Degradation and Mineralization of Sulfamethoxazole by Photo-Fenton Reaction

Degradation and mineralization of sulfamethoxazole by the photo-Fenton reaction (Fe2+/H2O2/UV) were investigated. It was found that 176 mg•L-1 sulfamethoxazole was completely degraded by the photo-Fenton reaction in 5 min with an initial total iron ion concentration of 15 mg•L-1 and an initial hydrogen peroxide concentration of 500 mg•L-1 under ultraviolet light irradiation. About 65% mineralization of the initial total organic carbon concentration of 83 mg•L-1 was achieved in 40 min. Under the initial total iron ion concentration of 5 mg•L-1, the degradation rate constant of sulfamethoxazole (SMX) increased with the initial total iron ion concentration. However, over the initial total iron ion concentration of 5 mg•L-1, the degradation rate constant of SMX did not increase with the initial total iron ion concentration owing to scavenger effects. From the results of the measurement of the organic acid concentration during the sulfamethoxazole degradation and mineralization by the photo-Fenton reaction, organic acids were found to accumulate in the solution. The comparison between the reaction rate constants of SMX and coexisting substances in real sewage revealed that degradation of micropollutants such as pharmaceuticals could be significantly affected by matrix effects.