Enhancement of TiO2 activity under visible light by doping S element from sulfur core for Pb(II) photo-oxidation

This paper deals with doping TiO 2 with sulfur powder by sol–gel method, in order to extend the photocatalytic activity under visible light exposure. Weigh of the sulfur powder was varied as 5, 10, and 20 mg doped into 12.5 mmoles of TTIP, (theoretically the same as 100 mg of TiO 2 ) to get 5%, 10%, and 20% of S contained in the prepared TiO 2 –S. The S-doped TiO 2 prepared was characterized by specular reflectance UV–Visible, X-ray diffraction, Fourier Transform Infrared, and Scanning Electron Microscope instruments. The effect of S doping on TiO 2 photocatalytic activity was examined through photo-oxidation of Pb(II) under visible light. In order to obtain the highest photo-oxidation of Pb(II), optimization of S content, photocatalyst mass, reaction time, and solution pH were conducted by batch experiment. The results of the research assign that sulfur from the powder has been successfully dopped into TiO 2 , which has significantly decreased the band gap energies and enhanced its activity under visible light. The enhancement was found to be controlled by the amount of S doped and the highest activity was shown by 10% of S doped. Furthermore, the most effective removal of Pb(II) 10 mg/L, (~ 98%), could be reached by employing 500 mg/L of the TiO 2 -S (10) dose, 45 min of the time, and the solution pH at 7. The Pb(II) removal is due to the photo-oxidation induced by OH radicals to form the handleable PbO 2 .