New way to extract lithium from seawater

Why in news?

Recently, scientists at the Bhabha Atomic Research Centre (BARC) have developed a chemical technique that can extract nearly 90% of the lithium dissolved in natural seawater.  

• Largest reservoir – Seawater is the world’s largest reservoir of lithium, containing an estimated 230 billion tonnes of the metal.
• Extracting from seawater is challenging – Lithium occurs at extremely low concentrations—about 0.17 mg per litre—while the ratio of magnesium to lithium exceeds 6,000.
• Processing the enormous volumes of water required also makes material and energy efficiency critical to the process’s viability.
• Need for the new technique
  • Rising demand – The global shift towards electric transport and renewable energy is driving unprecedented demand for lithium (Li).

Lithium-ion batteries remain the dominant energy storage technology due to their high energy density, long cycle life and operational reliability.

• • Import dependence – India relies entirely on imports for raw lithium and battery-grade lithium-ion cells, leaving its EV and energy storage sectors vulnerable to shifts in global markets.
  • Limitations of existing technology – Existing methods can suffer from slow extraction rates, structural degradation, complicated regeneration processes, require expensive chemicals, large volumes of solvents and complex processing.
• New technique’s working
• Removal of impurities – Treating seawater with a specialised chemical process using sodium hydroxide and sodium carbonate, helping to remove unwanted elements such as magnesium and calcium.
• The process removed more than 99% of these interfering elements while retaining most of the lithium in the water.
• Lithium Extraction – By using dibenzoyl methane (an organic compound), dissolved in a solvent known as methyl isobutyl ketone (MIBK), to help extract the lithium.
• Lithium Recovery – By using dilute nitric acid to separate the lithium from the solvent. This transfers the lithium into a separate solution, leaving the organic solvent available for reuse.

• Advantages
• High recovery rate – Achieved around 90% lithium recovery, suggesting that the solvent can be reused.
• Low chemical use – It requires fewer chemicals and additives than many existing methods.
• MIBK serves not only as a solvent but also helps stabilise the chemical complexes formed with lithium, reducing the need for separate additives.
• Requires low solvent consumption – They used about 100 ml of organic solvent for every litre of treated water, making the process more economical.
• Challenges – Before commercial deployment, researchers will need to assess
  • Its long-term performance,
  • Energy requirements,
  • Chemical costs,
  • Environmental effects on marine ecosystems and
  • Feasibility at industrial scale, and the
  • Foam formation due to prolonged mixing.

Reference

Down to Earth | Indian scientists develop new way to extract lithium from seawater