Competitive Uptake of Pb ²⁺ /Cr ⁶⁺ by an EDTA‐Grafted Salix Psammophila Wood Membrane: Mechanistic Insights

Abstract The escalating severity of heavy metal pollution in aquatic environments presents a critical environmental challenge. In this study, a novel high‐performance heavy metal ion adsorption membrane—EDTA/CS/CMSM—was developed using Salix psammophila wood (SPP) as the base material, modified through carboxymethylation and amidation reactions. The competitive adsorption capabilities of this membrane for Pb 2+ and Cr 6+ ions were systematically investigated. The structural characteristics and adsorption mechanisms were comprehensively elucidated using various characterization techniques, such as FTIR, TG, SEM, EDS, XRD, and XPS, alongside adsorption kinetics, isotherms, and thermodynamics. The results demonstrate that the adsorption capacities of EDTA/CS/CMSM for Pb 2+ and Cr 6+ ions were 507.02 mg·g −1 and 516.15 mg·g −1 , respectively, values that are 16 times greater than those of the SPP substrate. Furthermore, EDTA/CS/CMSM exhibited remarkable reusability, retaining a desorption efficiency of over 75% for both Pb 2+ and Cr 6+ ions even after five consecutive adsorption‐desorption cycles. Adsorption kinetics, isotherms, and thermodynamic studies revealed that the adsorption behavior of EDTA/CS/CMSM for Pb 2+ and Cr 6+ ions is spontaneous, endothermic, and characterized by multilayer adsorption. Overall, the adsorption process is predominantly governed by electrostatic interactions, reduction reactions, and coordination involving ─COOH, ─NH 2 , and ─OH functional groups. This study seeks to offer a novel approach for the high‐value utilization of SPP and the efficient competitive adsorption of Pb 2+ and Cr 6+ , thereby contributing to the green and sustainable exploitation of biomass resources.