Oxidative and reductive degradation of sulfamethoxazole in aqueous solutions: decomposition efficiency and toxicity assessment

Under radiolytic conditions at a concentration of 0.1 mmol dm(-3) the reactions of sulfamethoxazole, a worldwide used anti-infective sulfonamide antibiotic, were mainly induced by hydroxyl radicals. With a dose of 5 kGy complete degradation of aromatic system was observed. The sulfur of the molecule was entirely transformed to SO42-, while NO3- and NH4+ were formed from the nitrogen content. The chemical oxygen demand and total organic carbon values indicated complete mineralization during irradiation. In pursuance of toxicity tests, the observed increase in mortality of Vibrio fischeri bacteria was mainly due to H2O2 formed during the radiolytic procedure. The results showed that the degradation was effective; therefore, the irradiation technology can be recommended for treatment of wastewater containing sulfamethoxazole.