Radiation-induced removal of sulphadiazine antibiotics from wastewater

The radiation-induced removal of sulphadiazine (SD) belonging to the heterocyclic sulphonamides pharmaceuticals was investigated by gamma irradiation at different conditions in laboratory scale. The influence of initial SD concentrations, pH values, O-2 and N-2 on SD degradation was determined. The experimental results showed that gamma-ray irradiation was efficient for removing SD from wastewater. SD could be completely removed at an absorbed dose of 10kGy. The degradation kinetics of SD conformed to the first-order kinetic equation. When SD concentration was in the range of 10-30mg/L, the dose constant (d) decreased with an increasing initial SD concentration. The mineralization of SD, in terms of total organic carbon removal, was not obvious at a low absorbed dose, but it increased to more than 75% at 100kGy. The biodegradability of SD was improved after irradiation, suggesting that irradiation could be used as a pretreatment technology for treating SD-containing wastewater. The possible degradation pathway of SD was tentatively proposed based on the analysis of intermediate products during gamma irradiation.