Photocatalysed Degradation of Two Selected Herbicide Derivatives in Aqueous Suspensions of Titanium Dioxide

The photocatalytic degradation of two selected herbicide derivatives, such as 2-(2,4,5-trichlorophenoxy)propionic acid (Fenoprop, 1) and dichloroprop-P (2) has been investigated in aqueous suspensions of titanium dioxide (TiO₂) under a variety of conditions, which is essential from application point of view. The reactions were studied by monitoring the change in substrate concentration employing UV spectroscopic analysis technique as a function of irradiation time. The degradation was studied using different parameters such as types of TiO₂, reaction pH, catalyst concentration, substrate concentration and in the presence of different electron acceptors such as hydrogen peroxide (H₂O₂), potassium bromate (KBrO₃) and ammonium persulphate (NH₄)₂S₂O₈ besides air. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst, Degussa P25 was found to be more efficient for the degradation of both the pollutants under investigation.