Enhanced silicate remediation in cadmium-contaminated alkaline soil: Amorphous structure improves adsorption performance

Abstract

Silicates have been used as soil heavy metal passivators, but low remediation efficiency limited their development. In order to solve this problem, in this paper, an economical and environmentally friendly amorphous iron silicate was prepared by a simple co-precipitation method. It could be proved from the passivation experiments that the remediation efficiency of amorphous iron silicate (AIS) on Cd-contaminated soil was better than that of natural silicates (montmorillonite and diatomite), which reflected the superiority of amorphous materials. Plant experiments showed that AIS could effectively inhibit the absorption and accumulation of Cd²⁺ in the edible parts of garlic. In addition, it may effectively reduce the potential ecological risk assessment of soil, and its immobilization mechanism of Cd²⁺ includes electrostatic adsorption, co-precipitation, ion exchange, and complexation of surface functional groups. This study demonstrates the advantages of amorphous iron silicate as a new functional material in the remediation of Cd-contaminated soil and provides a reference for the development and application of environment-friendly passivators.

Keywords: Amorphous iron silicate; Cadmium; Passivation; Soil pollution remediation.