Microwave assisted rapid and complete degradation of atrazine using TiO 2 nanotube photocatalyst suspensions

Abstract

A technology, microwave-assisted photocatalysis on TiO 2 nanotubes, which can be applied to degrade atrazine rapidly and completely, was investigated. TiO 2 nanotubes were prepared, and confirmed by XRD, TEM and ESR. Microwave-assisted photocatalytic degradation of atrazine in aqueous solution was investigated. The result indicates that atrazine is completely degraded in 5 min and the mineralization efficiency is 98.5% in 20 min, which is obviously more efficient than that by the traditional photocatalytic degradation methods. It may be attributed to the intense UV radiation generated by electrodeless discharge lamps under microwave irradiation, the increased number of OH, additional defect sites on TiO 2 under the irradiation of microwave and larger specific surface area of TiO 2 nanotubes which could adsorb more organic substances to degrade than TiO 2 nanoparticles. Along with the degradation of atrazine, the concentrations of Cl − and NO 3 − increase gradually. In 20 min [Cl −] and [NO 3 −] are 3, 27.8 mg/L, respectively, which are close to their stoichiometric values. The major intermediates of atrazine were identified by HPLC/MS and possible degradation pathways of atrazine in microwave-assisted photocatalysis on TiO 2 nanotubes were proposed.