Synthesis and performance of a europium ion–imprinted polymer for highly selective Eu ³⁺ adsorption and recovery

BACKGROUND Selective recovery of Eu 3+ ions from aqueous solutions remains a problem due to the chemical similarity of rare earth ions. In this study, Eu 3+ ion‐imprinted polymer was prepared using a previously synthesized ligand, MAISH, prepared by reducing a Schiff base formed between isatin and 1‐amino‐1H‐pyrrole‐2,5‐dione. The ligand was used to prepare a complex with Eu 3+ , [Eu(MAIS)(NO₃)₂(H₂O)₂], which was copolymerized with styrene and divinylbenzene. RESULTS MS, EA, FTIR, UV–vis, and NMR results confirmed the formation and coordination ability of the ligand. The morphology and surface area of Eu‐IIP and NIP indicated that Eu‐IIP possessed a rougher surface and larger surface area compared to the NIP, as expected. At pH 6, the maximum adsorption capacity of Eu‐IIP was 435 mg g −1 , much higher than that of the NIP (232 mg g −1 ). The isotherm data correlated well with the Langmuir model, and the kinetic data fitted the pseudo‐second‐order model well, indicating chemisorption as the main adsorption mechanism. Eu‐IIP exhibited high selectivity towards Eu 3+ compared to La 3+ , Gd 3+ , Ce 3+ , Cu 2+ , Ni 2+ , and Co 2+ . Moreover, Eu‐IIP retained 87% of its original adsorption efficiency after ten regeneration cycles. CONCLUSION MAISH‐based Eu‐IIP is a selective, efficient, and reusable adsorbent material for the recovery of Eu 3+ ions. Its adsorbent capacity (435 mg g −1 ) is almost double that of the NIP adsorbent material (232 mg g −1 ), which demonstrates the effectiveness of the present imprinting strategy.