Study On Chemical Oxidation Remediation Technology Of Multiple Organic Compounds In Soil And Groundwater

In recent years,the groundwater and soil pollution are becoming more and more serious in our country,many traditional and new pollutants present in groundwater and soil need to be degraded by treatment.Advanced oxidation technology based on hydroxyl radical and sulfate radical has received extensive attention and in-depth research.This technology can completely degrade organic pollutants and produce harmless water and carbon dioxide.Therefore,advanced oxidation technology is used to degrade several typical target pollutants in this paper.Two new pollutants,benzotriazole and benzothiazole,were used as target pollutants,and multiple oxidants were used to explore their degradation process in aqueous phase.The results showed that the sodium persulfate is the best oxidants for degrading benzotriazole.Decreasing the concentration of benzotriazole,increasing the concentration of sodium persulfate,increasing the reaction temperature,and adding alkali can effectively accelerate the degradation rate of benzotriazole.The free radical that oxidizes under acidic conditions is SO₄^·-,and in alkaline condition,SO₄^·-,·OH and¹O₂ synergizes in the oxidation of benzotriazole.Sodium persulfate can completely mineralize benzotriazole.Increasing the concentration of sodium persulfate and increasing the p H value can accelerate the mineralization rate of benzotriazole.Different anions in water at high temperature will affect the degradation of benzotriazole by sodium persulfate.The effect of each anion is different.At low temperature,the anion has little effect on the degradation of benzotriazole by sodium persulfate.Benzotriazole is gradually degraded mainly by processes such as carboxylation,hydroxylation,and ring opening.Sodium persulfate is the best oxidant for the degradation of benzothiazole.Increasing the reaction temperature,decreasing the initial concentration of benzothiazole and increasing the concentration of sodium persulfate can accelerate the degradation rate of benzothiazole.The degradation rate of benzothiazole is approximately the same under acidic to weak alkaline conditions,and the degradation rate of benzothiazole decrease when the alkalinity is too strong.When there are low concentration anions in the reaction system,only Br^-can decrease the reaction rate,and other anions(Cl^-,CO₃^2-,HCO₃^-,NO₃^-,SO₄^2-)have no obvious effect on the degradation of benzothiazole.When high concentration of anions existed in the reaction system,Cl^-,Br^-,CO₃^2-and HCO₃^-could slow down the degradation of benzothiazole,and NO₃^-,SO₄^2-had no obvious effect on the degradation of benzothiazole.The dominant free radical in the reaction system under acidic conditions is SO₄^2-.Under alkaline conditions,·OH and SO₄^2-synergistically degrade benzothiazole.Four kinds of polycyclic aromatic hydrocarbons?PAHs?,fluorene,phenanthrene,fluoranthene and pyrene were used as target pollutants for PAHs contaminated soil remediation experiments.Experiments show that long-term soil placement does not affect the extraction recovery rate of PAHs.Adding water to the soil can reduce the recovery rate of PAHs extraction,and there are microorganisms in the soil that can degrade PAHs.KMn O₄ and sodium persulfate can effectively degrade PAHs.H₂O₂ and four kinds of solid peroxide can not degrade PAHs in soil.Adding Fe²⁺can effectively enhance the oxidation effect of sodium persulfate and H₂O₂.The degradation effect of high concentration Fe²⁺activated sodium persulfate is the best,and the degradation rates of the four PAHs are 87.6%,85.5%,69.5%,96.1%.