The growing global demand for lithium, driven by the battery and renewable energy industries, calls for more efficient and environmentally responsible extraction technologies. Conventional methods, based on open-pond evaporation, generate significant ecological impact and exhibit low selectivity [1]. Direct Lithium Extraction (DLE) has emerged as a key alternative, with hybrid membranes functionalized with metal–organic frameworks (MOFs).

In this work, polymeric membranes were modified via in situ synthesis of bimetallic ZIF-type MOFs, incorporating zinc and cobalt metal centers coordinated with 2-methylimidazole. Using a layer-by-layer approach, three variants were prepared with molar Zn:Co ratios of 1:2, 1:1, and 2:1. Morphological and compositional characterization was performed using FTIR, SEM, and XRD, while Li⁺ extraction efficiency was evaluated through electrochemical techniques and ion chromatography under simulated brine conditions.

Successful integration of MOFs onto the membranes was achieved through layer-by-layer coatings [2] , revealing a direct correlation between the Zn:Co ratio and surface morphology. Preliminary analyses indicate that the metallic composition modulates membrane permeability and selectivity toward lithium ions, potentially affecting extraction efficiency. Although quantitative selectivity data against competing ions (Na⁺/Mg²⁺/Ca²⁺/K⁺) are still under investigation, structural differences suggest variable lithium affinity depending on the material’s composition.

These findings pave the way for the rational optimization of hybrid membranes for DLE, with potential to reduce chemical consumption, minimize waste generation, and enhance process sustainability.

Acknowledgments

This work was supported by the Ministry of Science and Higher Education of the Russian Federation under the state assignment of the national project "Science and Universities" No. FSER-2025-0016

References
1.Calvo E.J. New methods of direct lithium extraction: Impact on sustainable exploitation of Puna salt flats // Ciencia Hoy. – 2022. – Vol. 30. – No. 180. – P. 51–59.

2.Kida K. et al. Layer-by-layer aqueous rapid synthesis of ZIF-8 films on a reactive surface // Dalton Transactions. – 2013. – Vol. 42. – No. 31. – P. 11128–11135.