Removal efficiency of six typical organic pesticides from water by different oxidation technologies

Abstract

Abstract This study presents a comprehensive evaluation of five different oxidation technologies, namely potassium permanganate, sodium hypochlorite, potassium persulfate (PS), Fenton, and UV/PS process, in the context of oxidation degrading six typical organic pesticides (cyromazine, dinotefuran, chloridazon, atrazine, diuron, and tebuconazole) in water. The investigation also extends to the effects of critical operational parameters, encompassing initial catalyst/oxidant concentration and solution pH, on the degradation efficiencies of the five oxidation technologies. The findings disclose a consistent degradation pattern typified by pseudo–first–order reaction kinetics across the spectrum of the six pesticides. Notably, the oxidation by potassium permanganate, sodium hypochlorite, and potassium persulfate exhibited limited removal efficiencies for the six pesticides, so they were unsuitable choices for pesticide removal from water in practical engineering. The Fenton process has a higher removal efficiency than the above three oxidation methods for the six pesticides, with its performance intricately linked to solution pH values and the H2O2/Fe2+ ratio. Interestingly, the removal rates of the six pesticides by the Fenton process show a trend of first increasing and then decreasing with the increase of solution pH values from 2 to 6, and their removal rates reach the highest when the solution pH value is equal to 3. Moreover, the UV/PS process showcases superior effectiveness by consistently registering the highest removal rates among the six pesticides. At a PS concentration of 2.0 mg/L, the pesticides displayed the highest reaction rate constants and removal efficiencies, consistently achieving removal rates exceeding 95% for the six pesticides during the UV/PS process. Consequently, this study demonstrated the applicability of UV/PS process as a potent method for the removal of organic pesticides from aqueous solutions.