Thesis (M.S.)--Rochester Institute of Technology, 1987. / Typescript. Includes bibliographical references (leaves 59-60).

Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

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Thesis (MTech (Chemical Engineering)--Cape Technikon, Cape Town, 2002 / This 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

Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town, 2000 / Cyanide 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

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.

O uso do cianeto em processos de eletrodeposição proporciona à prática industrial risco ambiental e ocupacional. Com isso, estudos têm buscado alternativas para a substituição desse agente nocivo. O Instituto de Pesquisas Tecnológicas (IPT) desenvolveu um banho de cobre alcalino sem cianeto, que utilizou como substituinte o HEDP (1-hidroxietano-1,1-difosfônico). Para a recuperação desse ácido a eletrodiálise foi avaliada, que consiste no uso de um sistema de membranas trocadoras de íons (MTI) e de corrente elétrica como força motriz. Meios oxidantes, corrosivos e com materiais orgânicos favorecem a degradação da membrana, inibindo sua capacidade em separação. Alternativas de manutenção têm sido estudadas para o aumento da vida útil das membranas, como o uso de agentes de limpeza. O estudo do envelhecimento proporciona a avaliação de um material em condições específicas, a fim de monitorar alterações em função do tempo de contato com o meio. O presente estudo propõe o envelhecimento de membranas aniônicas comerciais em soluções diluídas, provenientes do banho sintético de cobre à base de HEDP. Como objeto de estudo, foram selecionadas duas membranas, sendo uma heterogênea e uma membrana homogênea. Essas foram envelhecidas em três concentrações distintas (CuHEDP 1%, 5%, 10% v/v), por 400h de contato, sob agitação. As possíveis modificações estruturais foram avaliadas por meio de técnicas como a microscopia eletrônica de varredura acoplada à espectroscopia de energia dispersiva de raios-X (MEV-EDS), a análise termogravimétrica (TGA) e espectroscopia por infravermelho com transformada de Fourier (FTIR-ATR). As propriedades intrínsecas das membranas estão diretamente relacionadas ao seu caráter seletivo e morfológico. Para avaliar tais propriedades, foram utilizados ensaios cronopotenciométricos e a titulação potenciométrica. As propriedades investigadas foram o grau de inchamento, a capacidade de troca, a resistência elétrica, a densidade de corrente limite e a permeseletividade. Paralelamente, submeteu-se a membrana heterogênea ao envelhecimento em um sistema de eletrodiálise por 400h, monitorando-se as alterações em sua densidade de corrente e resistência elétrica a cada 100h de ensaio. Em adição, realizou-se a avaliação de agentes de limpeza de caráter ácido e básico, em concentrações distintas. O agente que atingiu melhor desempenho em remover a incorporação iônica foi aplicado às membranas envelhecidas em 100h de envelhecimento. Em seguida, essas foram reavaliadas a partir de ensaios eletroquímicos. Observou-se que houve interação entre os íons em solução e as membranas estudadas, que proporcionaram alterações em sua estrutura e propriedades, porém sem causar modificações que indicassem o descarte para ambas membranas. / The use of cyanide in electrodeposition processes provides industrial practice environmental and occupational risk. Thereby, studies have looked for alternatives for the substitution of this noxious agent. The Institute of Technological Research (ITR) developed an alkaline copper bath cyanide-free, which used HEDP (1-hydroxyethane- 1,1-diphosphonic) as a substitute. For the recovery of this acid the electrodialysis was evaluated, which consists of the use of an ion-exchange membrane (IEM) system and electric current as the driving force. Oxidizing, corrosive and organic materials favor membrane degradation, inhibiting their separation ability. Maintenance alternatives have been studied to increase the shelf life of membranes, such as the use of cleaning agents. The ageing study provides the evaluation of a material under specific conditions, in order to monitor changes as a function of the time of contact with the medium. The present study proposes the ageing of commercial anionic membranes in dilute solutions from the synthetic copper bath with HEDP. The purpose of the study was selected two membranes, being a heterogeneous and homogeneous membrane. These were aged in three distinct concentrations (CuHEDP 1%, 5%, 10% v/v) for 400 hours of contact, under stirring. The possible structural modifications were evaluated by techniques such as scanning electron microscopy coupled to X-ray dispersive energy spectroscopy (SEM-EDS), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR-ATR). The intrinsic properties of the membranes are directly related to their selective and morphological character. To evaluate such properties, chronopotentiometric assays and potentiometric titration were used. The investigated properties were swelling degree, ion-exchange capacity, electrical resistance, current density, and permselectivity. In parallel, the heterogeneous membrane was subjected to ageing in an electrodialysis system for 400h, monitoring the changes in its current density and electrical resistance every 100h of the test. In addition, acid and basic cleaning agents were evaluated in different concentrations. The agent that achieved the best performance in removing the ionic incorporation was applied to the membranes aged in 100h of ageing. These were then reevaluated from electrochemical tests. It was observed that there was interaction between the ions in solution and the membranes studied, which provided alterations in its structure and properties, but without provide modifications that indicated the need of disposal for both membranes.

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