Abstract Bio-based materials for selective metal cation capture are increasingly sought after as economic and sustainable alternatives to conventional polymeric/ceramic membranes. Here, spruce wood membranes were carboxylated via anhydride esterification with succinic anhydride (SA) and maleic anhydride (MA). Said membranes were used in cation-exchange filtration processes to capture/recover lithium (Li + ) and ferric (Fe 3+ ) ions from aqueous solutions. Structural and chemical analyses, e.g., FTIR, SEM-EDX, WAXS, TGA and DVS experiments, confirmed formation of Na-carboxylate exchange sites, following anhydride esterification and Na-charging with NaHCO 3 , while preserving the aligned wood microchannel architecture. Gravity-driven filtration experiments demonstrated significant differences as a result of these two modification routes. MA-modified membranes achieved near-quantitative Li + removal (≈99.9%) with excellent regeneration stability over three cycles, whereas SA-modified membranes showed greater variability and partial performance decline. For Fe 3+ , MA-modified membranes exhibited significantly higher, stable removal efficiencies (≈72%) than succinic-modified membranes. Equilibrium ion-exchange experiments showed Langmuir-type monolayer adsorption on chemically homogeneous carboxylate sites, with higher affinity for Fe 3+ (K = 0.017–0.020 L·mmol -1 ) than for Li + (K = 0.0063-0.0078 L·mmol -1 ), reflecting the influence of the cation valence and coordination. Overall, MA modification provides a balanced combination of ion-exchange efficiency, structural robustness, and regeneration compatibility, establishing chemically modified wood membranes as promising, sustainable platforms for metal cation capture and recovery in water treatment applications.
Sánchez‐Ferrer et al. (Mon,) studied this question.