Study on the effects and influencing factors of reducing heavy metal Cr(Ⅵ) in soil by sulfides and iron reductants
In order to investigate the effects of different chemical reducing agents on the removal efficiency of heavy metal Cr(Ⅵ) in soil of Xinzhuangzi mining area,Huainan City,China,a orthogonal experiment of soil,re-ducing agent,dosage ratio and pH value was constructed,simulating the soil with different pH values and other fac-tors,the change of chemical reduction,soil remediation removal rate and the stability of soil aqueous solution,and at the same time,the optimal reducing agent input ratio was explored. The results showed that the chromium content in the soil to be repaired was 4.065 and 1.560 times of that in the first and second type construction land. The highest leaching rate of Cr(Ⅵ) was observed when the ratio of aqueous solution was 1∶5(g·mL-1). The combination of reducing agent FeCl2·4H2O and Na2S·9H2O had better reducing effect on Cr(Ⅵ) than other reducing agents. The reaction of reducing agent FeCl2·4H2O with Na2S·9H2O to produce FeS was the reason for its excellent reduction effect. When the molar ratio of reducing agent FeCl2·4H2O to Na2S·9H2O was 1∶1.5,the removal rate of Cr(Ⅵ) reached the best effect. The addition of catalyst hydrogen peroxide solution and manganese dioxide further increased the removal rate of chemical reduction and soil remediation. The pH value of the soil aqueous solution repaired by reducing agents ferrous chloride tetrahydrate and sodium sulfide nine-water was neutral,which avoided the damage to the soil pH. In conclusion,the combination of reducing agent FeCl2·4H2O and Na2S·9H2O has a significant removal effect on the soil heavy metal Cr(Ⅵ);the addition of catalyst increases the removal rate of Cr(Ⅵ);the pH value of soil aqueous solution is neutralized with reducing agent.
万方数据
维普
