Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 106-113). Also available via the Internet.

No description available.

Thesis (Ph. D.)--University of Michigan, 1922.

M.S.

No description available.

Ce projet de travail est divisé en deux études principales: (a) l'influence des certains additifs organiques sur la consommation d'énergie et la pureté du métal de zinc déposé dans le processus d'extraction électrolytique, et (b) l’électrodéposition des alliages binaires et ternaires de Fe-Mo et Fe-Mo-P sur des substrats d’acier doux afin d’agir comme cathodes pour la production de chlorate. (a) Parmi les sept différents additifs organiques examinés, les sels des liquides ioniques ont réussi à augmenter le rendement du courant jusqu'à 95,1% comparé à 88,7% qui a obtenu à partir de l'électrolyte standard en présence des ions de Sb3+. La réduction maximale de la consommation d'énergie de ~173 kWh tonne-1 a été obtenue en ajoutant de 3 mg dm-3 du chlorure de 1-butyl-3-méthylimidazolium dans le même électrolyte. La teneur en plomb dans le dépôt de zinc est réduite de 26,5 ppm à 5,1-5,6 ppm en utilisant les sels des liquides ioniques. (b) Des différents binaires Fe-Mo et ternaires Fe-Mo-P alliages ont été électrodéposés sur des substrats d’acier doux. Les alliages préparés ont une tenure en Mo entre 21-47 at.% et une tenure en P de 0 à 16 at.%. L'activité électrocatalytique de ces alliages vers la réaction de dégagement d'hydrogène (RDH) a été étudiée dans des solutions de chlorure de sodium. La réduction maximale de la surtension de RDH de ~313 mV a été obtenue par l’alliage ternaire préparé Fe54Mo30P16 par rapport à celle obtenue pour l'acier doux. La rugosité de surface et l'activité intrinsèque des revêtements de Fe-Mo-P peuvent être l'origine du comportement prometteur de ces électrocatalyseurs vers la RDH. / This work project is divided into two main studies: (a) the influence of certain organic additives on the power consumption and the purity of deposited zinc during electrowinning process, and (b) the electrodeposition of binary and ternary alloys of Fe-Mo and Fe-Mo-P on mild steel substrates to act as cathodes for chlorate production. (a) Among seven different examined organic additives, the ionic liquid salts succeeded to increase the current efficiency up to 95.1% compared to 88.7% obtained from standard electrolyte in presence of Sb3+ ions. Maximum reduction of power consumption of ~173 kWh ton-1 was observed by addition of 3 mg dm-3 of 1-butyl-3-methylimidazolium chloride to the same electrolyte. Lead content in the zinc deposit is reduced from 26.5 ppm to 5.1-5.6 ppm by using the ionic liquid salts. (b) Different binary Fe-Mo and ternary Fe-Mo-P alloys have been electrodeposited on mild steel substrates. The prepared alloys have Mo content between 21-47 at.% and P content from 0 to 16 at.%. The electrocatalytic activity of these alloys towards the hydrogen evolution reaction (HER) was investigated in sodium chloride solutions. The maximum reduction of HER overpotential of ~313 mV was achieved from the prepared ternary alloy Fe54Mo30P16 compared to that obtained from mild steel. The surface roughness and intrinsic activity of Fe-Mo-P coatings could be the origin of the promising behavior of these electrocatalysts towards the HER.

Up-coming regulations on chlorine dioxide in drinking water treatment require low level measurement of chlorite ion (CI0₂-) and chlorate ion (CI0₃-). This research investigated analysis of CI0₂- and CI0₃-; in drinking water by flow injection analysis with iodometric detection (FIA) and ion chromatography with conductivity detection (IC). Both the FIA and IC methods were accurate for the determination of CIO₂-; and CIO₃-; in reagent water. The IC method was accurate in drinking water, however, FIA responded to chloramines and other oxidants present in drinking water causing inaccurate analysis of CIO₂-; and CIO₃-; by FIA. The two IC eluants investigated, a carbonate/bicarbonate mixture and a borate/boric acid mixture, performed well. By taking advantage of the slightly different separation abilities of each eluant, the IC method can be modified to maximize resolution of CIO₂-; and CIO₃-; in different drinking water matrices. Chlorite was unstable in chlorinated drinking water but was stable for up to three days when sodium oxalate was added and stable up to eighteen days when ethylene diamine was added as a preservative. Chlorate was stable in drinking water for up to eighteen days with or without a preservative. The propagation of errors method for determining detection limits yielded limits of detection for CIO₂- (mg/L) of 0.05 for FIA, 0.03 for the IC carbonate eluant and 0.01 for the IC borate eluant. For CIO₃- the limits of detection (mg/L) were 0.24 for FIA; 0.11 for the IC carbonate eluant and 0.02 for the borate eluant. / Master of Science