Study on photocatalytic degradation of gaseous dichloromethane using pure and iron ion-doped TiO2 prepared by the sol-gel method.

The synthesis of TiO2 and Fe-TiO2 by sol-gel method is demonstrated and characterized. The characterization of TiO2 and Fe-TiO2 is performed with instruments, including TGA/DTA, FTIR, UV-Vis, N2 adsorption and SEM. Dichloromethane is used for the photocatalytic activity test. From the results of dichloromethane photocatalytic degradation, the calcined temperature of TiO2 and the presence of water vapor influence the photocatalytic activity. The optimum doping amount of iron ions is 0.005 mol%, and this can enhance the photocatalytic activity, while too great an amount will make the iron ions become recombination centers for the electron-hole pairs and reduce the photocatalytic activity. UV-Vis diffuse reflectance spectra of Fe-TiO2 show an increase in absorbency in the visible light region with the increase in iron ions doping concentration The intermediate of dichloromethane photodegradation includes CHCl3, CCl4, CH2Cl2 and COCl2. The presence of iron ions may reduce the adsorption of Cl element on the surface of the photocatalyst.