Reduction in adsorbent granule dimensionality to strengthen lithium adsorption in low-grade salt lakes

Abstract

Sluggish internal mass transfer within granulated adsorbents constrains the efficiency of Li⁺ extraction from low-grade salt lakes. In this study, Li⁺ diffusion behavior simulations using finite element analysis indicated that reducing the granule dimensionality enhanced Li⁺ transfer in aluminum-based lithium adsorbents, with ionic strength as the driving force. Hence, low-dimensional aluminum-based adsorbent granules (LD-LDHs) with fast transport channels and highly accessible adsorption sites were directionally prepared via a wet-spinning method. Adsorption kinetics suggested LD-LDHs with reduced internal diffusion resistance achieved equilibrium in less than 30 min, which was significantly shorter than the 36 h required for larger granules prepared by conventional extrusion molding, while maintaining the performance of the encapsulated active components. During continuous lithium extraction from low-grade Qarhan old brine, LD-LDHs reached adsorption saturation in 60 min, with a 1.8-fold increased working capacity, and the desorption solution was of higher quality, favorable for subsequent lithium carbonate production processes.