Fenton试剂和活化过硫酸钠氧化降解土壤中的二氯酚和三氯酚

Oxidative degradation of dichlorophenol and trichlorophenol in soils by Fenton reagent and activated persulfate

氯酚类物质(chlorophenols,CPs)在环境介质中广泛存在且具有很强环境毒性。为探究化学氧化修复场地氯酚类污染的可行性,通过室内实验、模拟搅拌实验、现场中试,开展应用Fenton试剂和活化过硫酸钠氧化降解土壤CPs的研究。结果表明,化学氧化可有效降解土壤中的CPs,在氧化剂用量和CPs总量摩尔比为15:1时,Ca O活化Na2S2O8能高效降解土壤中的二氯酚(2,4-DCP)和三氯酚(2,4,6-TCP),室内实验和现场中试的去除率均达90%以上,处理后的2,4-DCP和2,4,6-TCP浓度均低于《展览会用地土壤环境质量评价标准》(HJ 350-2007)A类标准限值。Fenton试剂在室内实验中降解率达90%以上,但现场中试对2,4-DCP和2,4,6-TCP的降解率仅为66.1%、23.8%,处理后2,4-DCP浓度仍超过A类标准限值1倍以上。此外,在修复过程中,约70%的2,4-DCP、2,4,6-TCP会向液相转移,因此,需要关注修复系统引入水后污染物向液相中的转移可能造成的二次污染。研究结果可为氯酚类污染土壤的修复提供新思路,并为实际工程应用提供理论依据。

Chlorophenols（CPs） widely exist in environment and have strong environmental toxicity. In this paper,laboratory experiments, simulating stirring studies and field pilot tests were conducted to evaluate the efficiency of Fenton and activated persulfate in removal of 2,4-DCP and 2,4,6-TCP from soils through oxidative degradation. The results showed that chemical oxidation could effectively degrade CPs in soils. When the molar ratio of oxidant and total CPs concentration was 15：1, 2,4-DCP and 2,4,6-TCP in soils could be degraded effectively by Ca O-activated persulfate, and the removal efficiencies were above 90% in all laboratory tests and field pilot experiments. The residual concentrations of 2,4-DCP and 2,4,6-TCP were lower than the class A standard limit values of Standard of Soil Quality Assessment for Exhibition Sites（HJ 350-2007）. Fenton had a removal efficiency of 90% in laboratory tests, but it was relatively low at field pilot tests, which was 66.1%, 23.8% for 2,4-DCP and 2,4,6-TCP, respectively.The residual concentration of 2,4-DCP was still more than double of the class A standard limit value. It was also found that during the remediation about 70% of 2,4-DCP and 2,4,6-TCP in soil were transferred to aqueous phase.Therefore when introducing water into remediation system we need pay attention to the secondary pollution caused by the transfer of pollutants into the aqueous phase. This research provides new approaches for the remediation of CPs contaminated soil, and sets up theoretical basis for practical engineering application.