Photocatalytic oxidation of monuron in the suspension of WO3 under the irradiation of UV-visible light.
A comprehensive study of the degradation of monuron, one of the phenylurea herbicides, was conducted by UV-Vis/WO(3) process. It was found that hydroxyl radicals played a major role in the decay of monuron while other radicals (e.g. superoxide) and hole might also contribute to the decomposition of monuron. The oxidation path likely plays a major role in the generation of hydroxyl radicals. The effects of initial pH level, initial concentration of monuron, and inorganic oxidants on the performance of UV-Vis/WO(3) process were also investigated and optimized. Comparison between monuron decay pathways by UV-Vis/WO(3) and UV/TiO(2) was conducted. The decay mechanisms, including N-terminus demethylation, dechlorination and direct hydroxylation on benzene ring, were observed to be involved in the oxidation of monuron in these two processes. Sixteen intermediates were identified during the photodegradation of monuron and degradation pathways were proposed accordingly.
Department of Civil and Structural Engineering, Research Centre for Urban Environmental Technology and Management, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. cewchu@polyu.edu.hk
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D006540:Herbicides / Q000032:analysis / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008782:Methylurea Compounds / Q000032:analysis / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D055668:Photochemical Processes / Q000187:drug effects*; D014414:Tungsten / Q000737:chemistry*; D014466:Ultraviolet Rays
D006540:Herbicides; D008782:Methylurea Compounds; D010087:Oxides; C511604:tungsten oxide; C100088:monuron; D014414:Tungsten