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

Abstract

Lithium-aluminum layered double hydroxide (LiAl-LDH) is the most successful industrialized adsorbents for lithium extraction from salt lake brines with high Mg2+/Li+ ratios. Nevertheless, its applications in SO42−-type brines hit an “Achilles heel”, i.e., the poor Li+ extraction due to the desorption obstacle arising from spontaneous intercalation of SO42−. Herein, a novel strategy of steering interlayer interaction was developed by embedding portion of PO43− into interlayers of LiAl-LDH beads (BLDH-P). Owing to the lower binding energy (Eb) and stronger diffusion energy barrier of SO42− within interlayers, BLDH-P featured property of preventing SO42− intercalation, with the unchanged adsorption and desorption capacity in Lop Nor brine (the largest SO42−-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+/Mg2+, 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 SO42−-type brines, and inspires the development and design of next-generation lithium adsorbents.