Microwave assisted rapid and complete degradation of atrazine using TiO2 nanotube photocatalyst suspensions

A technology, microwave-assisted photocatalysis on TiO2 nanotubes, which can be applied to degrade atrazine rapidly and completely, was investigated. TiO2 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 TiO2 under the irradiation of microwave and larger specific surface area of TiO2 nanotubes which could adsorb more organic substances to degrade than TiO2 nanoparticles. Along with the degradation of atrazine, the concentrations of Cl− and NO3− increase gradually. In 20 min [Cl−] and [NO3−] 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 TiO2 nanotubes were proposed.