Synthesis of lithium ion-imprinted polymers for selective recovery of lithium ions from salt lake brines

With the rapid development of electric vehicles and new energy industries, there has been a significant increase in demand for lithium resources. This study presents a novel approach using a lithium ion-imprinted polymer (Li-IIP) prepared through bulk polymerization, which can effectively adsorb lithium ions from salt lake brines. The Li-IIP was synthesized using Li+ as the template ion, methacrylic acid (MAA) as the functional monomer, and methanol/acetonitrile as the solvent. Crosslinking of the polymerization reaction was achieved with ethylene glycol dimethacrylate (EGDMA), initiated by azobisisobutyronitrile (AIBN). Additionally, benzo-15-crown-5 (B15C5) was introduced as a selective ligand to enhance immobilization of the template ion. Characterization techniques including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), BET nitrogen adsorption analysis, thermogravimetric analysis (TG), and zeta potentiometry were employed to analyze Li-IIP properties. The effects of preparation conditions on Li-IIP synthesis and adsorption conditions on its capacity were investigated. Results showed that after 30 min of adsorption in a 300 mg·L-1 solution at pH = 8.5, the equilibrium adsorption capacities of imprinted material (IIP) and non-imprinted material (NIP) were found to be 30.53 mg·g−1 and 17.81 mg·g−1 respectively, resulting in an imprinting factor of 1.71. Moreover, Li-IIP displayed good selectivity towards Li+ in the presence of Na+, K+, Ca2+, and Mg2+, exhibiting an adsorption capacity retention rate of 89.20 % even after eight adsorption–desorption cycles. Therefore, the synthesized Li-IIP demonstrates good selective adsorption capacity for Li+, and provides a new approach for lithium extraction through adsorption from salt lake brines.