Selective adsorption of Ga(III) from aqueous solutions using magnetic chitosan-based ion-imprinted polymers:...

A magnetic chitosan-based ion-imprinted polymer (IIP) with high adsorption capacity, excellent selectivity for Ga(III), easy magnetic separation, and remarkable reusability was synthesized via a simple crosslinking polymerization. The IIP exhibited a Ga(III) adsorption capacity of 434.00 mg/g at pH 4, demonstrating high efficiency for Ga(III) removal from aqueous solutions. The material showed excellent selectivity for Ga(III) over competing ions such as Zn(II), Ge(IV), and In(III). Kinetic studies revealed that the adsorption follows the pseudo-second-order model, suggesting chemical adsorption as the dominant mechanism. Adsorption data fitted the Langmuir model, indicating monolayer adsorption. Thermodynamic analysis showed endothermic adsorption with an increase in entropy, suggesting a favorable adsorption process. Characterization confirmed a large specific surface area, abundant functional groups, and strong magnetic properties, contributing to high Ga(III) recovery performance. Gaussian and Multiwfn software analyses revealed that chelate coordination between the -OH and -NH₂ groups in CS and Ga(III) ions drives selective adsorption. The IIP demonstrated excellent recyclability, maintaining performance after multiple cycles. This study presents a novel, cost-effective, and environmentally friendly approach for Ga(III) extraction, with significant potential for selective Ga(III) adsorption and efficient recovery.