The remediation of heavy metal contaminated soil is an important subject of environmental treatment,and chemical passivation is one of the effective methods.A composite passivate of sulfhydryl-based functionalized montmorillonite(SH-Mont)was prepared by the solvent dispersion method,and its passivation effect on heavy metal cadmium was investigated by pot experiment in soil.The results of FTIR,XRD,BET and SEM characterization showed that SH-Mont had a rougher surface and more developed pore structure,with the basic layered structure of montmorillonite not changed,the specific surface area increased from 46.58 m2/g to 158.28 m2/g,which could provide many more adsorption sites.Owing to the formation of complexes by electrostatic interaction,ion exchange and coordination between SH-Mont and Cd2+,the morphological transformations of Cd were from the highly active exchangeable and carbonate-bound states to the stable Fe-Mn oxidation-bound,organic-bound and residue states originates,which effectively reduced biological activity of Cd in the soil,thus the risk of Cd migration was attenuated in the soil.Especially,due to the strong combination of species-S-Cd,the Cd content dramatic decline in soil and Brassica rapa L,and exhibit decdecreased trend with increasing amount of passivator added,but the opposite trend for the growth rate of Brassica rapa L.The leaching of cadmium in 2％addition was only 0.72 mg/kg under the condition of acid rain.In conclusion,sulfhydryl-based functionalized montmorillonite showed good passivation properties and stability.
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