Photocatalytic degradation of 4-chlorophenol using Pt/TiO2-SiO2 prepared by the sol-gel method

Abstract

Photocatalytic degradation of 4-chlorophenol was studied using TiO2, Pt/TiO2, TiO2-SiO2 and Pt/TiO2-SiO2 prepared by the sol-gel method. The effects of catalyst amount, calcination temperature and initial pH of solution on the degradation were investigated. In the experiment, a photocatalyst was suspended in the 4-chlorophenol solution under irradiation from an 11 W low-pressure mercury lamp producing wavelengths of 100-280 nm. The results showed that the reduction rate of total organic carbon (TOC) increased with increasing the amount of TiO2 catalyst and the optimum amount of TiO2 was found to be 0.7 g/l. The TOC reduction rate decreased with increasing calcination temperature because of the transformation of TiO2 from anatase to rutile at higher calcination temperatures. The initial pH of solution did not significantly affect the TOC reduction rate. For Pt/TiO2 catalyst, addition of small amount of Pt into TiO2 improved the catalyst activity and the highest activity was obtained with 1%Pt/TiO2. For TiO2-SiO2 catalyst, the highest activity was achieved at 10%SiO2-TiO2 because of its highest adsorption capacity. For Pt/TiO2-SiO2 catalyst with 1%Pt and 10%SiO2, although 1%Pt or 10%SiO2 alone in TiO2 could improve the catalyst activity, the synergistic effect of adding both 1%Pt and 10%Si was not observed due to the agglomeration of the catalyst which, in turn, lowered the catalyst activity