Nano-silica as an important part of soil is an ideal carrier of passivator material. In this paper, nano-silica was modified by silane coupling agent containing mercapto group and iron (II) salt to afford an organic-inorganic hybrid containing –S-Fe-S functional group (coded as RNS-SFe) on the surface of nano-silica. Results demonstrate that the RNS-SFe nanoparticle has network-like spheroidal shape and a primary particle size is about 18.0 nm. The RNS-SFe hybrid as a potential immobilization agent for heavy metal in soil shows excellent performance for the remediation of the contaminated soil. Specifically, with a dosage of 3.0% (mass ratio) in the soil, it can immobilize bioavailable Pb, Cd, and As by 97.1%, 85.0%, and 80.1%, respectively. Namely, the RNS-SFe hybrid can transform the bioavailable Pb, Cd, and As into insoluble mercapto metal compounds (–S-Pb-S- and –S-Cd-S-) and less soluble iron arsenate (Fe₃(AsO₄)₂, FeAsO₄) precipitate on the surface of nano-silica particle, thereby reducing the toxicity and mobility of the toxic contaminant fractions. In the meantime, the immobilized products of the Pb, Cd and As fractions have good resistance against acid leaching. These results are contributive to the application of RNS-SFe for the remediation of multi-heavy metal-contaminated soils in field.

纳米二氧化硅是土壤的重要组成部分，是钝化剂材料的理想载体。本文用含巯基和铁（II）盐的硅烷偶联剂对纳米二氧化硅进行了改性，从而在纳米表面上形成了含-S-Fe-S官能团（编码为RNS-SFe）的有机-无机杂化体。 -二氧化硅。结果表明，RNS-SFe纳米颗粒具有网络状的球形形状，并且初级粒径为约18.0nm。RNS-SFe杂化物作为土壤中重金属的潜在固定剂显示出优异的修复污染土壤的性能。具体地，在土壤中以3.0％（质量比）的剂量，其可以将生物利用的Pb，Cd和As固定化分别为97.1％，85.0％和80.1％。也就是说，RNS-SFe杂种可以转化生物利用的Pb，Cd，₃（AsO ₄）₂，FeAsO ₄）沉淀在纳米二氧化硅颗粒的表面，从而降低了毒性污染物部分的毒性和迁移率。同时，固定化的Pb，Cd和As馏分产物具有良好的抗酸浸性。这些结果有助于RNS-SFe在野外修复重金属污染土壤中的应用。