Progress and prospects of forward osmosis membranes for lithium extraction and recovery: a review

ABSTRACT It first shows the main sources of lithium deposits, and then illustrates a forward osmosis (FO) membrane process for lithium recovery. The rapid expansion of the lithium economy, driven by increasing demand for batteries and renewable energy storage, has established lithium as a critical resource in modern technologies. This growing reliance highlights the urgent need for sustainable separation systems to meet future supply demands. This study presents the advantages of forward osmosis (FO) membranes for lithium extraction, examining key factors influencing their performance and recent advances in membrane design, material development, and operational strategies. The performance of FO membranes is critically evaluated, with emphasis on the mechanisms governing selective Li+ separation from competing ions in complex feed solutions. Various membrane modification approaches, including functional polymers, nanomaterials, and optimized draw solutions, are discussed in relation to their influence on water flux, ion selectivity, and overall separation efficiency. These strategies have demonstrated improvements in FO membrane performance for lithium recovery, although their effectiveness depends strongly on membrane structure, material properties, and operating conditions. Compared with nanofiltration, FO membranes can achieve comparable Li+/Mg2+; selectivity under significantly lower hydraulic pressures, offering notable energy-saving potential. This work also outlines current challenges and proposes future research directions toward achieving efficient, scalable, and environmentally sustainable FO-based lithium recovery systems.