Photocatalytic performance of titanium and zinc oxides in diuron degradation
Janile Quaresma Lopes, Bruno César Barroso Salgado
Abstract
Diuron is an herbicide used for weed control in agricultural crops that can cause a range of complications in humans from skin irritation to cancer. In this study, heterogeneous photocatalysis were performed using TiO2 and ZnO as catalysts in a batch reactor for Diuron degradation. Experimental designs were carried out in order to assess the influence of pH, catalyst and substrate concentration, in addition to optimizing the Diuron degradation. After 3 h of reaction, the pH showed to be the most important variable on the Diuron degradation using TiO2 as a catalyst. The use of ZnO led to a conversion rate higher than 98% in all tests performed. ZnO showed higher efficiency than TiO2, was attributed to the adsorption step. The mechanistic study suggested different reaction routes compared to the catalysts employed, with the participation of holes and photo-generated electrons in ZnO, whereas in TiO2 only the conduction band was relevant in the process.