Comparison of Persulfate Activation and Fenton Reaction in Remediating an Organophosphorus Pesticides-Polluted Soil

Organophosphorus pesticides (OPs) are one of the most regular pollutants and frequently detected in the contaminated sites, so developing an efficient method for the treatment of OPs is highly required. The aim of the present study was to compare the effectiveness of persulfate (PS) activation and Fenton reaction in remediating the soil polluted with OPs. The polluted soil used in this study was sampled from an abandoned insecticide factory in Nantong, Jiangsu Province of China, mainly containing chloropyrifos (CP) and 4-bromo-2-chlorophenol (BCP, the raw material of profenofos) with total concentration of about 30 000 mg kg−1. The results showed that both BCP and CP were efficiently degraded by base activation of PS, and increasing the ratio of NaOH/PS enhanced CP degradation, but slightly decreased BCP degradation. The greatest degradation rates for CP and BCP were 92% and 97%, respectively, with 7.0 mol L−1 NaOH and 0.21 mol L−1 PS and a soil-to-liquid ratio of 1:1. Furthermore, ferrous iron activation of PS also degraded BCP efficiently, but only 60% of CP was degraded under the same reaction conditions. These results indicated that base activation of PS was more feasible than Fe2+ activation and Fenton reaction in remediating the soil polluted with OPs. The high degradation rate for CP may be linked to the initial hydrolyzation of CP by base to 3,5,6-trichloro-2-pyridinol, which can be further rapidly degraded by free radicals generated from base activation of PS.