Comparative photocatalytic study of two selected pesticide derivatives, indole-3-acetic acid and indole-3-butyric acid in aqueous suspensions of titanium dioxide

Heterogeneous photocatalysed degradation of two selected pesticide derivatives such as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) has been investigated in aqueous suspensions of titanium dioxide by monitoring the change in substrate concentration employing UV spectroscopic analysis technique and depletion in total organic carbon (TOC) content as a function of irradiation time. The degradation kinetics was studied under different conditions such as pH, types of TiO2. substrate and catalyst concentration, and in the presence of electron acceptor such as hydrogen peroxide (H2O2) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 showed comparatively highest photocatalytics. The pesticide derivative, indole-3-acetic acid was found to degrade slightly faster than indole-3-butyric acid. (c) 2005 Elsevier B.V. All rights reserved.