title: Photocatalytic degradation of aqueous 4-chlorophenol by silica-immobilized polyoxometalates.
abstract: The degradation of 4-chlorophenol with near-UV light by silica-immobilized polyoxometalate (POM-in-SiO2) catalysts has been studied. The silica-immobilized Na6W7O24 (SW7), H4W1032 (SW10), H3PW12O40 (SPW12), and H6P2W18O62 (SP2W18) were prepared by means of the sol-gel hydrothermal technique through the hydrolysis of tetraethoxysilane in aqueous solution of the corresponding polyoxometalate, respectively. The degradation of 4-chlorophenol was monitored by measuring Cl- and CO2 concentrations and analyzing reaction intermediates by GC/MS analysis. During irradiation, 4-chlorophenol first dechlorinated to form hydroquinone and p-benzoquinone, and then these intermediates further mineralized to form CO2 and H2O. The degree to which 4-chlorophenol was mineralized by photocatalytic oxidation was investigated. Results indicate less than 15% for SW7 but nearly complete mineralization for SW10 after 60 min of photoirradiation. The present studies suggest that POM-in-SiO2 catalysts may be a novel type of photocatalyts for the purification of the environmentally chlorophenol-contaminated water.
authors.affiliation: Department of Chemistry, Fudan University, Shanghai, China. ymtianc@online.sh.cn
authors.forename: Bin
authors.initials: B
authors.lastname: Yue
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jingyu
authors.initials: J
authors.lastname: Xu
authors.forename: Zhuzhi
authors.initials: Z
authors.lastname: Wu
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhang
authors.forename: Yefen
authors.initials: Y
authors.lastname: Zou
authors.forename: Songlin
authors.initials: S
authors.lastname: Jin
mesh_terms: D002384:Catalysis; D002733:Chlorophenols / Q000737:chemistry*; D006868:Hydrolysis; D010777:Photochemistry; D012822:Silicon Dioxide / Q000737:chemistry; D017973:Tungsten Compounds / Q000737:chemistry; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000032:analysis; D000099294:Polyoxometalates
chemical_list: D002733:Chlorophenols; D012822:Silicon Dioxide; D017973:Tungsten Compounds; D014874:Water Pollutants, Chemical; C102296:polyoxometalate I; D000099294:Polyoxometalates; C029107:4-chlorophenol