Selective Lithium Adsorption of Silicon Oxide Coated Lithium Aluminum Layered Double Hydroxide Nanocrystals and Their...

Silicon oxide-coated lithium aluminum layered double hydroxide (Li_x Al₂ -LDH@SiO₂ ) nanocrystals (NCs) are investigated to selectively separate lithium cations in aqueous lithium resources. We directly synthesized Li_x Al₂ -LDH NC arrays by oxidation of aluminum foil substrate under a urea and lithium solution. Various lithium salts, including Cl^- , CO₃ ^2- , NO₃ ^- , and SO₄ ^2- , were applied in aqueous solution to confirm the anion effect on the captured and released lithium quantity of the Li_x Al₂ -LDH NCs. In a 5% solution of sulfate ions mix with lithium chloride, the Li_x Al₂ -LDH NCs separated a larger quantity of lithium than in other anion conditions. To enhance regeneration stability and lithium selectivity, thin layers of SiO₂ were coated onto the Li_x Al₂ -LDH nanostructure arrays for inhibition of nanostructure destruction after desorption of lithium cations in hot water. The Li_x Al₂ -LDH@SiO₂ nanostructures showed enhanced properties for lithium adsorption, including increase of stable regeneration cycles from three to five cycles, and they showed high lithium selectivity in the Mg²⁺ , Na⁺ , and K⁺ cation mixed aqueous resource. Our nanostructured LDH lithium adsorbents would provide a facile and efficient application for cost-efficient and large-scale lithium production.