硫化亚铁对As(Ⅲ)的吸附机理及其对As污染土壤的修复

Adsorption mechanism of ferrous sulfide on As(Ⅲ)and its remediation of As contaminated soil

本文研究了低成本、高活性的磁性硫化亚铁(FeS)对水体中As(Ⅲ)的吸附机理,并将其应用于As污染土壤进行磁分离修复试验。首先开展硫化亚铁在模拟液中对As(Ⅲ)的吸附试验,结合硫化亚铁吸附As(Ⅲ)前后的SEM-EDS、XRD谱、XPS分析以及Raman光谱分析,研究硫化亚铁对As(Ⅲ)的去除机理,随后在实验室和半工业规模上将其应用于As污染土壤的修复。结果表明:在模拟液的pH值为3~9时,硫化亚铁对As(Ⅲ)的拟合最大饱和吸附量可达100 mg/g;硫化亚铁对As(Ⅲ)的去除机理包括H_(3)AsO_(3)/H_(2)AsO_(3)^(-)与FeS的反应、无定形态FeOOH对As的化学吸附,以及FeS_(2)中S与As的取代。在液固比为3、硫化亚铁添加量为2%、土壤pH值为3~6的条件下,修复后土壤中As的去除率最高可达41.3%。磁性硫化亚铁有效吸附As后,通过磁分离可实现对土壤中As的有效去除。

This paper studied the low-cost,highly active material of magnetic ferric sulfide(FeS)in As(Ⅲ)adsorption and its mechanism,and applied it to the As contaminated soil remediation.Firstly,the adsorption experiments of ferrous sulfide for As(Ⅲ)in simulated solution were carried out,then the removal mechanism of ferrous sulfide for As(Ⅲ)was studied through adsorption experiments of ferrous sulfide on As(Ⅲ)in simulated solution,combined with SEM-EDS,XRD,XPS and Raman spectrum analysis of ferrous sulfide before and after As(Ⅲ)adsorption.Subsequently,FeS was applied to the remediation of As-contaminated soil in laboratory and semi-industry scales,respectively.The results show that the saturation adsorption capacity of ferrous sulfide for As(Ⅲ)can reach 100 mg/g when the pH value of the simulated solution is 3−9.The removal mechanism of As(Ⅲ)by ferrous sulfide includes the reaction of H_(3)AsO_(3)/H_(2)AsO_(3)^(-)with FeS,the chemisorption of As(Ⅲ)/As(Ⅴ)by amorphous FeOOH,and the substitution of S and As on the FeS_(2).Under the conditions of liquid-solid ratio of 3,ferrous sulfide addition of 2%and pH values of 3−6,the removal rate of As in contaminated soil can reach 41.3%.After the effective adsorption of As on magnetic FeS,it can be efficaciously removed from contaminated soil by magnetic separation.