Degradation of oxytetracycline with SO4•- under simulated solar light

Degradation of OTC under simulated solar light with Fe2+/PS was investigated. Results showed the OTC-Fe(II or III) complex could disturb the detection of OTC by HPLC. However, acidification (pH < 2.3) could greatly reduce the effect of the OTC-Fe(II or III). Response surface methodology was used to optimize the Fe2+/PS dosage at low concentrations of PS and Fe2+. When the OTC concentration was 0.04 mM, the optimal dosage was OTC:Fe2+:PS = 1:0.5:2 to attain a removal rate of 86% after 60 min of illumination. Further optimization showed that the best dosage ratio of the OTC:Fe2+:PS for 45 min of illumination was 1:0.2:2, which achieved a removal rate of 81%. The influence of Cl-, CO32-, HCO3-, NO3-, NO2- or H2PO4- on the degradation of OTC with Fe2+ and PS under simulated solar light was studied. Cl-, NOT, HCO3, or H2PO4- could inhibit degradation when their concentrations were higher than 4 mM, whereas NO3- had no influence on degradation. Degradation acceleration caused by CO32- was mainly due to the facilitated direct photolysis of OTC under alkaline conditions. Four products were detected by LC-MS, and the OTC degradation pathway was discussed. The mineralization of OTC with Fe2+/PS under simulated solar light was analyzed. (C) 2016 Elsevier B.V. All rights reserved.