Mechanism, kinetics and DBPs formation of UV/NH2Cl process on sulfathiazole removal in aqueous solution

In this paper, UV/NH2Cl process was used to research the degradation of sulfathiazole (STZ) and the formation of disinfection by-products (DBPs) after disinfection were detected. UV and NH2Cl process showed a synergistic effect on the removal of STZ. Natural organic matter and CO32− inhibited the STZ degradation, NO3− promoted the degradation of STZ, whereas NH2Cl concentration, HCO3− and Cl− had dual effects on the removal of STZ. The removal of STZ by UV/NH2Cl was slightly influenced by pH. The contribution of reactive chlorine species and reactive nitrogen species to STZ degradation was significantly higher than that of HO·. Possible STZ degradation pathways were presented by analyzing intermediate products. In addition, the pretreatment of UV/NH2Cl significantly reduced the formation of DBPs during NH2Cl or NaClO disinfection. In conclusion, UV/NH2Cl process is an effective water treatment technology and can be well applied for practical purposes.