Dissertations / Theses on the topic 'Ion exchange resins'
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Houghton, Mark Phillip. "Polymer-supported reactions using ion-exchange resins." Thesis, Lancaster University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255343.
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Abonijim, M. N. "Ion exchange properties of poly(vinylimidazoline) resins." Thesis, University of Salford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381642.
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Pearson, C. H. G. "New ion exchange resins for ion chromatography applied to anions." Thesis, University of Kent, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372771.
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Leonard, Danièle. "Adsorption of bile acids by ion-exchange resins." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74309.
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The interactions of cholestyramine with bile acids in aqueous buffer solutions were studied by in vitro adsorption experiments. Application of the Donnan theory, which is based on ion partitioning between two phases, indicates that the adsorption is an ion-exchange process--the bile acid anion displaces the chloride counter-ion of cholestyramine. Donnan considerations indicate that the bile acid in the resin phase exists in two forms, bound and unbound, but at higher Ceq the bound form is increasingly favoured. Since the concentrations of bound bile acid in the resin phase are above the critical micellar concentration, micelle-type ordering is occurring. It is also possible that the unbound bile acid in the resin phase aggregates to form "regular" micelles. The micellization promotes the partitioning of glycocholic acid into the resin phase, explaining the ability of cholestyramine to adsorb glycocholic acid significantly, in vitro.Ion-exchange resins were prepared by solid phase peptide synthesis with active sites chosen to resemble those of cholestyramine. They were produced by coupling 4-(aminomethyl)benzoic acid, 4-aminophenylacetic acid or 4-(aminomethyl)phenylacetic acid to the backbone. The ion-exchange resins were prepared both as primary amines and in the quaternized form. The cholestyramine-like sorbents were synthesized with systematic changes in the structure, to determine which structural parts of cholestyramine are involved in the adsorption process. As compared to cholestyramine, both sets of resins were remarkably ineffective in adsorbing bile acids in vitro. It was found that the nature of the backbone determines the accessibility to the active site; that the resins with the methylene group positioned between the phenyl group and the amino group have higher adsorption capacity for glycocholic acid; and that quaternization increases the adsorption capacity. The two latter observations indicate the importance of the basicity of the active site. Therefore, in cholestyramine, the backbone is such that it permits the transfer of ionic species and the quaternary ammonium group is involved in the interaction with bile acids.
Computer modelling showed that the cholestyramine pendants are close to one another and are separated by benzene rings, thus leaving too little space between them to allow a bile acid molecule to interact with the benzene rings. Therefore, the bile acids must interact with the quaternary ammonium group, leaving the bile acid molecule inside the cavity where they interact with one another to form micelles. The possible modes of interactions of bile acids with the synthesized resins are more numerous since the pendants are not as close together. (Abstract shortened by UMI.)
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Ntemi, Pascal Vitalis. "Taste masking of clarithromycin with ion exchange resins." Thesis, Rhodes University, 2017. http://hdl.handle.net/10962/65178.
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Rejaldien, Moegamat Zain. "Base metal equilibrium prediction on ion exchange resin." Thesis, Cape Technikon, 2002. http://hdl.handle.net/20.500.11838/875.
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Thesis (MTech (Chemical Engineering)--Cape Technikon, Cape Town, 2002This study is the first phase of an investigation into an alternative process to recover base metals from solution, namely ion exchange. An identified ion exchange resin was employed to study the recovery of copper, nickel and cobalt from electrolytic solutions. The main focus of the investigation was the prediction of equilibrium conditions in this multi-component system using a batch configuration. In order to predict equilibrium conditions. existing multi-component isotherms such as Fritz and Schleunder were tested. It has been shown that traditional isothem15 did not accurately predict equilibrium conditions. hence the need for development of new isotherms. Essentially two approaches were followed in the development of new isotherms namely. an effective concentration approach as well as a heat transfer approach. Both yielded positive outcomes with the effective concentration approach proving to be the most accurate. In addition to these two approaches a thermodynamical approach was also tested which also showed favourable predictions for Cu loading
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Omar, Mokhtar Bukhres. "Synthesis and ion exchange properties of polydithiocarbamate chelating resins." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327923.
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Strangfeld, Vinzenz Klaus. "The recovery of metal cyanides by ion exchange resins." Thesis, Cape Technikon, 2000. http://hdl.handle.net/20.500.11838/882.
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Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town, 2000Cyanide is used extensively in the mining industry to leach gold and silver from their ores. Cyanide, in the form of sodium or potassium cyanide, is added in excess to that required theoretically due to equilibrium and kinetic considerations in the leaching step. This results in free cyanide and various other cyanide complexes reporting to the effluent streams of these operations In this study the removal of these species from solution by means of ion exchange resins was investigated Equilibrium conditions, kinetic parameters and the competitive exchange nature of the process was evaluated. The experimental work focused on contacting the various resins individually in a batch reactor with free cyanide, Iron cyanide and copper cyanide complexes. The experimental data obtained was found to be well explained by the Freundlich-type multiand single-component isotherms. Furthermore, mass transfer parameters were investigated revealing that ceI1ain cyanide species outperform others kinetically in the ion exchange process. During this study it was shown that ion exchange processes could be effective in effluent clean-up of those streams containing cyanide complexes
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Kogovsek, Laurie Maylish. "Magnetic resonance imaging of elastomers and ion exchange resins." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057869238.
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Hackney, Paul Anthony. "An investigation of the destruction of ion exchange resins." Thesis, Aston University, 1992. http://publications.aston.ac.uk/9754/.
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Ion exchange resins are used for many purposes in various areas of science and commerce. One example is the use of cation exchange resins in the nuclear industry for the clean up of radioactively contaminated water (for example the removal of 137Cs). However, during removal of radionuclides, the resin itself becomes radioactively contaminated, and must be treated as Intermediate Level Waste. This radioactive contamination of the resin creates a disposal problem. Conventionally, there are two main avenues of disposal for industrial wastes, landfill burial or incineration. However, these are regarded as inappropriate for the disposal of the cation exchange resin involved in this project. Thus, a method involving the use of Fenton's Reagent (Hydrogen Peroxide/soluble Iron catalyst) to destroy the resin by wet oxidation has been developed. This process converts 95% of the solid resin to gaseous CO2, thus greatly reducing the volume of radioactive waste that has to be disposed of. However, hydrogen peroxide is an expensive reagent, and is a major component of the cost of any potential plant for the destruction of ion exchange resin. The aim of my project has been to discover a way of improving the efficiency of the destruction of the resin thus reducing the cost involved in the use of hydrogen peroxide. The work on this problem has been concentrated in two main areas:-1) Use of analytical techniques such as NMR and IR to follow the process of the hydrogen peroxide destruction of both resin beads and model systems such as water soluble calixarenes. 2) Use of various physical and chemical techniques in an attempt to improve the overall efficiency of hydrogen peroxide utilization. Examples of these techniques include UV irradiation, both with and without a photocatalyst, oxygen carrying molecules and various stirring regimes.
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Nesbitt, Allan Bernard. "Recovery of metal cyanides using a fluidized bed of resin." Thesis, Cape Technikon, 1996. http://hdl.handle.net/20.500.11838/906.
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Thesis (MTech(Chemical engineering))--Cape Technikon, Cape Town,1996Metal cyanide complexes are a toxic pollutant in waslewater originating from various industrial and mining activities. The removal/retrieval ofcyanide and metal cyanide complexes has been studiedby researches for many years, leading to the establishment of a variety of patents. The mechanisms used by these patents vary from purely chemical techniques to those using ion exchange Iesins. In this thesis, ,the feasIbility ofthe recovery ofmetal cyanide complexes by using a strong base macroreticular resin, in a fluidized bed configuration, has been investigated. The resin in question is presently used in the sugar indnstry where its main application is the recovery oflarge organic molecules similar in nature to metal cyanides. The selected resin was contacted with synthetic solntions of various metal cyanide complexes. for the purposes of evaluating performance in the adsorption th..."feOf. It was found that polyvalent metal cyanide molecules were adsOlbed efficiently, while divalent metal cyanide molecules were adsorbed satisfactorily. The loaded resin was also evalnated for the ease with which the metal cyanides conId be removed. It was discovered that a brine solntion ofpH 7, conId effectively remove all metal cyanide complexes. This test-work was of particular importance as it is well !moon that the removal ofmetal cyanides from strong base metals is not easily achieved. To distingnish the fluidization characteristics of the selected resin (or any resin for that matter), a method of modelling the expansion of a flnidized resin bed was proposed, that takes into account the diflicnIties associated with the byclrod:)nantic charncteristics of a macroporous resin of this nature. The technique is based on the Serial Afadel which is a discretised application of the Z3ki and Richardson equation. From the interpretation of the resnIts of a matrix of fluidization tests, it was fonnd that the algorithm proposed conId effectively model the expansion of a fluidized bed of ion exchange resin, independently of the dimensions ofthe accomodatiog receptical. Finally. it was shown that the change in the fluidization characteristics of the selected resin, between its chloride and metal cyanide states, could clearly be modelled by the technique referred to above.
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Bowley, Michael Allan. "The adsorption of colloidal material to highly porous ion-exchange resins." Master's thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/23171.
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Pathak, Sudhir Kumar. "Treatment of Landfill leachates using anion exchange resins." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51812.
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Landfill leachates are often discharged to wastewater treatment plants (WWTPs) but their highly varied composition makes their treatment in WWTPs difficult. Landfill leachates contain bio-refractory organic matter which easily passes the biological treatment processes at WWTPs and increases the organic matter in the effluent. Leachates also interfere with the UV disinfection process at treatment plants. Another concern is the presence of large amounts of bio-refractory organic nitrogen in the leachates which makes it difficult for WWTPs to meet the tightening total nitrogen requirements.
Studies were conducted to evaluate the applicability of anion exchange resins to remove organic matter, UV quenching substance and organic nitrogen from landfill leachates. Leachate samples based on varying age and treatment methods were utilized. The anion exchange resins were found to work effectively for all studied leachates. The resins were found to remove more bio-refractory UV absorbing substances as compared to total organic carbon (TOC), suggesting that anion exchange resins could be employed for removal of UV absorbing substances. Multiple regenerations of the resin showed slight loss in the capacity to remove UV and organic carbon. Fractionation of leachate samples showed effective removal of humic acid (HA) fraction which is responsible for most of UV quenching. The resin was also found to effectively remove the bio-refractory hydrophilic (Hpi) fraction which tends to persist even after HA fraction has bio-degraded. Membrane filtration (1000 Da and 3000 Da Molecular weight cut off) in conjunction with ion exchange resins achieved better removal of organic matter and UV254 absorbing substances. In addition, this also significantly improved the performance of resins. Significant removal of organic nitrogen was also observed using anion exchange though it was less than both UV and TOC. Around 80% removal of organic nitrogen associated with bio-refractory Hpi fraction was achieved using anion exchange suggesting ion exchange as a viable alternative for removing organic nitrogen.Master of Science
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Fernando, Kapila Chemical Sciences & Engineering Faculty of Engineering UNSW. "The treatment of cyanidation tailings using ion exchange resin." Awarded by:University of New South Wales. Chemical Sciences & Engineering, 2007. http://handle.unsw.edu.au/1959.4/40697.
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This thesis explores the behaviour of metal cyanide complexes under oxidative acid conditions in ion exchange systems, with the objective of developing an ion exchange based process for the treatment of gold cyanidation tailings. The novel cyanide detoxification process developed from this study employs strong base ion exchange resins to extract cyanide from tailings. Variations in the stability of cyanide complexes are exploited to concentrate, recover, or destroy cyanide species loaded on the resin, through the use of an oxidative acid eluent containing H2O2 and H2SO4. This eluent removes all base metal cyanide complexes from strong base resins, while regenerating the resin. The spent eluent, containing the base metals recovered from the tailings, can be used as a source of such base metals. Copper can be recovered separately from other base metals if necessary. Low levels of precious metals present in the tailings are accumulated on the resin as the ion exchange bed is cycled between loading and elution stages. They can be recovered economically, so as to offset the cost of the tailings detoxification. Cyanide is initially concentrated as an alkaline solution, which can be detoxified within the process or recovered for recycling. This process was successfully tested at pilot scale by treating approximately 14,000 m3 of cyanide contaminated tailings solution, over 14 loading/elution cycles on a standard strong base ion exchange resin bed. This treatment reduced the total cyanide concentration of the contaminated solution from approximately 50 mg/L to an average of 1.5 mg/L. The reagent cost was approximately ADD 0.50 per m3 of treated liquor. When the resin was repeatedly loaded with mixed metal cyanide species and eluted with the oxidative acid eluent, a gradual deterioration of the ion exchange resin performance was noted. The reduction of net operating capacity of the columns due to resin deterioration was in the order of 1-3% per loading/elution cycle. The oxidation of resin catalysed by copper, the precipitation of metal hexacyanoferrates on the resin and the oxidation of Au(CN)2- to Au(CN)4- were identified as possible factors giving rise to the reduction of resin loading capacity.
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Van, der Meulen Nicholas. "Ion exchange behaviour of 42 selected elements on AG MP-50 cation exchange resin in nitric acid and citric acid mixtures." Thesis, Stellenbosch : University of Stellenbosch, 2003. http://hdl.handle.net/10019.1/16452.
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Thesis (MSc)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: The equilibrium distribution coefficients of 42 elements [Li(I), Na(I), K(I), Rb(I), Cs(I), Sc(III), Ti(IV), V(IV), V(V), Mn(II), Fe(III), Ni(II), Zn(II), Al(III), Ga(III), As(V), Y(III), Zr(IV), Nb(V), Mo(VI), Cd(II), In(III), Sn(IV), Sb(V), Ta(V), W(VI), Pb(II), Bi(III), La(III), Ce(III), Th(IV), U(VI), Co(II), Ag(I), Ge(IV),Mg(II), Sr(II), Ba(II), Tb(III), Yb(III), Cr(III) and Cu(II)] on Bio Rad AG MP-50 macroporous cation exchange resin in varying citric acid – nitric acid mixtures were successfully determined. The equilibrium distribution coefficients of these selected elements were determined in 0.1 M and 0.25 M citric acid at various concentrations of nitric acid, namely, 0.2 M, 0.5 M, and 1.0M, respectively. Two component [Mo(VI)-Y(III); Zr(IV)-La(III) and As(V)-Zn(II)] and three component [Nb(V)-Ta(V)-V(V)] elemental separations on a 10 ml AG MP-50 resin column were successfully determined to illustrate how the results of the above equilibrium distribution coefficients can be utilised. From the equilibrium distribution coefficients obtained for magnesium(II) and sodium(I), a proposal was put forward to modify the current sodium-22 production performed at iThemba LABS. While the results did not predict a possible separation between the two elements, a theory concerning the use of citric acid in the production was proven not to hold under the chosen conditions.
AFRIKAANSE OPSOMMING: Die ewewig verdelingskoëffisiënte van 42 elemente [Li(I), Na(I), K(I), Rb(I), Cs(I), Sc(III), Ti(IV), V(IV), V(V), Mn(II), Fe(III), Ni(II), Zn(II), Al(III), Ga(III), As(V), Y(III), Zr(IV), Nb(V), Mo(VI), Cd(II), In(III), Sn(IV), Sb(V), Ta(V), W(VI), Pb(II), Bi(III), La(III), Ce(III), Th(IV), U(VI), Co(II), Ag(I), Ge(IV),Mg(II), Sr(II), Ba(II), Tb(III), Yb(III), Cr(III) en Cu(II)] is op Bio Rad se AG MP-50 makroporeuse kationiese uitruilerhars in verskillende sitroensuur – salpetersuur mengsels met sukses bepaal. Die verdelingskoëffisiënte is in 0.1 M en 0.25 M sitroensuur met verskillende konsentrasies van salpetersuur (0.2 M, 0.5 M en 1.0 M) bepaal. Twee-komponent [Mo(VI)-Y(III); Zr(IV)-La(III) en As(V)-Zn(II)] en drie-komponent [Nb(V)-Ta(V)-V(V)] skeidings op ’n 10 ml AG MP-50 harskolom is suksesvol bepaal om te demonstreer hoe die verdelingskoëffisiëntresultate gebruik kan word. As ’n uitvloeisel van die verdelingskoëffisiëntresultate vir Mg(II) en Na(I), is ’n voorstel ingedien om die huidige natrium-22 produksiemetode, tans in gebruik by iThemba LABS, te modifiseer. Die resultate het nie ’n skeiding tussen die twee elemente voorspel nie, maar het bewys dat ’n teorie oor die gebruik van sitroensuur in die produksie nie heeltemal korrek was onder die huidige toestande nie.
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Lindsay, D. "Polymer-supported ligands for hydrometallurgical applications." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381352.
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LIU, CHUN HUNG. "Imobilizacao de resinas de troca ionica em polimeros." reponame:Repositório Institucional do IPEN, 1994. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10375.
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Harrower, Jason Scott. "Waste encapsulation in cement matrices." Thesis, University of Aberdeen, 1997. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU532244.
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Ion exchange resins have been used for retrieving radiocaesium from aqueous waste streams since the earliest days of the nuclear power industry. The physical and chemical properties of Lewatit DN ion exchange resins encapsulated in silica fume (SF)-blended cement were investigated with the aim of producing a stable solid wasteform for possible future disposal in an underground repository. Expansive reactions involving resin swelling in the high pH pore fluid and Ca(OH)2 formation around the resin particles can be suppressed by the addition of 50-75% SF at w/c ratios of 1.400-1.71. The basis of this suppression is the pozzolanic reaction between Ca(OH)2 and SF which consumes Ca(OH)2 and lowers the pH of the pore fluid to less than 10. The total heat evolution of blended cements is similar to that of a neat Portland cement, demonstrating the exothermic nature of the pozzolanic reaction. The use of high w/c ratios in cements containing 50% SF increases the permeability of the matrix. Porosity measurements indicate that this is due to the high free water content of the paste and the relatively high porosity of SF agglomerates. Elevated curing temperatures (up to 85oC) also increase the permeability as a result of coarsening of the microstructure. Despite the inferior physical immobilisation of caesium in high SF-content cements, leach tests, sorption measurements and pore fluid analysis show that chemical retention of caesium is enhanced by blending, more so in blends containing a permanent excess of SF, due to the formation of highly sorptive silica gel and low ratio C-S-H (Ca/Si as low as 0.80). On the other hand, SF-blended cements are more susceptible to physiochemical degradation in simulated groundwater's containing MgSO4. Chemical attack by MgSO4 converts C-S-H gel and silica gel to a non-cementitious magnesium silicate hydrate (identified as sepiolite) in 50-75% SF pastes, resulting in extensive deterioration of the attacked zone.
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Jackson, Sarah J. "The use of ion exchange resins as potential bioadhesive drug delivery systems." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311924.
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Soto, López Rodrigo. "Simultaneous etherification of C4 and C5 iso-olefins with ethanol over acidic ion-exchange resins for greener fuels." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/402609.
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The use of tertiary alkyl ethers as gasoline components has been gaining relevance in the last decades because they can enhance the gasoline octane rating at the time that they reduce the environmental impact of combustion processes, being therefore considered as environmentally friendly additives. Methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) are the most produced ethers at industrial scale. More recently, ETBE market is acquiring a predominant role compared to MTBE, due to environmental concerns associated with MTBE usage and because ETBE can be manufactured from bioethanol, what confers a bioether character. Apart from MTBE and ETBE, other ethers as tert-amyl methyl ether (TAME) and tert-amyl ethyl ether (TAEE) are interesting alternatives since they can be manufactured from C5 reactive olefins present in gasoline that present drawbacks as high blending vapor pressure or high potential of tropospheric ozone formation. Similar to ETBE, TAEE can be considered as a bioether since bioethanol can be used as reactant. In this sense, ETBE and TAEE can be envisaged as the most promising alternatives as gasoline additives to fulfill the progressively stricter legislation while being compatible with current engines and therefore, a plausible solution at medium-short term.
The optimization and integration of chemical processes is an incentive for industrial plants since several benefits can be obtained as savings in operating and maintenance costs. The simultaneous production of several ethers in the same reaction unit can be a clear example of such technology. A simultaneous etherification unit yielding a mixture of ETBE and TAEE would be one of the most interesting configurations. To the best to our knowledge, such a process has not been yet studied at bench scale. The present PhD thesis is focused on the study of the feasibility of producing ETBE and TAEE as one pot synthesis in the same reaction unit since the industrial interest of such ethers implies a realistic possibility of implementation in the near future.
The main topics covered and assessed throughout the present manuscript are: the comparison of different chemical pathways to evaluate the process feasibility, the optimization of experimental conditions that maximize etherification yields, the study of the effect of water presence on the ethanol used as reactant, the characterization of potential byproducts and how to avoid side reactions, the study of the chemical equilibrium and the implicit thermodynamics of involved reactions, the assessment of several catalysts in order to find the best catalyst and the catalytic properties influencing the observed catalytic activity, the study of the intrinsic kinetics of the main reactions involved in order to find a reliable kinetic model, the study of the adsorption equilibrium of involved species in a potential catalytic surface and finally, the study of the catalyst deactivation process caused by the presence of acetonitrile in the feed stream.
As for the main results, the optimum chemical pathway for producing ETBE and TAEE has been found. Reactants equilibrium conversions and selectivity have been obtained over a wide range of experimental conditions and etherification yields have been empirically modeled and optimized to obtain the experimental conditions that maximize them. Equilibrium constants and thermodynamic state functions of main reactions involved have been experimentally determined, resulting that main etherification reactions are all of exothermic nature. Amberlsyt™35 has been obtained as the best catalyst among evaluated ones. The relation between acid capacity and volume of swollen polymer have been found as the catalyst properties with more influence on the observed catalytic activity. Reliable kinetic models including activation energies and adsorption parameters have been obtained for the main reactions. An Eley-Rideal mechanism has been deduced as the most probable for the reaction system studied. Adsorption equilibrium constants of species on Amberlsyt™35 have been determined in liquid and gas phase. Adsorption of olefins and ethers are comparable and notably lower than that of alcohols. Also diffusivities of species have been estimated. Finally, the catalyst poisoning is enhanced by the concentration of acetonitrile and temperature and a first order kinetic law has been found to describe better the deactivation process.El uso de éteres terciarios como aditivos para las gasolinas ha estado ganando relevancia en las últimas décadas ya que además de aumentar el número de octano de la mezcla, reducen el impacto medioambiental generado por la quema del combustible. La optimización e integración de procesos químicos es un incentivo para muchas plantas industriales ya que se pueden obtener cuantiosos beneficios en los costes de operación y mantenimiento. La producción simultanea de varios éteres terciarios en la misma unidad podría considerarse un ejemplo claro de esta tecnología. Una unidad de eterificación simultanea de isobuteno e isoamilenos con etanol para producir una mezcla de etil terc-butil éter (ETBE) y terc-amil etil éter (TAEE) es una configuración industrial muy interesante y que hasta el momento no se ha planteado ni estudiado a escala de laboratorio. La presente tesis doctoral se basa en el estudio de la viabilidad de la producción simultánea de ETBE y TAEE en la misma unidad de reacción ya que el interés industrial y medioambiental la hace una alternativa plausible y realista que podría ser una realidad industrial a corto medio plazo. Los principales temas abordados en la tesis son: la comparación de diferentes rutas químicas con el objetivo de elucidar la ruta más verde desde un punto de vista medioambiental; la optimización de las condiciones experimentales que permiten maximizar el rendimiento a éteres; el estudio del efecto de agua como potencial impureza del etanol a usar como reactante; el estudio de las constantes de equilibrio y propiedades termodinámicas de las reacciones implicadas; la evaluación de varios tipos de catalizadores con el objetivo de encontrar un catalizador potencial para el proceso e indagar en las propiedades morfológicas que más influencia presentan sobre la actividad catalítica observada; un estudio cinético exhaustivo con el fin de elucidar información importante sobre la cinética del proceso y los posibles mecanismos de reacción implicados en el mismo; el estudio de la adsorción de las especies implicadas sobre un catalizador potencial con el fin de evaluar las constantes de equilibrio y propiedades de adsorción termodinámicas de los diferentes compuestos químicos; y finalmente, el estudio de la desactivación del catalizador por la presencia de posibles venenos en las corrientes de alimento de reactantes.
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Wells, Ricardo Angelo. "Comparison of distribution coefficients of 14 elements on three cation exchangers." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2641.
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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2017.Certain resins used in ion-exchange separation techniques have become very expensive. Although ion-exchange is an economical method to soften water it is important to keep the cost low during the process. Any exorbitant costs will make a process unattractive and eventually obsolete. Bio-Rad AG MP-50 macroporous resin (supplied by Bio-Rad Laboratories, Ltd.) at present costs approximately R20000 (twenty thousand rand) for 500 g compared to Amberlyst 15 R840.00 for 500 mL and Dowex Marathon MSC R312.34 macroporous resin for 500 mL (both supplied by Dow, Rohm and Haas Co). This motivated the research to determine by a comparative study if there is any difference in the efficiency and effectiveness in the quantitative analysis of trace elements when these resins are used. The following elements will be used to determine distribution coefficients for the elements on these resins: Mn, Fe(III), Co, Ni, Cu, Zn, Al, Ag, Cd, In, Ga, Tl, Pb and Bi in 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 4.0 M nitric acid solutions. Another question is whether there is a difference or a preference when selecting either a microporous or a macroporous resin for the ion-exchange separation. Determination of distribution coefficients for 46 elements had been done by Strelow (Strelow F. W., 1984) in nitric acid on Bio-Rad AG 50W-X8. The results obtained in this study will be compared with the distribution coefficients obtained by Strelow. The Bio-Rad, Amberlyst and Dowex resins were stirred for approximately 30 minutes in deionised water and then packed in a column. Impurities in the resin column were eluted with 5 M HCl and the resin was then rinsed with deionised water to remove the acid. Thereafter the resins was rinsed out of the column with deionised water, filtered off and then dried under vacuum in an oven at 60 0C for approximately 24 hours. Stock solutions of the elements were prepared as 0.1 M solutions and then diluted with deionised water to obtain solutions having the respective concentrations of 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, and 4.0 M. Quadruplicate reference standards of each element were prepared. Distribution coefficients of the elements on each resin were determined as described by Strelow (Strelow F. W., Distribution coefficients and ion exchange behaviour of some chloride complex forming elements with Bio Rad AG50W - X8 cation exchange resin in mixed Nitric-Hydrochloric acid solutions, 1989). From the distribution coefficients, obtained from the ICP-OES data, a selectivity series for the 14 elements, mentioned above, was arranged in the decreasing order for each resin’s affinity for the elements. The distribution coefficients also give an indication whether the elements can be quantitatively separated by the cation exchangers in nitric acid media. Elution curves for some elements were done to establish the experimental conditions for quantitative separations of the elements by column cation exchange chromatography.
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Dietrich, Theo Henry. "The removal of heavy metals from dilute aqueous streams by the use of ion exchange resins." Thesis, Cape Technikon, 1998. http://hdl.handle.net/20.500.11838/887.
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Thesis (MTech (Chemical Engineering)--Cape Technikon, Cape Town, 1998Ion exchange resins are widely used to remove or concentrate heavy metals from aqueous solutions or slurries.This thesis attempts to properly evaluate the interaction between ion exchange resins and heavy metals at trace metal concentrations.The durability of the resins and their effectiveness in real slurries were also investigated. In this study, a chelating resin, as well as a cation, and anion exchange resin was contacted with aqueous solutions of heavy metals in both free and complexed form. Zinc, nickel and copper cyanide complexes were adsorbed onto the anion exchange resin, while the chelating and cation exchange resins were contacted with zinc and nickel nitrates, and cupric sulphate. All the tests were conducted in batch stirred tank reactors. All the metal cyanide complexes behaved in a similar manner when contacted with the anion exchange resins. These tests were p~rf0nned under variations in temperature, stirring speed, pH., ionic strength and . initial metal 90E~entrations. Fitting of a dual resistance model to the profiles for thetlptllk:e" of the complexes, show that both film diffusion and intraparticle diffusion rates were improved with an increase in temperature, and that film diffusion rates improved with an increase in stirring speed. A high ionic strength negatively affected equilibrium loading as well as diffusional rates.It was found that at these low concentrations, the diffusional rates improves with a decrease in the external metal concentration. A comparative study involving the chelating and cation·exchange resins were performed, during which the resins were contacted with the metals in free fonn. It was found that at high metal concentrations, the chelating resin induced a rate limiting effect, but at trace concentrations, this effect is virtually negated. Whereas the cation exchange resin exhibited little selectivity in adsorbing the metals, it was found that the chelating resin prefers the metals in the eu > Ni > Zn. The chelating resin proved to be no less durable then the cation exchange resin, and both slightly lost their ability to adsorb the metal cations as a result of the effects of an inert coarse sand slurry.Tests performed with a real ore leachate, showed the cation exchange resin to be efficient at a low pH , but also relatively non selective, since the adsorption of copper from the leachate was greatly reduced due to the presence of other heavy metals.
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Singare, Pravin U. "Ion-Isotopic exchange reaction kinetics in characterization of anion exchange resins Dowex 550A LC and Indion-820." Diffusion fundamentals 19 (2013) 4, S. 1-21, 2013. https://ul.qucosa.de/id/qucosa%3A13706.
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The present paper involves application of nondestructive radioactive tracer technique in characterization of Dowex 550A LC and Indion-820 anion exchange resins. The characterization study was based on kinetic of exchange reactions between inactive iodide/bromide ions on the resins with radioactive iodide/bromide ions in the solution. During iodide exchange reaction performed at a constant temperature of 40.00C, using 1.000 g of ion exchange resins and labeled iodide ion solution of concentration 0.003 mol/L, for Dowex 550A LC resin the specific reaction rate and initial rate of ion exchange was 0.271 min-1 and 0.141 mmol/min respectively, while the amount of iodide ions exchanged was 0.522 mmol, and log Kd was calculated to be 12.1. The above values calculated for Dowex 550A LC resin was higher than the respective values of 0.108, 0.330, 0.036 and 6.0 as obtained for Indion-820 resins. Similar results were obtained for the two resins during bromide exchange reactions, thereby indicating superior performance of Dowex 550A LC resin over Indion-820 resins.
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Singare, Pravin U. "Ion-Isotopic exchange reaction kinetics in characterization of anion exchange resins Dowex 550A LC and Indion-820." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-184151.
Full textAbstract:
The present paper involves application of nondestructive radioactive tracer technique in characterization of Dowex 550A LC and Indion-820 anion exchange resins. The characterization study was based on kinetic of exchange reactions between inactive iodide/bromide ions on the resins with radioactive iodide/bromide ions in the solution. During iodide exchange reaction performed at a constant temperature of 40.00C, using 1.000 g of ion exchange resins and labeled iodide ion solution of concentration 0.003 mol/L, for Dowex 550A LC resin the specific reaction rate and initial rate of ion exchange was 0.271 min-1 and 0.141 mmol/min respectively, while the amount of iodide ions exchanged was 0.522 mmol, and log Kd was calculated to be 12.1. The above values calculated for Dowex 550A LC resin was higher than the respective values of 0.108, 0.330, 0.036 and 6.0 as obtained for Indion-820 resins. Similar results were obtained for the two resins during bromide exchange reactions, thereby indicating superior performance of Dowex 550A LC resin over Indion-820 resins.
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Jayasinghe, Nivari School of Chemical Engineering & Industrial Chemistry UNSW. "Ion exchange equilibria of the gold cyanide complex in aqueous and mixed solvent environments." Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2005. http://handle.unsw.edu.au/1959.4/23056.
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Ion exchange equilibria are presented for [ ]??? ??? Au(CN)2 / Cl , [ ]??? ??? Au(CN)2 / SCN and SCN??? / Cl??? in aqueous solution, and in various mixed solvents, at 303K using Purolite A500 as the ion-exchanger. The mixed solvents investigated include water-acetone, water-dimethylsulfoxide (DMSO) and water-N-methyl-2-pyrrolidone (NMP). In aqueous solution, the selectivity of Purolite A500 for a given anion increases in the order: [ ]??? ??? < ??? < Cl SCN Au(CN)2 . This selectivity sequence confirms the high affinity of the ion exchange resin for the [ ]??? Au(CN)2 species. In mixed solvents, however, the selectivity of Purolite A500 for [ ]??? Au(CN)2 decreases with an increase in the composition of the organic solvent in the external solution. Mixed solvents containing greater than 60 mol% organic solvent are preferred for the displacement of [ ]??? Au(CN)2 from the resin. The effectiveness of a given type of mixed solvent generally increases in the following order: DMSO &it acetone &it NMP. The ion exchange equilibria are correlated using the Law of Mass Action, modified with activity coefficients, to determine the equilibrium constant for each binary system. The fitted values of the equilibrium constants are consistent with the trends observed in the ion exchange isotherms. The accuracy of the correlation results in the mixed solvent systems range from 1 to 10% and this is similar to the level of accuracy obtained for the ion exchange equilibria in aqueous solution. From these results it can be concluded that the Law of Mass Action is equally valid in mixed solvent systems. The variation in the equilibrium constant with mixed solvent composition, for a given binary system, correlates well with the dielectric constant of the mixed solvent. For a given value of the dielectric constant, however, the equilibrium constant, however, the equilibrium constant is dependent on the type of mixed solvent. A fundamental relationship is derived between the equilibrium constants and the Gibbs energies of transfer associated with the solvation of the ions in the mixed solvents. Based on this relationship, the redistribution of ions between the pore solution and the bulk mixed solvent, appears to be the most significant factor that governs the selectivity of the resin in mixed solvent systems.
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Rahmani, Sonia. "The removal mechanism of natural organic matter by ion exchange resins from thermodynamic perspectives." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62566.
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Natural organic matter (NOM), a constituent in surface drinking water sources, requires removal to minimize its negative impacts on water quality and water treatment processes. Ion exchange (IEX) has been considered as an effective technology for the removal of NOM. However, despite many studies on the IEX removal of NOM, the removal mechanism and the molecular interactions involved in the IEX process are quite unknown due to the complexity of the NOM molecular structure.
This research aimed to investigate the NOM removal with a focus on fundamentals underpinning the IEX process and the molecular interactions/forces that drive the retention of NOM onto the IEX resins. Different isolates of NOM along with some pure organic acids were studied. Hydrophobicity was found to play a key role in the removal process. The changes that the hydrophobic moieties impose to the structure of water molecules (i.e., entropy reduction) were found very influential in determining the selectivity of the IEX process. Moreover, the removal of UV-absorbing compounds (more hydrophobic fraction of NOM) was enhanced in the presence of sodium sulphate, as the electrostatic interactions are screened by added salt and consequently the entropic contribution to the removal is promoted. Nonetheless, the entropic contribution from the resin phase (i.e., hydrophobic resin backbone) was shown to negatively impact the removal of UV-absorbing compounds. Overall, combining the findings, it is concluded that the difference in the hydrophobicity (entropy) of the water and the resin phase is the main driving force in transferring NOM molecules from water to the resin. The contribution of the electrostatic and hydrophobic effects to the removal of NOM by IEX resins was further evaluated by quantitative characterization of the thermodynamic properties using isothermal titration calorimetry technique. The results confirmed the significance of entropic contribution to the removal of components with higher hydrophobic characteristics.
Findings of this research provide a quantitative framework for the interpretation of the experimental results and facilitate the proper design of the IEX process for different water sources and under various conditions.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Zainal-Abidin-Murad, Sumaiya. "Production of biodiesel from used cooking oil (UCO) using ion exchange resins as catalysts." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10276.
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This study focuses on the development of novel two-stage esterification-transesterification synthesis of biodiesel from used cooking oil (UCO) using novel heterogeneous catalysts. The esterification of the UCO was investigated using three types of ion exchange resins catalysts including Purolite D5081, Purolite D5082 and Amberlyst 15. Of all the catalysts investigated, Purolite D5081 resin showed the best catalytic performance and was selected for further optimisation studies. From the optimisation study, it was found that the external and internal mass transfer resistance has negligible effect on the esterification reaction. At the optimum reaction conditions, Purolite D5081 achieved 92% conversion of FFA. During reusability study, the conversion of FFA dropped by 10% after each cycle and it was found that progressive pore blockage and sulphur leaching were dominant factors that decreased the catalytic performance of the Purolite D5081 catalyst. A kinetic modelling for FFA esterification was carried out using Purolite D5081 as a catalyst. Three types of kinetic models were investigated i.e. pseudo homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Hougen-Watson (LHHW). Experimental data obtained from the batch kinetic studies was successfully represented by the PH model and a good agreement between experimental and calculated values was obtained. The activation energy for esterification and hydrolysis reaction was found to be 53 and 107 kJ/moL. The transesterification of pre-treated cooking oil (P-UCO) was investigated using various types of heterogeneous catalysts including Purolite CT-122, Purolite CT-169, Purolite CT-175, Purolite CT-275, Purolite D5081, Diaion PA306s and Cs-supported heteropolyacids catalysts. Of all the catalysts investigated, Diaion PA306s catalyst showed the highest conversion of triglycerides and was selected for further optimisation studies. At the optimum reaction conditions, Diaion PA306s achieved ca. 75% of triglycerides conversion. During the reusability study, Diaion PA306s catalyst gave a similar conversion of triglycerides after being reused once. Therefore, it was concluded that the resin can be used several times without losing catalytic activity. Several purification methods have been investigated and dry washing method was chosen as the best alternative for biodiesel purification.
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Els, Ellis Raymond. "The adsorption characteristics of precious and base metals on four different ion-exchange resins." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51936.
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Dissertation PhD--University of Stellenbosch, 2000.ENGLISH ABSTRACT: Adsorption tests were conducted with four different ion-exchange resins to determine the equilibrium adsorption of a range of precious and base metals. The adsorption characteristics were determined for synthetic single metal, as well as for multicomponent and base metal solutions. The effect of the el- concentration on the equilibrium adsorption was established for three different Hel concentrations in the above solutions. From the ion-exchange characteristics determined, a selective adsorption sequence is proposed for the separation of precious and base metals. Pure platinum, palladium and gold were dissolved in aqua regia and diluted to 2000 ppm (as metal) in 4M Hel. Ruthenium, rhodium and iridium were dissolved from pure salts in Hel. A 2000 ppm base metal solution was prepared by dissolving all the required components, including precious metals, to match an in-plant industrial basemetals solution composition. For each precious metal the equilibrium adsorption was determined for a couple of solution concentrations. Data points for adsorption curves were established by varying the amount of resin added to the test solution of a specific concentration. The equilibrium solution concentrations were determined by Iep analysis after 24 hours of exposure, using the bottle-roll technique. The experimental results obtained indicate a possible process route for the separation of precious metals with ion-exchange resin. The XAD7 resin is highly selective for gold from mixed solutions containing precious and base metals. It is also evident that, with the gold removed from the solution, the A22 resin adsorbs only palladium. IR200 resin adsorbs only the base metals from the solution. With all other precious metals removed from the solution (platinum and ruthenium must be extracted by other means), iridium can be adsorbed from the solution by IRA900 resin which is highly selective for iridium over rhodium. For all of the anion resins, XAD7, IRA900, and A22, the chloride concentration of the solution did not have a big effect on the adsorption capacity. However, the adsorption of base metals on IR200 is sensitive to chloride concentration, with a rapid reduction in adsorption at higher chloride concentrations. Statistical models were developed for the adsorption of each of the precious metals, as well as for the base metal solution. All adsorption data, obtained for a resin (typically 250 equilibrium data points), was used in the development of the model. The SPSS statistical software package was used to develop linear regression models. The interaction between all the input parameters, e.g. the interaction of gold and chloride ions, was modelled by specifying the product of the gold and the chloride concentrations as an input variable. The variables that determine the adsorption quantities were identified. High solution concentrations of the target adsorption component increase the adsorption quantity. It has been established that a higher platinum concentration increases the adsorption quantity of gold on XAD7 resin. However, the adsorption quantity is reduced at higher ruthenium concentrations. The adsorption quantity of iridium on IRA900 is reduced with increased rhodium concentration. The adsorption quantity of palladium on A22 is increased by the presence of rhodium and decreased by larger concentrations of iridium and platinum. The adsorption of base metals on IR200 is decreased at higher acid concentrations. Higher concentrations of gold in the base metal solution also decrease the adsorption quantity of base metals. The model predicted adsorption of each component compares well with the actual measured values. In batch adsorption tests the counter ion is not removed from the resin. The resin capacity for a specific ion concentration could therefore not be determined. As such, the adsorption models are only valid for the initial part of the ion-exchange process. The effect of kinetics on the adsorption was not determined.
AFRIKAANSE OPSOMMING: Adsorpsietoetse is gedoen met vier verskillende ioonuitruilharse om die ewewig adsorpsie van edelmetale en basismetale te bepaal. Die adsorpsie karakteristieke is bepaal vir sintetiese enkelmetaal-, meermetaal-, en basismetaaloplossings. Die effek van die Cl konsentrasie op die ewewigadsorpsie is bepaal vir drie soutsuurkonsentrasies in al die bogenoemde oplossings. 'n Prosesvloeidiagram vir die selektiewe adsorpsie van edelmetale en basismetale met behulp van die vier verskillende ioonuitruilharse word voorgestel. Suiwer platinum, palladium en goud is opgelos in koningswater en verdun na 2000 dpm (uitgedruk as metaal) in 4 molaar HCl. Rutenium-, rodium- en iridiumoplossings is verkry deur die oplos van suiwer edelmetaalsoute in HCl. 'n Basismetaaloplossing van 2000 dpm is voorberei deur die individuele komponente, wat die edelmetale ingesluit het, in die regte verhouding te kombineer om die samestelling van 'n industriële basismetaaloplossing te verkry. Vir elke edelmetaal is die ewewigadsorpsie bepaal vir tipies twee konsentrasies van edelmetaaloplossings. Verskillende data punte by 'n spesifieke edelmetaalkonsentrasie is bepaal deur die hoeveelheid hars wat by die toets oplossing gevoeg word te varieer. Die oplossingkonsentrasies by ewewig is bepaal deur IGP analise na 24 uur blootstelling met die roterende botteltegniek. Die resultate wat verkry is dui op 'n moontlike ioonuitruiigebaseerde proses vir die skeiding van edelmetale. Die XAD hars is selektief vir goudadsorpsie uit gemengde oplossings wat al die edelmetale, asook basismetale bevat. Dit is ook bevind dat indien goud uit die gemengde oplossing verwyder word, die A22 hars slegs palladium adsorbeer uit die oplossing. Die IR200 hars adsorbeer slegs basismetale. Wanneer al die ander edelmetale uit die oplossing verwyder is (platinum en rutenium moet met alternatiewe prosesse verwyder word) kan iridium geadsorbeer word met !RA900 hars vanuit 'n iridium- en rodium- gemengde oplossing. Vir al drie die anioonharse wat getoets is, naamlik, XAD7, !RA900 en A22, het die chloriedkonsentrasie nie 'n groot effek op die adsorpsie gehad nie. Die hoeveelheid basismetale wat op IR200 hars geadsorbeer word is egter baie sensitief vir die chloriedkonsentrasie, met 'n vinmge afname In adsorpsie by hoër chloriedkonsentrasies. Statistiese modelle is ontwikkel vir elke hars en vir elk van die edelmetale, asook die basismetaaloplossing. Al die eksperimentele data wat vir elke hars verkry is, tipies 250 ewewigspunte, is gebruik in die ontwikkeling van lineêre regressie modelle vir die primêre absorberende spesie op die hars. Hoër konsentrasies van die teiken adsorpsie komponent verhoog die adsorpsie daarvan. Hoër platinumkonsentrasies verhoog die adsorpsie van goud op XAD7, maar die teenwoordigheid van rutenium verlaag adsorpsie. Die adsorpsie van iridium op IRA900 word verlaag met hoër rodiumkonsentrasies. Die adsorpsie van palladium op A22 verhoog met die teenwoordigheid van rodium, maar neem af met hoër konsentrasies van iridium en platinum. Die adsorpsie van basismetale op IR200 neem af by hoër suurkonsentrasies. 'n Hoër goudkonsentrasie verlaag ook die adsorpsie van basismetale. Die gemodelleerde adsorpsie hoeveelhede vergelyk goed met die gemete waardes. Aangesien die uitgeruilde ioon nie verwyder word uit die toetsoplossing nie, kon die harskapasiteit vir 'n spesifieke ioonkonsentrasie nie bepaal word nie. Die modelle is derhalwe slegs getoets vir die aanvanklike deel van die ewewigsdata en die kinetika van adsorpsie is nie in ag geneem nie.
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Khan, Nadeem Ishaque [Verfasser]. "Oral Controlled Release Liquid Dosage Forms (Reconstitutable Powder) by Ion-exchange Resins / Nadeem Ishaque Khan." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1187243809/34.
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Yalala, Bongani Ndhlovu. "Ion exchange resins an functional fibres :a comparative study for the treatment of brine waste water." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8342_1298358875.
Full textAbstract:
To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80°
C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM)
Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker.
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Wightman, Alan. "Some studies on polymer-supported quaternary 'onium salts as phase transfer catalysts and ion-exchange resins." Thesis, Lancaster University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279953.
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Bari, Klaudio. "Assessing the feasibility of encapsulating spent fuel particles (TRISO) and ion exchange resins in borosilicate glass." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/assessing-the-feasibility-of-encapsulating-spent-fuel-particles-triso-and-ion-exchange-resins-in-borosilicate-glass(98ff8368-041f-43b0-b349-1f8277ed04d9).html.
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A safe treatment and disposal of spent Tri-Structural Isotropic (TRISO) coated fuel particles is one of the most important issues for developing the next generation of nuclear reactors, such as a Very High Temperature Reactor (VHTR). The project investigates the encapsulation of surrogated TRISO particles in Glass-Graphite Composite (GGC) and in Alumina Borosilicate Glass (ALBG) and compares their geological performance in the repository. The study deals with the assessment and performance of both matrices in a geological repository's conditions, measuring their chemical durability for 28 days at temperatures ranging 25-90°C and using American Standard for Testing Material (ASTM-C1220-98). The leach test revealed that only sintered ALBG with TRISO particles doped in cesium oxide could provide a safe Engineering Barrier System (EBS). The thermal property of the matrices was examined by measuring their thermal diffusivities. The thermal diffusivity of ALBG bearing various proportions of TRISO particles was measured experimentally using Laser Flash Analysis (LFA). The experimental results validated through a numerical method using Image Based Modelling (IBM). The effect of the porosity in decreasing the thermal diffusivity of TRISO particles was also discussed. In addition, the study deals with the immobilisation of ion exchange resins (doped with radioactive and non-radioactive cesium and cobalt) in borosilicate glass. The thermal analysis revealed that a successful immobilisation could be achieved once the sulfur functional group in the resin was decomposed and evaporated in a form of SO2/SO. The minimum required temperature of the heat treatment was 500°C under air environment as a pre-conditioning stage before immobilisation.
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Liu, Dan. "Removal of Emerging Contaminants from Aqueous Solutions by Using Polymeric Resins." Master's thesis, Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/149804.
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Civil EngineeringM.S.E.
The emerging contaminants (ECs) such as estrogen hormones, perfluorinated compounds (PFCs), bisphenol A (BPA) and 1, 4-dioxane have been detected in natural water bodies at a noticeable level worldwide. The presence of ECs in the aquatic environment can pose potential threats to aquatic organisms as well as human world. Ion-exchange is a highly efficient technology for the removal of heavy metal ions and natural organic materials (NOMs) due to the nature of exchanging similar charged ions. However, this technology has not been explored for removing ECs. In this study, four categories of ECs: estrogen hormones (12), perfluorinated compounds (10), bisphenol A and 1, 4-dioxane were used as model contaminants. The adsorption of each category of ECs onto various types of polymeric resins (MN100, MN200, A530E, A532E and C115) was investigated. The removal of ECs was tested under batch and column mode. The effects of pH, resin dosage, and contact time on the removal of ECs were studied in batch mode; isotherm and kinetics models were applied to fit the experimental data. Column experiments were conducted to verify the practicability of the polymeric resins. Adsorption results have shown that both MN100 and MN200 resins could efficiently remove estrogen hormones mixture (more than 95%), and bisphenol A (more than 80%) with the initial concentration of 100 ìg/L; A532E and A530E could remove perfuorinated compounds mixture (more than 99%) with the initial concentration of 100 ìg/L. As pH increased from 9 to 11, the adsorption capacity onto polymeric resins decreased dramatically for estrogen hormones such as 17á-ethinylestradiol, estriol, 17â-estradiol, 17á-estradiol, estrone, 17á-dihydroequilin and equilin as well as bisphenol A. The adsorption of estrogen hormones and bisphenol A onto MN100 and MN200 resins reached the equilibrium within 24 hours, whereas the adsorption of perfluorinated compounds onto A532E and A530E reached the equilibrium within 8 hours. It was also observed that the adsorption of PFCs largely depends on the C-C chain length. PFCs with longer chain yielded lower adsorption efficiency onto the ion-exchange resins A532E and A530E. Adding salinity decreased the first-order rate constants for the adsorption of bisphenol A onto MN100 and MN200 resins. Fixed-bed column experiment results with estrogen hormones mixtures confirmed that the polymeric resins were good candidates in the removal of estrogen hormones. Trimegestone was the first compound detected in the effluent in the column test while 17â-estradiol, 17á-estradiol were the last. 80% of the exhausted resins (MN100 and MN200) by bisphenol A were regenerated by using pure methanol as regeneration solution. Polymeric resins were not effectively removing 1, 4-dioxane from the aqueous solution.
Temple University--Theses
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Pérez-Maciá, María Ángeles. "Liquid Phase Dehydration of 1-Butanol to Di-n-butyl ether Experimental Performance, Modeling and Simulation of Ion Exchange Resins as Catalysts." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/336975.
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Di-n-butyl ether (DNBE) is considered a very attractive oxygenate compound to reformulate diesel fuel. The research work performed along this thesis has clearly proven that sulfonic P(S-DVB) ion exchange resins are suitable catalysts for the synthesis of DNBE from the liquid phase dehydration of 1-butanol at the temperature range of 140-190 °C. A catalyst screening of acidic P(S-DVB) ion exchange resins showed that resins activity is enhanced with high acid capacities and with polymer matrices that are able to swell moderately allowing 1-butanol ready access to the active sites but without resulting in very large distance between the active centers. The resin Amberlyst 36 (oversulfonated, medium values of %DVB) proved to be the most active catalysts tested. However, in an industrial process a high selectivity to DNBE is extremely desirable from an environmental and economic standpoint, and resins that present a more elastic polymer matrix and higher ability to swell (gel type resins and Amberlyst 70) are the ones that present higher selectivities. Among all the tested resins, Amberlyst 70 was selected as the most suitable catalyst for industrial use given its excellent property balance: satisfactory activity, high selectivity to DNBE and thermal stability up to 463 K.
The relatively large value found for the thermodynamic equilibrium constant of DNBE formation and the fact that the formation of the secondary product 1-butene was extremely slow assure high conversion levels in an industrial etherification process. DNBE formation proved to be a slightly exothermic reaction, almost athermic, whereas 1-butene formation was found to be an endothermic reaction.
A comprehensive kinetic analysis enlightened that the reaction rate to form DNBE on Amberlyst 70 is highly influenced by the temperature and the presence of water. Two kinetic models that are able to predict the reaction rates of DNBE formation were identified. One of them stems from a Langmuir-Hinshelwood-Hougen-Watson (LHHW) formalism in which two adsorbed molecules of 1-butanol react to yield ether and water, being the reversible surface reaction the rate limiting step. The other one stems from a mechanism in which the rate limiting step is the desorption of water and where the adsorption of DNBE is negligible. Both models present several characteristics in common: in both water inhibition effect is correctly represented by a correction factor derived from a Freundlich adsorption isotherm; the number of free active sites is found to be negligible compared to the occupied ones; both present similar values of apparent activation energies (122 ± 2 kJ/mol). The study of the influence of typical 1-butanol impurities (isobutanol or ethanol and acetone, depending on the production process) demonstrated that isobutanol enhances the formation of branched ethers whereas ethanol leads to the formation of ethyl butyl ether and di- ethyl ether and acetone hardly reacts. In the second part of this thesis, it was demonstrated the suitability of molecular dynamics simulations in the understanding of the microscopic structure of P(S-DVB) ion-exchange resins and the prediction of their properties. Atomistic simulations of the structure of sulfonated P(S-DVB) resins reveled the decisive role that internal loops (closed polymer chains) play in defining the properties (i.e. density, porosity and structures) of highly cross-linked resins. Thus, although crosslinks ensure the local backbone structure, internal loops confer rigidity and loop architecture. It was also demonstrated that the developed atomistic model is able to predict the swelling behavior of ion-exchange resins in 1-butanol. From the swelling study performed by means of molecular dynamic simulation it was possible to characterize and quantify the structure of the swollen polymeric network at molecular level and to conclude that alcohol molecules tend to interact with the sulfonic groups of the resin.
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Riani, Josiane Costa. "Utilização de resinas de troca-iônica em efluentes de galvanoplastia." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-30092008-151250/.
Full textAbstract:
A crescente industrialização acompanhada do uso de metais pesados nos processos industriais nas últimas décadas resultou num aumento da contaminação do meio ambiente, principalmente em ambientes aquáticos. Assim, sendo a água um recurso natural de suma importância para a vida, métodos de tratamento de efluentes tornam-se indispensáveis para empresas geradoras de efluentes. O objetivo desse trabalho é a utilização de um sistema de troca iônica constituído por micro-colunas de resinas catiônicas e aniônicas para adsorção de metais pesados de soluções industriais, visando à recirculação de água de lavagem de processos de galvanoplastias. As resinas utilizadas são: Amberlyst 15 WET e Amberlyst A-21; Dowex Marathon C e Dowex Marathon A; Purolite C-150 e Purolite A-850. Também se avalia a eluição dos íons metálicos nas resinas em questão. O efeito que a temperatura possui na eluição é avaliado para as resinas catiônicas, Purolite C-150 e Dowex Marathon C. A cinética e a termodinâmica de adsorção do cromo trivalente e do zinco são avaliados. A metodologia consiste em realizar experimentos de adsorção e eluição em colunas de troca-iônica e experimentos de adsorção em batelada para análise da cinética e termodinâmica dos íons presentes em solução. Os resultados mostram que a qualidade da água após a adsorção nos três sistemas propostos está de acordo com os valores permitidos pela Resolução CONAMA 357/05. Analisando os resultados da eluição nas resinas se verifica que o aumento da temperatura favorece a remoção de íons presentes nos sítios de troca da resina, com exceção do cromo trivalente. As reações de troca-iônica dos íons Cr3+ e Zn2+ seguem os modelos de reação pseudo-segunda ordem. A natureza das reações de troca-iônica do cromo trivalente nas resinas estudadas é exotérmica e a do zinco é endotérmica.The increasing industrialization carried out with the use of heavy metal in industrial processes over the last decades resulted in increasing environmental contamination, mainly in aquatic environments. Thus, as water is an extremely important natural resource for life, effluent treatment methods become essential for effluent generating companies. This work aims at using an ionic exchange system made of micro-columns of both cathionic and anionic resins for heavy metals adsorption of industrial solutions, for the recirculation of wastewater from electroplating processes. The resins used are: Amberlyst 15 WET and Amberlyst A- 21; Dowex Marathon C and Dowex Marathon A; Purolite C-150 and Purolite A-850. An evaluation of the metallic ions elution is also carried out for such resins. The effect of temperature on the elution is assessed for cathionic resins, Purolite C-150 and Dowex Marathon C. The adsorption kinetics and thermodynamics for trivalent chrome and zinc are assessed. The methodology consists of carrying out experiments of adsorption and elution in ion exchange columns and experiments of adsorption by batch for both kinetic and thermodynamic analyses of ions present in the solution. The results show that the water quality after the adsorption in all three systems proposed is in accordance with the values allowed by the CONAMA 357/05 Resolution. By analyzing the results of the elution in the resins, one can observe that the temperature increase favors the removal of ions present in resin-exchange sites, except for the trivalent chrome. The reactions of ionic exchange of Cr3+ and Zn2+ ions follow the models of pseudo-second order reaction. For the resins analyzed, the nature of ionic exchange reactions of the trivalent chrome is exothermic and of the zinc is endothermic.
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Guilera, Sala Jordi. "Ethyl octyl ether synthesis from 1-octanol and ethanol or diethyl carbonate on acidic ion-exchange resins." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/120755.
Full textAbstract:
Ethyl octyl ether is a bioethanol-derived component that has excellent properties as diesel fuel. This work proved that ethyl octyl ether can be produced successfully in liquid-phase at the temperature range of 130-190ºC by using acidic ion-exchange resins, as suitable and economic catalysts. The use of two promising reactants that can be a renewable compound source, ethanol and diethyl carbonate, have been explored. Both reactants are able to ethylate 1-octanol and form the desired product. However, an identical industrial drawback is observed on both reactants, the loss of ethyl groups to form diethyl ether, which is not suitable as diesel compound.
In order to minimize the diethyl ether formation, and in this way, to maximize the ethyl octyl ether production; several commercial acidic resins were tested, or else, prepared and subsequently tested. The best catalysts are those allowing 1-octanol to access to most sulfonic groups of the catalyst. Such desired properties can be achieved by decreasing the amount of crosslinking agent of resins, as a result, the resin has a high capacity to swell and at the same time a low gel-phase density. Another tailoring technique that lets 1-octanol to access to the vast majority of sulfonic groups is by locating them only in the least crosslinked domains of the gel-phase. Both tailoring techniques involve higher selectivity to ethyl octyl ether, which can be extrapolated to other bulky molecules. However, the former involves a reduction of the catalytic activity per volume unit of the catalyst bed, and the latter, per mass unit.
Interestingly for the resin designers and exploiters, it is proved that the Inverse Steric Exclusion Chromatography characterization technique allows predicting the catalyst performance in polar environments with high accuracy. In such a manner that polymeric catalysts having high specific volume of the swollen gel-phase and predominant domains with low polymer density are desired to enhance selectivity and yield to ethyl octyl ether formation.
The comparison between both ethylating agents, ethanol and diethyl carbonate, revealed that similar selectivity and yield can be potentially obtained over acidic resins. Nevertheless, diethyl carbonate is less competitive at shorter reaction times in a batch reactor, or at lower catalyst mass in continuous units, as a result of the slow decomposition of the required intermediate, ethyl octyl carbonate. On the other hand, the production of CO2 via diethyl carbonate and the availability of ethanol nowadays suggest that use of the alcohol to form ethyl octyl ether is preferred.
Reaction rates to form ethyl octyl ether from ethanol and 1-octanol showed similar, or slightly higher, dependency on the temperature than that to form the main side product, diethyl ether. Thus, an enhancement of the reactor temperature clearly increases the feasibility of an ethyl octyl ether production unit. Accordingly, the use of chlorinated resins, which proved to be thermally stable up to 190ºC in the ethyl octyl ether production, is desired. Among the commercial ones, Amberlyst 70 is the most suitable catalyst in terms of selectivity to ethyl octyl ether due to its low polymer density in aqueous swollen state. Such polymeric expansion should be taken into account to not block the liquid flow when fixed-bed reactors are employed. That is to say, Amberlyst 70 must be loaded to the reactor in a swollen state.
The relatively large values found of the thermodynamic equilibrium constant of ethyl octyl ether formation assure high conversion levels in an industrial etherification process. Interestingly, the equilibrium values of the formation of diethyl ether are around a half than those of ethyl octyl ether (150-190ºC). A comprehensive kinetic analysis enlightened that reaction rates to form ethyl octyl ether on Amberlyst 70 are strongly inhibited by the presence of water. Thus, reaction rates would be enhanced if most water is removed from bioethanol.La utilització de bioetanol per produir compostos diesel seria una forma d’incrementar la producció de diesel (deficitària a Europa), i tan ho més important, de millorar-ne la qualitat i així reduir les emissions nocives de material particulat, òxids de nitrogen, sofre i compostos volàtils. Un èter derivat del bioetanol que té excel•lents propietats com a combustible diesel és l’etil octil èter. L’objectiu d’aquesta tesis és l’estudi de la producció d’etil octil èter en fase líquida mitjançant catalitzadors heterogenis. Això implica la selecció dels reactius i catalitzadors més adequats des d’un punt de vista de rendiment i selectivitat. A més, l’estudi termodinàmic i cinètic de la reacció en permeten tan el disseny com la optimització del procés. Els assajos catalítics s’han realitzat en un reactor de tanc agitat operant en discontinu i en un reactor tubular operant en continu utilitzant resines àcides de bescanivi iònic com a catalitzadors (P=25 bars, T=130-190ºC). Els resultats experimentals han mostrat que el compost etil octil èter es pot formar mitjançant l’etilació de 1-octanol a partir de dos reactius provinents d’origen renovable, l’etanol i el dietil carbonat. La comparació de dos agents etilants, etanol i dietil carbonat, ha revelat que es poden obtenir similars selectivitats i rendiments en temps de reacció elevats mitjançant resines àcides de bescanvi iònic, preferiblement de baix contingut de divinil benzè. Tanmateix, l’ús de dietil carbonat és menys competitiu en temps de reacció curts. A més, la formació de CO2 via dietil carbonat i la més alta disponibilitat d’etanol suggereix que l’ús de l’alcohol és preferit des d’un punts de vista tan industrial com ambiental. L’estudi termodinàmic ha revelat que els valors relativament alts de la constant termodinàmica d’equilibri químic en la formació de l’etil octil èter asseguren alts nivells de conversió en un procés industrial. Finalment, un exhaustiu estudi cinètic ha revelat que la velocitat de formació d’etil octil èter a partir d’etanol i 1-octanol és altament inhibit per l’adsorció de l’aigua en els centres actius de les resines. Finalment, s’ha observat que les velocitats de reacció són optimitzades utilitzant una raó molar 1-octanol / etanol de 1.4, un diàmetre de partícula menor a 0.63 mm d’Amberlyst 70 i una temperatura de reactor de 190ºC.
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Bazri, Mohammad Mahdi. "Kinetics and fate of natural organic matter under different water matrices using strong basic ion exchange resins." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57229.
Full textAbstract:
This research has investigated the factors influencing the kinetics and efficacy of natural organic matter (NOM) removal during the anionic ion exchange process (IEX). A holistic approach was undertaken to evaluate various IEX resins in terms of their NOM removal kinetics and regeneration efficiency under batch and consecutive multiple loading cycles. Initial screenings indicated the strongly basic resin as a better candidate for NOM removal, and hence it was employed for subsequent experiments.
Different treatment parameters (resin dose, contact time, NOM source) were tested and detailed kinetic evaluations were conducted to determine the affinity and removal rate of NOM as well as nitrate, and sulfate that are generally present in natural waters. Results obtained showed a substantial removal of NOM (up to 80 %) and nitrate (up to 80 %), and a superior removal for sulfate (up to 98 %). Charge density and molecular weight were found to play a major role in the removal process. Different mathematical and physical models were employed to predict the experimental data and the rate-limiting step was found to be pore diffusion which was affected by the resin dose/solute concentrations ratio. Moreover, the impact of IEX resins on NOM fractions and subsequent water quality parameters was investigated in this study. Humic (-like) substances were mainly targeted by IEX, and more hydrophilic and/or non-ionic fractions were slightly removed. Application of IEX reduced the formation potential of carbonaceous and nitrogenous disinfection by-products by 13-20 % and 3-50 %, respectively. Also, the practice of IEX treatment reduced the assimilable organic carbon levels by 30-40 %. Additionally, a positive effect of IEX, as a pretreatment to UV/H₂O₂, at reducing the ⦁OH scavenging characteristics of the water was observed. Electrical energy per order for removing a probe compound (i.e., pCBA) showed 20-40 % reduction indicating the improvement in the efficacy of UV/H₂O₂ treatment.
Findings of this study display the robustness of IEX process for drinking water applications and lay down a quantitative approach for evaluating the kinetics of this process under various treatment conditions.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Kadry, Ahmed Y. "Removal of selected water disinfection byproducts, and MTBE in batch and continuous flow systems using alternative sorbents." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3285/.
Full textAbstract:
A study was conducted to evaluate the sorption characteristics of six disinfection byproducts (DBPs) on four sorbents. To investigate sorption of volatile organic compounds (VOCs), specially designed experimental batch and continuous flow modules were developed. The investigated compounds included: chloroform, 1,2-dichloroethane (DCE), trichloroethylene (TCE), bromodichloromethane (BDCM), methyl tertiary butyl ether (MTBE), bromate and bromide ions. Sorbents used included light weight aggregate (LWA), an inorganic porous material with unique surface characteristics, Amberlite® XAD-16, a weakly basic anion exchange resin, Amberjet®, a strongly basic anion exchange resin, and granular activated carbon (GAC). Batch experiments were conducted on spiked Milli-Q® and lake water matrices. Results indicate considerable sorption of TCE (68.9%), slight sorption of bromate ions (19%) and no appreciable sorption for the other test compounds on LWA. The sorption of TCE increased to 75.3% in experiments utilizing smaller LWA particle size. LWA could be a viable medium for removal of TCE from contaminated surface or groundwater sites. Amberlite® was found unsuitable for use due to its physical characteristics, and its inability to efficiently remove any of the test compounds. Amberjet® showed an excellent ability to remove the inorganic anions (>99%), and BDCM (96.9%) from aqueous solutions but with considerable elevation of pH. Continuous flow experiments evaluated GAC and Amberjet® with spiked Milli-Q® and tap water matrices. The tested organic compounds were sorbed in the order of their hydrophobicity. Slight elevation of pH was observed during continuous flow experiments, making Amberjet® a viable option for removal of BDCM, bromate and bromide ions from water. The continuous flow experiments showed that GAC is an excellent medium for removal of the tested VOCs and bromate ion. Each of the test compounds showed different breakthrough and saturation points. The unique design of the continuous flow apparatus used in the study proved to be highly beneficial to assess removal of volatile organic compounds from aqueous solutions.
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Basitere, Moses. "Desorption of lithium 7 isotope from a degraded amberlite lithiated mixed-bed-resin." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/2166.
Full textAbstract:
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2011.Lithium 7 (⁷Li⁺) is an isotope, which is used in the nuclear industry as lithium hydroxide (⁷LiOH) for the chemical control (pH control) of the high purity reactor coolant water process in order to prevent corrosion in the Pressurised Water Reactor (PWR). Furthermore, the ⁷Li⁺ isotope is used in an ionic form in the nuclear grade cation ion-exchange resin. This resin is used to purify the nuclear reactor coolant water by reducing cationic corrosion by-products such as Cesium and Cobalt, which are generated from nuclear fission reactions. In view of the fact that an inorganic salt of the isotope is used as an alkali sing agent in the PWR, the use of lithiated resin prevents the removal of the ⁷Li⁺ isotope in the coolant water. As most users of the nuclear grade resin purchase their resin in bulk, it follows that the resin has to be evaluated in order to determine its usability. In certain cases, the resin may be considered unusable as a result of the degradation caused by unsuitable transportation and storage conditions. These, in turn, perpetuate the release of leachates, which may further contribute to corrosion in the PWR. This necessitated the undertaking of this study, which was to evaluate whether it is possible to recover the high value ⁷Li⁺ isotope from a degraded nuclear grade resin in such a way that the isotope may be used in the PWR.
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Peyton, Daniel Junior. "Nitrogen-compound removal by ion exchange a model system study of the effect of nitrogen-compound type on the removal performance of two sulfonated styrene/divinylbenzene ion-exchange resins." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183467365.
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Basaran, Tolga Yener. "Ion Exchangers In The Recovery Of Tartaric Acid From Aqueous Solutions." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607367/index.pdf.
Full textAbstract:
Tartaric acid is a dicarboxylic acid naturally present in grapes, and has many application areas with its salts. It can be produced synthetically, manufactured as a by-product in wine industry, or can be recovered by electrodialysis and solvent
extraction methods. Since, ion exchange is one of the oldest processing techniques for the recovery and purification of valuable materials, it can be applied to obtain this valuable organic acid. In this study it is aimed to investigate the
effects of resin basicity, initial concentration, and initial pH of the solution on ion exchange equilibrium.
The model tartaric acid solutions were prepared for the equilibrium analysis with two different anion exchange resins in a batch type system. A shaker bath at 28 oC with 300-rpm agitation rate was used. The weakly basic resin Lewatit MP62, and strongly basic resin Lewatit M511, which are in polystyrene structure, was obtained from the producer Bayer AG. In the analysis, Shimadzu PDA Detector at 210 nm
with Waters Atlantis dC18 column was used. 20 mM NaH2PO4 at pH = 2.7 was introduced to the HPLC as the mobile phase at 0.5 ml/min flow rate.
In the investigation of the resin basicity, MP62 presented better performance than M511. The equilibrium experiments were performed at three different initial acid concentrations (0.01, 0.02, and 0.10 M) for both resin, and in the pH ranges pH <pKa1, pKa1 <
pH <
pKa2, and pKa2 <
pH for weakly basic resin, and in the pH ranges pH <
pKa1, pKa1 <
pH <
pKa2 for strongly basic resin at each concentration. Results show that the pH of the solution is a more important parameter than the initial concentration that affects the ion exchange equilibrium. Also, Langmuir and Freundlich isotherms were plotted, and it was shown that they were in good agreement with the experimental data especially for the systems that are at low total ion concentrations.
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De, Villiers Pieter Gabriel Retief. "The use of ion-exchange resins for the recovery of valuable species from slurries of sparingly soluble solids." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53181.
Full textAbstract:
Thesis (PhD)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: The availability of vast deposits of high-grade ore bodies are rapidly becoming something of the past in the modern mining and metallurgical scenario. Apart from the lower grade content of these ore bodies, complex mineralogy are an even greater obstacle in the recovery of valuable metal species. The development of new technology to deal with these type of ore bodies is therefore critical and worth investigating, as the world's easily exploitable high grade ore deposits are decreasing. Valuable species can be recovered from sparingly soluble solids, which slightly dissociate to give traces of the valuable ions in solution, with the use of ion-exchange resins in a slurry mixture. A dissociation equilibrium exists between the dissolved ions in solution and the solid ore body. Jf the dissolved ions are removed from the solution by ion-exchange, the solid / liquid dissociation equilibrium is continually displaced. According to Le Chatelier's principle further dissolution of the sparingly soluble solid is required to restore the equilibrium concentration of the valuable species in solution. It is possible to recover valuable metal species from metal precipitates, such as metal sulphides, by contacting a slurry of the precipitate with a suitable ion-exchange resin. The resulting ion exchange reaction between the valuable metal species and counter ions creates electrolyte solutions that may facilitate the further dissolution of the metal precipitate. These counter ion electrolyte solutions may easily become significantly concentrated. This occurs in the event of a Resin-in-Leach (RIL) mixture that results in a continuous ion-exchange reaction taking place due to the continually changing electrolyte composition of the mixture, which significantly changes the activities and hence the solubility of the valuable metal species in solution. Complete dissolution and liberation of the metal precipitate can often be achieved provided that a sufficient amount of a suitable high capacity ion-exchange resin is used in a properly engineered Resin-in- Leach (RIL) circuit. The simultaneous dissolution and adsorption of various base metal precipitates were tested. Various interactions that take place in the slurry at molecular level as well as the effects of various variables on the "adsorption by dissolution process" are discussed through the development of fundamental thermodynamic models. These thermodynamic mathematical models are developed for the three phase system that exists in a Resin-in- Leach mixture, i.e. the solid ore body, the electrolyte solution and the ion-exchange resin, and can be used for possible other applications such as the recovery of rare earths from low grade ores in the minerals processing industry. A typical example of an industrial process for the recovery of rare earth species is the percolation leaching of rare earths from low-grade kaolinitic ores, which continually shifts the solid / liquid dissociation equilibrium condition. The rare earth content of these ores is usually between 0.05%and 0.3 %, which is very low by any modern industrial extraction and refining standards.
AFRIKAANSE OPSOMMING: Die beskikbaarheid van ryk mineraal ertsneerslae is spoedig besig om iets van die verlede te word in die huidige mineraalontginning en metallurgiese veredelings industrie. Afgesien van die lae graad van die huidige mineraal ertsneerslae, blyk die komplekse mineralogiese samestelling van hierdie neerslae In veel groter struikelblok te wees in die herwinning en veredeling van die edelmetale teenwoordig in hierdie ertse. Die ontwikkeling van nuwe veredelings en ekstratiewe tegnologie vir die herwinning van edel metale, vanuit hierdie lae graad mineraal ertsneerslae, word dus benodig wat verdere navorsing in hierdie gebied regverdig. Dit is wel moontlik om metaal spesies afkomstig van ertse met 'n baie lae oplosbaarheid in waterige oplossings te herwin met ioon-uitruilings harse vanweë die feit dat die metaal spesies wel teen baie lae konsentrasies in die waterige oplossings teenwoordig is. Die metaal spesies los op in die waterige oplossings volgens hulle karakteristieke oplossings termodinamika. Indien die opgeloste metaal spesies vanuit die waterige oplossing verwyder word, sal die vaste stof / vloeistof ewewigs balans weer herstel word deurdat die vaste stof verder saloplos as gevolg van Le Chatelier se beginsel. Dit is dus moontlik om metaalagtige spesies, soos metaal sulfiedes, te herwin deur 'n waterige oplossing wat die metaal erts bevat in kontak te bring met 'n ioon-uitruilings hars. Die daaropvolgende ioon-uitruilings reaksie tussen die metaalagtige spesies en die spesies teenswoordig op die ioon-uitruilingshars het tot gevolg dat die elektrolitiese samestelling van die waterige oplossing verander. Dit is die gevolg van die migrasie van spesies aanvanklik teenswoordig op die hars wat in die waterige fase eindig. Die veranderende samestelling van die waterige oplossing mag verder tot gevolg hê dat die oplosbaarheid van die metaalagtige spesie verder verhoog mag word. Die gevolg van bogenoemde reaksies is dat die waterige oplossing ionies sterk gekonsentreerd kan word soos meer en meer spesies aanvanklik teenswoordig op die hars migreer na die oplossing. Die ioniese verandering van die waterige oplossing van 'n suiwer waterige fase tot 'n ionies sterk gekonsentreerde oplossing vind plaas tydens die oplos van erste in 'n hars-inpulp (HIP) oplossing. Die nuwe ioniese aktiwiteit in die oplossing kan die oplosbaarheid van die vaste stof drasties verander. Die volledige oplossing van 'n bepaalde kwantiteit van die vaste stof kan bereik word deur die genoegsame toevoeging van 'n geskikte hars tot die waterige oplossing wat die vaste stofbevat. Die gelyktydige oplossing en absorpsie van die metaalagtige vastestowwe vanuit waterige oplossings met behulp van ioon-uitruilings harse is eksperimenteel getoets vir die doeleindes van hierdie werkstuk. Verskeie interaksies wat op molekulêre vlak in die pulp plaasvind asook die adsorpsie proses van die spesies vanuit die waterige oplossing op die harse word bespreek en gemodelleer. Wiskundige modelle wat die termodinamika van die verskillende fases wiskundig verteenwoordig is ontwikkel vanaf bestaande termodinamiese beginsels. Die drie verskillende fases wat in ag geneem is, is die waterige fase met opgeloste metaal spesies, die vaste stof fase wat as die erts in bostaande paragrawe beskryf is en die ioon-uitruilings fase wat 'n komplekse vastestof en water fase gekombineerd is. Die doel van die werkstuk is om die basis te skep vir die ontwikkeling van modelle wat gebruik kan word om die herwinning van skaars-aarde mertale vanuit lae oplosbare erstse te modelleer en beskryf. 'n Tipiese industriële voorbeeld is die herwinning van skaars-aarde metale van lae-graadse kalkagtige erste deur gebruik te maak van perkolerende logings reaksies wat geduring die vastestof / vloeistof ewewig versteur. Die konsentrasie van die skaars-aarde metale in hierde erts gesteentes kan wissel vanaf so laag as 0.05% tot 0.3% per massa. Hierdie konsentrasies is uiters laag gesien vanuit enige industriële herwinnings proses oogpunt.
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Guarilloff, Philippe. "Guidelines for the nitrate selectivity from ion-exchange resins having a quaternary ammonium group as a binding site /." Title page, table of contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phg915.pdf.
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Scott, Greg Michael. "The virucidal properties of silver ion-exchange resins and metal-based nanoparticles and their potential use in water purification." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3755.
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Bringué, Tomás Roger. "Thermally stable ion-exchange resins as catalysts for the liquid-phase dehydration of 1-pentanol to di-n-pentyl ether." Doctoral thesis, Universitat de Barcelona, 2007. http://hdl.handle.net/10803/670248.
Full textAbstract:
En este trabajo, se propone di-n-peintil éter (DNP) como un buen producto para la reformulación delos combustibles diesel por sus buenas propiedades, en especial un elevado número de cetano y buen comportamiento en frío. El DNPE se podría obtener mediante deshidratación de 1-pentanol en fase líquida utilizando resinas de intercambio iónico como catalizadores, en especial las resinas termoestables. Los experimentos se realizaron en un autoclave de 70 mL de volumen útil operado en discontinuo. El intervalo de temperaturas estudiado fue de 120 a 190ºC, y la presión se fijo en 16bar para trabajar en fase flíquida.
Primero se estudiaron las variables de operación (masa de catalizador, velocidad de agitación, efecto del diámetro de partícula) para encontrar las condiciones en las cuales no hay influencia del a transferencia de materia. Posteriormente se probaron 7 catalizadores comerciales con el objetivo de encontrar el apropiado para realizar un estudio cinético y evaluar el equilibrio termodinámico de la reacción.
De todos los catalizadores ensayados, la mayor conversión se consiguió con Amberlyst 70 (68%) a 190ºC, con una selectividad aceptable a esa temperatura. Se observó que la capacidad ácida jugaba un papel importante puesto que a una temperatura constante, a mayor capacidad ácida, mayor conversión y velocidad de reacción. Se utilizó la resina Amberlyst 70 para los estudios cinéticos y de equilibrio.
Se estudió el equilibrio termodinámico de la deshidratación de 1-pentanol a DNPE y agua en el intervalo de temperaturas de 150 a 190ºC. Se vio que esta reacción es ligeramente exotérmica, con una entalpía de reacción de -6.5 Kj/mol si esta se considera constate en el intervalo de temperatura (-3.8 Kj/mol si no se considera constante). A partir de este valor se propone una entalpía de formación del DNPE de -423.9 Kj/mol (-421.1 Kj/mol si no se considera constante), y una entropía para el DNPE de 464.9 J(K mol) (476.
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Quattrini, Federico. "Emerging Techniques for Inorganic Metal Speciation and Bioavailability." Doctoral thesis, Universitat de Lleida, 2018. http://hdl.handle.net/10803/664422.
Full textAbstract:
El coneixement profund de la especiació dels metalls pesants és clau per a determinar la seva biodisponibilitat. Per això cal complementar la informació sobre les concentracions amb la informació sobre els fluxos d’internalització. Diverses tècniques analítiques han estat desenvolupades amb aquesta fi, i algunes d’elles aprofiten les propietats de les resines d’intercanvi iònic o quelants.
D’una banda, aquesta tesi investiga la velocitat d’acumulació d’ions metàl·lics a la resina Chelex 100, sigui experimentalment o a través d’un model teòric. Aquesta interpretació permet descriure els efectes dels lligands competidors i determinar les constants de dissociació dels complexes.
D’altra banda, dues noves tècniques analítiques han estat desenvolupades. La primera deriva de la IET, una tècnica comunament utilitzada en equilibri, però n’extreu informació dinàmica. La segona és una modificació del popular DGT, que s’ha emprat un cop el sistema ha assolit l’equilibri.El conocimiento profundo de la especiación de los metales pesados es clave para determinar su biodisponibilidad. Por eso es necesario complementar la información sobre las concentraciones con la información sobre los flujos de internalización. Diversas técnicas analíticas han sido desarrolladas con este fin, y varias aprovechan propiedades de las resinas de intercambio iónico o quelantes. Por un lado esta tesis investiga la velocidad de acumulación de iones metálicos en la resina Chelex 100, tanto experimentalmente, como a través de un modelo teórico. Esta interpretación permite, asimismo, describir los efectos de los ligandos competidores y determinar las constantes de disociación de los complejos. Por otro lado, dos nuevas técnicas analíticas han sido desarrolladas. La primera deriva de la IET, una técnica comúnmente utilizada en equilibrio, pero extrae información dinámica de ella. La segunda es una modificación del popular DGT, que se ha empleado una vez el sistema ha alcanzado el equilibrio.
A deep knowledge of heavy metal ions speciation is key to assessing their bioavailability. In this regard, data about concentrations should be complemented with data about the internalization fluxes. Several analytical techniques have been developed to this purpose, and many of them exploit properties of ion-exchange or chelating resins. On the one hand, this thesis studies the rate of metal ions uptake on Chelex 100 resin, both experimentally and through a theoretical model. This interpretation also allows describing the effect of competing ligands and determining the dissociation constants of the complexes. On the other hand, two new analytical techniques are developed. The first one stems from IET, a technique commonly used at equilibrium, but aims at extracting dynamic information from it. The second one is a modification of the well-known DGT, devised to provide information once equilibrium has been attained.
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Less, John Ryan. "Comparison of Natural Organic Matter (NOM) Removal Processes on Disinfection Byproduct (DBP) Formation During Drinking Water Treatment." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1293217404.
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Shields, Anthony J. "UNDERSTANDING AND MODELING THE SORPTION ON ANION EXCHANGE RESINS USING POLY-PARAMETER LINEAR FREE-ENERGY RELATIONSHIPS AND PHASE CONVERSION." Master's thesis, Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/217867.
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Civil EngineeringM.S.Env.E.
Priority organic and emerging contaminants are a growing concern for drinking water treatment due to their increasing presence in the environment. This study developed a predictive model for the sorption of anionic organic contaminants from drinking water on three anion exchange resins: a strong polystyrenic (IRA-910), weak polystyrenic (IRA-96), and a strong polacrylic (A860). The model quantifies the individual mechanisms of sorption using poly-parameter linear free energy relationships (pp-LFERs) and the feasibility of phase conversion (e.g., an ideal gas phase as the reference state) for ionic species was examined. To develop the model, a training set of isotherms was obtained using aliphatic and aromatic carboxylates, phenols, anilines, nitrobenzene, and ibuprofen. These compounds were chosen as model organic contaminants in the environment. The training set and 1-3 test compounds (3-methyl-2-nitrobenzoate, phenol, and 4-nitroaniline) were accurately predicted using the created model for each resin. An understanding of the effects of resin structure on sorption interactions was also developed that focused on ionic functional groups, resin matrix, and hydrophilicity (i.e. water content). It was shown that greater sorption efficiency was achieved when electrostatic (ion exchange) and nonelectrostatic (adsorption) interactions were present together to create a synergistic addition. However, sorption on ion exchangers was poor if the pH of the system approached levels lower than the sorbate pKa. Additionally, weak base exchanges lose exchange capacity as pH levels approach resin pKa (IRA-96 pKa = 6.0). Additional contributions to the sorption mechanisms were observed by studying various electron donating/withdrawing functional groups on the contaminants. It was concluded that π-π and H-bonding interactions contributed a greater amount to the nonelectrostatic mechanisms than cavity formation forces and nonspecific forces. A comparison between the three resins showed that IRA-96 (weak base polystyrenic) had a greater removal capacity than IRA-910 (strong base polystyrenic), followed far behind by A860 (strong base polyacrylate). This is due to differences between the resins, such as the hydrophilicity, the density of the ion exchange group, and the presence of aromatic rings within the matrix structure. Although the modeling method accurately predicted the phase change from aqueous to sorbent phases, it was shown that the SPARC calculated aqueous-gas ion transfer energies were poor estimations of the transfer energy to the ideal gas phase and further study is necessary to accurately determine this value. This modeling methodology is believed to be applicable to emerging contaminants such as pharmaceuticals in water systems and helps further new water treatment technologies while developing a mechanistic understanding of electrostatic and nonelectrostatic interactions in general. This can be applied to additional separation processes such as chemical purification and chromatographic separation.
Temple University--Theses
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Menendez-Alonso, Elena. "Trace metal and speciation analysis using ion-exchange and energy dispersive X-ray fluorescence spectrometry." Thesis, University of Plymouth, 2000. http://hdl.handle.net/10026.1/896.
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Studies have been carried out on specific ion-exchange (Dowex 50W-X8 and Dowex 1-X8) and chelation (Chelex-100) resins, in order to determine their physical and chemical characteristics, to understand and explain their limits of function and to optimise their use as substrates in trace metal and speciation measurement by EDXRF. Structural information was obtained by scanning electron microscopy and x-ray microanalysis showing a homogeneous distribution of functional groups and retained ions on both sectioned and whole resins. Particle size experiments performed on Dowex 50W-X8 (38 - 840 µm) showed that this parameter has no effect on the relationship between intensity of fluorescence and concentration or mass of resin. Inter-element effects were not observed in the analysis of multielemental specimens prepared on ion-exchange / chelation media by EDXRF. This indicates that the proposed method has a significant advantage when compared with other methodologies. A theoretical ‘model’, based on the formation of thin films on the surface of the resin beads, has been proposed in order to link and explain the effects observed in these experiments. The use of a batch retention system has shown distinct advantages over using columns in terms of linearity, accuracy, precision, rapidity and simplicity. Parameters such as pH and ionic strength of the solution, concentration of competing ions and volume of the sample have been proven to be critical. The maximum retention capacity has been determined as 3.2, 1.1 and 0.67 mEq/g for Dowex 50W-X8, Dowex 1-X8 and Chelex-100 respectively. The optimum mass of resin for XRF analysis was found to be 0.5 g, for all resins tested. The linear range covered 4 to 5 orders of magnitude. These findings show the potential of the investigated media to overcome instrumental and sample limitations. Based on the physico-chemical information found, methodologies for three different applications of the resins to EDXRF determinations have been developed and their analytical possibilities explored. The multi-elemental determination of metals in sewage sludge digests was achieved by retaining the metals on Dowex 50W-X8 at pH 2 and Chelex-100 at pH 4. Chelex-100 allows quantitative recoveries for Cu and Zn. A wider range of elements was determined on Dowex 50W-X8, although with poorer recoveries (60 - 90%). The limits of detection were 10 - 21 µg when Dowex 50W-X8 was used and 8 - 49 µg for Chelex-100. The method was validated by the analysis of a certified material. The determination of Kβ/Kα intensity ratios for Cr and Mn species and its potential as a tool for direct elemental speciation has also been studied. A difference in Kβ/Kα between the oxidation states of the analytes was only observed during the analysis of solutions of the metal species by EDXRF at the 98% level of confidence. Finally, the speciation and preconcentration of Cr(III) and Cr(VI) in waters has been performed by retention on Dowex 50W-X8 and Dowex 1-X8 followed by EDXRF determination. Efficient recoveries and preconcentration factors of up to 500 were achieved, leading to limits of detection of 30 µg/L for Cr(VI) and 40 µg/L for Cr(III). This method is simple, fast and inexpensive, allowing quantitative recoveries in the speciation of chromium in waste waters.
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Badia, i. Córcoles Jordi Hug. "Synthesis of ethers as oxygenated additives for the gasoline pool." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/400771.
Full textAbstract:
Functionalized ion-exchange resins are polymer-based materials that can be used as catalysts, in a wide variety of chemical reactions, to achieve highly selective formation of desired products at cost-effective rates. Among these catalysts, sulfonic macroreticular ion-exchange resins have become critical in major industrial processes, such as the etherification of isoolefins to obtain branched ethers.
The production of branched ethers, which are oxygenated antiknocking additives used in commercial gasoline formulation, became massive after the phase out of lead-based compounds in the 1990s. Among the ethers which are used nowadays, the most relevant ones, in terms of their global market share, are methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE). These ethers are industrially obtained under mild conditions (i.e., at relatively low temperature and pressure) by means of the catalytic reaction between 2-methylpropene (isobutene) and methanol or ethanol, respectively, over sulfonic macroreticular ion-exchange resins.
On the other hand, the use of reactants obtained from renewable feedstocks to produce fuel components is convenient, since it allows reducing the carbon footprint of transportation fuels in a context in which the global vehicle fleet is growing. In this sense, the trend has been to use biomass-derived ethanol as an alternative to carbon-based alcohols. Nevertheless, this option has generated concerns regarding its competition with the food supply chain. Alternatively, the use of other alcohols, such as 1-propanol and 1-butanol, which can also be obtained through fermentative processes, is becoming more attractive, given that they would not compete with food supplies. Etherification of isobutene with these alcohols would produce heavier ethers (i.e., propyl tert-butyl ether, PTBE, and butyl tert-butyl ether, BTBE, respectively), which have potential benefits as gasoline additives. Nowadays, this is one of the alternatives at hand to achieve an actual improvement of the gasoline formulation in the short- midterm.
Even though the industrial-scale production of MTBE and ETBE is today widely spread, relevant physicochemical aspects regarding ion-exchange resins have not been completely understood. Therefore, studies aimed at providing a deeper insight into the catalytic behavior of these materials are of interest.
The present PhD thesis contains several studies related to the liquid phase syntheses of MTBE, ETBE, PTBE, and BTBE. In the first place, an investigation was carried out aimed to determine the chemical equilibrium composition and thermodynamic properties of the liquid-phase syntheses of the mentioned reactions. Secondly, a study was performed regarding the products distribution and the conditions that favor side reactions taking place along with etherification reactions. On the other hand, in order to further understanding the catalytic behavior of sulfonic macroreticular ion-exchange resins, relations were established between the catalytic activity of sixteen different resins and their most relevant properties, taking into account the reaction media properties, in the four reaction systems. Also, the viability of an integrated process to
obtain, simultaneously, ETBE and BTBE over sulfonic macroreticular ion-exchange resins was studied. In this sense, individual and simultaneous processes were compared, a catalytic screening study was carried out to determine the most suitable catalyst and the effect of temperature and initial reactants composition on the ethers formation, in terms of conversion, selectivity and reaction rate, was discussed. Finally, a kinetic study of three of the studied reaction systems is provided. These are the individual syntheses of PTBE and BTBE and the simultaneous syntheses of ETBE and BTBE over AmberlystTM 35. A mechanistic kinetic model, in terms of components activities, was proposed for each studied reaction and it was found that the most likely reaction mechanism is an Eley-Rideal mechanism in which the surface reaction step is the rate-determining step.Les resines de bescanvi iònic funcionalitzades són materials polimèrics que s’utilitzen com a catalitzadors en una gran varietat de reaccions químiques. Entre aquests catalitzadors, les resines sulfòniques han assolit una importància cabdal en processos industrials molt rellevants, com ara l’eterificació d’isoolefines per obtenir èters ramificats, els quals, s’utilitzen com a additius oxigenats en la formulació de gasolines comercials. D’èters ramificats, se’n pot destacar el metil terc-butil èter (MTBE) o l’etil terc-butil èter (ETBE), que s’obtenen per reacció entre isobutè i metanol o etanol, respectivament, utilitzant resines de bescanvi iònic sulfòniques macroreticulades com a catalitzadors. Alternativament, l’ús d’1-propanol i 1-butanol produeix propil terc-butil èter (PTBE) i butil terc-butil èter (BTBE). Tot i que la producció d’MTBE i ETBE està molt estesa, hi ha aspectes de la naturalesa fisicoquímica dels processos catalítics en què participen les resines que continuen sense comprendre’s completament. En conseqüència, calen estudis que aportin nous coneixements en aquest sentit. És per això, doncs, que aquesta tesi inclou diversos estudis relatius al comportament catalític de resines de bescanvi iònic sulfòniques macroreticulades en les reaccions de síntesi en fase líquida d’MTBE, ETBE, PTBE i BTBE. Pel que fa a l’estudi sobre l’equilibri químic d’aquestes reaccions, s’han pogut determinar les propietats termodinàmiques corresponents i s’han pogut estimar els increments d’entalpia i entropia de formació dels èters resultants. En relació amb la formació de subproductes en aquests processos, s’ha pogut concloure que totes les reaccions secundàries es veuen afavorides per un increment de la temperatura d’operació. També s’han establert relacions entre les propietats dels catalitzadors i el nivell d’activitat catalítica que presenten i s’ha determinat que la capacitat àcida i el volum expansible de la fase gel de les resines determinen l’activitat catalítica que presenten. Quant a la producció simultània d’ETBE i BTBE, s’ha comprovat que el procés de síntesi simultània de tots dos èters presenta avantatges significatius respecte de la producció de cada èter individualment. Finalment, l’anàlisi cinètica de les reaccions estudiades ha permès determinar que el mecanisme de reacció més probable és del tipus Eley-Rideal i que l’etapa controlant del procés de síntesi és la de reacció en superfície.