Boosting Nanofiltration Membrane Selectivity via Amine-Polymer Additive Engineering for Efficient Lithium Extraction...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Direct lithium extraction (DLE) using nanofiltration (NF) membranes is a sustainable alternative to evaporation.
• Conventional polyamide (PA) NF membranes exhibit poor lithium/magnesium selectivity due to surface charge and permeance-selectivity trade-offs.

Purpose of the Study:

• To develop a scalable method for enhancing lithium separation performance in NF membranes.
• To improve Li+/Mg2+ selectivity for efficient lithium enrichment from brine.

Main Methods:

• Incorporation of poly(allylamine) (PAA) into polyamide (PA) membranes during interfacial polymerization.
• Characterization of membrane properties including water permeance and ion rejection.
• Testing the optimized membrane in a two-stage NF process with simulated brine.

Main Results:

• The optimized PA membrane, synthesized with PAA additive, showed a water permeance of 12.1 L m−2 h−1 bar−1.
• Magnesium chloride (MgCl2) rejection significantly increased from 18.8% to 94.7%.
• A two-stage NF process using the optimized membrane successfully purified lithium from simulated brine.

Conclusions:

• The PAA-modified PA membrane offers enhanced Li+/Mg2+ selectivity and high water permeance.
• This strategy presents a promising approach for efficient lithium enrichment and purification in DLE applications.
• The developed membranes show potential for industrial application in sustainable lithium recovery from brines.