TiO2-mediated photocatalytic degradation of a triphenylmethane dye (gentian violet), in aqueous suspensions

TiO2-mediated photocatalytic degradation of a triphenylmethane dye (gentian violet. 1), was investigated in aqueous suspensions of titanium dioxide under a variety of conditions. The degradation was studied by monitoring the change in substrate concentration employing UV-spectroscopic analysis and decrease in total organic carbon (TOC) content as a function of irradiation time. The degradation of dye was studied under a variety of conditions such as pH, catalyst concentration, substrate concentration, different types of TiO2 and in the presence of electron acceptors such as hydrogen peroxide (H2O2) and ammonium persulphate ((NH4)(2)S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with other photocatalysts. The degradation products were analysed by GC-MS technique and probable pathways for the formation of the products were proposed. (C) 2002 Elsevier Science Ltd. All rights reserved.