by Yeung Chung Kin. / Bibliography: leaves 105-106 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

Ce travail de thèse a eu pour thème central la birnessite, un oxyde de manganèse ubiquiste dans le milieu naturel et jouant un rôle fondamental dans la géochimie des sols. La première partie de cette thèse a été consacrée à l’électrodépôt et à la caractérisation de la birnessite par des méthodes électrochimiques couplées à la diffraction des rayons X. La caractérisation DRX in-situ au cours de l’électrodépôt a permis de mettre en évidence, lorsqu’on est en présence du cation électrolytique Na+, la formation d’un précurseur, la busérite, alors qu’en présence du cation électrolytique K+, la synthèse aboutit directement à la birnessite sans formation d’intermédiaire. La réduction électrochimique de la birnessite a également été étudiée en fonction du milieu ([Mn(II)], pH, potentiel). Cette dernière se réduit en hausmannite(Mn3O4), feitknechtite (-MnOOH), ou en composé amorphe de Mn(II), selon les conditions expérimentales. Dans la deuxième partie de cette thèse, les films minces ont été utilisés pour étudier la réactivité de la birnessite vis-à-vis du glyphosate, ainsi que celle de son principal métabolite l’AMPA (acide amino-méthyl-phosphonique). Le glyphosate est dégradé avec formation simultanée d’AMPA, de formaldéhyde, d’ions phosphate, nitrate et ammonium sans modification macroscopique de la birnessite. Les quatre derniers sous-produits sont également obtenus lors de la dégradation de l’AMPA par la birnessite. Les bons rendements de dégradation obtenus au cours des interactions glyphosate/birnessite et AMPA/birnessite laissent envisager une possible application de ces échantillons pour le traitement des eaux usées. / This thesis has been focused on birnessite, a ubiquitous manganese oxide in the environment, which plays a fundamental role in soil geochemistry. The first part of this thesis has been devoted to the electrodeposition and the characterizations of birnessite by electrochemical methods coupled with X-ray diffraction. The in-situ XRD characterization during electrodeposition has shown, in presence of the electrolytic cation Na+, the formation of a precursor, buserite, whereas no precursor is formed in presence of electrolytic cation K+, the synthesis leading directly to birnessite. The electrochemical reduction of birnessite has also been studied in function of the medium ([Mn (II)], pH, potential). Birnessite is reduced into hausmannite (Mn3O4), feitknechtite (-MnOOH), or an amorphous compound of Mn (II), as function of experimental conditions. In the second part of this thesis, the thin films have been used to study the reactivity of birnessite for degrading glyphosate and its metabolite AMPA (amino-methyl phosphonic). Glyphosate is degraded with simultaneous formation of AMPA, formaldehyde, phosphate ion, nitrate ion and ammonium ion, without macroscopic modification of birnessite. The last four by-products are also obtained during the degradation of AMPA by birnessite. The good yields obtained during glyphosate / birnessite and AMPA / birnessite interactions permit to envisage a possible application of these thin films for the treatment of wastewater.

This thesis describes the application of macro, micro, ultra-microelectrodes and microelectrode arrays to the measurement of trace concentrations of nickel and cobalt in sediment and natural waters by adsorptive cathodic stripping voltammetric methods. In addition the measurement of tin by adsorptive cathodic stripping voltammetry in sediment and natural waters is discussed. Also, the application of macroelectrodes and microelectrode arrays to the measurement of lead, cadmium and zinc in sediment and natural waters by anodic stripping voltammetry is considered. In all cases the determination of the six metals was optimised by investigating the influence of various significant parameters, such as in-situ mercury plating, complexing agent concentration, scan rate, pulse height, accumulation time and potential, buffer concentration and pH. The results obtained for these investigations are discussed in this thesis / Doctor of Philosophy (PhD)

[No Abstract]

In this research,we used the electrochemical (cyclic voltammetry) method to synthesize (polyaniline) PANI thin film on the top of ITO substrate which applied extensively on polymer organic light emitting diodes based on ITO (170nm) / PANI (55nm ) / PFG(60 nm )/LiF(1nm)/Ca(10nm) / Al (200nm) . The PANI thin films have excellent optical and electric properties. According to the measurement results of ultraviolet visible spectrophotometry, the PANI thin films with different aniline monomer concentrations display the absorption peak at the range of 500nm to 600nm and have high light transmission near 90%. The conductivity of PANI thin film (2.02x10-2(s/cm)) is higher than that of PEDOT:PSS thin film (1.28x10-2(s/cm)). The highest occupied molecular orbital value of PANI thin film is about 5.0 eV that close to PEDOT:PSS thin film. Therefore, it is suitable act as hole transporting layer. In this study, we can control the surface morphology of PANI thin film by exchanging synthesized parameters. Finally, we have fabricated a PLED device with PANI as a hole transporting layer by electrochemical synthesis with at the aniline monomer concentration of 0.3M and the scan rate of 0.0.1 V/s. The device exhibits a maximum luminance of 10500 cd/m2 at 15 V and power efficiency of 0.25 lm/W at 10V.

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains ix, 178 p. : ill. Includes abstract. Includes bibliographical references (p. 171-178).

Thesis (M. Phil.)--University of Hong Kong, 1978.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

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