Journal article
Harvesting lithium from brines via high-selectivity nanofiltration integrated with membrane distillation
Chemical engineering journal (Lausanne, Switzerland : 1996), v 528, 172766
15 Jan 2026
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Abstract
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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Details
- Title
- Harvesting lithium from brines via high-selectivity nanofiltration integrated with membrane distillation
- Creators
- Amir Aghaei - University of AlbertaMuhammad Amirul Islam - Quantum and Nanotechnology Research Centre, National Research Council Canada (NRC), 11421 Saskatchewan Drive, Edmonton, Alberta, T6G 2M9, CanadaVahid Rad - Drexel UniversityAria Khalili - University of AlbertaAfrouz Yousefi - University of AlbertaAhamd Arabi Shamsabadi - University of PennsylvaniaMasoud Soroush - Drexel UniversityJae-Young Cho - University of AlbertaYoung-Hye La - IBM Almaden Research Center, 650 Harry Road, San Jose, California, 95120, USAMohtada Sadrzadeh (Corresponding Author) - University of Alberta
- Publication Details
- Chemical engineering journal (Lausanne, Switzerland : 1996), v 528, 172766
- Publisher
- Elsevier
- Number of pages
- 15
- Grant note
- Natural Science and Engineering Research Council of Canada (NSERC)Canada's Oil Sands Innovation Alliance (COSIA)Alberta Innovates
The financial support for this work by the Natural Science and Engineering Research Council of Canada (NSERC), Canada's Oil Sands Innovation Alliance (COSIA), and Alberta Innovates is gratefully acknowledged.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemical and Biological Engineering
- Web of Science ID
- WOS:001664759300004
- Scopus ID
- 2-s2.0-105026655200
- Other Identifier
- 991022155373104721