Titanium dioxide-mediated photcatalysed degradation of two herbicide derivatives chloridazon and metribuzin in aqueous suspensions

Abstract

The aim of this paper is to find out the optimal degradation condition for two potential environmental pollutants, chloridazon and metribuzin (herbicide derivatives), employing advanced oxidation process using TiO2 photocatalyst in aqueous suspensions. The degradation/mineralization of the herbicide was monitored by measuring the change in pollutant concentration and depletion in TOC content as a function of time. A detailed degradation kinetics was studied under different conditions such as types of TiO2 (anatase/anatase-rutile mixture), catalyst concentration, herbicide concentration, initial reaction pH, and in the presence of electron acceptors (hydrogen peroxide, ammonium persulphate, potassium persulphate) in addition to atmospheric oxygen. The photocatalyst, Degussa P25, was found to be more efficient catalyst for the degradation of both herbicides as compared with two other commercially available TiO2 powders like Hombikat UV100 and PC500. Chloridazon (CHL) was found to degrade more efficiently under acidic condition, whereas metribuzin (MET) degraded faster under alkaline medium. All three electron acceptors tested in this study were found to enhance the degradation rate of both herbicides. © 2012 A. Khan et al.