Development of Cellulose‐Based Hydrogels: Optimization of Cross‐Linking for Metal Ion Removal

ABSTRACT This study investigated the preparation of cellulose‐based hydrogels cross‐linked with epichlorohydrin (ECH) to optimize the removal of metal ions from contaminated water. A design of experiments (DOEs) was used to evaluate the effects of cellulose and ECH concentrations on the degree of swelling (DS) and the adsorption capacity for metals, including copper (Cu 2 + ), chromium (Cr 6 + ), manganese (Mn 2 + ), and nickel (Ni 2 + ). Response surface analysis revealed that the highest DS value (954.2%) was achieved with a cellulose concentration of 6 g and 100% ECH. Sorption tests indicated that the hydrogels exhibited greater adsorption capacities for Cr 6 + and Ni 2 + , with removal efficiencies of 22.6% and 12.7%, respectively. Fourier‐transform infrared spectroscopy (FTIR), x‐ray diffraction (XRD), and scanning electron microscopy (SEM) analyses confirmed successful cross‐linking between cellulose and ECH, demonstrating the formation of a stable 3D network with excellent water‐absorption capacity and effective contaminant‐removal performance. The results suggest that optimizing the cross‐linking conditions and the cellulose‐to‐ECH ratio is crucial for obtaining hydrogels with high performance in metal ion adsorption.