Keywords: 
• TiO2 nanoparticles /
• sulfur doping /
• microemulsion method /
• photocatalysis /
• methyl orange

Abstract: Sulfur-doped TiO2 (S-TiO2) nanoparticles were synthesized by microemulsion method， using tetrabutyl titanate (Ti(OBu) 4) and sulfourea as precursors and water-in-oil (W/O) microemulsions system of Triton X-100，n-hexanol，cyclohexane and ammonia water. The structure of the synthesized TiO2 nanoparticles was characterized. In addition， the photocatalytic property of the nanoparticles under UV-light irradiation was investigated by degradation of methyl orange solution. The results show that the calcination temperature affects greatly the photocatalytic degradation through its influence on the crystallite transformation and particle size of TiO2. The degradation rate increases rapidly with the increase of the calcination temperature， but decrease dramatically when the calcination temperature is too high. When the calcination temperature is 600℃ and the calcination time is 2 h， the degradation rate reaches the maximum value. In addition， the doping amount of S can improve the degradation obviously when the S amount is relatively low. The degradation rate decreases slowly when the S amount is too high， and the largest degradation rate can be obtained at a molar ratio of S/Ti=1%. The degradation rate can be dramatically enhanced with the increase of catalyst load but decreases with the further increase of catalyst load. The optimum catalyst load is 1.5 g/L.