Chitosan grafted with crown ether with high selectivity and adsorption on lithium-ion

Currently, Lithium is the lightest metal known in nature, which is widely applied in most walks of life. However, the present storage of lithium resources in the world is far from meeting the consumption market surge demand for lithium resources. Liquid lithium resources such as Salt Lake brine and seawater brine will become the primary source and inevitable choice for lithium extraction in the future due to a large amount of lithium, and its recovery requires a simple and effective process. This study synthesized TEG4MEC, a pseudo-crown ether monomer with a ring unit, to achieve effective Lithium-ion (Li+) recognition through specific interaction with Li+. Then, the TEG4MEC monomer was grafted onto the surface of cross-linked chitosan microspheres (CCS) by surface initiation polymerization. A series of static and dynamic adsorption studies showed that the pH value of the solution had a significant effect on Li+ adsorption. For CCS-TEG4MEC microspheres, the best adsorption effect was observed at pH = 7.0. The maximum adsorption capacity of Li+ on CCS-TEG4MEC microspheres obtained by Langmuir isotherm fitting is 156.16 mg g−1. In addition, CCS-TEG4MEC microspheres also showed effective regeneration performance and highly stable adsorption capacity, which could be reused.