Steering interlayer interaction of lithium-aluminum layered double hydroxide beads for stable lithium extraction from sulfate-type brines

Lithium-aluminum layered double hydroxide (LiAl-LDH) is the most successful industrialized adsorbents for lithium extraction from salt lake brines with high Mg 2+ /Li + ratios. Nevertheless, its applications in SO 4 2− -type brines hit an “Achilles heel”, i.e., the poor Li + extraction due to the desorption obstacle arising from spontaneous intercalation of SO 4 2− . Herein, a novel strategy of steering interlayer interaction was developed by embedding portion of PO 4 3− into interlayers of LiAl-LDH beads (BLDH-P). Owing to the lower binding energy ( E b ) and stronger diffusion energy barrier of SO 4 2− within interlayers, BLDH-P featured property of preventing SO 4 2− intercalation, with the unchanged adsorption and desorption capacity in Lop Nor brine (the largest SO 4 2− -type brine in the world) during the long-term recycling. BLDH-P also showed excellent Li + extraction performance, as the results of enlarged interlayer spacing and selective electrostatic repulsion. The static and dynamic Li + uptake reached 5.26 mg/g and 3.96 mg/g, with high separation factors of 39.84, 48.14, and 144.87 for Li + /K + , Li + /Na + , and Li + /Mg 2+ , respectively, superior to those of reported and commercialized LiAl-LDH. This work offers a feasible strategy of using interlayer modulation for long-term Li + extraction by LiAl-LDH from SO 4 2− -type brines, and inspires the development and design of next-generation lithium adsorbents.