Degradation of ketoprofen by sulfate radical-based advanced oxidation processes: Kinetics, mechanisms, and effects of natural water matrices

Ketoprofen (KET) is a mostly used nonsteroidal anti-inflammatory drug that has been frequently detected in wastewater effluents and surface waters. In this study, we investigated the degradation of KET by sulfate radical (SO4-) based advanced oxidation processes (SR-AOPs) in aqueous solution. The degradation kinetics, mechanisms, and effects of natural water matrices on thermally activated persulfate (TAP) oxidation of KET were systematically investigated. Increasing the temperature and persulfate (PS) concentrations greatly enhanced the degradation of KET. KET degradation is pH-dependent with an optimum pH of 5.0. Reactions in the presence of radical quenchers revealed the dominant role of SO4- in oxidizing KET. Water matrix significantly influenced the degradation of KET. The common inorganic anions present in natural waters exhibited inhibitory effect on KET degradation, and the inhibition followed the order of Cl− > CO32− > HCO3− > NO3−; however, no significant inhibition of KET degradation was observed in the presence of Ca2+ and Mg2+ cations. The presence of natural organic matter (NOM) suppressed KET degradation, and the suppression increased as NOM concentration increase. Products identification and mineralization experiments revealed that KET and its degradation intermediates were finally transformed into CO2 and H2O. The results of this study indicated that applying SR-AOPs for the remediation of KET contaminated water matrix is technically possible.