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The Influence of Surface Alumina and Silica on the Photocatalytic Degradation of Organic Pollutants
School of Chemical Engineering and Advanced Materials, Merz Court, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, UK
Received: 23 November 2012; in revised form: 21 January 2013 / Accepted: 7 February 2013 / Published: 21 March 2013
Abstract: Practical photocatalysis for degradation of organic pollutants must take into account the influence of other chemicals. Significant Al deposition on titania can occur at naturally occurring concentrations of dissolved Al. This paper reviews the author’s work on the influence of deliberately deposited hydrous oxides of aluminium on the behavior of a ~130 m2 g−1 rutile TiO2, and then compares the behavior of deposited alumina with that of deposited silica. On rutile some adsorbed nitrogen is infrared-active. Alumina and silica deposited on the rutile reduce, and ultimately eliminate, this infrared-active species. They also reduce photocatalytic oxidation of both propan-2-ol and dichloroacetate ion and the photocatalytic reduction of diphenyl picryl hydrazine. The surface oxides suppress charge transfer and may also reduce reactant adsorption. Quantitative measurement of TiO2 photogreying shows that the adsorbed inorganics also reduce photogreying, attributed to the capture of photogenerated conduction band electrons by Ti4+ to form Ti3+. The influence of adsorbed phosphate on photocatalysis is briefly considered, since phosphate reduces photocatalytic disinfection. In the context of classical colloid studies, it is concluded that inorganic species in water can significantly reduce photoactivity from the levels that measured in pure water.
Keywords: photocatalysis; rutile; silica; alumina; coating; oxidation; reduction; photogreying
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Egerton, T.A. The Influence of Surface Alumina and Silica on the Photocatalytic Degradation of Organic Pollutants. Catalysts 2013, 3, 338-362.
Egerton TA. The Influence of Surface Alumina and Silica on the Photocatalytic Degradation of Organic Pollutants. Catalysts. 2013; 3(1):338-362.
Egerton, Terry A. 2013. "The Influence of Surface Alumina and Silica on the Photocatalytic Degradation of Organic Pollutants." Catalysts 3, no. 1: 338-362.