Solar-driven membrane separation for direct lithium extraction from artificial salt-lake brine

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Growing demand for lithium necessitates efficient extraction methods.
• Current nanofiltration for lithium extraction requires freshwater dilution and yields only Li+-enriched solutions.
• Mangrove-inspired biomimicry offers new strategies for selective ion transport.

Purpose of the Study:

• To develop a direct lithium extraction method from salt-lake brines using a combined ion separation membrane and solar evaporator.
• To achieve high Mg2+/Li+ separation efficiency without freshwater dilution.
• To directly obtain lithium chloride powder.

Main Methods:

• Fabrication of a multilayer solar evaporator with photothermal, hydrophilic porous, and ion separation layers.
• Utilizing capillary pressure and selective ion transport for water evaporation and Li+ enrichment.
• Testing the system with artificial salt-lake brine at high salt concentrations.

Main Results:

• The solar evaporator directly extracts lithium from brine, inspired by mangrove salt secretion.
• Achieved a 66-fold reduction in the Mg2+/Li+ ratio (from 19.8 to 0.3) in brine with 348.4 g/L salt.
• Successfully obtained lithium chloride powder.

Conclusions:

• The ion separation membrane-based solar evaporator offers an efficient and sustainable approach for direct lithium extraction.
• This technology overcomes the limitations of traditional nanofiltration by eliminating the need for freshwater dilution.
• The biomimetic design provides a promising solution for addressing lithium supply shortages.