Oxytetracycline Degradation by Heat-Activated Peroxydisulfate and Peroxymonosulfate Oxidation: Optimization by Box-Behnken Design

Abstract

This study investigates the removal of oxytetracycline performed by persulfate (PS) and peroxymonosulfate (PMS) processes. For this purpose, response surface methodology was used to examine the effectiveness of PS and PMS processes under both alkaline and thermal conditions. The effect of four independent variables, which were selected as pH, PS/PMS concentration, temperature, and time, were analyzed in a wide range. The working pH was between pH 3–11 to compare acidic and alkaline conditions, and the temperature was selected between 30 and 90°C to evaluate the effect of thermal activation of sulfate radicals for both processes. According to the results of prepared Response Surface Methodology (RSM) models, all four independent variables were determined to be highly significant for both PS and PMS. Especially in the PMS process, the highest PMS concentration was observed to complete degradation of OTC. The conditions for the highest removal were pH 9 and PS/PMS concentration was approximately 4mM for both processes, while the temperature and required time were 72.9°C and 75°C, 26.5 min and 20 min, for PS and PMS processes, respectively. PS process has higher kinetic constants at all pH values than the PMS process.