Over the past decade, many studies have been done on the semiconductor photominieralization of water pollutants. There is still an apparent lack of knowledge or further calcification required concerning details of the photocatalytic degradation mechanism, and factors associated with the reaction. The aim of this thesis is to address various fundamental aspects of semiconductor photocatalysis. Thus in Chapter three, the often used concept that O<SUB>2</SUB> is a necessary reactant in the semiconductor photocatalysis of organic pollutants is challenged in a detailed study of the kinetics of photomineralisation of 4-chlorophenol and acetone, sensitised by TiO<SUB>2</SUB> using metal ions, such as Fe<SUP>3+</SUP>, Cu<SUP>2+</SUP> and Hg<SUP>2+</SUP>, rather than, and in addition to, O<SUB>2</SUB>, as the electron acceptors. Chapter four highlights the poorly understood world of semiconductor photocatalysis kinetics and mechanisms with a study of the effect of light intensity upon the apparent Langmuir-Hinshelwood constants found for the photomineralisation of 4-chlorphenol, sensitised by Degussa P25 powder dispersions. Chapter five describes the results of a detailed study of the kinetics of photomineralisation of 4-CP, sensitised by a film of Degussa P25 - the first example of such a study. The similarities and differences in kinetics of photomineralisation of the dye methylene blue sensitised by TiO<SUB>2</SUB> are explored. This dye features widely in semiconductor photocatalysis as test organic pollutant and is used to evaluate the activities of different photocatalysts. However, the kinetics and underlying mechanisms for photobleaching are much more complex than previously recognised, as revealed by the results of this study.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:639340 |
| Date | January 1999 |
| Creators | Wang, J. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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