New Types Of Polyoxometallates Photocatalytic Degradation Of Simulated Phenol Wastewater With Sunlight Irradiation

Phenol with high toxicity,which has a severe harm to the environment and human,thus,the degradation of phenol wastewater has been highly valued.In this paper,the aqueous phenol solution was selected as the goal dagradation compound.A series new types of 1:11 Keggin polyoxometallates,K6TiW11O39Sn?(TiW11Sn),K6ZrW11O39Sn?(ZrW11Sn),K8SiW11O39Sn?(SiW11Si),and commercial 1:12 Keggin polyoxometallate,H3PW12O40 and H4SiW12O40,were chosen as photocatalysts.The photocatalytic degradation of the homogenous aqueous phenol solution under the sunlight irradiation was studied.Experiment results indicated that aqueous phenol solution could be degradated with the above five photocatalysts under the sunlight irradiation.The degradation effects of the aqueous phenol solutions were quite different with different experimental conditions.The orthogonal test results showed that the photocatalytic degradation efficiency of the aqueous phenol solution was affected by the initial concentration and the initial pH values of the phenol solution,the photolysis time,the kinds of catalysts and the dosage of the catalyst.The order of the importance of the above influence factors were the kinds of catalysts>the illumination time>the initial pH of the phenol solution>the dosage of catalyst>the initial concentration of the phenol solution.TiW11Si is the best photocatalyst for degradation of phenol.When the initial concentration of the phenol solution(40 mL)was 3.05 mg/L,the initial pH values of it was 5,and the amount of TiW11Sn catalyst in the solution was 0.25 g/L,the decolorization rate of the aqueous phenol solution was 51.72%with sunlight irradiation 5h.The reactions of phenol photocatalytic degradation follow the Langmuir-Hinshelwood pseudo-first-order kinetics.A novel composite photocatalyst,TiW11Sn/TiO2,was also synthesized by sol-gel method which was characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscope(TEM),Energy Dispersive Spectrometer(EDS),UV-Vis diffuse reflectance spectroscopy(UV-Vis DRS),Frontier Fourier Transform Infrared Spectrometer(FTIR).The effects of the doping ratio of TiW11Si and TiO2 and the calcination temperature on the photocatalytic performance of TiW11Sn/TiO2 for degradation of the aqueous solution of phenol with sunlight irradiation were studied.Results showed when the calcination temperature was 370?,the doping amount of TiW11Sn was 1.8 wt%,the photocatalytic decolorization rate of the aqueous phenol solution was more than 70%with the above prepared TiW11Sn/TiO2.The effect of the photocatalytic degradation of the aqueous phenol solution was better than the pure Ti02(self-made)which was prepared as the same conditions of TiW11Sn/TiO2.the commercial anatase TiO2 and the homogeneous TiW11Sn photocatalytic effect.Tnd superior to that of the ZrW11Sn/TiO2.