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 compare d with that of a well studied material (i.e., Degussa P25). Laboratory experiments using dichloroacetate (DCA) as the model pollutant have b een carried out showing a very high photonic efficiency (zeta) reachin g almost unity at low-light intensities. The effect of pH substrate co ncentration, catalyst concentration, and addition of various inorganic salts has been thoroughly investigated. The inhibiting effect of anio ns such as chloride, nitrate, sulphate, and phosphate was completely r eversible upon washing the catalyst powder with pure water or diluted base, respectively. The overall photonic efficiency of the DCA degrada tion was found to decrease with increasing illumination intensity. Var ious kinetic and mechanistic models ai-e proposed to explain this effe ct as well as the results of the other experiments. Implications of th ese laboratory results for ''real world'' applications, e.g.,for the d esign of appropriate photoreactors, are discussed.