A kinetic study for the degradation of 1,2-dichloroethane by S-doped TiO₂ under visible light

Sulfur-doped TiO₂ prepared by a sol-gel method to degrade 1,2-dichloroethane (1,2-DCE) under visible light irradiation was investigated. The photocatalytic decomposition rate of 1,2-DCE under visible light condition was expected to increase via doping. Additionally, the physical and chemical properties of the photocatalysts measured by thermo-gravimetric/differential- thermal analysis, X-ray diffraction, UV-Vis spectroscopy, elemental analysis, BET surface analysis, and X-ray photoelectron spectroscopy were obtained for a better understanding of TiO₂ particles. The results indicate that S-doped TiO₂ are mainly nano-size with an anatase-phase structure, and doping sulfur leads to the formation of Ti-O-S in the TiO₂ lattice. The role of S⁶⁺ as h⁺/e^- traps promotes photocatalytic activity, and prevents h⁺/e^- recombination. S-doped TiO₂ photocatalysts show superior photocatalytic activity compared to that of TiO₂. Among all photocatalysts, 10 mol% S/TiO₂ exhibits the best decomposition rate of 1,2-DCE. The 10 mol% S-doped TiO₂ was, therefore, chosen for the kinetic study. A variety of models were used for best fit of the kinetic data in this study. The results demonstrate that the bimolecular Langmuir-Hinshelwood kinetic model is more feasible than other two to illustrate the photocatalytic reaction of 1,2-DCE.