The semiconductor industry has been growing at a fast pace in the last several decades and this growth is expected to continue in the future. One process that is repeated several times in a microchip fabrication is the Chemical Mechanical Planarization (CMP). CMP is a critical process that must be employed after the metal deposition step to eliminate any topography over which the next layer must be processed. Today, copper interconnect is widely used. In addition to possess a high resistance to electro migration effects and low electrical resistivity, copper techniques require fewer (approximately 25%) processing steps. CMP and post-CMP cleaning processes are projected to account for 50 percent of the water consumed by fabrication's ultra pure water. While there are a variety of treatment schemes currently available for the removal of heavy metals from CMP wastewater streams, many introduce additional chemicals to the process, have large space requirement, or are not effective. Polyethyleneimine (PEI) is well known to use in the ion metal affinity chromatography (IMAC) due to the great metal ion binding abilities. While work has been conducted on the use of PEI on membrane filtration for binding metals from industrial wastewaters, the experiments performed in this research are novel with respect to the waste (Cu CMP) treated as well as the method of packed bed column treatment. This research focused primarily on the study of an alternative technique to remove both metal ions and metal-chelated complexes from Cu CMP wastewater streams. Not only copper, wastewater often contains chelating agents, surfactant, organic compounds, and inhibitors. Thus, most of the time copper ions form complexes with chelating agents, which made typical ion exchange resins ineffective. The work, then, explored the effect of components typically found in Cu CMP waste streams on the binding of copper ions to PEI. The competitive binding of copper between PEI and other complexing agents were also investigated. A secondary focus of this study was to fully develop and characterize the column performance and behavior. This includes the understanding of the chemistry of CMP waste characterization. This treatment technique using a PEI packed bed column showed great copper binding capacity. The column is capable of removing Cu CMP waste streams, which contain both copper ions and copper complexes, due to the unique ability of PEI that can play both cation and anion exchanger roles. This waste treatment technique is feasible for the semiconductor industry as large volumes of copper contaminated solutions from actual waste can be concentrated twelve-fold for metal recovery using hydrochloric acid. The adsorbent can be regenerated more than hundred of times with changing in the performance and the reproducibility.

Le combustible nucléaire usé, après avoir été débarrassé de l'uranium, du plutonium et potentiellement du neptunium par le procédé PUREX, est encore constitué d'environ la moitié des éléments du tableau périodique. Au sein de ceux-ci, l'américium est majoritairement responsable des émissions thermiques à long terme des colis de déchets. En le recyclant, la compacité des sites de stockage pourrait être significativement améliorée. Le procédé d'extraction liquide-liquide EXAm, dont l'étape clé est la séparation Am/Cm, a donc été développé afin de séparer l'Am seul. Pour ce faire, un mélange d'extractants est utilisé conjointement au TEDGA (N,N',N,N'-tétraéthyl-diglycolamide), un complexant aqueux. Ce dernier permet en effet d'améliorer la séparation Am/Cm en maintenant préférentiellement le curium en phase aqueuse, mais sa relation structure sélectivité est encore mal comprise. Ces travaux de thèse concernent donc la synthèse et l'évaluation d'analogues structuraux du TEDGA afin de mieux comprendre l'influence de sa structure sur la sélectivité Am/Cm dans le procédé EXAm. Durant cette étude, 14 analogues du TEDGA ont été synthétisés et 17 molécules ont été évaluées en extraction liquide-liquide. Plusieurs modifications structurales ont été étudiées : la longueur et l'encombrement stérique des chaines alkyle portées par les azotes, la taille de l'espaceur, ainsi que l'utilisation d'amides secondaires. Ainsi, ces travaux ont montré qu'à partir des chaines tétrabutyle, il n'est plus possible de maintenir les molécules en phase aqueuse et que l'ajout d'encombrement stérique sur les chaines alkyles ou la modification de la balance hydrophilie/lipophilie diminue systématiquement la sélectivité des ligands. L'introduction d'amides secondaires (-CONHR) donne des ligands extractibles par le solvant (formation de liaison hydrogène avec les extractants) ce qui les rend inutilisables dans le procédé EXAm. Quant à l'espaceur, il joue un rôle prépondérant sur la sélectivité : le raccourcir (malonamides) entraine la disparition du caractère complexant de la molécule à forte acidité, et l'allonger entraine une préférence du ligand pour l'Am au lieu du Cm (inversion de sélectivité). L'ensemble de l'étude met en lumière la particularité de la sélectivité apportée par le TEDGA face aux autres diglycolamides ainsi que la difficulté d'améliorer le procédé en utilisant cette famille de molécules. Néanmoins la meilleure compréhension de sa chimie a permis d'affiner sa modélisation dans le procédé et l'étude de sa relation structure sélectivité montre qu'une amélioration de la sélectivité des ligands pourrait encore être envisagée en rigidifiant l'espaceur. / After the reprocessing of uranium, plutonium and eventually neptunium by the PUREX process, the spent fuel is still composed of half of the periodic table. Among these elements, the main responsible for the heat of the wastes is americium. Its reprocessing could allow improving the compactness of deep geological storage of the wastes. Thus the liquid-liquid extraction process called EXAm was developed in order to recover the americium alone. The key step of the process is the Am/Cm separation. An extractant mixture is used with an aqueous complexing agent: TEDGA (N,N',N,N'-tetraethyl-diglycolamide). It allows to enhance the Am/Cm separation by keeping preferentially curium in the aqueous phase, but its structure selectivity relationship is not well known yet. Therefore, the purpose of this thesis is to synthesize and evaluate some structural analogues of TEDGA, in order to better understand the impact of its structure on the Am/Cm selectivity in the EXAm process.During this study, 14 analogues of TEDGA were synthesized and 17 molecules were evaluated in liquid-liquid extraction. Several structural modifications were studied: length and steric hindrance of the N-alkyl chains, size of the spacer, and the introduction of secondary amide functions. This work shows that it is not possible to maintain the ligand in the aqueous phase from tetrabutyl derivatives, and the addition of steric hindrance, or modification of hydrophilicity/lipophilicity balance, systematically decreases the selectivity of ligands. The addition of secondary amide functions (-CONHR) makes the molecules extractible by the solvent (formation of hydrogen bonds with the extractants), therefore they are unsuitable to be used in the EXAm process. The spacer has the main impact on the selectivity: the complexation capacity in high acid medium disappears when it is shortened (malonamide), whereas the ligand has a preference for Am instead of Cm (inversion of selectivity) when it is lengthen (TEDOODA and TETOUDA derivatives).This whole study shows the peculiar selectivity given by the TEDGA in comparison with other diglycolamides, and the difficulties to enhance the process using this family of ligands. Nevertheless, a better understanding of its chemistry has allowed to define more clearly its modeling in the process and the studying of its structure/selectivity relationship has shown that the enhancing of the ligands selectivity probably requires spacer preorganization.

No description available.

Motor car exhaust catalysts are some of the most important users of platinum, and much attention is given to the recycling of scrap platinum from spent exhaust systems. The dissolution of platinum from waste exhausts was previously only possible by pyrometallurgical processes or by the use of aggressive chemicals, such as aqua regia and cyanide, all of which, however, cause pollution problems. Recently the potential for the development of hydrometallurgical processes was identified. These processes are more efficient and more environmentally friendly than traditional processes. It was the aim of this study to investigate the oxidation of platinum with ozone as oxidizing agent in the presence of chloride as complexing agent. The influence of various factors, such as chloride ion concentration, pH and temperature were studied thermodynamically and electrochemically in order to achieve efficient leaching. The thermodynamic investigation, leading to the construction of Pourbaix diagrams of platinum in the presence of chloride, confirmed the possibility of the formation of stable aqueous complexes, as well as platinum oxides. From the electrochemical results obtained it can be concluded that ozone may be useful as an oxidizing agent, but according to the leaching results obtained, ozone holds few benefits compared to aqua regia and cyanide, although they still present some environmental challenges. The relatively low percentages of recovery obtained with leaching may be attributed to the rapid decomposition of ozone, which is affected by several factors, such as temperature, pH, initial concentration of ozone, ionic strength and stirring rate. Further optimisation of these factors can possibly prove ozone to be a useful oxidizing agent for the recovery of platinum. / Thesis (MSc (Chemistry))--North-West University, Potchefstroom Campus, 2013.

Motor car exhaust catalysts are some of the most important users of platinum, and much attention is given to the recycling of scrap platinum from spent exhaust systems. The dissolution of platinum from waste exhausts was previously only possible by pyrometallurgical processes or by the use of aggressive chemicals, such as aqua regia and cyanide, all of which, however, cause pollution problems. Recently the potential for the development of hydrometallurgical processes was identified. These processes are more efficient and more environmentally friendly than traditional processes. It was the aim of this study to investigate the oxidation of platinum with ozone as oxidizing agent in the presence of chloride as complexing agent. The influence of various factors, such as chloride ion concentration, pH and temperature were studied thermodynamically and electrochemically in order to achieve efficient leaching. The thermodynamic investigation, leading to the construction of Pourbaix diagrams of platinum in the presence of chloride, confirmed the possibility of the formation of stable aqueous complexes, as well as platinum oxides. From the electrochemical results obtained it can be concluded that ozone may be useful as an oxidizing agent, but according to the leaching results obtained, ozone holds few benefits compared to aqua regia and cyanide, although they still present some environmental challenges. The relatively low percentages of recovery obtained with leaching may be attributed to the rapid decomposition of ozone, which is affected by several factors, such as temperature, pH, initial concentration of ozone, ionic strength and stirring rate. Further optimisation of these factors can possibly prove ozone to be a useful oxidizing agent for the recovery of platinum. / Thesis (MSc (Chemistry))--North-West University, Potchefstroom Campus, 2013.

Characterising the geochemistry and speciation of major contaminant radionuclides is crucial in order to understand their behaviour and migration in complex environmental systems. Organic complexing agents used in nuclear decontamination have been found to enhance migration of radionuclides at contaminated sites; however, the mechanisms of the interactions in complex environments are poorly understood. In this work, radionuclide speciation and sorption behaviour were investigated in order to identify interactions between four key radionuclides with different oxidation states (Cs(I) and Sr(II) as important fission products; Th(IV) and U(VI) as representative actinides), three anthropogenic organic complexing agents with different denticities (EDTA, NTA and picolinic acid as common co-contaminants), and natural sand (as simple environmental solid phase). A UV spectrophotometric and an IC method were developed to monitor the behaviour of EDTA, NTA and picolinic acid in the later experiments. The optimised methods were simple, applied widely-available instrumentation and achieved the necessary analytical figures of merit to allow a compound specific determination over variable background levels of DOC and in the presence of natural cations, anions and radionuclides. The effect of the ligands on the solubility of the radionuclides was studied using a natural sand matrix and pure silica for comparison of anions, cations and organic carbon. In the silica system, the presence of EDTA, NTA and, to a lesser extent, picolinic acid, showed a clear net effect of increasing Th and U solubility. Conversely, in the sand system, the sorption of Th and U was kinetically controlled and radionuclide complexation by the ligands enhanced the rate of sorption, by a mechanism identified as metal exchange with matrix metals. Experiments in which excess EDTA, NTA and picolinic acid (40 – 100 fold excess) were pre-equilibrated with Th and U prior to contact with the sand, to allow a greater degree of radionuclide complex formation, resulted in enhanced rates of sorption. This confirmed that the radionuclide complexes interacted with the sand surface more readily than uncomplexed Th or U. Overall this shows that Th and U mobility would be lowered in this natural sand by the presence of organic co-contaminants. In contrast, the complexation of Sr with the complexing agents was rapid and the effect of the ligands was observed as a net increase on Sr solubility (EDTA, picolinic acid) or sorption (NTA). As expected, Cs did not interact with the ligands, and showed rapid sorption kinetics. Finally, ESI-MS was used to study competitive interactions in the aqueous Th-Mn-ligand ternary system. Quantification presented a challenge, however, the careful approach taken to determine the signal correction allowed the competitive interactions between Mn and Th for EDTA to be studied semi-quantitatively. In an EDTA limited system, Th displaced Mn from the EDTA complex, even in the presence of a higher Mn concentration, which was consistent with the higher stability constant of the Th-EDTA complex.

Tesis por compendio / [EN] The increase in energy needs, particularly in terms of environmental protection, has greatly stimulated research in the field of photovoltaic conversion in recent years. Solar radiation provides an excellent resource for producing clean and sustainable electricity without toxic pollution or global warming, but in terms of high demand for energy for electricity production as well as the toxicity or scarcity of components constitute the solar cells, this solar transformation technology is still somewhat limited. Because these parameters constitute the main environmental concerns surrounding the photovoltaic industry. The compound Cu2ZnSnS4 (CZTS) can be considered as one of the most promising absorbent layer materials for low cost thin film solar cells. The abundance and non-toxicity of the constituent elements this promising material is the subject of this work. Obviously, this leads us to think about optimizing the other parameters influencing the formation of thin layers by the electrodeposition method. An electrochemical deposition technique which offers an advantageous alternative from an economic point of view and especially from the possibility of using large surface substrates. The initial focus was on determining the optimal parameters for the CZTS quaternary thin film development process. The electrodeposition is implemented by the technique of polarization of a potentiostatic electrode. Because this technique is based on the deposition potential of each substance constituting the electrolytic bath, a study has been conducted on the effect of the factors of complexity in order to assimilate these reduction potentials. Then, the annealing process which is a necessary step in the formation of absorbent layers in CZTS was mastered, under the influence of the complexity factor so as to reduce the annealing temperature while preserving the properties of the material. High quality kesterite films with a compact morphology and a well-defined crystal structure at low temperatures were synthesized using Na2SO4 as the complexing agent. Subsequently, the CZTS kesterite films were prepared on different conductive substrates (ITO, FTO and Mo / glass) due to specifying the effect of back contact. The best behavior is a specific combination of the parameters studied. This work made it possible in particular to master the composition of the films deposited, the annealing process as well as the necessary characterization techniques. Finally, our strategy implements a digital simulation of the CZTS solar cell using the SCAPS-1D software. After the experimental visualization of the thin layers of CZTS on different conductive substrates, modeling by the SCAPS-1D software of the CZTS solar cell device showed that the back-contact Mo mounts the best performances. / [ES] El aumento de las necesidades energéticas, particularmente en términos de protección del medio ambiente, ha estimulado en gran medida la investigación en el campo de la conversión fotovoltaica en los últimos años. La radiación solar proporciona un recurso excelente para producir electricidad limpia y sostenible sin contaminación tóxica o calentamiento global, pero en términos de alta demanda de energía eléctrica, así como la toxicidad o escasez de componentes que constituyen las células solares, esta tecnología de transformación solar todavía es algo limitada. En consecuencia estos parámetros constituyen las principales preocupaciones ambientales que rodean a la industria fotovoltaica. El compuesto Cu2ZnSnS4 (CZTS) puede considerarse como uno de los materiales absorbentes más prometedores para las células solares de película delgada de bajo costo. La abundancia y la no toxicidad de los elementos constitutivos de este prometedor material es el tema de este trabajo. Este objetivo nos ha llevado a pensar en optimizar los parámetros que influyen en la formación de capas delgadas por métodos electroquímicos. La técnica de deposición electroquímica o electrodeposición catódica ofrece una alternativa ventajosa desde un punto de vista económico y especialmente ofrece la posibilidad de utilizar sustratos de gran superficie. El enfoque inicial fue determinar los parámetros óptimos para el proceso de desarrollo de película delgada cuaternaria de CZTS. La electrodeposición se implementó mediante la técnica de polarización de un electrodo por el método potenciostático, o sea a potencial constante. Debido a que esta técnica se basa en el potencial de deposición de cada sustancia que constituye el baño electrolítico, se ha llevado a cabo un estudio sobre el efecto de los factores de complejidad para acercar estos potenciales de reducción. Una vez fueron depositadas las capas, se continuó con el estudio del proceso de recocido, que es un paso necesario en la formación de capas absorbentes de CZTS bajo la influencia del factor de complejidad, debido a que conviene reducir la temperatura de recocido mientras se intenta conservan las propiedades del material. Se sintetizaron películas de kesterita de alta calidad con una morfología compacta y una estructura cristalina bien definida a bajas temperaturas usando Na2SO4 como agente acomplejante. Posteriormente, las películas de kesterita CZTS se prepararon en diferentes sustratos conductores (ITO, FTO y Mo / vidrio) para estudiar el efecto del contacto posterior. Comprobamos que el mejor comportamiento se produce para una combinación específica de los parámetros estudiados. En particular este trabajo nos ha permitido controlar la composición de las películas depositadas, dominar el proceso de recocido y usar las técnicas de caracterización necesarias para evaluar la composicion, calidad y propiedades optoelectrónicas de las capas de CZTS sintetizadas. Finalmente, nuestra estrategia implementa una simulación digital de la célula solar CZTS utilizando el software SCAPS-1D. Después de la visualización experimental de las capas delgadas de CZTS en diferentes sustratos conductores, el modelado por el software SCAPS1D del dispositivo de células solares CZTS demostró que el contacto trasero Mo ofrece los mejores rendimientos. / [FR] L'augmentation des besoins énergétiques, notamment en matière de protection de l'environnement, a fortement stimulé la recherche dans le domaine de la conversion photovoltaïque ces dernières années. Le rayonnement solaire fournit une excellente ressource pour produire de l'électricité propre et durable sans pollution toxique ni réchauffement climatique, mais en termes de forte demande d'énergie pour la production de l’électricité ainsi que la toxicité ou la rareté des composants constituent les cellules solaires, cette technologie de transformation solaire est encore un peu limitée. En raison que ces paramètres constituent les principales préoccupations environnementales entourant l'industrie photovoltaïque. Le composé C2ZnSnS4 (CZTS) peut être considéré comme l'un des matériaux de couche absorbante les plus prometteurs pour les cellules solaires en couches minces à faible coût. L’abondance et la non-toxicité des éléments constitutifs ce matériau prometteur fait l'objet de ce travail. De toute évidence, cela nous amène à réfléchir pour optimiser les autres paramètres influençant la formation de couches minces par la méthode d'électrodéposition. Une technique de dépôt par voie électrochimique qui offre une alternative avantageuse du point de vue économique et surtout de la possibilité d’utiliser des substrats de grande surface. Initialement, l'accent était mis sur la détermination des paramètres optimaux pour le processus d’élaboration de couches minces du quaternaire CZTS. L'électrodéposition est mise en œuvre par la technique de polarisation d'une électrode potentiostatique. En raison, que cette technique reposant sur le potentiel de dépôt de chaque substance constituant le bain électrolytique, une étude a été menée sur l'effet des facteurs de complexité afin de rapprocher ces potentiels de réduction. Ensuite, Le processus de recuit qui est une étape nécessaire dans la formation de couches absorbantes en CZTS a été maîtriser, sous l'influence du facteur de complexité en raison de réduire la température de recuit tout en conservant les propriétés du matériau. Des films de kësterite de haute qualité avec une morphologie compacte et une structure cristalline bien définie à basse température ont été synthétisés en utilisant Na2SO4 comme agent complexant. Par la suite, les films de kestérite CZTS ont été préparés sur différents substrats conducteurs (ITO, FTO et Mo / verre) en raison de spécifier l'effet du contact arrière. Le meilleur comportement est une combinaison spécifique des paramètres étudiés. Ces travaux ont permis notamment de maîtriser la composition des films déposés, le processus de recuit ainsi que les techniques de caractérisation nécessaire. Finalement, notre stratégie met en œuvre une simulation numérique de la cellule solaire CZTS à l'aide du logiciel SCAPS − 1D. Après la visualisation expérimentale des couches minces de Czts sur différent substrats conducteur, une modélisation par le logiciel SCAPS-1D du dispositif CZTS cellules solaires a montré que le Mo contact arrière monte les meilleures performances. / [CA] L'augment de les necessitats energètiques, particularment en termes de protecció de l'entorn, ha estimulat en gran mesura la investigació en el camp de la conversió fotovoltaica en els últims anys. La radiació solar proporciona un recurs excel·lent per produir electricitat neta i sostenible sense contaminació tòxica ni escalfament global, però en termes de l'alta demanda d'energia elèctrica, així com la toxicitat o escassetat de components que constitueixen les cèl·lules solars, aquesta tecnologia de transformació solar encara trova barreres limitadores. En conseqüència aquests paràmetres constitueixen les principals preocupacions ambientals que envolten a la indústria fotovoltaica. El compost Cu2ZnSnS4 (CZTS) pot considerar-se com un dels materials absorbents més prometedors per a les cèl·lules solars de pel·lícula prima i de baix cost. L'abundància i la no toxicitat dels elements constitutius d'aquest prometedor material és el tema d'aquest treball. Aquest objectiu ens ha portat a treballar en l’optimització dels paràmetres que influeixen en la formació de capes primes de CZTS per mètodes electroquímics. La tècnica de deposició electroquímica o electrodeposició catòdica ofereix una alternativa avantatjosa des d'un punt de vista econòmic i especialment ofereix la possibilitat d'utilitzar substrats de gran superfície. L'enfocament inicial va ser determinar els paràmetres òptims per al procés de desenvolupament d’una pel·lícula prima quaternària de CZTS. La electrodeposició es va implementar mitjançant la tècnica de polarització d'un elèctrode pel mètode potenciostàtic, o siga a potencial constant. Aquesta tècnica es basa en el potencial de deposició de cada substància que constitueix el bany electrolític es diferent i per tant s'ha dut a terme un estudi sobre l'efecte dels factors de complexitat per tal apropar aquests potencials de reducció de tots els components involucrats. Un cop van ser dipositades les capes, es va continuar amb l’estudi del procés de recuit, que és un pas necessari en la formació de capes absorbents de CZTS sota la influència del factor de complexitat, a causa de la reducció de la temperatura de recuit mentre es conserven les propietats de l'material. Es van sintetitzar pel·lícules de kesterita d'alta qualitat amb una morfologia compacta i una estructura cristal·lina ben definida a baixes temperatures usant Na2SO4 com a agent acomplexant. Posteriorment, les pel·lícules de kesterita CZTS es van preparar en diferents substrats conductors (ITO, FTO i Mo / vidre) per estudiar l'efecte del contacte posterior sobre les capes fines. Obtinguerem que el millor comportament és una combinació específica dels paràmetres estudiats. En particular aquest treball ens ha permès controlar la composició de les pel·lícules dipositades, controlar el procés de recuit i usar les tècniques de caracterització necessàries per avaluar la composició, qualitat i propietats optoelectròniques de les capes de CZTS depositades. Finalment, en la nostra estratègia es va implementar una simulació numérica d’una cèl·lula solar de CZTS utilitzant el programari SCAPS-1D. Després de la visualització experimental de les capes primes de CZTS en diferents substrats conductors, el modelatge pel programari SCAPS-1D del dispositiu fotovoltaic de CZTS va demostrar que el contacte posterior de Mo és el que ofereix el millor rendiment. / I would like to thank the Moroccan Center for Scientific and Technical Research and the Doctoral school of the Polytechnic University of Valencia for the financial assistance they have allocated. I also extend my sincere thanks to the UPV Electron Microscopy Service and to Mr Ángel Sans Tresserras for their help to learn how to work with characterization techniques. / Toura, H. (2020). Elaboration and characterization by electrochemical technique CZTS thin layers for photovoltaic application [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/154334 / TESIS / Compendio