| The UV photolysis of S2O2-8 is a novel advanced oxidation technologies (AOTs), which leads to the formation of strong oxidizing radicals, sulfate radicals (SO·-4）. The effect of oxidant K2S2O8concentration, the initial pH of solution and various inorganic anions (H2PO-4, HCO-3, NO-3 and Cl-) were investigated using AO7, a kind of azo dye, as a model pollutant. The degradation kinetics of AO7 followed pseudo first-order kinetics and reaction rates related to PMS concentrations. When the initial concentration of AO7 was 0.14 mmol/L, the optimal molar ratio of oxidant K2S2O8 to pollutants AO7 was 20. The effect of initial pH had great effect on the AO7 degradation rate during UV/ K2S2O8 system. Increasing system pH results in the formation of ·OH from SO·-4. The effects of four inorganic anions (H2PO-4, HCO-3, NO-3 and Cl-) all had some negative effect on the degradation of AO7. Based on the results of GC/MS, three main intermediates (2-naphthalenol, coumarin and 1,2-benzenedicarboxylic acid) were identified, thus the degradation pathway for SO·-4 induced by UV/K2S2O8 was proposed accordingly. |
