Study on the photocatalytic degradation of glyphosate by TiO2 photocatalyst

In this paper, the photocatalytic degradation of glyphosate selected as the deputy of organic pollutant in aqueous solution with TiO2 powder as a photocatalyst has been studied. The effects of various parameters, such as the amount of the photocatalyst, illumination time, initial pH value, electron acceptors, metal ions, and anions on the photocatalytic degradation of glyphosate were investigated. From the studies, the best condition for the effect of the parameters on the photocatalytic degradation of glyphosate was obtained. The results show that the optimum amount of the photocatalyst used is 6.0 g l(-1) for the photocatalytic reactions. The photodegradation efficiency of glyphosate increases with the increase of the illumination time. With the addition of Fe3+, Cu2+, H2O2, K2S2O8 or KBrO3, the photocatalytic degradation of glyphosate is accelerated. However, with the addition of Na+, K+, Mg2+, Ca2+, Zn2+, Co2+ and Ni2+, or with the addition of trace amounts of Cl-, Br-, SO42-, there are no obvious effects on the reactions. Acidic or alkaline mediums are favorable for the photocatalytic degradation of glyphosate. The possible roles of the additives on the reactions and the possible mechanisms of effect were discussed. (c) 2006 Elsevier Ltd. All rights reserved.