Degradation of ofloxacin in water using heat/S2O82− process

Abstract

BackgroundThis work examines the degradation of ofloxacin (OFL) in water using the heat/S2O82− process (70 °C). MethodsThe dependences of the degradation of OFL using this process on the Na2S2O8 dosage, pH, initial OFL concentration, and addition of anions were studied. Significant FindingsThe pseudo-first-order kinetic model can fit the degradation of OFL under diverse operating conditions and can be used to obtain the apparent rate constants thereof. Increasing the Na2S2O8 dosage promoted the degradation of OFL. However, the degradation of OFL was inhibited by an excessive Na2S2O8 dosage. The optimal Na2S2O8 dosages in the degradation of OFL at pH 3, pH 7, and pH 11 were 1.92 g/L, 0.96 g/L, and 0.48 g/L, respectively. The degradation of OFL at pH 3 dramatically exceeded that at pH 11. Radical scavenging studies using alcohols reveal that SO4•− predominated at pH 3 and pH 7 but HO• predominated at pH 11. When the initial OFL concentration was increased, the degradation of OFL decreased. Adding CO32− and HCO3− significantly slowed the degradation of OFL. At pH 3 and a duration of 30 min with an Na2S2O8 dosage of 1.92 g/L, and an initial OFL concentration of 10 mg/L, the heat/S2O82− process (70 °C) in the absence of anions degraded 97% of the OFL with a corresponding apparent rate constant of 0.2359 min−1. TOC analysis reveals that the heat/S2O82− process (70 °C) mineralized OFL efficiently. Therefore, the heat/S2O82− process (70 °C) effectively degraded OFL in water.