Photocatalytic degradation of Congo Red by hydrothermally synthesized nanocrystalline TiO 2 and identification of degradation products by LC–MS

Abstract

Degradation of Congo Red (CR) dye in aqueous solutions was investigated by means of photocatalysis of TiO 2 which was hydrothermally synthesized at 200 °C in 2 h, in anatase phase with 8 nm crystallite size. Efficiency of TiO 2 in photocatalytic degradation under visible irradiation was studied by investigating the effects of amount of TiO 2, irradiation time, initial CR concentration and pH. It was found that complete decolorization is achieved within 30 min of irradiation. Effects of nitrate and sulphate ions and humic acid on the degradation were also tested. The results were compared with Degussa P-25 TiO 2 at the same degradation conditions. Degradation products were detected using LC–MS technique. The probable pathways for the formation of degradation products were proposed.