Recovery of salt lake resources to produce magnesium-based metal-organic frameworks

Lithium (Li) stands as a pivotal resource in the 21st century and is mainly stored in the brines of salt lakes. However, the high Mg content and Mg/Li ratio in brines pose a challenge to the recovery of Li resources. This work introduces a reactive separation strategy for Mg/Li separation from brine characterized by a high Mg/Li ratio. By using gallic acid as an organic ligand to react with Mg in solution, a high-valued metal–organic framework of Mg-gallate can be obtained. At the same time, Li remains unaffected in the mixture of Mg/Li reaction residue. Through optimization of reaction parameters, an excellent Mg 2+ removal rate of 98 % and a Li + retention rate nearing 100 % can be achieved. Also, equally excellent separation performances can be achieved in scaled-up reactions and high Mg 2+ concentration brines. Experimental characterization confirms that the obtained Mg-gallate has the same topological structure as that of the simulated one. In addition, the obtained material has outstanding chemical and thermal stability and exhibits a CO 2 adsorption capacity of 81.6 cm 3 /g and CO 2 /CH 4 selectivity of 1807, which is expected to be used for carbon capture and natural gas purification. Therefore, this work not only successfully segregated Li + and Mg 2+ from salt lake brine but also yielded a valuable metal–organic framework, providing an efficient means of resource recovery and utilization.