Efficient Lithium Extraction from Shale Gas Wastewater Using Sodium Alginate/H_1.33Mn_1.67O₄ Composite Granular Adsorbents

Dual carbon policies have spurred rapid growth in the electric vehicle and energy storage industry, leading to a surge in demand for lithium batteries. To help meet this demand sustainably, the natural polymer sodium alginate (SA) was cross-linked with Ca2+, and the SA/hydrogen manganese oxide (HMO) composite granular adsorbent was successfully prepared by the cross-linking method. The aim is to extract lithium from shale gas wastewater in the Sichuan Basin, China. The produced microporous composite granular adsorbents have an average pore size of 20 nm and excellent hydrophilicity, with a swelling ratio of roughly 15 g/g at a mass concentration of 3.5 wt % alginate and 2 wt % HMO. When deployed with real wastewater, this material achieved a lithium adsorption capacity of 4.3 mg/g. In laboratory-scale fixed-bed filtration experiments, the optimal adsorbent material was saturated after approximately 700 min at an approach velocity (hydraulic load) of 0.47 cm/min and using a total bed volume of 15 cm(3) containing approximately 0.55 g of adsorbent. In the subsequent recovery step of the adsorbed lithium through desorption, a lithium solution with a concentration of 113 mg/L was achieved. The results suggest that this novel composite granular adsorbent has promising adsorption capacity and that optimization of adsorption and desorption cycles and engineering of the separation system deploying this material would allow high-efficiency lithium adsorption.