Application of Substrate Materials Derived from Plant Roots, Stems, Leaves, and Microbes for Remediation of Soil Heavy Metal Pollution

This study focuses on the remediation of chromium (Cr), a heavy metal, in soil using substrate materials synthesized from plant roots, stems, leaves, and microbes. Corn was chosen as the source material for biochar production through high-temperature pyrolysis of corn roots, stems, and leaves. The biochar was then modified with an iron solution, and microbial adsorption was employed to remediate heavy metal Cr in the soil. The study involved physical and infrared analyses of the substrate materials and experiments to determine the adsorption contribution of different pH conditions, sites, and substrate materials to metal Cr. The effectiveness of plant roots, stems, leaves, and microbial combinations in remediating soil heavy metal pollution was verified. The experimental results demonstrate a decrease in the Zeta potential values of both materials as the pH increases. Moreover, as pH gradually increases, the form of Cr ions changes, and the reproductive ability of microbes weakens. The substrate materials exhibit a notable increase in negative charge, leading to enhanced repulsion towards Cr, which impacts their adsorption performance. At neutral pH, the adsorption capacity of the substrate materials for Cr is enhanced. The contribution rate of the composite substrate materials in the adsorption process is 6.78%, while that of microbial organisms is 56.45%, significantly higher than that of Fe-CBC. The main reason is that microbial adsorption activity for Cr is enhanced under higher pH conditions, with the contribution rate of microbial organisms continuing to increase significantly at a pH of 9.