The purpose of this study was to evaluate the ability of typical cation and anion exchange resins to remove Escherichia coli from water. The objective was to obtain a method of purifying slightly polluted, private well water supplies. The investigation consisted of passing water samples, inoculated with known concentrations of Escherichia coli, through resin columns of known volumes. The resins were subjected to varying Escherichia coli concentrations and cycles of regeneration. The results indicated the anion exchange resin, Amberlite IRA-400, possessed the highest potential for removing Escherichia coli. / Master of Science

103Pd is an important therapeutic radionuclide and has recently found great interest due to its higher radiobiologic effect. 109Cd decays by electron capture and is generally used as calibration sources in industrial and medical fields. A new method for the production of 103Pd and 109Cd using the 66 MeV proton beam of iThemba LABS on a tandem natural silver target (Ag/Ag) has been developed. The tandem targets (each target with a mass of 9 g and a thickness of 3 mm) were placed in the high energy slot (62.515 MeV - 40.173 MeV) and low energy slot (38.652 MeV – 0 MeV) to produce the bulk 103Pd and 109Cd, respectively. The radiochemical separation of the Pd radionuclides (103Pd, 100Pd) and the co-produced Rh radioisotopes (mainly 101Rh and 100Rh which are produced from decay of their Pd parents) from the bulk natAg was achieved using a Chelex chelating resin column. In the preliminary studies, different size columns (3 cm x 1 cm, 11 cm x 1 cm, 13 cm x 1 cm and 16 cm x 1.5 cm) were investigated to determine the optimal column conditions for the separation. It was determined that the optimal conditions for the chemical separation was with a 13 cm x 1 cm resin column with the elution of Rh and Ag radionuclides carried out with 1 M HNO3 and the elution of Pd radionuclides with 10 M HCl. No Ag or Rh impurities were detected in the final product and the average recovery of Pd was > 96 %. This work was repeated using a ―hot‖ irradiated Ag target and the chemical processing was done in a hot cell using the same resin column conditions. The recovery of the high purity 103Pd from the irradiated natAg target was found to be > 95 %. The radiochemical separation of 109Cd from the bulk natAg target was done in two parts. In the first part, the precipitation method was used to reduce the silver into a metallic form using 30 g of Cu turnings. The resulting 109Cd filtrate was loaded onto a AG-X10 anion exchange resin column (6 cm x 1 cm). For the optimal chemical separation, the elution of Ag and Cu(II) was carried out with 2 M HCl containing H2O2 and the elution of 109Cd was accomplished with 1 M HNO3. The recovery yield of 109Cd was > 99 %. / Chemistry / M.Sc. (Chemistry)

Metal contamination is a considerable environmental problem because metals are persistent contaminants. Ion exchange is one of the most commonly used treatment options for trace metal removal. This research develops and evaluates a redox active modified ion exchange system that has the potential to reduce the ionic strength of ion exchange regeneration streams. Poly-L-cysteine (PLC) was selected as the redox active, adsorbing functional group on the surface of a reticulated vitreous carbon (RVC) electrode. PLC is an excellent soft acid metal chelator and is unique in that its thiol groups can form disulfide bonds with each other. The reduction of available thiols changes the metal binding capacity of the peptide since the thiol is the primary binding group. RVC provides a macroporous conductive monolithic resin to support the peptide. An experimental apparatus was designed to study the properties of this system and estimate performance. Distinct oxidized and reduced states of PLC on the surface of the RVC were confirmed by changes in metal binding characteristics. Adsorption edges showed a sharper pH dependence for the reduced electrode compared to the oxidized electrode from pH 3-7. Adsorption isotherms performed at pH 7 showed increased capacity for the reduced electrode. The change was reversible by chemical and electrical reduction. This difference was confirmed at the molecular level with Cd- EXAFS of oxidized and reduced electrodes. A greater degree of cadmium-sulfur coordination was observed on the reduced electrode and a greater cadmium-oxygen coordination was apparant on an oxidized electrode. A multidentate adsorption model was developed to model the pH dependent behavior of cadmium adsorption on the PLC-RVC surface. Nickel adsorption showed increased adsorption in the oxidized state. The most likely explanation is increased carboxylate complexation. The electronically switchable ion exchange system (ESIE) provides a framework for modifying traditional ion exchange processes. The system has 5 to 10 times less specifc capacity than current ion exchange systems, but uses solutions 10-100 times lower in ionic strength for regeneration. Further studies on the effect of ionic strength on adsorption and current usage are necessary to compare the cost of the ESIE process to traditional ion exchange. / text

No description available.

To understand the glass electrode needs knowledge from more than one level. The construction ofthe glass electrode is one part, an other is the composition and structure of glass. The Nernstequation have an important role, but also the sources of errors in the analysis and the calibration ofthe glass electrode. Focus for this article is how the glass electrode really works and how Gibbs freeenergy made the potential dependent of the concentration of H+and gives the logarithm to thefunction. Nikolskii's ion exchange theory starts to explain the question about how the potentialcreates and Baucke's dissociation mechanism made it more explicit. The big different in theequations from the both theories respectively is the meaning of the constants, but for practical useof the glass electrode in analysis it is not important when the value of the constant is given bycalibration. This is not an excuse for that fact that the dissociation mechanism is more completethan the ion exchange theory in the understanding of the glass electrode. / För att förstå hur glaselektroden fungerar krävs kunskap från mer än ett plan. Glaselektrodenskonstruktion är en del, glasets kemiska struktur en annan. Nernst ekvationen spelar en viktig roll,men även felkällorna i de analyser som görs med glaselektrod, (vanligtvis pH-mätning), samtkalibreringen av glaselektroden. I den här uppsatsen ligger fokus på hur glaselektroden faktisktfungerar och hur Gibbs fria energi gör potentialen beroende av koncentrationen vätejoner och tillförlogaritmen i funktionen för glaselektroden. Nikolskii's ion exchange theory påbörjar förklaringen avpotentialens uppkomst och Baucke's dissociation mechanism gör den tydligare. Skillnaden mellanrespektive teori och dess matematiska funktion är konstantens innebörd och betydelse, men för denpraktiska användningen av glaselektroden till analyser är detta av mindre vikt då konstantens värdefås genom kalibrering. Detta är dock ingen ursäkt för det faktum att the dissociation mechanism geren mer fullständig förklaring och ökad förståelse för hur glaselektroden fungerar än the ionexchange theory.

103Pd is an important therapeutic radionuclide and has recently found great interest due to its higher radiobiologic effect. 109Cd decays by electron capture and is generally used as calibration sources in industrial and medical fields. A new method for the production of 103Pd and 109Cd using the 66 MeV proton beam of iThemba LABS on a tandem natural silver target (Ag/Ag) has been developed. The tandem targets (each target with a mass of 9 g and a thickness of 3 mm) were placed in the high energy slot (62.515 MeV - 40.173 MeV) and low energy slot (38.652 MeV – 0 MeV) to produce the bulk 103Pd and 109Cd, respectively. The radiochemical separation of the Pd radionuclides (103Pd, 100Pd) and the co-produced Rh radioisotopes (mainly 101Rh and 100Rh which are produced from decay of their Pd parents) from the bulk natAg was achieved using a Chelex chelating resin column. In the preliminary studies, different size columns (3 cm x 1 cm, 11 cm x 1 cm, 13 cm x 1 cm and 16 cm x 1.5 cm) were investigated to determine the optimal column conditions for the separation. It was determined that the optimal conditions for the chemical separation was with a 13 cm x 1 cm resin column with the elution of Rh and Ag radionuclides carried out with 1 M HNO3 and the elution of Pd radionuclides with 10 M HCl. No Ag or Rh impurities were detected in the final product and the average recovery of Pd was > 96 %. This work was repeated using a ―hot‖ irradiated Ag target and the chemical processing was done in a hot cell using the same resin column conditions. The recovery of the high purity 103Pd from the irradiated natAg target was found to be > 95 %. The radiochemical separation of 109Cd from the bulk natAg target was done in two parts. In the first part, the precipitation method was used to reduce the silver into a metallic form using 30 g of Cu turnings. The resulting 109Cd filtrate was loaded onto a AG-X10 anion exchange resin column (6 cm x 1 cm). For the optimal chemical separation, the elution of Ag and Cu(II) was carried out with 2 M HCl containing H2O2 and the elution of 109Cd was accomplished with 1 M HNO3. The recovery yield of 109Cd was > 99 %. / Chemistry / M.Sc. (Chemistry)

Nesse estudo foram desenvolvidas metodologias para remoção e recuperação do cobre presente em resíduos sólidos industriais provenientes de processos de galvanostegia/galvanoplastia. O desempenho de quatro resinas comerciais trocadoras de íons (Amberlyst 15 wet, Lewatit VP OC 1955, Lewatit VP OC 1960 e Lewatit VP OC 1800) foi investigado de acordo com o percentual de recuperação e a seletividade ao cobre. Os resíduos sólidos foram primeiramente caracterizados e, após a determinação de metodologia para solubilização dos mesmos, verificou-se que ambos apresentam, além do Cu outros metais como Sn, Al, Fe, Ni e Cr em sua composição. Foram realizados estudos variando-se o pH, tempo de contato e quantidade de resina, visando a confecção das isotermas de adsorção e a determinação das condições ideais do processo. A maior remoção percentual de cobre foi observada para as resinas catiônicas: superior a 95% em massa. Entretanto, maior seletividade em relação ao cobre foi observada para as aniônicas. O cobre retido nas resinas foi recuperado na forma de solução de Cu (II) em percentuais que variaram de acordo com a resina e com o agente de regeneração utilizado. / Methodologies for copper removal and recovery from industrial solid residues proceeding from galvanostegy/galvanoplasty processes had been developed in this study. The performance of four commercial ion exchange resins (Amberlyst 15 wet, Lewatit VP OC 1955, Lewatit VP OC 1960 e Lewatit VP OC 1800) was investigated in accordance with the percentage of recovery and the selectivity to copper. The solid residues first had been characterized and, after the determination of the best methodology for solubilization of the same ones, were verified that beyond the Cu other metals as Sn, Al, Fe, Ni and Cr were in the composition of the residues. The influence of pH, time of contact and amount of resin had been investigated, aiming at the confection of the adsortion isotherms and the determination of the ideal conditions of the process. The biggest percentile copper removal was observed for cationic resins: above 95% in mass. However, greater selectivity to copper was observed for the anionic ones. The restrained copper in resins was recovered as solution of Cu (II) in percentages that had varied with the resin and with the regeneration agent.

Nesse estudo foram desenvolvidas metodologias para remoção e recuperação do cobre presente em resíduos sólidos industriais provenientes de processos de galvanostegia/galvanoplastia. O desempenho de quatro resinas comerciais trocadoras de íons (Amberlyst 15 wet, Lewatit VP OC 1955, Lewatit VP OC 1960 e Lewatit VP OC 1800) foi investigado de acordo com o percentual de recuperação e a seletividade ao cobre. Os resíduos sólidos foram primeiramente caracterizados e, após a determinação de metodologia para solubilização dos mesmos, verificou-se que ambos apresentam, além do Cu outros metais como Sn, Al, Fe, Ni e Cr em sua composição. Foram realizados estudos variando-se o pH, tempo de contato e quantidade de resina, visando a confecção das isotermas de adsorção e a determinação das condições ideais do processo. A maior remoção percentual de cobre foi observada para as resinas catiônicas: superior a 95% em massa. Entretanto, maior seletividade em relação ao cobre foi observada para as aniônicas. O cobre retido nas resinas foi recuperado na forma de solução de Cu (II) em percentuais que variaram de acordo com a resina e com o agente de regeneração utilizado. / Methodologies for copper removal and recovery from industrial solid residues proceeding from galvanostegy/galvanoplasty processes had been developed in this study. The performance of four commercial ion exchange resins (Amberlyst 15 wet, Lewatit VP OC 1955, Lewatit VP OC 1960 e Lewatit VP OC 1800) was investigated in accordance with the percentage of recovery and the selectivity to copper. The solid residues first had been characterized and, after the determination of the best methodology for solubilization of the same ones, were verified that beyond the Cu other metals as Sn, Al, Fe, Ni and Cr were in the composition of the residues. The influence of pH, time of contact and amount of resin had been investigated, aiming at the confection of the adsortion isotherms and the determination of the ideal conditions of the process. The biggest percentile copper removal was observed for cationic resins: above 95% in mass. However, greater selectivity to copper was observed for the anionic ones. The restrained copper in resins was recovered as solution of Cu (II) in percentages that had varied with the resin and with the regeneration agent.

The present study involves the determination of traces of thallium and mercury in aqueous solution by forming ion-association complexes of these metals with rhodamine 6G (R6G) in the presence of iodide. Thallium(lll) and mercury(Il) are able to quench the fluorescence of R6G in the presence of iodide by forming ion—association complexes, and the degree of quenching correlates with the thallium(III) or mercury(II) concentrations . By using this method, the minimum amount of thallium- (III) that can be determined in aqueous solutions is approximately 4.00 X 10-6m, while the minimum amount of mercury(II) is approximately 3.00 X 10-6m. Thallium(I) cannot be determined by this method because it is not possible to form ion-association complexes under similar experimental conditions therefore, this method can be used to differentiate between Tl(I) and Tl(III) in aqueous solution. To elucidate the composition of the ion-association complexes in aqueous solutions two spectrophotometric methods are used: the mole-ratio method and the continuous- variation method. The experimental results seem to indicate that two complexes are formed for the mercury(II)-R6G-iodide system. The empirical compositions of these complexes are tentatively determined to be [(R6G)HgI3] and [(R6G)2HgI4).

No description available.