TiO 2-mediated photocatalytic degradation of a textile dye derivative, bromothymol blue, in aqueous suspensions

Abstract

Photocatalysed degradation of a textile dye derivative, bromothymol blue, has been investigated in aqueous suspensions of titanium dioxide under a variety of conditions. The degradation was monitored by measuring the change in substrate concentration as a function of irradiation time employing UV spectroscopic analysis technique. In these studies, a number of byproducts are formed during the photooxidation process, which can potentially be harmful to the environment, therefore, we have studied the mineralization of the pollutant by measuring the total organic carbon (TOC) as a function of irradiation time. The degradation kinetics were studied under different conditions such as pH, catalyst concentration, substrate concentration, different types of TiO 2 and in the presence of electron acceptors such as hydrogen peroxide (H 2O 2), potassium bromate (KBrO 3) and ammonium persulphate (NH 4) 2S 2O 8 besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst, titanium dioxide (TiO 2) Degussa P25, was found to be more efficient as compared with other TiO 2 powders. All the electron acceptors markedly enhanced the degradation of the pollutant under investigation.