The degradation of oxytetracycline with low concentration of persulfate sodium motivated by copper sulphate under simulated solar light

Degradation of OTC with Cu2+/PS under simulated solar light was investigated. Under simulated solar light or UV-254 light, metal ions could increase the degradation of OTC (< 10%) and the order was that Cu2+ > Mn2+ > Zn2+ > Cr3+ > Mg2+ approximate to Ca2+. When PS was used, the degradation of OTC under simulated solar light improved only with Cu2+. The optimum condition of OTC/Cu-2+/PS under simulated solar light was OTC:Cu2+:PS= 1:1.5:1.75 and the removal rate of OTC could reach 93.5% after 1 h irradiation. In addition, the improvement of degradation of OTC with Cu2+/PS could also be found under UV-254 light or visible light, and the results showed that the energy of light could play an important role in the degradation of OTC. The mechanism of OTC/Cu2+/PS under light was discussed, and it could be that, under light irradiation, Cu2+ could change into Cu+ which could motive PS to produce SO4 center dot-. The degradation of OTC with Cu2+/H2O2 under simulated light was studied to verify the mechanism. Moreover, The mineralization of OTC with Cu2+/PS under simulated solar light was analyzed. Furthermore, seven products were detected by LC-MS (EI+) and the OTC degradation pathway was discussed.