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Harvesting lithium from brines via high-selectivity nanofiltration integrated with membrane distillation
Journal article   Open access   Peer reviewed

Harvesting lithium from brines via high-selectivity nanofiltration integrated with membrane distillation

Amir Aghaei, Muhammad Amirul Islam, Vahid Rad, Aria Khalili, Afrouz Yousefi, Ahamd Arabi Shamsabadi, Masoud Soroush, Jae-Young Cho, Young-Hye La and Mohtada Sadrzadeh
Chemical engineering journal (Lausanne, Switzerland : 1996), v 528, 172766
15 Jan 2026
DOI: https://doi.org/10.1016/j.cej.2026.172766
Featured in Collection :   UN Sustainable Development Goals @ Drexel
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https://doi.org/10.1016/j.cej.2026.172766View
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Abstract

Li+/Mg2+ separation Lithium recovery from brines Lithium-selective nanofiltration Membrane distillation Star-shaped block copolymers Thin-film composite membranes
Effective separation of Li+ from Mg2+ in salt-lake brines is critical to meeting the growing demand for lithium. Nanofiltration (NF) membranes are particularly attractive due to their high separation efficiency and low energy consumption, but pristine polyamide NF membranes exhibit intrinsically low Li+/Mg2+ selectivity. To overcome this limitation, we modified the membrane surface with star-shaped block copolymers (SPs) comprising a hydrophobic polystyrene (PS) core and multiple positively charged hydrophilic poly(N, N-dimethylaminoethyl methacrylate) (PDMAEMA) arms. The SPs self-assembled onto the polyamide surface via combined hydrophobic and ionic interactions, resembling brisingid starfish anchoring to rocks. The compact architecture and high charge density of the SPs substantially increased the membrane's positive surface charge, thereby enhancing Li+/Mg2+ selectivity through the Donnan exclusion principle. The SP-modified membrane (M200) demonstrated a remarkable Li+/Mg2+ selectivity of 95.4, with 97.2% Mg2+ rejection, −167.0% Li+ rejection, and a water flux of 35.5 Lm−2 h−1 at 70 psi, representing a substantial improvement over the unmodified thin-film composite (TFC) membrane (selectivity 14.3). To further enhance lithium recovery, a two-stage NF process reduced Mg2+ concentration to 0.33 ppm while enriching Li+ to ~40 ppm. Since this concentration was insufficient for direct precipitation, the Mg-depleted solution was concentrated using a hydrophobic poly(vinylidene fluoride) (PVDF) nanocomposite membrane in a membrane distillation (MD) process to a volume concentration factor (VCF) of 240. This process yielded a Li+ concentration of 10 g/L with >99.8% salt rejection and 99.78% Li+ retention. Finally, precipitation with Na2CO3 at 80 °C yielded Li2CO3, with a recovery efficiency of 94.4% of the theoretical maximum and a purity of 97.85%. By integrating NF with MD and precipitation steps, we demonstrated a practical workflow for lithium harvesting from brines. •Self-assembled star-copolymer boosts nanofiltration Li+/Mg2+ selectivity to 95.4.•Crosslinker-free positive corona preserves flux and ~ 50 nm polyamide thickness.•Two-stage nanofiltration yields 97.2% Mg2+ rejection and − 167% Li+ rejection.•Membrane distillation concentration yields >99.8% salt 99.78% Li+ rejection.•Final precipitation with Na2CO3 yields 94.4% Li2CO3 recovery at 97.85% purity.

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#6 Clean Water and Sanitation

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Collaboration types
Industry collaboration
Domestic collaboration
International collaboration
Web of Science research areas
Engineering, Chemical
Engineering, Environmental
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