| With the growing water pollution, a large number of chemical industrial wastewater that contains various toxic and harmful refractory compounds flow into the global water cycle system in recent years. Chlorophenols is a representative refractory compound, which is an intermediate product in industrial production process of textile, paper printing and dyeing, and is used widely as pesticides, herbicides and preservatives. Chlorophenols will cause serious damage to human health because have three-induced effects including carcinogenic, teratogenic and mutagenic. The priority pollutant lists have included chlorophenols in America and China. Now, how to effectively degrade and remove chlorophenols has become an important research topic for environmental researchers.In this paper, nanometer TiO2/H3PW12O40Ag ternary composite film was prepared by the sol-gel combined temperature programmed hydrothemal method and spin coating technique. The prepared TiO2/H3PW12O40Ag composite film was analysised and characterized by various testing methods such as ICP-AES, XRD, UV-Vis DR, XPS, Nitrogen adsorption-desorption and TEM. The results show the Ti02/H3PW1204o/Ag composite film has excellent surface morphology, physical and chemical properties. H3PW12O40and Ag had doped and deposited successfully in the composite film and distributed uniformly. TiO2showed pure anatase crystal in as-prepared composite film. Comparing TiO2film, the absorption wavelength of composite film happened redshift and-appeared absorption in the visible light region. The catalyts possessed microporous and mesoporous structures, and larger specific surface area.Through the study on photocatalytic activitie of TiO2/H3PW12O40Ag composite film and influencing factors for the degradation of o-chlorophenol (o-CP), the optimum reaction condition is comfirmed. The optimum condition of o-CP:the H3PW12O40loading is10%, the Ag deposition is1%, solution pH is6.3, initial concentration is5mg/L. Under the optimum condition; after240min irradiation, the efficiency of photocatalytic degradation is82.40%, and the reaction initial rate is3.77×10-2mg/L-min. After simulated sunlight irradiation for12h, mineralization degree of o-CP (20mg/L) reaches76.50%by Ti02/H3PW1204o/Ag composite film, and is higher than TiO2/H3PWi2O40composite film (52.20%) and TiO2film (49.20%). This is mainly due to the deposition of noble metal Ag has restrained effectively the recombination between photoproduction electrons and holes to increase quantum efficiency, and has appeared the visible absorption to enhance sunlight utilization.Using the TiO2/H3PW12O40/Ag composite film to degrade o-chlorophenol (o-CP), p-chlorophenol (p-CP),2,4-dichiorophenol (2,4-DCP),2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), the research found the degradation efficiency follows the sequence:p-CP and PCP (100.00%)>2,4-DCP (99.97%)>2,4,6-TCP (90.72%)> o-CP (82.40%). The react initial rate is respectively0.1435mg/L-min (p-CP),0.1573mg/L-min (PCP),0.1610mg/L-min (2,4-DCP),0.0472mg/L-min (2,4,6-TCP) and0.0377mg/L-min (o-CP) after240min irradiation. So, there is a close relationship between the degradation of chlorophenols and the replace position and quantity of chlorine. |
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