| Due to various industrial and agricultural activities of human beings,a large amount of metal causing serious soil environmental pollution has entered the soil,which has seriously threatened the ecological environment and the health of human.Therefore,the restoration of metal-contaminated soil has great practical significance.In this paper,the types of contaminated metals,the concentration and time of tartaric acid as an auxiliary reagent,the mechanism of tartaric acid as an electrokinetic remediation intensifying reagent and the combined remediation technology of electrokinetic remediation,fixation and stabilization were studied by using the artificially arranged metal-contaminated soil as the research object.Joint repair techniques have been studied.The results show that:1.Electromigration and redox reactions of Cr(Ⅵ)occur during electrokinetic remediation of Cr(Ⅵ)contaminated soil when using different concentration of tartaric acid as electrolyte.Cr(Ⅵ)mainly undergoes redox reaction when pure water is used as the electrolyte,and the Cr(T)removal rate is low while Cr(Ⅵ)removal rate is high;Adding low concentration of tartaric acid can promote the analysis of Cr(Ⅵ),which can enhance the removal ability of Cr(Ⅵ)and Cr(T);The addition of high tartaric acid concentration promotes the redox reaction of Cr(Ⅵ).2.The removal efficiency of five heavy metals was low when pure water was used as electrolyte for electrokinetic remediation of simulated soil contaminated by Cr(Ⅵ),Zn(Ⅱ),Cd(Ⅱ),Pb(Ⅱ)and Cu(Ⅱ).The addition of tartaric acid can promote the desorption of heavy metals,reduce the formation of heavy metal hydroxide precipitation,and significantly improve the removal efficiency of heavy metals in electric repair.3.When using tartaric acid as electrolyte to enchanced electrokinetic remediation of Mn(Ⅱ),Zn(Ⅱ),Cd(Ⅱ),Pb(Ⅱ)and Cu(Ⅱ)multi-metals contaminated kaolin,H~+produced by ionization of tartaric acid can provide acidic conditions to promote the dissolution of metal ions in soil,inhibit the formation of metal hydroxide precipitation,and the chelation of tartaric acid with metal ions can promote the desorption of metal on the surface of soil particles,changing the existence form of metals,which was conducive to electric remediation.Acid extractable state is easy to migrate,while residual state is relatively stable,tartaric acid can promote the transformation of residual metal to acid extractive state;Under the condition of high soil moisture content,metal ions will diffuse freely to cathode and anode electrolyte in the initial stage of electrokinetic remediation.4.Remediate actual contaminated soil,the removal efficiency of metal is lower than that of simulated soil,using tartaric acid as electrolyte can enhance the removal efficiency of electrokinetic remediation;Soil acidification after remediation can be improved by adding plant ash. |
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