Influence Of Dissolved Organic Matter On The Chemical Oxidation Degradation Of Organic Contaminated In Soil

Advanced oxidation processes?AOPs?have been successfully applied in the remediation of polluted water and contaminated soil.AOPs can degrade refractory organic pollutants into non-polluting small molecular substances and even mineralize into inorganic substances.At present,hydrogen peroxide?H₂O₂?/potassium persulfate?K₂S₂O₈?double oxidizer technology is a kind of advanced oxidation technology which can effectively remediate contaminated soil.Dissolved organic matter?DOM?is a natural electronic shuttle with strong electron transfer ability,which can accept and provide electrons.However,DOM has little research on the oxidative remediation of organic contaminated soil by H₂O₂/K₂S₂O₈,and the mechanism is not clear.Therefore,this paper mainly studies the effect of DOM on the removal of o-NCB by the oxidation system of H₂O₂/K₂S₂O₈ in the presence of natural iron in soil.The main research results are as follows:In the first part,the degradation effects of different ratios of H₂O₂ and K₂S₂O₈ on o-NCB in soil were studied and compared.The results showed that within a certain range,the higher the concentration of H₂O₂,that is,the higher the ratio of H₂O₂ to K₂S₂O₈,the higher the removal efficiency of o-NCB in soil.Quantitative analysis of free radicals(OH·and SO₄^·-)in the systems of H₂O₂ and K₂S₂O₈ with different proportions.Quantitative analysis of OH·and SO₄^·-can accurately analyze the effect of H₂O₂/K₂S₂O₈ system on the removal of refractory organic compounds.The results show that the addition of hydrogen peroxide not only increases the production of OH·,but also increases the production of SO₄^·-and K₂S₂O₈.It provides theoretical support for subsequent experiments.The second part mainly studies the influence of dissolved organic matter from different sources on the removal of o-NCB from soil by the system of H₂O₂/K₂S₂O₈.The results show that DOM can promote the removal of o-NCB from soil by the system of H₂O₂/K₂S₂O₈.However,the structure of DOM from different sources is different,and the promotion effect is slightly different.The different sources of DOM are characterized by infrared spectroscopy and three-dimensional fluorescence spectroscopy,and the origin of DOM Different sources lead to different structures.In addition,the mechanism of DOM in removing o-NCB from soil in the system of H₂O₂/K₂S₂O₈ was investigated through experiments.The results showed that the electron transfer ability of DOM played an important role in the process of removing o-NCB from soil in the system of H₂O₂/K₂S₂O₈.In the third part,the effects of organic contaminated soil remediation on soil physical and chemical properties,microorganisms and phytotoxicity were studied.Soil pH,organic matter content,enzyme activity and seed germination rate were measured.The results showed that the seed germination rate of plants increased and some indexes decreased after the treatment of organic contaminated soil with H₂O₂/K₂S₂O₈ system,but had little effect on soil quality and plant growth.Therefore,the system of H₂O₂/K₂S₂O₈ can remove the refractory organic pollutants in the soil better,and has less impact on the soil,so it is an efficient advanced oxidation technology.