Selective recovery of lithium ions from acidic medium based on capacitive deionization-enhanced imprinted polymers

With the increasing demand for lithium resources, recovering lithium from solid wastes (such as spent lithium batteries, lithium-rich fly ash) has become a new source of lithium. To meet the requirements for lithium recovery from acid leached solution of fly ash and spent lithium batteries, a novel imprinted capacitive deionization electrode (Li+-ICDI) was synthesized by cross-linking with dibenzo-14-crown-4 (DB14C4) as the trapping agent, multi-walled carbon nanotubes (MWCNT) as keleton, and polypyrrole (PPy) as the conducting agent. The adsorption capacity in the presence of electric field was about 6 times higher than that without electric field, up to 2047.71 μmol/g in acidic environments (pH = 2). In the presence of Na+, K+, Mg2+ and Al3+, the selectivity factor of Li+-ICDI to Li+ was 5.94, 9.16, 42.95 and 73.93, respectively. The experimental data can be well described by the pseudo-second-order model and Langmuir adsorption isotherm model. The adsorption capacity remained at 96.18% after 5 cycles, indicating that the obtained electrode materials had excellent regeneration ability. Through the synergistic effect of electric field-driven rapid ion transport and Li+ selective recognition of crown ether, Li+-ICDI achieved excellent separation of Li+ ions in acidic medium.