A crown-like ether for lithium extraction from brine

With the rapid development of clean energy industry, the demand for lithium resources has significantly risen. It makes brine-based lithium extraction into a focal point of research field. Here, we have addressed the challenge of selectively extracting lithium from high-salinity brine by incorporating 2,2′-(propane-1,3-diylbis(oxy))diphenol (PDD) crown-like ether materials onto layered titanium carbide nanosheet substrates, leveraging charge and size sieving mechanisms. The oxygen atoms in the crown-like ether framework of PDD exhibit optimal electronegativity, facilitating the rapid adsorption of metal cations. Simultaneously, the cavity structure of the crown ether remains intact, enabling the size-selective extraction of lithium ions. Separation experiments and simulation calculations, have validated that the crown ether structures exhibit selective lithium-ion extraction through charge and size sieving effects by using sets such as Li⁺/Na⁺ and Li⁺/Mg²⁺. In simulated Longmucuo salt lake brine with a Mg²⁺/Li⁺ mass ratio of approximately 87, the retention rate of Li⁺ using PDD reached 23.42%, and the separation factors for Li⁺/Na⁺, Li⁺/Mg²⁺, Li⁺/K⁺ were 6.85, 3.20, and 33.69, respectively. Compared to other crown ethers (12C4, 14C4, 15C4), this specific crown-like ether demonstrates superior lithium extraction performance. This innovative approach utilizing PDD crown-like ether for efficient lithium recovery enhances the feasibility of lithium extraction from brine, contributing significantly to the sustainable development of the global lithium supply.