Heterogeneous photocatalytic degradation of an anthraquinone and a triphenylmethane dye derivative in aqueous suspensions of semiconductor

The photochemical reactions of two selected dye derivatives, such as acid blue 45 (1) and xylenol orange (2) have been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions. The reactions were studied by monitoring the change in substrate concentration employing UV spectroscopic analysis technique as a function of irradiation time. The dye derivatives under investigation were found to degrade during irradiation in the presence of TiO2 and oxygen. The degradation of the dye derivatives was studied under different conditions such as different types of TiO2, reaction pH, catalyst concentration, substrate concentration, and in the presence of electron acceptors like hydrogen peroxide and potassium bromate, besides oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The degradation of dyes was also investigated under sunlight and the efficiency of degradation was compared with that of the artificial light source. The photocatalyst Hombikat UV100 was found to be more efficient for the degradation of acid blue 45 (1). However, Degussa P25 showed better photocatalytic activity in case of xylenol orange (2).