Highly selective, regenerated ion-sieve microfiltration porous membrane for targeted separation of Li⁺

A novel adsorbent lithium ion-sieve membrane (LISM) toward Li⁺ was successfully prepared by the phase inversion technique using synthesized lithium ion-sieve ultrafine powder as the precursor, poly(vinylidene fluoride) (PVDF) as a binder, N,N-dimethylacetamide (DMAc) as the solvent. The key design for the synthesis of LISM is the formation of lithium ion-sieve dropping with PVDF powder to obtain a highly selective adsorbent. The prepared LISM have been characterized. The X-ray diffraction illustrated that the synthesized lithium ion-sieve were purity phase cubic spinel structure, the scanning electron microscopy shown that the LISM with a poriferous surface morphology and lithium ion-sieve equably dispersed on the surface of the membrane. The membrane flux (9.7 mL cm⁻¹ min⁻¹) suggested that the LISM achieved high hydrophily and stability. The maximum adsorption capacity is 27.8 mg g⁻¹ in a high adsorption rate towards Li⁺ within 60 min. In addition, the LISM has excellent adsorption selectivity, since the separation factor α is 4.76 with respect to Mg²⁺. Overall results revealed that the LISM as a good candidate for Li⁺ separation and concentration from salt lake brine with a relatively high value of Mg²⁺/Li⁺ ratio.