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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 5min and the mineralization efficiency is 98.5% in 20min, 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 20min [Cl(-)] and [NO(3)(-)] are 3, 27.8mg/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.

In this work photodegradation rates and pathways of malachite green were studied under simulated and solar irradiation with the goal of assessing the potential of photolysis as a removal mechanism in real aquatic environment. Factors influencing the photodegradation process were investigated, including pH, humic acid, Fe 2+ , Ca 2+ , HCO 3 − , and NO 3 − , of which favorable conditions were optimized by the orthogonal array design under simulated sunlight irradiation in the presence of dissolved oxygen. The degradation processes of malachite green conformed to pseudo first-order kinetics and their degradation rate constants were between 0.0062 and 0.4012 h −1 . Under solar irradiation, the decolorization efficiency of most tests can reach almost 100%, and relatively thorough mineralization could be observed. Forty degradation products were detected by liquid chromatography–mass spectrometry, and thirteen small molecular products were identified by gas chromatography–mass spectrometry. Based on the analyses of the degradation products and calculation of the frontier electron density, the pathways were proposed: decomposition of conjugated structure, N -demethylation reactions, hydroxyl addition reactions, the removal of benzene ring, and the ring-opening reaction. This study has provided a reference, both for photodegradation of malachite green and future safety applications and predictions of decontamination of related triphenylmethane dyes under real conditions.

Nanocrystalline TiO2 composite thin ZnO/TiO2, Fe2O3/ZnO/TiO2 and Fe2O3/TiO2 films were developed on titanium substrates by applying dip-coating technique formed by the sol–gel method. Scanning electron microscopy (SEM) evaluated the surface characteristics of the films. Results on their structure and crystallinity were obtained by means of X-ray diffraction. The samples were also characterized by X-ray energy dispersive spectrometer (EDS) and ultraviolet-visible diffuse reflectance spectroscopy. The photocatalytic activity of these films towards photodegradation of pentachlorophenol pollutant was examined and their efficiency was compared to those of the different TiO2films. It has been shown that the film photocatalysts can efficiently decompose the pollutant. The photoelectrocatalytic degradation of PCP showed important variation that decreases in the order: ZnO/TiO2 > TiO2 > Fe2O3/ZnO/TiO2 > Fe2O3/TiO2. The results showed that Zn2+ doped could improve PEC activity of titania film electrode while Fe3+ doped can not improve that of titania film electrode.