Atrazine Degradation in Solar Irradiation/S-Doped Titanium Dioxide Treatment

Atrazine is a widely-used herbicide and always contaminates water bodies due to its relatively higher solubility and persistence. The removal efficiency of atrazine in water and the influencing factors by combined process of solar irradiation and S- doped TiO₂ were studied in detail, in which S-doped TiO₂ photo-catalyst with high sunlight activity was prepared by acid catalyzed hydrolysis method using thiourea as sulfur source; As a comparison, solar/TiO₂ process was studied in the meantime; The experiment results showed that atrazine could be more effectively oxidized by the solar/S-doped TiO₂ process than by solar/ TiO₂ process, whose removal effect were 60% and 40% after 30 min´s irradiation, respectively; Pseudo-first-order model could be used to simulate the oxidation process in which the degradation rate coefficients were independent of the initial concentration of atrazine; Degradation rate could be greatly affected by the concentration of H₂O₂, the optimum concentration for the system of solar/S-doped TiO₂ was found to be 20 mg/L, which was 5 mg/L higher than that of solar/TiO₂ system; Lower water pH favor the degradation of atrazine for the change of charge density of both the atrazine molecular and photo-catalyst surface; Humic acids decreased both the degradation rate of the two processes, and solar/S-doped TiO₂ process more easily affected, for the humic acids could not only compete with molecular atrazine for radicals but also adsorb part of sunlight which can excite radical with TiO₂.