(381u) Development of Chitosan-Based Ionic Imprinted Polymer Via Alkaline/Urea Dissolution for Nd3+ Recovery from Mining Wastes

A significant shortage of rare earth elements (REEs) has stimulated exploration into finding alternative REE-containing resources, including extraction of REEs from mining tailings and mine drainage. Chitosan ionic imprinted polymers (IIPs), exhibiting high selectivity for ion species, may be particularly suitable for secondary recovery of REEs from acid mine drainage. However, existing chitosan-based IIPs suffer from pH sensitivity and low mechanical strength, inherent to chitosan gels formed via acidic dissolution. This study aims to use alkali/urea solvent dissolution system to create a more robust chitosan hydrogel imprinted polymer (AUCH) for the selective extraction of Nd³⁺ from aqueous solution and mine tailings. Two types of membrane were formed by employing glutaraldehyde and 1,2,7,8-diepoxyoctane as crosslinkers (AUCH-G & AUCH-DEO), and their performance for Nd³⁺ extraction was evaluated in terms of their adsorption kinetics, adsorption isotherm, selectivity in the presence of interfering ions, and performance in real mine tailing waste. The AUCH-G and AUCH-DEO were stable in pH range 1-10, and had adsorption capacities of 72.74 mg/g and 50.66 mg/g, respectively, at their optimal pH values. The AUCH was characterized by SEM, EDS, zeta potential, FT-IR, Raman Spectroscopy, and TGA. Nd³⁺ recovery was achieved by leaching using 0.5M EDTA. The selectivity was investigated in the presence of interfering ions (Sm³⁺, La³⁺, Eu³⁺) as well as in mine tailing wastewater. Regeneration and reusability studies with 3 cycles revealed consistent adsorption efficiencies of >80%.