Advances in integrated membrane processes for sustainable lithium extraction

The lithium market, driven by major players and varied extraction sources, is projected to see significant demand growth in the coming decades. There is an urgent need for cost-effective, eco-friendly lithium extraction methods from diverse sources to ensure a sustainable supply aligned with the circular economy. Current evaporative lithium extraction processes face major challenges, such as low selectivity and recovery rates, freshwater scarcity, wetland damage, long production cycles, and limited use with only concentrated brine. To help address these challenges, this review assesses the potential of advanced membrane processes for efficient Li recovery from aqueous brines. After introducing the various sources of Li, we assess membrane processes involved in the various steps of Li enrichment and recovery, focusing on recent advances and related challenges. In this context, the review addresses a gap in the existing literature by introducing the innovative concept of integrated membrane systems, to provide synergistic technical and environmental benefits, focusing on achieving selective, cost-effective, and energy-efficient lithium extraction. Latest developments in terms of pre-treatment step to mitigate aggressive scaling phenomena occurring when processing concentrated multi-ions solutions, pressure-driven Nanofiltration (NF) for preliminary separation between mono- and multi-valent ion streams, membrane contactors such as Membrane Distillation (MD) and photothermal variant at concentration stage, (electro-)membrane operations for Li-enrichment such as Donnan Dialysis (DD), Electrodialysis (ED), Capacitive Deionization (CDI), Supported Liquid Membranes (SLM), and Membrane-assisted Crystallization (MCr) and chemical precipitation at solid recovery stage, are critically reviewed and discussed. Finally, the techno-economic evolution required to scale-up integrated membrane systems from pilot-scale projects to large-scale industrial implementation is analyzed by discussing the challenges and identifying critical areas for future research and development.