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

Abstract In this study, ascorbic acid (AA) and cysteine (Cys) were used as homogeneous potassium persulfate (S 2 O 8 2− ) activators. The efficiency of the S 2 O 8 2− /AA and S 2 O 8 2− /Cys systems was investigated to generate sulfate radicals (SO 4 −• ) for the oxidation of sulfathiazole (STZ). The presence of AA and Cys displayed a promoting effect on the activation of S 2 O 8 2− . The results indicated that the STZ/S 2 O 8 2− redox reaction followed pseudo‐first order kinetics with respect to STZ concentrations. The oxidative degradation of STZ is accelerated by temperature, dose of S 2 O 8 2− , AA, Cys, and pH with S 2 O 8 2− /AA and/or S 2 O 8 2− /Cys systems. The degradation rates of STZ followed the order S 2 O 8 2− /AA > S 2 O 8 2− /Cys > S 2 O 8 2− under similar experimental conditions. The presence of SO 4 −• and HO • were tested with two radical scavengers, tertiary butanol (TBA) and ethanol, in which HO • was mainly responsible for STZ degradation at higher pH. In summary, S 2 O 8 2− /AA and S 2 O 8 2− /Cys systems might provide a potentially useful technique for remediation of water contaminants.