| With the continuous adjustment of urban functions and layout,the pollution problems left by the industrial development in the soil are gradually exposed,and the problem of heavy metal pollution in the soil has received attention,and it has gradually become one of the hot issues in the environmental protection industry.Heavy metal pollution in soil pollution can cause various damages to animals,plants and human bodies,causing various degrees of harm.Nowadays,there are many methods for soil heavy metal remediation,such as plant remediation,animal remediation,microbial remediation,solidification and stabilization,leaching repair,etc.Among them,leaching repair technology is gradually paid attention to due to its fast,efficient and permanent repair characteristics.This paper mainly studies the remediation effect of the leaching agent on the pollution of composite heavy metals through indoor simulation experiments,and continuously extracts the soil before and after leaching,so as to conduct morphological analysis and discuss the removal of heavy metal pollutants from the morphological point of view.In this paper,the real soil of the contaminated site was collected,and the soil in the sample site was contaminated with Pb,Cr,Ni,Cu,Zn and other heavy metals.Carry out leaching simulation experiments in the laboratory,select three solutions of NaOH,OX and EDTA as the leaching agent after consulting the literature,and explore their effects on Pb,Cr,Ni,Cu,Zn under different leaching process conditions to remove the effect,and then conduct morphological analysis on this basis,and draw the following conclusions:1)The removal effect of EDTA solution on Pb is better than that of NaOH solution and oxalic acid solution;the effect of oxalic acid solution on Cr and Ni is better;the treatment effect of EDTA solution and OX solution on Cu is better than that of NaOH solution;Zn pollution Can be treated with EDTA solution and hot NaOH solution;2)The solid-liquid ratio of 1: 5 and 1: 3 is better than that of 1: 1.The smaller the solid-liquid ratio,the better the treatment effect;3)The solution of 0.10 mol/L EDTA,solid-liquid ratio of 1: 5 is the best for treating Pb,Cu,Zn;1.00 mol/L oxalic acid solution,solid-liquid ratio of 1: 3 and 0.50 mol/L oxalic acid solution,solid-liquid The ratio of 1: 5 is similar to the removal efficiency of Cr and Ni(P> 0.05)and better;4)It can be seen from the aspect of morphological analysis:The conversion rate of hot NaOH to the carbonate binding state of heavy metal Pb is the largest;the conversion rate of the OX solution to the exchangeable state of Pb is the largest;the EDTA solution has the greatest effect on the exchangeable state of Pb,and the effect of EDTA among the three eluents optimal.Hot NaOH has the greatest influence on the residual state content of heavy metal Cr;OX solution has the largest conversion rate of the combined state of iron and manganese oxide of Cr;EDTA solution has the greatest influence on the organic state content of Cr.Among the three rinses,the OX solution works best.The three leaching agents mainly affect the content of the combined state of iron and manganese oxide of heavy metal Ni and the state of residue,and have no significant effect on other forms(P> 0.05).The three leaching agents have little difference in Ni removal,the relatively high one is OX solution.The hot NaOH solution has the greatest influence on the content of Cu in the ironmanganese oxide binding state;the OX solution has the greatest influence on the content of the exchangeable state of Cu;although the EDTA solution has an effect on the content of each form of Cu,it is not significant(P> 0.05).Among the three rinses,EDTA works best.The conversion rate of the hot NaOH solution to the residual state of Zn is the largest;the conversion rate of the OX solution to the exchangeable state of Zn is the largest;the conversion rate of the EDTA solution to the exchangeable state of Zn is the largest.The effect of hot NaOH among the three rinses is better. |
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