Solar water detoxification: Novel TiO2 powders as highly active photocatalysts

The photocatalytic activity of a novel anatase titanium dioxide powder, namely Sachtleben Hombikat UV 100, has been investigated and compared with that of a well studied material (i.e., Degussa P25). Laboratory experiments using dichloroacetate (DCA) as the model pollutant have been carried out showing a very high photonic efficiency (zeta) reaching almost unity at low-light intensities. The effect of pH substrate concentration, catalyst concentration, and addition of various inorganic salts has been thoroughly investigated. The inhibiting effect of anions such as chloride, nitrate, sulphate, and phosphate was completely reversible upon washing the catalyst powder with pure water or diluted base, respectively. The overall photonic efficiency of the DCA degradation was found to decrease with increasing illumination intensity. Various kinetic and mechanistic models ai-e proposed to explain this effect as well as the results of the other experiments. Implications of these laboratory results for ''real world'' applications, e.g.,for the design of appropriate photoreactors, are discussed.