Thin Film and Interlayer Thin Film Nanocomposite Membranes Based on MOFs for Purification of Lithium from Brine

Metal–organic framework (MOF)–based nanocomposite membranes offer a promising route to overcome the long-standing permeability–selectivity trade-off in nanofiltration for lithium recovery from complex brines. In this work, we systematically investigate the role of nanoparticle chemistry, interlayer architecture, and interfacial polymerization engineering in shaping membrane performance. Three functional nanomaterials─ZIF-8-PSS, UiO-66-NH 2, and UiO-66-SO 3 H─were incorporated into thin-film nanocomposite (TFN) and interlayered thin-film composite (TFCi) membranes fabricated on PAN substrates. Structural and chemical analyses (XRD, FTIR, SEM-EDX) confirmed successful nanoparticle integration and revealed distinct differences in polyamide morphology between TFN and TFCi configurations. ZIF-8-PSS membranes exhibited a high water flux but suffered from severe polyamide defects, resulting in poor ion rejection. In contrast, dual-charged UiO-66-NH 2 /SO 3 H nanoparticles significantly enhanced Mg 2+ /Li + selectivity, particularly in the TFCi configuration, where the interlayer promoted a more uniform and defect-free polyamide film. Unexpected performance shifts were observed when dodecyl phosphate (DDP) was introduced during interfacial polymerization, suggesting complex surfactant–MOF interactions at the oil–water interface. Overall, this study demonstrates that rational nanocomposite design─combining tailored MOF surface chemistry with interlayer-assisted polymerization─can substantially improve lithium recovery from multivalent brines and provides mechanistic insights for next-generation selective nanofiltration membranes.