Effect of the initial pH and the catalyst concentration on TiO2-based photocatalytic degradation of three commercial pesticides

Abstract

The photocatalytic degradations of three pesticides: 2,4-D, diuron, ametryne and a specific mixture of these ones, were carried out in a lab-scale reactor with artificial ultraviolet radiation. The effects of initial pH and catalyst concentration for each substrate were analyzed, and the degradation kinetics was modeled at the optimal operating conditions for each mineralization process. The parameters of the Langmuir-Hinselwood models fitted satisfactorily to the experimental data. The incidence of the studied variable was evaluated by analysis of variance (ANOVA). The catalyst concentration was the most important variable for the 2,4-D degradation, whereas for diuron, ametryne and the considered mixture was the initial pH. The degradations of the pesticides mixture were favored at an initial pH of 7 and 0.6 g/L of TiO2 concentration.