Photocatalytic degradation of linuron in aqueous suspensions of TiO2

Abstract

The photocatalytic degradation of linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea), a widely used herbicide and potential environmental contaminant, in irradiated titanium dioxide aqueous suspensions is investigated. The photocatalytic performance of two nano-sized materials prepared by a sol–gel process, and the influence on the degradation rate of some operational parameters, such as catalyst amount, pH of the medium and hydrogen peroxide concentration, are evaluated. Within the range of the explored experimental conditions, degradation of linuron in an aqueous suspension of TiO₂ at mg l⁻¹ contamination levels is described by a pseudo-first-order kinetic model, the apparent half-life time of the herbicide being about 30 min in optimal conditions. Based on the evolution of total organic carbon and the fate of inorganic species, the disappearance of linuron seems to be accompanied by its almost quantitative mineralization.