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Title: Catalysis, photocatalysis and corrosion involving metal oxides
Author: Sawunyama, P.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1994
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In today's environmentally conscious society, greater emphasis is now on clean chemical technologies. Reactions at metal oxide-solution interfaces have received much attention in this respect. Although progress has been made in applying the associated technology to such fields as hydrometallurgy, solar energy conversion, descaling of pipework and nuclear plant decontamination, and environmental decontamination, the fundamental processes involved are not always understood. There is a need, therefore, to investigate these processes further. Chapter Three describes the oxidative dissolution kinetics of ruthenium dioxide hydrate to ruthenium tetroxide by periodate in perchloric acid. The kinetics fit a soft-centre model, in which ruthenium dioxide hydrate particles are assumed to be monodispersed, spherical but inhomogeneous in composition, comprising a difficult-to-corrode outer shell and a more easy-to-corrode inner core. Chapter Four details the kinetics of oxidative dissolution of chromium(III) oxides to chromic acid by periodate in perchloric acid. The kinetics obey a simple inverse-cubic rate model, in which chromium(III) oxide particles, are assumed to be monodispersed, spherical and homogeneous in composition. A kinetic model that can simulate this process under reaction conditions that produce non-linear inverse-cubic plots is described. In Chapter Five, the photocatalytic efficiencies of laboratory made and commercial titanium dioxide samples are compared using a standard test reaction; the photomineralisation of 4-chlorophenol to carbon dioxide, water and hydrochloric acid, mediated by Degussa P25 titanium dioxide in a batch reactor. The results show that there is no clear simple dependence upon physical characteristics of the titanium oxide sample such as: degree of crystallinity, surface area, and percentage water content. The kinetics of photomineralisation of 4-chlorophenol sensitised by the most active laboratory made titanium dioxide sample are discussed. Chapter Six outlines the photo-oxidation of manganese(II) to manganese dioxide, in the presence of, first, the nitrate ion, and then titanium dioxide in nitrate free solutions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available