Efficient Separation of Magnesium from Lithium Brines Using Ionic Liquids

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Magnesium (Mg2+) is a critical impurity in lithium (Li+) extraction from brines.
• Its chemical similarity to lithium complicates separation processes.
• Magnesium is an abundant element that can be selectively removed and recovered.

Purpose of the Study:

• To synthesize and evaluate novel ionic liquids (ILs) for selective Mg2+ extraction.
• To investigate the efficiency of ILs in removing magnesium impurities during lithium recovery.
• To explore the potential of ILs as valuable extractants in industrial brine processing.

Main Methods:

• Synthesis of two ILs: [A336]-[D2EHPA] and [A336]-[Dec], based on Aliquat 336.
• Evaluation of Mg2+ extraction from simulated brines using varying IL concentrations and organic/aqueous (O/A) phase ratios.
• Assessment of magnesium stripping efficiency under different experimental conditions.

Main Results:

• Extraction efficiency was pH-independent but sensitive to IL concentration and O/A phase ratio.
• [A336]-[D2EHPA] achieved 75.3% Mg2+ extraction at 0.5 M, while [A336]-[Dec] reached 62.1%.
• Maximum extraction efficiencies of 84.1% and 77.5% were observed with increased O/A ratios, respectively, with 100% stripping achieved for both ILs.

Conclusions:

• The synthesized ILs demonstrate significant potential for selective magnesium removal from brines.
• These ILs offer an efficient method for managing magnesium impurities in industrial lithium extraction.
• The findings highlight the viability of ILs for valuable element recovery in brine processing.