Photocatalytic degradation of H-acid over a novel TiO2 thin film fixed bed reactor and in aqueous suspensions

Abstract

The present work is focused on the heterogeneous photocatalytic degradation of H-acid, a toxic and non-biodegradable dye intermediate, in TiO2 suspensions and TiO2 thin film fixed bed reactor (TFFBR). The degradation studies in slurry form are investigated using TiO2 Degussa P25 and different Millennium PC50, PC100 and PC500 photocatalysts under UV illumination. The study includes dark adsorption experiments in different pH conditions, influence of the amount of photocatalyst, effect of H-acid concentration, effect of pH on chemical oxygen demand (COD), biological oxygen demand (BOD) and the sulfate ion formation during the photocatalytic degradation. Photocatalytic treatment significantly reduces COD and increases the biodegradability of H-acid. The intermediates have been identified by LCMS. The study with slurry is extended to the immobilization of preformed TiO2 Degussa P25 in thin film using an acrylic emulsion by simple spray technique on inert Cuddapah stone. This method of immobilization does not require the thermal treatment of the catalyst at high temperatures. It may be used for the photocatalytic treatment of effluents at a higher scale.