Corn stalk biochar modified with imidazolium-based ionic liquids for the removal of Cd²⁺ from mine water

Mining-induced heavy metal pollution poses an urgent ecological challenge. Recently, biochar, especially corn stover biochar (CSB) modified with ionic liquids (ILs) for weak interactions, has shown promise in mine water remediation. In this study, we used charred corn stover as biochar and synthesized 1-methyl-3-[3-(trimethoxysilyl) propyl] imidazolium IL as modifier to create imidazolium-based IL-modified biochar. The chemical structure of the IL and the chemical composition of the biochar were analyzed with the help of <i>¹H</i> NMR and FT-IR. Characterization techniques such as XPS, SEM, and nitrogen adsorption–desorption measurements were employed to investigate the elemental composition, surface morphology, pore size, porosity, and other physicochemical properties of the corn straw biochar. Cd²⁺ was chosen as the representative of heavy metal ions in mine water, and the adsorption kinetics and isotherm experiments were conducted to study the adsorption performance of CSB on heavy metal ions. The results exhibited that the adsorption performance of IL-modified CSB material (<i>Q_e</i> = 48.1000 mg/g) for heavy metals was enhanced to a certain extent compared with that of unmodified CSB material (<i>Q_e</i> = 44.0000 mg/g). This provided a foundation for using corn straw biochar to remove heavy metals in mine water.