Macroporous Lithium Adsorbent Monolith Prepared via High Internal Phase Emulsion Technique

A facile strategy to fabricate macroporous polymeric foam composites with uniformly distributed lithium-ion sieves (LIS) was fabricated toward lithium ion (Li⁺) selective recovery. With LiMn₂O₄ nanoparticles as stabilizers, oil-in-water (o/w) high internal phase emulsions (HIPEs) were prepared, and then a series of porous hydrophilic materials containing LIS (LNP@polyHIPEs) was obtained by the polymerization of water-soluble monomers in the Pickering HIPEs and followed by acid pickling. Lithium-ion adsorption was conducted by flowing lab made seawater through a LIS@polyHIPEs monolith. The LIS@polyHIPE exhibited a high adsorption capacity (∼35.6 mg/g (LiMn₂O₄)) and fast adsorption kinetics (the equilibrium time was ∼3.0 h). The kinetics data and fitting them by a pseudo-first-order model showed that the loading of LIS onto polyHIPE had little influence on the adsorption rate, and the uptake of Li⁺ onto LIS@polyHIPE was an ion exchange or chemical adsorption control process. After the Li⁺ was extracted by washing the foam with a 0.5 mol/L HCl aqueous solution, the LIS@polyHIPE could be reused for recovery of Li⁺ from seawater. Its adsorption capacity and Li⁺ extraction rate were more than 31 mg/g (LiMn₂O₄) and 90% in four cycles, respectively.