Oxidative Degradation Of Organic Pollutants In Soil By Hydrogen Peroxide/persulfate System

Hydrogen peroxide?H₂O₂?/potassium persulfate?K₂S₂O₈?double oxidant technology to repair organic contaminated soil is a very promising in situ chemical oxidation technology.The method can overcome the drawbacks of the rapidly decomposes of H₂O₂ of traditional Fenton-like method,but also to overcome the too stable of persulfate to react with the target contaminant's problem,is an effective means of repairing organic contaminated soil.The study of oxidative degradation of organic pollutants in soil in H₂O₂/K₂S₂O₈ double oxidants is very low,and the mechanism of H₂O₂/K₂S₂O₈ double oxidants in the process of degradation of organic pollutants in soil is also unclear.Therefore,the mechanism of o-NCB in soil in oxidative degradation of H₂O₂/K₂S₂O₈ double oxidation system catalyzed by natural iron is studied in this paper.The main research results are as follows:?1?Firstly,the effects of catalyzed H₂O₂,activated persulfate,and catalyzed H₂O₂/K₂S₂O₈ processes for the degradation of ortho-nitrochlorobenzene?o-NCB?in soil were evaluated.The results showed that the degradation efficiency of o-NCB in H₂O₂/K₂S₂O₈double oxidant system was much higher than that of o-NCB in soil by single oxidant system.Secondly,the effects of initial concentration of H₂O₂,initial concentration of o-NCB,initial p H value,chelating agent and free radical scavenger on o-NCB degradation were studied in soil.The results indicated that o-NCB can be degradated 60%in 4 h reaction when initial o-NCB concentration was 6 mg/L,H₂O₂ concentration was 4 mmol/L,persulfate concentration was 20 mmol/L,and the initial p H was 7.8.Therefore,H₂O₂/K₂S₂O₈ double oxidant technology is an effective repair of organic pollution of soil chemical oxidation technology.?2?The effects of humic acids on o-NCB in soil in H₂O₂/K₂S₂O₈ dioxin oxidant system were studied.The results showed that humic acids could promote the degradation of o-NCB in soil by H₂O₂/K₂S₂O₈ dual oxidation system.The humic acids from different sources were characterized by elemental analysis,infrared spectroscopy and three-dimensional fluorescence spectra.The results showed that the structure of humic acid was different and the promotion effect was also different.In addition,the mechanism of humic acid on oxidative degradation of o-NCB in soil in H₂O₂/K₂S₂O₈ double oxidant system was further studied by humic acid modification.The results show that the carboxyl group,quinone group and phenolic hydroxyl group in humic acid play an important role in the oxidative degradation of o-NCB in soil in H₂O₂/K₂S₂O₈ double oxidant system.In addition,humic acids is naturally occurring in nature,will not cause secondary pollution to the environment,is a highly efficient green catalyst.?3?In order to study the effect of H₂O₂/K₂S₂O₈ double oxidant system on the toxicity of organic contaminated soil during oxidative degradation of o-NCB in soil.We measured the soil seed germination rate,soil organic matter content and catalase activity.The results showed that the germination rate of plant seeds increased with the increase of K₂S₂O₈ and H₂O₂ concentration in the process of oxidative degradation of organic pollutants in H₂O₂/K₂S₂O₈ double oxidant system,and the soil organic matter content and catalase activity decreased.Therefore,H₂O₂/K₂S₂O₈ double oxidant technology is a kind of green technology with low effect on soil quality,which is suitable for the remediation and treatment of organic contaminated soil.