Thermo-responsive ion imprinted polymer on the surface of magnetic carbon nanospheres for recognizing and capturing low-concentration lithium ion
Chang Liang, Xiaopei Zhang, Weifeng Liu, Xingfu Song, Shu‐Ying Sun, Dongju Fu, Geng Dong, Meiling Wang, Yonghui Bai, Xuguang Liu
Abstract
Ion imprinted polymer (IIP) on the surface of magnetic carbon nanospheres, using N-propylacrylamide and benzo-12-crown 4-ether (B12C4) as bi-functional monomers, is designed and synthesized for the selective recognition and recovery of Li + from aqueous medium. The adsorption behaviors of Li + -IIP including adsorption kinetics, isotherms, selective recognition, and regeneration are investigated in detail by inductively coupled plasma-optical emission spectroscopy. The adsorption capacity of Li + -IIP towards Li + reaches a maximum value of 23.46 mg g −1 at 25 ˚C within 60 min. The Langmuir and pseudo-second-order models manifest the apparent adsorption behavior dominated by single layer chemisorption. The Li + -IIP realized selective adsorption of Li + against Na + , K + , Mg 2+ , Al 3+ , and Fe 3+ in their coexistence solution. It is reused five times without a significant decrease with the assistance of externally applied magnetic field for solid/liquid separation. The recognition mechanism of Li + -IIP towards Li + is the combined action of dehydration effect, electrostatic attraction, and size and imprinting effect, as identified by theoretical simulated calculation based on density functional theory and experimental data. The temperature-responsive adsorption of Li + -IIP towards Li + facilitates the adsorption/desorption operations. Li + -IIP shows good separation from the treated solution by applying an external magnetic field. This work provides new insights into the recovery of lithium.