A Scalable Route to Constructing Hydrogel-Encapsulated Lithium-Ion Sieves-Based Photothermal Fabric Adsorbent for Solar-Enhanced Lithium Extraction from Seawater

Lithium extraction from seawater is deemed as the promising solution to coping with the booming demand for lithium. However, the trace lithium concentration and low temperature in seawater limit the adsorption amount of lithium on conventional adsorbents. Here, a novel scalable method is developed for constructing a photothermal fabric adsorbent for lithium extraction by encapsulating graphite powder (GP) and lithium-ion sieves (LISs) with polyvinyl alcohol (PVA), which is then simultaneously coated onto commercial cotton fabric through electron beam (EB) irradiation-induced crosslinking. Benefited from the evaporation-induced ion concentration effects and solar-heated microenvironment, the lithium adsorption kinetics of the adsorbent is accelerated with the assistance of solar illumination, which achieve a 55.0% lithium removal ratio in seawater in just 30 min sun illumination, whereas just 30.0% under dark condition. A 21-day solar-assisted offshore adsorption test confirmed the photothermal fabric adsorbent can sequester 15.71 mgLi g-1, approximate to 25.9% increase in comparison with that without solar illumination. Considering the cost of the adsorbent as low as 2.98 $ kg-1, this research provides a simple and scalable method for the preparation of low-cost photothermal adsorbent for efficient extraction of lithium from seawater on an industrial scale.