conditions (20 mg/I of Rh and < 100 mg/I of NH₄⁺-N) was found to be PBR-CSTR-PBR process, which achieved overall NH₄⁺-N and N0₃⁻-N removal efficiencies of > 90 % and 95 %, respectively. Finally, a rudimentary microbial characterisation was carried out on subsamples from the CSTR and PBRsecondary. It was found that the CSTR biomass consisted of both rods and cocci while PBRsecondary consisted of rods only. Based on these experimental works, further research needs and recommendations were made for optimisation of the developed bioprocess for removal of nitrogenous compounds from PMR wastewater.
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Stoquart, Céline. "Performance of aged PAC suspensions in a hybrid membrane process for drinking water production". Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209254.
Testo completoAbstract (sommario):
Les procédés membranaires hybrides (PMH) allient la filtration membranaire basse pression à l’usage du charbon actif en poudre (CAP). Afin de diminuer les coûts opérationnels du procédé, il a été proposé de laisser vieillir le CAP dans le PMH et donc de minimiser le dosage de CAP frais. Peu d’information est disponible quant à la capacité résiduelle d’adsorption de suspensions de CAP âgées. L’importance relative de l’adsorption et de la biodégradation dans les réacteurs à CAP âgés sur le traitement des composés dissous est inconnue, ce qui empêche notamment l’optimisation du procédé. Le principal objectif de ce projet de recherche est de décrire la performance du contacteur à CAP du PMH pour l’enlèvement de l’azote ammoniacal, du carbone organique dissous (COD), du COD biodégradable (CODB) et des micropolluants. Dans ce projet, l’emphase est placée sur l’opération du PMH avec de hauts temps de rétention de CAP.
La première phase de ce projet a consisté en une série de développements méthodologiques, base nécessaire à l’étude du CAP âgé. Des méthodes permettant la quantification de la biomasse hétérotrophe et nitrifiante colonisant le CAP âgé ont mis en évidence des densités de biomasse similaires à celle du charbon actif en grain en surface de filtre biologiques. L’irradiation aux rayons gamma a été démontrée comme une méthode adéquate pour produire des témoins abiotiques à partir de CAP de 10 et de 60 jours.
La seconde partie de cette étude s’est concentrée sur la démonstration de l’efficacité du PMH pour l’enlèvement de l’azote ammoniacal, du COD, ainsi que d’un mélange de micropolluants. Les cinétiques d’enlèvements ayant lieu au sein de des contacteurs à CAP ont été simulées en laboratoire sous diverses conditions (température, concentration en CAP, âge de CAP, matrice d’eau variable, temps de contact). Deux modèles cinétiques prédisant l’enlèvement de l’azote ammoniacal et du COD dans le PMH ont été développés sur base des simulations en laboratoire suivies sur CAP neuf, colonisé et abiotique.
De manière générale, les travaux réalisés au cours de ce doctorat ont mis en évidence le rôle majeur de l’adsorption résiduelle sur l’enlèvement de la contamination dissoute. Alors que l’enlèvement d’azote ammoniacal a majoritairement eu lieu par nitrification, le COD et les micropollutants sont principalement adsorbés sur le CAP colonisé. Il a aussi été montré que la capacité d’adsorption résiduelle des suspensions de CAP âgées peut agir en tampon, permettant de faire face à une augmentation soudaine de la concentration en azote ammoniacal, en COD ou en micropolluants. Le suivi des cinétiques d’enlèvement a permis de démontrer que la concentration, l’âge de CAP et le temps de rétention hydraulique (TRH) sont trois paramètres clefs pour l’optimisation du procédé. D’un point de vue économique, un TRH inférieur à 15 min est néanmoins désiré pour limiter les coûts du procédé. Par ailleurs, l’intérêt économique associé à l’augmentation de l’âge du CAP peut-être atténué par le besoin d’augmenter la concentration en CAP si l’adsorption est le mécanisme visé. De façon générale, ce projet démontre qu’une optimisation à l’échelle pilote du procédé est nécessaire car les objectifs de traitement, la qualité de l’eau à traiter et le fait que les 3 paramètres d’opération soient inter-reliés complexifient l’optimisation du PMH. Étant donné l’impact du TRH sur le coût du PMH, de futures recherches devraient viser à l’optimisation du mélange.
Hybrid membrane processes (HMPs) couple membrane filtration with powdered activated carbon (PAC). In HMPs, low-pressure membranes ensure an efficient particle removal, including protozoan parasites such as Cryptosporidium, while the PAC contactor is devoted to the removal of dissolved compounds. Such processes are emerging as a promising alternative to conventional treatment chains, which no longer allow the drinking water facilities to comply with increasingly stringent regulations on the treated water quality. To decrease the operating costs associated with virgin PAC consumption, it was suggested to let the PAC age in the PAC contactor of the process. Until now, the potential of using aged PAC in HMPs has been demonstrated for ammonia and DOC removal, but the potential to remove micropollutants remains unknown. It is suggested that the biological activity in aged PAC contactors contributes significantly to the removal of the dissolved compounds. Yet, neither the extent of the biomass on the aged PAC, nor the residual adsorption capacity, was quantified. No study focused on discriminating the mechanisms responsible for the treatment when using aged PAC suspensions. Most of the data published on HMPs using aged PAC were gathered at pilot scale under warm water conditions, yet the efficiency of the process is most likely sensitive to temperature changes. There is currently little information available on the efficiency of HMPs under cold water conditions. This lack of information hinders the optimization of the HMP, leading to sub-optimal usage of aged PAC.
The main objective of this research project is to describe the performance of the PAC contactor of HMPs in removing ammonia, dissolved organic carbon (DOC), biodegradable DOC (BDOC) and micropollutants. In particular, emphasis was placed on the operation of the HMP under high PAC residence times. On a more detailed level, the objectives of this project were (1) to develop and compare methods to quantify the biomass developed on aged PAC, (2) to develop a method to produce an abiotic control for aged PAC, (3) to characterize the removal kinetics of ammonia, DOC, BDOC and micropollutants occurring in the carbon contactor of an HMP, (4) to evaluate the impact of water temperature on the performance of the carbon contactor of an HMP, (5) to discriminate the relative importance of adsorption versus biological oxidation as mechanisms responsible for ammonia, DOC and micropollutants removal in the PAC contactor of an HMP, and finally (6) to differentiate the relative importance of the hydraulic retention time (HRT), the PAC age and the PAC concentration as key operating parameters on the optimization of the performance of the PAC contactor of an HMP.
To set the basis on the study of aged PACs, the first part of this research project consisted in methodological developments i) to quantify the heterotrophic and nitrifying biomass colonizing aged PAC, and ii) to create a reliable abiotic control of the colonized PAC, which is required for discriminating the mechanisms occurring on aged PAC. Heterotrophic and nitrifying biomass quantifying methods developed for colonized granular activated carbon (GAC) were successfully adapted to the aged PAC. The preferred methods were the potential 14C-glucose respiration (PGR) rate and the potential nitrifying activity (PNA), as they quantify the active heterotrophic and nitrifying biomass, which is most likely responsible for the depletion of BDOC and ammonia. An alternative method to the PGR, the potential acetate uptake (PAU) rate, was developed to alleviate the logistical and budgetary issues associated with the utilization of radio-labeled glucose. The densities (per gram of dry PAC) of both active heterotrophic and nitrifying biomasses were found comparable to that of the GAC sampled from the surface of a biological GAC filter. The gamma-irradiation was demonstrated as a reliable method to produce abiotic samples from soils, and was therefore chosen to produce abiotic colonized PAC samples in this project. In order to determine the optimized dosage of gamma-rays, increased doses were applied on PAC samples. Heterotrophic plate counts and methylene blue adsorption kinetics were used to determine respectively the lowest gamma ray dose required to inhibit the bacterial activity, and the highest dose that could be applied without affecting the aged PAC adsorption capacity and kinetics. Refractory DOC (RDOC) adsorption kinetics confirmed the accuracy of the dose chosen as the adsorptive behavior of the aged PAC was not affected. PGR rates were decreased 83% at the optimized dose. The gamma-irradiation method was therefore proven efficient and used in the following work phases of this research.
The second part of this study focused on the removal of ammonia, DOC and a mixture of micropollutants. Firstly, the PAC contactor of an HMP was simulated at lab-scale to monitor ammonia removal kinetics. Three PAC concentrations (approximately 1-5-10 g/L) of three PAC ages (0-10-60 days) were tested at two temperatures (7-22°C), in settled water with ambient influent condition (100 µg N–NH4/L) as well as under a simulated peak pollution scenario (1000 µg N–NH4/L). The kinetics evidenced that ammonia flux at pilot scale limited biomass growth (HRT = 67 min). In contrast, PAC colonization was not limited by the available surface and thus, PAC concentration was not a key operating parameter under the colonizing conditions tested (5-10 g/L). Ammonia adsorption was significant onto virgin PAC but the ammonia nitrification was crucial to reach complete ammonia removal at 22°C. When using colonized PAC, the 60-d PAC offered a better resilience to temperature decreases (78% at 7°C) as well as lower operating costs than the 10-d PAC (<10% at 7°C). Significant ammonia adsorption was also evidenced on 60-d PAC suspension, most probably due to PAC and the presence of suspended solids, but not on 10-d PAC. Adsorption and nitrifying activity were superior on 60-d PAC than on 10-d PAC at 7°C. In case of peak pollution, the process was most probably phosphate-limited but a mixed adsorption/nitrification still allowed 50% ammonia removal on 10-d and 60-d PAC at 22°C. A kinetics based model was developed to predict ammonia removals and to determine the relative importance of the adsorption and nitrification on colonized PAC under the conditions tested.
DOC, BDOC and RDOC removals occurring in the PAC contactor of an HMP were also simulated at lab-scale. Similar conditions to that of the ammonia removal kinetics were tested. The initial ammonia concentration remained untouched in the water matrices (settled water and raw water) but the BDOC-to-DOC ratio was altered by pre-ozonation (0 to 1.5 g O3/g C). The 10-d and 60-d abiotic controls were used to discriminate DOC adsorption from biodegradation. DOC biodegradation contributed marginally to DOC removal in the investigated conditions and DOC adsorption was increased at higher temperature. An original model integrating the PAC age distribution was developed to predict DOC removal in aged PAC contactors operated at steady-state. At a mean PAC residence time of 60-d, the younger PAC fraction (25-d and less) was primarily responsible for DOC adsorption (> 80%). This fraction represents 34% of the mass of PAC in the contactor. When using a water matrix with a higher initial DOC concentration (raw water) or a lower affinity for PAC (pre-ozonated settled water), the residual adsorption capacity of that older fraction was proven useful.
Lastly, a mixture of micropollutants (atrazine, deethylatrazine (DEA), linuron, microcystin, caffeine, carbamazepine, sulfamethoxazole, diclofenac, progesterone and medroxyprogesterone) was spiked at environmentally relevant concentrations (from 130 ng/L to 33 µg/L) in settled water (0 and 0.85 gO3/gC). The micropollutants concentration depletion was monitored over a period of 7h to 48 h on 1 g/L of 0-d, 10-d, 60-d PAC and gamma-irradiated 60-d PAC. Even in presence of NOM, the spiked micropollutants were rapidly adsorbed on aged PAC. No biodegradation was observed. Removals superior to 95% were reached within 5 minutes, and direct competition with NOM did not impact the efficiency of the process when micropollutants were spiked at environmentally relevant concentrations. Therefore, HMPs operated to remove DOC and ammonia can control transient micropollutant pollution and comply with the World health Organization recommendations for atrazine (2 µg/L) and microcystin (1 µg/L). However, the stricter European regulations for atrazine and DEA (0.1 µg/L) could not be met with 10-d and 60-d PAC under the operating conditions tested. Reaching such strict treatment objective would require a specific optimization of the process.
In general, this PhD research evidenced the role of the residual adsorption of aged PAC suspensions for the treatment of dissolved compounds. From the results obtained in this project, the potential of HMPs using aged PAC to remove micropollutants was evidenced. Additional research is however required to validate this potential under varied operating conditions. The modeling work improved the understanding of aged PACs. Finally, this research work provides original information on the optimization of HMPs. The optimization of the operating parameters will vary with the water quality targeted and the quality of the influent water. The PAC concentration, PAC age and HRT are inter-related. Therefore, it is recommended to optimize the operation of HMPs at pilot scale. Seasonal variations should be accounted for. An HRT of at least 15 min is required when the biological activity is mandatory to reach the water quality objectives. Lower HRT might be applied if adsorption is favored. Finally, as the HRT has a strong impact on the total cost of the process (capital and operational expenditure), PAC contactors’ hydraulic should be the point of focus of future research.&
Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished
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Грайворонська, Інна Валерієвна, Инна Валерьевна Грайворонская e Inna Valeriievna Hraivoronska. "Обеспечение экологической безопасности при использовании металлургических шлаков в сорбционных технологиях очистки вод". Thesis, Харьковский нац. автомобильно-дорожный ун-т, 2014. http://essuir.sumdu.edu.ua/handle/123456789/37328.
Testo completoAbstract (sommario):
Дисертація присвячена вирішенню проблеми адсорбційної очистки промислових стічних вод від органічних сполук та виявленню ресурсної цінності металургійних шлаків з метою їх екологічно безпечного використання у виробництві сорбентів. Визначено елементний, оксидний, мінералогічний і радіонуклідний склад металургійних шлаків. Встановлено клас радіаційної небезпеки досліджених шлаків. Теоретично і експериментально обґрунтовано принципи визначення сорбційної активності металургійних шлаків. Визначено умови хімічної активації шлаку, природу функціональних груп, заряд і морфологічні особливості поверхні частинок сорбенту. Встановлено залежності кількісних показників адсорбції від параметрів процесу, які мають значення для використання шлакових сорбентів у виробничих умовах. Визначені механізм, кінетичні характеристики і виведені рівняння адсорбції. Доведено відсутність десорбції поглинених речовин. Представлено ресурсозберігаючі розробки, що дозволяють розширити сировинну базу для виробництва сорбентів, поліпшити екологічну ситуацію регіонів за рахунок запобігання скиду промислових стічних вод при впровадженні систем оборотного водопостачання підприємств.Диссертация посвящена решению проблемы адсорбционной очистки промышленных сточных вод от органических соединений и выявлению ресурсной ценности металлургических шлаков с целью их экологически безопасного использования в производстве сорбентов. Усовершенствован единый подход к исследованию сорбционных свойств металлургических шлаков, что позволяет наиболее эффективно и полно определить их адсорбционные характеристики, дать прогноз перспективам использования шлаков в сорбционных технологиях очистки промышленных сточных вод. В качестве шлаковых сорбентов использованы металлургические шлаки предприятий Украины. С помощью рентгенофазового анализа определена природа минералов шлаков, показано, что основным минералом является диопсид, подтверждено наличие аморфного состояния веществ. Выявлены гранулометрические фракции шлаков с повышенным содержанием алюмосиликатов кальция и магния, проявляющие адсорбционную активность. Химический анализ показал незначительное содержание в металлургических шлаках тяжелых металлов: Cu, Ti, Mn, Fe, что не представляет опасности при дальнейшей утилизации. Определены удельные поверхности шлаковых сорбентов. Гамма-спектрометрическим анализом доказано соответствие металлургических шлаков I классу радиационной опасности, определяющее отсутствие ограничений при использовании шлаков в качестве сорбентов. Показано, что кислотная и щелочная активация шлака могут использоваться в различных режимах сорбции органических соединений. При кислотной активации шлака достигается максимальное травление и разрыхление его поверхности, увеличивается количество силанольных групп Si–OН, диссоциация которых определяет отрицательный заряд поверхности шлаковых частиц. Доказано практическое отсутствие десорбции поглощенных веществ. На основании кинетических характеристик адсорбции органических соединений шлаковыми сорбентами определена смена порядка процесса во времени, связанная с реализацией двух механизмов: электростатическое взаимодействие между диссоциированными функциональными группами сорбента и ионами сорбата (второй порядок процесса); после связывания всех функциональных групп − протекание ван-дер-ваальсовской адсорбции на свободной поверхности шлака (первый порядок процесса). Доказано, что адсорбция органических соединений различной природы шлаковыми сорбентами является мономолекулярной, активированной специфической, вызванной дисперсионными взаимодействиями адсорбента и сорбатов. Адсорбция органических соединений шлаковыми сорбентами количественно описана с помощью уравнений Фрейндлиха и Ленгмюра. Для математического описания процесса адсорбции шлаком на основе минерала диопсида органического красителя МС использован пакет прикладных программ MATLAB и его подсистемы Toolbox в применении к экспериментальным данным по адсорбции при варьировании экспериментальных условий: соотношения «МС : шлак», времени и рН растворов МС. Получены уравнения регрессии зависимостей величины и эффективности адсорбции от двух экспериментальных факторов одновременно. Разработан способ получения шлакового адсорбента на основе минерала диопсида. Способ обеспечивает повышение величины адсорбции за счет химической активации поверхности шлаковых частиц и увеличение эффективности очистки промышленных сточных вод от органических соединений. Разработан способ противоточно-ступенчатой периодического действия адсорбционной очистки сточных вод от ПАВ в области высоких концентраций с использованием шлакового сорбента. Обоснован способ перекрестно-ступенчатой адсорбционной очистки сточных вод от органических соединений. Эколого-экономический эффект при очистке промышленных сточных вод с помощью шлаковых сорбентов доказал эколого-экономическую целесообразность данной сорбционной технологии. Экономия на расходе воды составляет 67,9 %. Ресурсосберегающие разработки позволяют решить экологические проблемы предприятий, в технологических процессах которых образуются сточные воды, содержащие органические соединения различных классов, − за счет ликвидации стоков и обеспечения цикла оборотного водоснабжения.
This thesis is dedicated to a solution of problems of identifying of industrial wastes resource value for environmentally safe utilization in production of organic compounds sorbents for wastewater treatment. The elemental, oxide, mineralogical and radionuclide composition of metallurgical slags is determined. The class of radiation danger of researched industrial waste is carried out. The principles оf metallurgical slag fractions sorption activity determination are substantiated theoretically and experimentally. Conditions of chemical activation of slag, type of functional groups, charge and morphological characteristics of sorbent’s surface are defined. The dependences of quantitative indicators from adsorption process parameters which have the implication for slag sorbents utilization in production environment are determined. The mechanism and kinetic properties are determined and adsorption equations are derived. The absence of desorption of absorbed substances is proved. The designs with resource saving effect which allow both to extend the raw materials base for the production of sorbents and to improve the environmental situation of the region through the prevention of dumping at the introduction of water recycling enterprises are presented.
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Almeida, Aline Rafaela de. "Estudo da retenção da toxina de microcystis aeruginosa no bagaço de cana-de-açúcar e no carvão ativado". Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1358.
Testo completoAbstract (sommario):
A crescente taxa de urbanização com descarga de esgoto sem tratamento prévio nos ecossistemas aquáticos e o aumento do uso de fertilizantes para desenvolvimento agrícola são causas da aceleração da floração de cianobactérias em águas de mananciais destinadas ao consumo humano. Cabe ao tratamento de água para abastecimento atender as especificações da legislação em relação à potabilidade necessitando remover as cianobactérias e suas toxinas. Este trabalho teve por objetivo estudar a utilização de bagaço de cana-de-açúcar in natura para adsorção de microcistina-LR da Microcystis aeruginosa em comparação com o carvão ativado. Foram realizados ensaios de adsorção a temperatura ambiente, com três concentrações iniciais de microcistina-LR: 3,83, 3,33 e 2,36 μg.L-1 no tempo total de 10 h, e a caracterização físico-química dos adsorventes para analisar a remoção da microcistina-LR. O desempenho da adsorção foi avaliado pela capacidade adsortiva e pela eficiência da remoção de toxina. Os resultados para o bagaço de cana-de-açúcar in natura não possibilitaram o alcance do limite inferior de concentração de microcistina de 1,0 μg.L-1 estabelecido na Portaria MS 2914/2011, porém, permitiram eficiência 8% maior de remoção da microcistina no bagaço de cana-de-açúcar comparado ao carvão ativado para maior concentração de adsorvato, mesmo apresentando área superficial de 1,28 m2.g-1 e superfície menos porosa e heterogênea que o carvão. A melhor taxa de remoção foi de 65%. de microcistina para concentração de 2,36 μg.L-1 no carvão ativado. Verificou-se também que o desempenho dos adsorventes foi melhor representado pelo Modelo da Isoterma de Freundlich do que pelo Modelo da Isoterma de Langmuir. De modo geral, a utilização do bagaço de cana-de-açúcar in natura para remoção de microcistina demonstra ser uma alternativa no tratamento de água comparado a outros adsorventes, porém, necessitando ser melhor estudada.Increasing urbanization rate with untreated sewage discharge in aquatic ecosystems, and the increased use of fertilizers for agricultural development are causes of the acceleration of cyanobacterial bloom in water fountains which are intended for human consumption. It is important that the treatment for water supply meets the specifications of legislation for the potability that requires removing cyanobacteria and their toxins. This work aimed to study the use of in natura sugarcane bagasse for microcystin-LR adsorption of Microcystis aeruginosa compared to activated carbon. Adsorption experiments were carried out at room temperature with three initial concentrations of microcystin-LR: 3.83, 3.33 and 2.36 μg.L-1 total time of 10 h, and physico-chemical characterization of adsorbents analyzing the removal of microcystin-LR. The performance was evaluated by the adsorption capacity and adsorption by the toxin removal efficiency. The results for in natura sugarcane bagasse did not allow the scope of microcystin concentration lower limit of 1.0 μg.L -1 established in the MS 2914/2011, however, it allowed 8% higher efficient removal of microcystin in bagasse sugarcane compared to activated carbon to higher concentration of adsorbents, even with surface area of 1.28 m2.g-1 and less porous and heterogeneous surface than coal. The best removal rate was 65% microcystin concentration to 2.36 μg.L-1 on activated carbon. It was also found that the performance of adsorbents was best represented by the Freundlich Isotherm of Model than the Model Langmuir Isotherm. In general, the use of in natura sugar bagasse for removing microcystin proves to be an alternative water treatment compared to other adsorbents, however, it needs further studies.
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Vijwani, Hema. "Hierarchical Porous Structures with Aligned Carbon Nanotubes as Efficient Adsorbents and Metal-Catalyst Supports". Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1433350549.
Testo completo
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Fourest, Eric. "Etude des mécanismes de biosorption des métaux lourds par des biomasses fongiques industrielles en vue d'un procédé d'épuration des effluents aqueux contaminés". Grenoble 1, 1993. http://www.theses.fr/1993GRE10142.
Testo completoAbstract (sommario):
Les micro-organismes etudies presentent a l'etat mort d'importantes capacites d'accumulation pour les cations metalliques en solution dans l'eau. La cinetique d'adsorption des metaux est controlee par leur diffusion dans les materiaux biosorbants. Avec rhizopus, 90% de l'adsorption se deroule en moins d'une heure. L'obtention de granules poreux et resistants de diametre moyen de 200 a 400 m offre les meilleures proprietes de transferts ioniques et de separabilite des particules solides. Des experiences d'adsorption du zinc, du nickel, du cadmium et du plomb en systeme ferme par r. Arrhizus montrent le role crucial du ph. L'adsorption de ces metaux est maximale a ph 7,0, et totalement inhibee en dessous de ph 3,0. Les capacites d'adsorption maximales obtenues a ph 7,0 pour le zinc sont de 42,5 mg/g (0,65 mmol/g) avec rhizopus, 40 mg/g avec mucor et seulement 20 mg/g (0,3 mmol/g) avec penicillium. La liberation de calcium observee lors de la fixation des metaux montre que la biosorption procede par echange cationique sur les groupements complexants de la paroi mycelienne. Les fonctions carboxyliques contribuent a 30% de l'adsorption du zinc par rhizopus et mucor, et a 50% pour penicillium. L'epuration de solutions metalliques a travers des colonnes de granules biosorbants (rhizopus et penicillium) montrent l'aptitude des biomasses fongiques a retenir les metaux en flux continu. Une colonne de 3 grammes de rhizopus permet de purifier 600 ml de solution de zinc a 50 mg/l jusqu'a une teneur inferieure a 0,1 mg/l. Le metal fixe peut etre elue dans un volume minimum d'acide. Le biosorbant peut etre ensuite etre regenere et reutilise durant 15 cycles successifs sans diminution importante des performances. Enfin, des essais d'epuration effectues sur un effluent industriel et dans un reacteur pilote de 150 litres montrent les possibilites d'exploitation de la biosorption pour des cas reels de pollution a grande echelle
25
Choo-Kun, Marlène. "Intégration de la méthanisation des boues dans une filière alternative de traitement des eaux usées basée sur le procédé A/B : Vers la station d’épuration à énergie positive". Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0142/document.
Testo completoAbstract (sommario):
Depuis le début des années 2000, la station d’épuration n’est plus seulement perçue comme une installation industrielle traitant les eaux résiduaires urbaines afin d’en minimiser leurs impacts sur le milieu naturel, mais aussi comme un moyen de récupérer des ressources : eau, nutriments, énergie. Ce travail de thèse traite de cette dernière ressource, l’énergie. Comment tendre vers la station d’épuration auto-suffisante en énergie, voire encore productrice d’énergie sans en affecter l’efficacité de traitement? A l’aide d’une filière de traitement ancienne revisitée : le procédé A/B (Adsorption/Bio-oxydation), le bilan énergétique de la station peut tendre vers la neutralité en réduisant les demandes liées à l’aération et en optimisant la production de biogaz. Ce travail de doctorat se concentre principalement sur la méthanisation des boues issues de ce procédé A/B afin d’en connaître leurs caractéristiques et leur digestibilité, de les comparer avec la digestion anaérobie de boues davantage connues et enfin d’utiliser ces résultats pour dresser le bilan énergétique du procédé A/B, ceci à partir des données récoltées sur un pilote de 50 m3/j installé sur la station d’épuration de Kranji à Singapour. Les boues A et B présentent respectivement les productions spécifiques de méthane respectives de 290 et 135 LCH4/kgMVentrante en conditions mésophiles. Le procédé A/B avec ses deux étages de boues activées permet de capter un maximum de carbone en première étape de traitement pour le transférer directement en digestion. En effet, la production totale de boues provient à 90% des boues A et seulement à 10% des boues B ce qui porte à 95% la production de méthane attribuée aux boues A. Ces résultats induisent une production d’énergie supérieure par rapport à une filière de traitement conventionnelle avec un seul étage de boues activées. Par ailleurs, ce procédé permet de diminuer les besoins en aération pour le traitement des pollutions carbonée et azotée, tout en gardant les mêmes efficacités de traitement. Il est ainsi possible de conclure que la filière de traitement des eaux usées en procédé A/B présente un degré d’efficacité énergétique proche de 300% (ratio entre l’énergie électrique produite à partir du biogaz et la consommation énergétique liée à l’aération), ce qui représente 73% d’auto-suffisance énergétique globale en considérant le cas de la station de Kranji en boues activées conventionnelles traitant les pollutions en carbone et en azoteSince the early 2000’s, wastewater treatment plants (WWTP) have not been only seen as a mean to reduce the impact of the harmful emissions towards water bodies but also as a way to recover the resources contained in the raw wastewater: water, nutrients and energy. This doctorate seeks to study the latter one. How to tend to the energy self-sufficient or even energy positive WWTP without altering its treatment efficiencies? Using an old wastewater treatment process: the A/B process (Adsorption/Bio-oxidation) and state-of-the-art technologies, the energy autarky of a WWTP can become a reality by reducing its electricity consumption related to the aeration and by optimizing its energy production through anaerobic digestion. This work mainly focuses on the anaerobic digestion of the sludge produced by the A/B process. It aims at evaluating their characteristics and digestibility and thus at comparing these to the ones of better-known sludge such as primary, secondary and mixed sludge from a conventional wastewater treatment system. Eventually, these results with the addition of data collected on a 50 m3/d A/B process pilot plant on the Water Reclamation Plant of Kranji, Singapore, are used to draw the energy balance of the A/B process and to try to make a comparison to conventional systems. The A/B process produces the A and B sludge which respectively show specific methane productions of 290 and 135 LCH4/kgVSintroduced in mesophilic anaerobic digestion and can be considered quite similar to primary and secondary sludge respectively from conventional WWTPs. With its two stages of activated sludge, this process enables the early entrapment of carbon to be directly transferred to the digesters. Indeed, 90% of the sludge production comes from the A sludge in matter of Volatile Solids, which brings to 95% the biogas production to be ascribed to this sludge. Hence, the A/B process does produce more energy than a conventional single-stage activated sludge. It also reduces the aeration demand for the biological treatment of the carbon and nitrogen pollutions whilst complying with the same treatment performances. Drawing the energy balance of the A/B process leads to the conclusions that this process presents an energy efficiency of 300% by comparing only the electrical needs for the aeration (40-70% of the whole plant demand) and the electricity production from biogas generation, which, at the end, represents an energy self-sufficiency of 73% considering the Kranji conventional water reclamation plant
26
Carricondo, Antón Juan Manuel. "Utilización de residuos vegetales para la eliminación de fósforo en aguas residuales mediante procesos de adsorción". Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/158614.
Testo completoAbstract (sommario):
[ES] La presente tesis doctoral tiene como objetivo la utilidad de restos vegetales de origen agrícola y no agrícola para la eliminación de fósforo de las aguas residuales, y con ello reducir la eutroficación del lago de l'Albufera de Valencia, en el este de España. Bajo el concepto de Economía Circular, la cual se basa en reducir la entrada de materiales y la generación de desechos en sistemas productivos, los restos vegetales son utilizados para la producción de energía renovable en plantas de biomasa, una vez incinerados en estas plantas los restos vegetales pasan a ser un residuo, la ceniza.
Se han estudiado las cenizas de materiales vegetales agrícolas como es la paja de arroz y los restos de podas de vegetación invasora como es el carrizo, ambos procedentes del Parque Natural de l'Albulfera de Valencia. Además, se han utilizado cenizas de una planta de biomasa de la comarca del Rincón de Ademuz, en el interior de la provincia de Valencia, alimentada con restos vegetales agrícolas como son la paja de trigo, paja de cebada y madera de plantaciones de paulonia cultivadas para la producción de bioenergía.
Para poder reducir la concentración de fósforo del agua, se ha seleccionado el proceso que hoy en día más posibilidades tiene de ser un sistema de bajo coste y alta eficiencia como es la adsorción. Mediante las isotermas de adsorción de Langmuir, Freundlich y Tempkin se han determinado las capacidades de adsorción de fósforo, llegando a una reducción de fosforo de hasta casi del 99%, siendo la isoterma de Langmuir la que mejor ajuste posee al proceso de adsorción de fósforo.
Por último, el residuo producido en el proceso de depuración, que es la ceniza con alta concentración de fosforo, puede ser utilizada para la fertilización de campos agrícolas.[CAT] La present tesi doctoral té com a objectiu la utilitat de restes vegetals d'origen agrícola i no agrícola per a l'eliminació de fòsfor de les aigües residuals, i amb això reduir l'eutrofització del llac de l'Albufera de València, en l'est d'Espanya. Sota el concepte d'Economia Circular, la qual es basa a reduir l'entrada de materials i la generació de deixalles en sistemes productius, les restes vegetals són utilitzats per a la producció d'energia renovable en plantes de biomassa, una vegada incinerats en aquestes plantes les restes vegetals passen a ser un residu, la cendra. S'han estudiat les cendres de materials vegetals agrícoles com és la palla d'arròs i les restes de podes de vegetació invasora com és el canyís, tots dos procedents del Parc Natural de l'Albulfera de València. A més, s'han utilitzat cendres d'una planta de biomassa de la comarca del Racó d'Ademús, a l'interior de la província de València, alimentada amb restes vegetals agrícoles com són la palla de blat, palla d'ordi i fusta de plantacions de paulonia cultivades per a la producció de bioenergia. Per a poder reduir la concentració de fòsfor de l'aigua, s'ha seleccionat el procés que hui dia més possibilitats té de ser un sistema de baix cost i alta eficiència com és l'adsorció. Mitjançant les isotermes d'adsorció de Langmuir, Freundlich i Tempkin s'han determinat les capacitats d'adsorció de fòsfor, arribant a una reducció de fòsfor de fins a quasi del 99%, sent la isoterma de Langmuir la que millor ajust posseeix al procés d'adsorció de fòsfor. Finalment, el residu produït en el procés de depuració, que és la cendra amb alta concentració de fòsfor, pot ser utilitzada per a la fertilització de camps agrícoles.
[EN] The objective of this doctoral thesis is the use of vegetable remains of agricultural and non-agricultural origin for the elimination of phosphorus from wastewater, and thereby reduce the eutrophication of the lagoon of l'Albufera de Valencia, in eastern Spain. Under the concept of Circular Economy, which is based on reducing the entry of materials and the generation of waste in production systems, plant remains are used for the production of renewable energy in biomass plants, once the remains are incinerated in these plants. Vegetables become a residue, the ash. The ashes of agricultural plant materials such as rice straw and the remnants of pruning of invasive vegetation such as reed have been studied, both from the Natural Park of l'Albulfera de Valencia. In addition, ashes from a biomass plant from the Rincón de Ademuz region, in the interior of the province of Valencia, have been used, fed with agricultural plant remains such as wheat straw, barley straw and wood from cultivated paulownia plantations for the bioenergy production. In order to reduce the phosphorus concentration of the water, the process that today has the most possibilities of being a low-cost and high-efficiency system, such as adsorption, has been selected. By means of the adsorption isotherms of Langmuir, Freundlich and Tempkin, the phosphorus adsorption capacities have been determined, reaching a reduction of phosphorus of up to almost 99%, being the Langmuir isotherm the one that best fits the phosphorus adsorption process. Finally, the residue produced in the purification process, which is ash with a high concentration of phosphorus, can be used for the fertilization of agricultural fields.
Carricondo Antón, JM. (2020). Utilización de residuos vegetales para la eliminación de fósforo en aguas residuales mediante procesos de adsorción [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/158614
TESIS
27
Hoppen, Mariana Irene. "Adsorção e dessorção do ácido acetilsalicílico em carvão ativado de casca de coco de babaçu in natura e funcionalizado com HNO3". Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/3020.
Testo completoAbstract (sommario):
A presença de fármacos em águas superficiais, subterrâneas, solo e efluentes tem gerado preocupações no que diz respeito à ineficiência dos tratamentos convencionais e os riscos ambientais associados ao descarte inadequado destes micropoluentes emergentes. Diante disto, o objetivo deste trabalho foi avaliar a adsorção e a dessorção de ácido acetilsalicílico (AAS) em solução aquosa em carvão ativado de babaçu in natura (CAB) e funcionalizado quimicamente com HNO3 (CAA). Foram determinados aos adsorventes os teores de cinzas, umidade e de material volátil, granulometria, análise elementar, aspectos morfológicos dos adsorventes, por meio de microscopia eletrônica de varredura (MEV), pH no ponto de carga zero (pHPCZ), características da superfície dos adsorventes por meio de adsorção/dessorção de N2 e os grupos funcionais por espectroscopia na região no infravermelho (FTIR) e método de Boehm. Ensaios cinéticos, de equilíbrio e termodinâmicos foram conduzidos para a adsorção e dessorção em batelada. Ensaios em coluna de leito fixo foram conduzidos preliminarmente. Os resultados dos ensaios cinéticos de adsorção e dessorção foram ajustados aos modelos de pseudo-primeira e pseudo-segunda ordem e os resultados de equilíbrio de adsorção aos modelos matemáticos de Langmuir e Freundlich e de dessorção ao modelo de Langmuir-Freundlich. Aos resultados termodinâmicos de adsorção e dessorção foram determinados os valores de ΔG º, ΔH º e ΔS º. Os adsorventes apresentaram características microporosas, com valores de pHPCZ de 6,4 para CAB e 4,5 para CAA que interferem diretamente na adsorção. Os dados da cinética de adsorção foram melhor ajustados ao modelo de pseudo-segunda ordem e os do equilíbrio de adsorção ao modelo de Langmuir. Os resultados do ΔG º e ΔH º resultaram negativos e o do ΔSº positivo nas temperaturas de 25 ºC, 45 ºC e 55 ºC, indicando que o processo é exotérmico e espontâneo. O aumento da temperatura favoreceu a adsorção com o CAB, e reduziu a capacidade adsortiva do CAA. Em pH ácido a quantidade máxima adsorvida do AAS foi de 119,80 mg g -1 para CAB e 115,08 mg g -1 para CAA. Nos ensaios de dessorção os melhores resultados foram observados com o CAB em pHPCZ = 6,4. Os resultados cinéticos tiveram melhor ajuste ao modelo de pseudo-primeira ordem. As isotermas de dessorção ajustadas ao modelo de Langmuir-Freundlich. Adicionalmente, com os ciclos foram obtidos os percentuais médios de adsorção e dessorção de 92% e 75% no CAB e de 72% e 10% no CAA, respectivamente. O conjunto de dados de pH e temperatura avaliados nos ensaios em coluna de leito fixo determinaram que a reação de adsorção é melhor definida em pH 2,0 e temperatura de 40 ºC.The presence of drugs in surface water, groundwater, soil and effluents has raised concerns regarding the inefficiency of conventional treatments and the environmental risks associated with the inappropriate disposal of these emerging micropollutants. The objective of this work was to evaluate the adsorption and desorption of acetylsalicylic acid (AAS) in aqueous solution of in natura activated babassu carbon (CAB) and chemically functionalized with HNO3 (CAA). The ash adsorbents, moisture and volatile matter, granulometry, elemental analysis, morphological aspects of the adsorbents were determined by scanning electron microscopy (SEM), pH at the zero load point (pHPCZ), surface characteristics of the adsorbents. adsorbents by adsorption/desorption of N2 and functional groups by infrared spectroscopy (FTIR) and Boehm method. Kinetic, equilibrium and thermodynamic tests were conducted for batch adsorption and desorption. Preliminary tests were conducted in a fixed bed column. The adsorption and desorption kinetics results were adjusted to the pseudofirst and pseudo-second order models and the adsorption equilibrium results to the Langmuir and Freundlich mathematical models. The values of ΔG º, ΔH º and ΔS º were determined for the thermodynamic adsorption and desorption results. The desorption equilibrium results were fitted to the Langmuir-Freundlich model. The adsorbents presented microporous characteristics, with values of pHPCZ of 6.4 for CAB and 4,5 for CAA that interfere directly in the adsorption. Adsorption was favored at acidic pH in both adsorbents. The adsorption kinetics data were better fitted to the pseudo second order model and those of the adsorption equilibrium to the Langmuir model, indicating the influence of the chemisorption on the adsorption. The results of ΔGº and ΔHº were negative and that of ΔSº positive at temperatures of 25 ºC, 45 ºC and 55 ºC, indicating the influence of the chemisorption in the process that is exothermic and spontaneous. The increase in temperature favored the adsorption with the CAB, and reduced the adsorptive capacity of the CAA. At acid pH the maximum adsorbed amount of ASA was 119.80 mg g -1 for CAB and 115.08 mg g -1 for CAA. In the desorption experiments the best results were observed with the CAB at pHPCZ = 6.4. The kinetic results had better fit to the pseudo first order model. Desorption isotherms fitted to the Langmuir-Freundlich model indicated affinity between the CAB, ASA and the chosen regenerant. Additionally, the average adsorption and desorption percentages of 92% and 75% in CAB and 72% and 10% in CAA, respectively, were obtained with the cycles. The set of pH and temperature data evaluated in the fixed bed column assays determined that the adsorption reaction is best defined at pH 2.0 and temperature of 40 ºC.
28
Zvinowanda, Caliphs M. "The utilisation of maize tassel as an adsorbent for the removal of heavy metals from aqueous solutions". Thesis, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000553.
Testo completoAbstract (sommario):
Thesis (DTech. degree in Environmental, Water & Earth Sciences)--Tshwane University of Technology, 2009.The potential of tassel from R52 maize cultivar for the removal of heavy metals from simulated and environmental aqueous samples as well as the physicochemical characteristics of tassel were investigated. Milled tassel powder was employed in metal removal from simulated aqueous sample and thereafter, the developed method was applied to environmental samples. This research has demonstrated the potential of maize tassel to adsorb metal ions from both simulated and environmental samples. Furthermore, metals adsorbed on tassel were easily desorbed suggesting that tassel can be employed in metal recycling.
29
"Polymeric nitrogen donor macro(meso)porous sorption materials for selected transition metals". Thesis, 2015. http://hdl.handle.net/10210/13835.
Testo completo
30
Puka, Lesiba Raymond. "Fluoride adsorption modelling and the characterization of clays for defluoridation of natural waters". Thesis, 2008. http://hdl.handle.net/10210/413.
Testo completoAbstract (sommario):
High F- groundwaters occur in various parts of South Africa, namely, the larger part of the Karoo, Limpopo, North West and Northern Cape Provinces. The use of these waters for drinking purposes on continual basis can lead to fluorosis. Fluorosis is a debilitating disease caused by drinking water with F- concentrations higher than ca. 1 mg.L-1. The disease is characterized by mottled teeth in dental fluorosis and brittle bones in severe skeletal fluorosis. Solution to this problem involves the implementation of a method for F- removal from water. Defluoridation has become a widely practiced process worldwide due to the problem of fluorosis caused by the presence of F- in drinking waters. Methods such as adsorption, precipitation, ion exchange and membrane processes have been employed for F- removal. Adsorption techniques, in particular using activated alumina have proven successful in removing F- from water. However, this method can not always be used in rural areas because of high costs and technical requirements. In this study, locally available clays were studied as potential substrates for F- removal from water. The first part of the study focused on the explanation of mechanisms and the development of an adsorption model. The exchange of OH- by F- in the clay structure is the principal mechanism that takes place during adsorption. The change in pH during this exchange process was studied to support and verify the fluoride-hydroxide exchange mechanism. In the second part of the study, locally available South African clays were studied as possible adsorbents for F- removal from water. Clays containing aluminium and iron oxide surfaces proved to be useful substrates for F- adsorption. The adsorption of F- onto clay samples was found to be pH dependent. Maximum adsorption was achieved at pH 5 for aluminium oxide type sorbents and pH 4 for iron oxides types such as goethite. The effect of physical and chemical pretreatment improved the adsorption capacity of some clays. Coating clay samples with aluminium and iron oxides enhanced the adsorption capacity of clays. The last part of the study involves the development of a cost-effective and quick way to assess the performance of clays as adsorbents for F- removal using laboratory scale defluoridation columns.Prof. P.P. Coetzee
31
Tzu-Yang, Hsien. "Synthesis of porous, magnetic chitosan beads and application to cadmium ion adsorption". Thesis, 1992. http://hdl.handle.net/1957/36143.
Testo completo
32
Lobanga, Kaluka Paul. "Natural organic matter removal from surface waters by enhanced coagulation, granular activated carbon adsorption and Ion exchange". Thesis, 2014. http://hdl.handle.net/10210/12109.
Testo completoAbstract (sommario):
M.Ing. (Civil Engineering)Natural organic matter (NOM) is a complex mixture of organic compounds resulting from the decay of plants and animals. When not properly removed, NOM reacts with disinfectants to form disinfection by-products, of which some are known to be carcinogenic. Regulations have become more and more stringent about the maximum level of NOM in drinking water. Different water treatment processes can be applied to remove NOM. However, because each process targets specific fractions of NOM, this results in the existence of recalcitrant NOM fractions that are not removed, for each treatment process. The main objective of the study was thus to investigate NOM removal by using three advanced water treatment processes alone and in combination. The processes used were enhanced coagulation, granular activated carbon adsorption and ion exchange resin processes. Strong and weak base ion exchange resins were used. Although NOM removal methods have been investigated intensively, little attention is given to a so-called “multi-barrier” approach of NOM removal through enhanced coagulation, granular activated carbon adsorption and ion exchange resin that could be applied in practice. In order to take the seasonal and geographical variability of NOM into account, water samples were collected at eight geographical areas over five to seven seasons from 2010 to 2013. Results showed that different treatment processes remove different NOM fractions with different efficiency. Results also confirmed that EC performs better than the adsorptive treatment processes. But the literature shows that NOM removal by EC is difficult for water with high alkalinity and low SUVA values, which is common with SA waters. The adsorptive processes used for NOM removal revealed that they are not viable options, because even low percentage of NOM removal would require high adsorbent dosages, which removes this approach as a practical option.
33
Tewari, Sanjay. "Regeneration of Carbon Aerogel Exhausted in Water Purification". Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10562.
Testo completoAbstract (sommario):
Carbon has been used electrochemically in various forms for water treatment and the carbon aerogel is one of them. Carbon Aerogels (CA) are used as electrodes due to their high surface capacity and high electrical conductivity. They are also known as Carbon Nanofoams (CNF). CA electrodes attract oppositely charged ions that are nearby. This concept is known as Capacitive De-Ionization (CDI). The use of CA in CDI for water purification is well documented, but not much work has been done on regeneration of CA electrodes. Once saturated, these electrodes lose their ability to adsorb additional ions and it must be restored by regeneration. If they cannot be regenerated, they would need to be replaced, which would greatly increase the cost of the treatment they are expensive. The goal of this study is to obtain data to define optimal regeneration conditions and to develop predictive capability by examining desorption behavior of adsorbed ions on CA electrodes.
This study focuses on desorption of adsorbed ions and regeneration of CA. Various experiments were conducted to explore the effects on regeneration of CA of shorting of electrodes, change of polarity of electrodes, flow speed of water over CA electrodes, and temperature of regeneration water. The optimal combination of experimental variables was identified and was used for remaining experiments that tested the effect of size, charge and mass of adsorbed ions on regeneration of CA. Also, the effect of thickness of CA and its pore size on regeneration of CA was studied.
Results indicated that application of reverse potential for the first few minutes of the total regeneration time provided the greatest regeneration. Longer application of reverse potential did not result in higher regeneration. The regeneration behavior when no potential applied with and without shorting was as expected. Application of reverse potential with variable temperature or variable flow speed of water over CA surfaces provided results that were different from the ones that were obtained with no potential being applied with or without shorting of electrodes.
34
Falayi, Thabo. "Absorption of heavy metals and neutralisation of acid mine drainage using clay minerals". Thesis, 2014. http://hdl.handle.net/10210/11027.
Testo completo
35
Savant, Vivek. "Protein adsorption on chitosan-polyanion complexes : application to aqueous food processing wastes". Thesis, 2001. http://hdl.handle.net/1957/26560.
Testo completoAbstract (sommario):
Chitosan has been proposed as a "natural" coagulating agent to solve
wastewater problems. The main hindrance in this commercial chitosan application has
been its low cost effectiveness. The hypothesis in our research is that chitosan
complexes with natural polyanions is more effective than chitosan alone, particularly
in recovering low concentration proteins from food processing wastewater.
Chitosan (Chi) was reacted with alginate (Alg), pectin (Pec) and carrageenan
(Car) ex-situ to obtain chitosan-polyanion complexes (Chi-Pol). Analysis by Fourier
Transform Infrared (FTER) spectroscopy confirmed electrostatic interactions as the
mechanism for complex formation. Scanning electron microscopy revealed a tight,
non-porous structure except for the porous Chi-Car complex. Tests with a bovine
serum albumin solution revealed low adsorption rates with slightly higher values for
Chi-Car suggesting the need for an improved complexation method.
Chi-Pol complexes prepared in-situ at different monomeric weight ratios (MR)
were evaluated using pH 6 adjusted Cheddar cheese whey and surimi wastewater
(SWW). Complexes used at 30 mg complex/L whey showed higher turbidity
reductions than at 10 mg/L. MR had no significant effect on turbidity reduction except for Chi-Alg at 30 mg/L; the value (72 %) at MR = 0.2 was higher than for MR = 0.8.
UV-Vis spectroscopy confirmed in-situ complex formation with a preference for the
adsorption of specific whey protein fractions.
Complexes formed at 0.2 and 0.8 MR were evaluated at two concentrations for
the treatment of SWW. Tests at 50 mg/L showed a turbidity reduction of up to 97 %
at 24 h with a 81-90 % recovery of SWW proteins. At 150 mg/L, similar efficacy was
achieved in only 1 h with turbidity reductions ranging 94-99 % and 78-94 % protein
recovery. FTIR analyses confirmed the adsorption of proteins as indicated by
similarities in the three amide bands for Chi-Alg recovered solids and untreated SWW.
Differential scanning calorimetry (DSC) was employed to study interactions
of SWW proteins and Chi-Alg complexes. Untreated and complex bound SWW
proteins revealed single exothermic peaks at 23.3 and 38.0°C, respectively. This
suggested Chi-Alg and SWW protein interactions increased the thermal stability of
SWW proteins. However, further thermal analysis studies are needed to confirm this
finding.Graduation date: 2001
36
Dlamini, Nonjabulo Prudence. "Micro-organisms for the removal of copper and cobalt from aqueous solutions". Thesis, 2010. http://hdl.handle.net/10210/3115.
Testo completoAbstract (sommario):
M.Sc.Inorganic pollutants like heavy metals are some of the major water pollutants worldwide. They are toxic and in some cases carcinogenic even at low concentrations. Their removal from industrial aqueous solutions, wastewater and hydrometallurgical process solutions prior to their release to the environment is necessary for a healthy biosphere which includes human beings, aquatic life and plants. There are several technologies used to remove metals such as Cu, Co, Zn, Hg from water. These include among others, ion exchange, membrane filtration, activated carbon, electrochemical treatment, chemical precipitation, reverse osmosis, coagulation and flocculation. Although they have been used in the removal of metal pollutants from water, these technologies produce high quantities of sludge. They are also expensive to operate and need well trained personnel to operate large chemical plants. Since current metal removal techniques have limitations, a need exists for the development of environmentally friendly and cost effective techniques for the removal of metal ions from aqueous media. The focus of this research project is on the use of micro-organisms as biosorbents for copper and cobalt pollutants in aqueous solutions. The experimental work was carried out on a laboratory scale and a summary of our findings is presented as follows: Synthetic sulphate solutions of copper and cobalt were prepared using CuSO4. 7H2O and CoSO4. 5H2O powders. Concentrations of 0.002 M, 0.07 M and 0.2 M copper and cobalt ions in solution were used as test synthetic solutions for our experiments. Mixed strains of bioleaching bacteria were sourced from Mintek (Randburg, South Africa) to test the viability of this research project. This consortium contained Acidithiobacillus caldus, Leptospirillum spp, Ferroplasma spp and Sulphobacillus spp. These bacteria were able to remove up to 55% copper and 25% cobalt from low concentrated copper and cobalt sulphate solutions with 69% and 58% removal demonstrated in the case of mine effluents emanating from metallurgical operations. Different strains of micro-organisms (bacteria) were isolated from mine dumps and mine operation effluents and soil from the Palabora Mining Company in Limpopo, a northern province in South Africa and Nigel Town in the Gauteng Province. The isolated bacterial strains were then identified using PCR analysis and strains from the Bacillus genre were found to be predominant. Shewanella spp was also present. Pseudomonas spp was isolated using Pseudomonas agar base. These bacteria were then cultured at different species-specific culture conditions and their capabilities to remove copper and cobalt ions first from synthetic solutions and subsequently from mine effluents emanating from metallurgical operations were tested. In the first stage of biosorption experiments, factors that affect biosorption mechanisms which include, solution concentration, biomass concentration, pH, contact time and the presence of other metal co-ions were investigated. A decrease in the amount of metal sorbed as solution concentrations increased was observed with all the bacterial strains. An increase in metal sorption was also observed when biomass concentration was increased. The pH was found to be a species dependant parameter.
37
Kanwar, Lalita. "Defluoridation Of Drinking Water Using Activated Alumina". Thesis, 2010. https://etd.iisc.ac.in/handle/2005/1991.
Testo completoAbstract (sommario):
Excess fluoride (F-) in drinking water poses a health threat to millions of people around the world. In the present work, activated alumina (AA) has been used as an adsorbent. Data obtained from batch experiments were fitted to the (i) pseudo-first order, (ii) pseudo-second order, and (iii) Langmuir kinetic model. Model (ii) performed better than model (i), and fitted the data well. However, the rate constant for adsorption ka had to be varied as a function of the initial concentration of F- in the liquid phase c0. A more satisfactory approach is provided by Langmuir model, which fitted the data reasonably even though ka was independent of c0.
Shreyas (2008) developed a model for the batch adsorption of F- onto porous pellets of AA. Some errors were detected in his computer program were corrected. The parameters of the model were estimated by fitting predictions to data. The parameter values suggest that the adsorption process is likely to be diffusion limited.
Column experiments were conducted as follows. The pellets were soaked in deionized water for a time ts before they were loaded into columns. A feed solution having a fluoride concentration cf = 3 mg/L was fed to column and the concentration of F- in the exit stream ce was measured at regular intervals. Breakthrough was deemed to have occurred when ce exceeded the permissible limit (= 1 mg/L). Constant values of the bed height H, and the empty bed contact time tc were used in the experiments.
The volume of treated water V, scaled by the volume of the bed Vb, varied strongly with the soaking time ts, with a maximum at ts = 24 h. To understand the possible reasons for this behaviour, XRD, FESEM, and FTIR were used to characterize the surface of AA. Though the concentrations of the surface hydroxyl groups may influence the adsorption of F-, FTIR studies show there is no direct correlation between V/Vb and the concentrations of these groups. The FESEM and XRD studies indicate that fresh AA consists mainly of boehmite, which gradually converted to gibbsite during soaking.
For fixed values of H and tc, the dimensionless volume of treated water V/Vb was a maximum at D = 45 mm. This behaviour may be caused by wall effects for small values of D and by occurrence of quasi-static regions near the wall for large values of D. The cost of treated of water was Rs. 0.42/L. It decreased slightly to Rs. 0.37/L after one regeneration cycle, but increased to Rs. 0.41/L after two cycles. The volume of treated water after two regeneration cycles was 595 L/kg. The concentration of Al3+ ions ca in the treated water increased and exceeded the permissible limit of 0.2 mg/L as the number of regeneration cycles increased. The concentration of F- in regeneration effluent cre was in the range 32-70 mg/L. The effluent was subjected to solar distillation, leading to a distillate whose fluoride concentration F- was in the range 9-12 mg/L. The distillate can be discharged into the public sewers, as the permissible limit is 15 mg/L.
38
Vilakati, Gcina Doctor. "Biodegradable polymer composites : synthesis, properties and application in water purification". Thesis, 2012. http://hdl.handle.net/10210/4672.
Testo completoAbstract (sommario):
M.Sc.The addition of lignocellulosic fibres to thermoplastic polymers is known to increase the toughness of the polymers but it compromises the tensile strength. On the other hand, inorganic fillers like TiO2 are known to improve the tensile strength of polymers. These plant fibres have been used as adsorbents of metal pollutants in water. Best results were obtained when such materials were ground to fine powder but due to low density, the fibres float and form aggregates in water. Being highly biodegradable in nature makes plant fibres unsuitable for water treatment over lengthy periods of time. They cannot be used as standalone materials. Mixing these adsorbents with polymers, which cannot only act as support for the adsorbents but also disperse the fibres within it thus preventing leaching, is a cause for concern. This study was aimed at fabricating plant fibre-polymer composites that will have improved mechanical and thermal properties. These composites were to be tested for their ability to be used as metal ion adsorbents. The composites were fabricated using a melt-mix compounding method. Two thermoplastic polymers, EVA and PCL were each mixed with either lignin or SCB and TiO2 in different ratios. A rheomex mixer coupled with a single screw extruder which was attached to a sheet die was used to synthesise the composites. TGA and DSC were used for thermal propagation while the mechanical properties were investigated using an instron. Metal ion adsorption measurements were analysed using an atomic absorption spectrometer (AAS). These adsorbents were used to remove Cr(VI), Cr(III) and Pb(II), varying different environmental parameters like pH, concentration, time and adsorbent at constant temperature. The reinforcing effect of both lignin and SCB resulted to poor thermal and mechanical properties. This was shown by a decrease in onset degradation temperature and the tensile and toughness of the composites compared to the neat polymers. The incorporation of TiO2 on SCB-EVA composites, however, improved the mechanical strength and resulted in a thermally stable composite compared to counterpart composites without TiO2. This observation was surpassed at high filler loading as the addition of TiO2 resulted in a decrease of the properties. For the tensile strength, neat EVA recorded 11.35 MPa while 2% TiO2-EVA registered 12.49 MPa for example. For the same composite, the onset degradation temperature for EVA was 353 oC but shifted to 368 oC after the addition of TiO2. At higher filler loading, no effect was observed when adding TiO2.
39
Yu, Yanjie. "Mesoporous Carbon Produced from Tri-constituent Mesoporous Carbon-silica Composite for Water Purification". Thesis, 2012. http://hdl.handle.net/10754/273073.
Testo completoAbstract (sommario):
Highly ordered mesoporous carbon-silica nanocomposites with interpenetrating carbon and silica networks were synthesized by the evaporation-induced tri-constituent co- assembly approach. The removal of silica by concentrated NaOH solution produced mesoporous carbons, which contained not only the primary large pores, but also the secondary mesopores in the carbon walls. The thus synthesized mesoporous carbon was further activated by using ZnCl2. The activated mesoporous carbon showed an improved surface area and pore volume. The synthesized mesoporous carbon was tested for diuron removal from water and the results showed that the carbon gave a fast diuron adsorption kinetics and a high diuron removal capacity, which was attributable to the primary mesopore channels being the highway for mass transfer, which led to short diffusion path length and easy accessibility of the interpenetrated secondary mesopores. The optimal adsorption capacity of the porous carbon was determined to be 390 mg/g, the highest values ever reported for diuron adsorption on carbon-based materials.
40
Muthui, Muliwa Anthony. "Magnetic adsorption separation process for industrial wastewater treatment using polypyrrole-magnetite nanocomposite". 2013. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001106.
Testo completoAbstract (sommario):
M.Tech. Engineering: Chemical.Aims at demonstrating the application of semi-continuous and continuous magnetic adsorption separation (MAS) techniques to extract Cr (VI) ions from wastewater streams using PPy-Fe3O4 nanocomposite. Specifically, the research aims to achieve the following objectives: to design, synthesize and characterize new generation PPy-Fe3O4 nanocomposite with varied magnetite composition for hexavalent chromium removal ; to generate batch adsorption kinetic data in a continuously stirred tank reactor (CSTR) and apply existing kinetic models to aid in water treatment system design.; to design and construct magnetic adsorption separation (MAS) device that can operate in a semi-continuous and continuous mode and explore their performances and to optimize the systems' performance.
41
"Separation of chromium species and adsorption of arsenic on titanium dioxide". 2000. http://library.cuhk.edu.hk/record=b5890315.
Testo completoAbstract (sommario):
Wu Xiujuan.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 88-93).
Abstracts in English and Chinese.
ABSTRACT (Chinese)
ABSTRACT
ACKNOWLEDGEMENT
TABLE OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
Chapter CHAPTER ONE: --- INTRODUCTION
Chapter 1.1 --- General B ackground --- p.1
Chapter 1.2 --- Chromium in Environment and its Analysis --- p.2
Chapter 1.2.1 --- Source of Chromium and its Harmful Effects on Human --- p.2
Chapter 1.2.2 --- Methods for Separation and Determination of Chromium Species --- p.4
Chapter 1.3 --- Arsenic in the Environment and its Toxicity --- p.4
Chapter 1.4 --- Properties of TiO2 and Its Applications --- p.6
Chapter 1.4.1 --- Photocatalytic Property of TiO2 --- p.6
Chapter 1.4.2 --- Surface Acid-Basic Property of TiO2 --- p.8
Chapter 1.5 --- Adsorption --- p.11
Chapter 1.6 --- Fundamental of ICP-AES and ICP-MS --- p.12
Chapter 1.6.l --- Principle of ICP-AES --- p.12
Chapter 1.6.2 --- Principle of ICP-MS --- p.14
Chapter 1.7 --- Scope of Work --- p.18
Chapter CHAPTER TWO: --- SEPERATION OF CHROMIUM SPECIES ON TIO2
Chapter 2.1 --- Introduction --- p.19
Chapter 2.2 --- Experimental --- p.23
Chapter 2.2.1 --- Materials --- p.23
Chapter 2.2.2 --- Instruments --- p.24
Chapter 2.2.2.1 --- Coupling of TiO2 column and ICP-AES --- p.24
Chapter 2.2.2.2 --- Coupling of TiO2 column and ICP-MS --- p.26
Chapter 2.2.3. --- Procedure --- p.29
Chapter 2.3 --- Results and Discussion --- p.33
Chapter 2.3.1 --- Preliminary study on the adsorption of Cr(III) and Cr(VI) on TiO2 --- p.33
Chapter 2.3.2 --- Development and Verification of the proposed method for speciation of Cr(III) and Cr(VI) in aqueous solution --- p.42
Chapter 2.3.3 --- Practical application of the proposed method for separation and determination of Cr(III) and Cr(VI) --- p.46
Chapter CHAPTER THREE: --- ADSORPTION OF ARSENIC SPECIES ON TiO2
Chapter 3.1 --- Introduction --- p.61
Chapter 3.2 --- Experimental --- p.66
Chapter 3.2.1 --- Materials --- p.66
Chapter 3.2.2 --- Instruments --- p.69
Chapter 3.2.3 --- Procedure --- p.70
Chapter 3.3 --- Results and Discussion --- p.71
Chapter 3.3.1 --- Adsorption Kinetics --- p.71
Chapter 3.3.2 --- Effect of pH on Adsorption of Arsenic Species --- p.71
Chapter 3.3.3 --- Adsorption Isotherm --- p.74
Chapter 3.3.4 --- Adsorption Model --- p.76
Chapter 3.3.5 --- Factors Affecting the Adsorption of Arsenic Species on p25 and Rutile TiO2 --- p.83
Chapter CHAPTER FOUR: --- CONCLUSION --- p.86
REFERENCES --- p.88
42
Leswifi, Taile Yvonne. "Removal of Lead, Fluoride and Chromium from water using Metal oxide nanostructured adsorption media". 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001339.
Testo completoAbstract (sommario):
M. Tech. Chemical Engineering.Discusses the application of nanotechnology process to offer wholesale benefits in water and wastewater treatment, extremely very few researches have been conducted in this field. Even with the few, studies have mainly focused on using single ion aqueous solution. Such approach is novel but the results may not give true picture of performance of nano-materials. It's known that water quality adversely affect sorption process. It's thus product to use real field water and wastewater to get valuable results. Presently, there is almost no information is open literature regarding the application of nano-scale adsorbents in treating real water and wastewater.
43
Mwangi, Isaac Waweru. "Functionalized synthetic-and bio-sorbents for removal of inorganic and organic contaminants in water". Thesis, 2013. http://hdl.handle.net/10210/8568.
Testo completoAbstract (sommario):
D.Phil. (Chemistry)This thesis describes the improvement of sorption capacity and efficiency of synthetic and biological adsorbents towards selected pollutants by introducing functional groups on the sorbents. Functionalization was achieved by chemically modifying the binding sites of the studied adsorbents. The sorbent materials considered were chemical resins (Amberlite XAD 1180) and biomass (maize tassels and seaweed). The adsorbents were modified with ethylenediamine in order to improve their capacity for extraction of heavy metals, namely lead, copper and cadmium from water. For the removal of phenols from water, maize tassels was modified with polydiallyldimethylammonium chloride (polyDADMAC). The main focus of the proposed study was to formulate cheap and sustainable ways of purifying contaminated water by exploiting the pollutants’ affinity towards the adsorbents. Parameters such as contact time, sorbent quantities, analyte concentrations, desorption solution (for stripping adsorbed metals for sorbent reuse) and pH were optimized. Different isotherms were applied on the experimental data to establish sorption mechanisms and energies involved during the sorption process. The Langmuir isotherm was used to test for monolayer sorption while the Freundlich model tested multilayer adsorption on heterogeneous surfaces...
44
Olorundare, Oluwasayo Folasayo. "Activated carbon from maize tassels and polymer composites for water decontamination". Thesis, 2014. http://hdl.handle.net/10210/11380.
Testo completoAbstract (sommario):
Ph.D. (Chemistry)This study presents work on the preparation, characterisation and application of agricultural waste residue, maize tassel in the production of activated carbon (AC) using both physical and chemical methods of activation in their production. The activated carbon produced from maize tassel (MTAC) or steam-produced activated carbon (STAC) were later added as a filler – together with beta-cyclodextrin (β-CD), and raw tassel (RT) – in the production of polyurethane composite adsorbent (PUCAD) material for the removal of selected inorganic (such as Cd2+, Cr3+, Pb2+) and organic pollutants (phenolic compound - bisphenol A (BPA), ortho-nitrophenol (O-NTP), para-chlorophenol (PCP), polychlorinated biphenyl (PCB), and methylene blue (MB) as adsorbate/analytes from aqueous medium. Both batch and solid-phase extraction adsorption methods (SPE), were used for separation and preconcentration. The investigations included reactivity using Fourier transform infrared (FT-IR) spectroscopy, surface morphology analysis using scanning electron microscopy (SEM), thermal stability using thermogravimetric analysis (TGA), heat flow using differential scanning calorimetry (DSC), and crystallinity using X-ray diffraction (XRD) coupled with energy dispersive X-ray spectrometry (EDX). The FT-IR analysis revealed that there was interaction between the polymeric material and all the fillers. The hydrogen bonding and N-H group interaction between all the materials and the polyurethane polymer composite (PCAD) showed compatibility between the polymeric materials and the fillers.
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Kanwar, Lalita. "Defluoridation Of Drinking Water Using Activated Alumina". Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1991.
Testo completoAbstract (sommario):
Excess fluoride (F-) in drinking water poses a health threat to millions of people around the world. In the present work, activated alumina (AA) has been used as an adsorbent. Data obtained from batch experiments were fitted to the (i) pseudo-first order, (ii) pseudo-second order, and (iii) Langmuir kinetic model. Model (ii) performed better than model (i), and fitted the data well. However, the rate constant for adsorption ka had to be varied as a function of the initial concentration of F- in the liquid phase c0. A more satisfactory approach is provided by Langmuir model, which fitted the data reasonably even though ka was independent of c0.
Shreyas (2008) developed a model for the batch adsorption of F- onto porous pellets of AA. Some errors were detected in his computer program were corrected. The parameters of the model were estimated by fitting predictions to data. The parameter values suggest that the adsorption process is likely to be diffusion limited.
Column experiments were conducted as follows. The pellets were soaked in deionized water for a time ts before they were loaded into columns. A feed solution having a fluoride concentration cf = 3 mg/L was fed to column and the concentration of F- in the exit stream ce was measured at regular intervals. Breakthrough was deemed to have occurred when ce exceeded the permissible limit (= 1 mg/L). Constant values of the bed height H, and the empty bed contact time tc were used in the experiments.
The volume of treated water V, scaled by the volume of the bed Vb, varied strongly with the soaking time ts, with a maximum at ts = 24 h. To understand the possible reasons for this behaviour, XRD, FESEM, and FTIR were used to characterize the surface of AA. Though the concentrations of the surface hydroxyl groups may influence the adsorption of F-, FTIR studies show there is no direct correlation between V/Vb and the concentrations of these groups. The FESEM and XRD studies indicate that fresh AA consists mainly of boehmite, which gradually converted to gibbsite during soaking.
For fixed values of H and tc, the dimensionless volume of treated water V/Vb was a maximum at D = 45 mm. This behaviour may be caused by wall effects for small values of D and by occurrence of quasi-static regions near the wall for large values of D. The cost of treated of water was Rs. 0.42/L. It decreased slightly to Rs. 0.37/L after one regeneration cycle, but increased to Rs. 0.41/L after two cycles. The volume of treated water after two regeneration cycles was 595 L/kg. The concentration of Al3+ ions ca in the treated water increased and exceeded the permissible limit of 0.2 mg/L as the number of regeneration cycles increased. The concentration of F- in regeneration effluent cre was in the range 32-70 mg/L. The effluent was subjected to solar distillation, leading to a distillate whose fluoride concentration F- was in the range 9-12 mg/L. The distillate can be discharged into the public sewers, as the permissible limit is 15 mg/L.
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Mgwetyana, Unathi. "Recovery of base metals from nitric and sulphiric solutions using carbon nanotubes". Thesis, 2014. http://hdl.handle.net/10210/8861.
Testo completoAbstract (sommario):
M.Tech. (Extraction Metallurgy)For many decades, carbon nanotubes (CNTs) have been used as adsorbents for the removal of pollutants from wastewaters because of their unique properties such as inert surface, resistance to acid and base environment, rigidity and strength. Herein is a report of application of functionalised CNTs on the adsorption of metal ions from aqueous solutions and mine leachates. The CNTs were first synthesised in-house, purified, functionalised and characterised with various characterisation techniques: FTIR (Fourier Transform Infrared), SEM (Scanning Electron Microscopy, TEM (Transmission Electron Microscopy), EDS (Energy Dispersive Spectroscopy), Raman Spectroscopy, TGA (Thermal Gravimetric Analysis) and BET (Brunauer-Emmet-Teller). Together, these techniques gave substantiation for structure, surface and chemical modification of the synthesised moieties. After characterisation, the functional groups were attached to the walls of the tubes and this implies successful functionalisation...
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Nyembe, Dumsile W. "Natural clinoptilolite for the removal of cobalt and copper from aqueous solutions". Thesis, 2011. http://hdl.handle.net/10210/3593.
Testo completoAbstract (sommario):
M.Sc.The metallurgical industrial losses of base metals with waste solutions are an environmental threat to water sources, hence these metal ions must be removed prior to discharge into receiving bodies. In this study, Southern African clinoptilolite’s capability as an ion-exchanger with respect to Cu2+ and Co2+ was investigated in order to consider its application in metal cation removal from aqueous solutions. The clinoptilolite was characterised with X-ray powder diffraction (XRD), X-ray fluorescence (XRF), FTIR, thermogravimetric analyser (TGA) and SEM-EDS. The clinoptilolite was found to be a thermally stable alumino-silicate with calcite, dolomite and quartz as the main minerals. Investigations of Co2+ and Cu2+ uptake were first performed on non-mixed solutions of these cations. It was found that Cu2+ was removed faster than Co2+ with removal efficiencies of 79% and 63% respectively. The column method was used in the cation-exchange processes with synthetic solutions of 0.0020 M, 0.0698 M and 0.2000 M of Co2+ and Cu2+ concentrations which were measured using atomic absorption spectroscopy (AAS). The effects of Co2+ and Cu2+ ions on one another’s removal efficiency were investigated on Co/Cu mixed synthetic solutions by varying their concentration ratios in solution. The Cu2+ was generally found to be removed at lower rates than the Co2+. Investigations on added impurities in the form of Si4+ and Fe2+ in the mixed Co/Cu synthetic solutions were carried out to determine their effect on the removal efficiencies of the targeted metals. It was found that both Si4+ and Fe2+ greatly reduced the removal efficiency of Cu2+, especially with increased amounts of Si4+ in the Co/Cu solution.
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Ntamo, Sihlangule Abenathi. "Sorptive removal of antibiotics from water using surfactant modified Zeolite". 2013. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001109.
Testo completoAbstract (sommario):
M. Tech. Engineering: Chemical.Focuses on the emerging application of clinoptilolite in removing aspirin and cephalexin from municipal wastewater streams. The mechanisms of sorbent-organic compounds interaction was studied in detail. Specifically, this research aims to achieve the following objectives: I. to investigate the sorption capacity of surfactant modified clinoptilolite on the removal of aspirin and cephalexin ; II. To relate sorbents performance to process variables with sorbent properties and water quality ; III. to compare the sorption capacity of surfactant modified clinoptilolite to commercial emerging adsorbents on the removal of aspirin and cephalexin from aqueous solution ; IV. to apply existing mathematical models to describe isotherms and kinetic data in order to extract design parameters.
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Sekhula, Mahlatse Mapula. "The use of maize tassel as a solid phase extraction sorbent for the recovery of copper, gold and silver from aqueous solution". 2011. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000465.
Testo completoAbstract (sommario):
M. Tech. Environmental ManagementInvestigates the possibility of using maize tassel powder as a solid phase extraction sorbent for the recovery of Ag, Au and Cu from aqueous solution. The surface characteristics of maize tassel and its ability to remove Ag, Au and Cu from aqueous solutions needed to be established before the preparation of maize tassel beads.
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Dlamini, Thulani. "Development of a small scale water treatment system for fluoride removal for rural areas". Thesis, 2015. http://hdl.handle.net/10321/1366.
Testo completoAbstract (sommario):
Submitted in fulfillment of the requirements for the degree of Master of Engineering in Chemical Engineering, Durban University of Technology. Durban. South Africa, 2015.Several areas in the world such as the United States of America, Sri Lanka, China, Argentina, Canada, Tanzania, Kenya, South Africa and many others have a problem of high fluoride content in drinking water. Generally fluoride levels above 1.5 ppm in water may result in dental and skeletal fluorosis in humans depending on quantity consumed (Fan et al., 2003; Meenakshi, 2004). Remote rural areas where there are no water treatment facilities are more vulnerable to this problem. Adsorbents such as activated alumina and FR-10 resin seem to have a potential for successful application in rural areas. These methods however require pre-treatment if the feed has high turbidity. A membrane based system called woven fabric microfiltration gravity filter (WFMFGF) developed by Durban University of Technology proved to be suitable for turbidity removal. The main objective of this research was to develop a small water treatment system for fluoride removal. The small water treatment system developed in this study consists of WFMFGF for pre-treatment and an adsorption column. The WFMFGF is made up of a 40 L container packed with 15 immersed flat sheet membrane elements. The operation of the WFMFGF is in batch mode, driven by varying static head. The static head variation results in flow rate variation through the system. This in turn result in variation of contact time, velocity as well as pressure drop in the fluoride removal unit. Specific objectives of the study were: (1) to establish the maximum and minimum flow rates through the WFMFGF system, the total run time before cleaning is required and the best cleaning method for this particular membrane system. (2) to evaluate and compare the performance of activated alumina and FR-10 resin on varying contact time, velocity and pressure drop on the fluoride removal unit. The adsorbents were also compared on adsorption capacity, cost and ease of operation. The minimum and maximum flow rates through the WFMFGF were found to be 5 l/hr and 100 l/hr respectively. It was found that the system can be run for more than a month before requiring cleaning. The suitable cleaning method was found to be soaking the membranes in 0.0225 percent sodium hypochlorite solution overnight and brushing them using a plastic brush. The comparison of the performance of FR-10 resin to activated alumina found that the adsorbents gave equal performance based on the given criteria. FR-10 resin had higher adsorption capacity, gave good quality treated water even with shorter contact time and operated at wider velocity range. Activated alumina on the other hand had an advantage of lower costs, lower pressure drop and ease of use. According to Pontius (1990), the performance of activated alumina can be improved by intermittent operation. Point of use (POU) systems are generally operated intermittently. This improves the fluoride removal efficiency of activated alumina giving it more advantage over FR-10 resin. Based on this activated alumina was selected as the best adsorbent for the system. After the adsorbent was selected, the adsorption column was designed. The column operation regime was 3.5 minutes minimum contact time and 1.17 to 7.8 m/hr velocity range. The activated alumina adsorption capacity was 1.53mg/g. The column had an inside diameter of 70 mm. It was packed with activated alumina to a bed height of 400 mm. The column inlet and outlet pipes were made of PVC with a standard pipe size of 20 mm outside diameter. A valve at the column inlet pipe allowed water to flow through the system.