Kinetic studies on the sulfathiazole degradation by activated persulfate with ascorbic acid and cysteine

In this study, ascorbic acid (AA) and cysteine (Cys) were used as homogeneous potassium persulfate (S2O82-) activators. The efficiency of the S2O82-/AA and S2O82-/Cys systems was investigated to generate sulfate radicals (SO4-center dot) for the oxidation of sulfathiazole (STZ). The presence of AA and Cys displayed a promoting effect on the activation of S2O82-. The results indicated that the STZ/S2O82- redox reaction followed pseudo-first order kinetics with respect to STZ concentrations. The oxidative degradation of STZ is accelerated by temperature, dose of S2O82-, AA, Cys, and pH with S2O82-/AA and/or S2O82-/Cys systems. The degradation rates of STZ followed the order S2O82-/AA > S2O82-/Cys > S2O82- under similar experimental conditions. The presence of SO4-center dot and HO center dot were tested with two radical scavengers, tertiary butanol (TBA) and ethanol, in which HO center dot was mainly responsible for STZ degradation at higher pH. In summary, S2O82-/AA and S2O82-/Cys systems might provide a potentially useful technique for remediation of water contaminants.