Lithium Race – New Method Makes Water-Derived Lithium Possible

Lithium is the mineral that everyone thinks of. Also referred to as the “white oil” of the renewable revolution, the material is a central component of electric vehicle (EV) batteries and energy storage solutions and economies around the world vie to monopolize the growing market. Currently, the largest lithium producers in the world are Australia and the producers of the “Lithium Triangle”; Chile, Bolivia and Argentina. While Australia mainly extracts the ore from the ground using surface mining methods, the latter countries have their abundance of lithium in its salt marshes that comes from solar evaporation – a time-consuming and expensive method. Finding economical and efficient ways to extract lithium from water has so far proven to be a challenge and has limited the amount of material that can be harvested from aqueous sources.

Today, a team of engineers from the University of Texas at Austin and the University of California, Santa Barbara announced the development of a new way to extract lithium from contaminated water using of a new membrane technology. While this solution is still in its infancy, it could prove to be a huge development for the lithium industry by providing a cost effective way to extract the mineral from aqueous brines. We took a closer look at the research and what it could mean for the rare earth industry.

The new technology

The latest research was published last week in Proceedings of the National Academies of Sciences and shows how the team introduced a new class of “polymer membranes” to separate lithium from water, leaving behind other ions such as than sodium (a common contaminant in water). While polymer membranes are already an established way of filtering water, traditional forms lack high levels of ionic selectivity and therefore produce low levels of lithium – something the researchers’ solution seeks to address.

“The extraction of lithium salts from brines is currently based on solar evaporation, which is inherently long and laborious,” the team said in an email. “Brines also contain high concentrations of other contaminating salts (eg, sodium and magnesium salts), which cause inefficient extraction of lithium salts.”

“We incorporated ion-specific chemical sites (ligands) into synthetic membranes to develop a material that permeates lithium salts faster than sodium salts and observed the highest LiCl / NaCl selectivity reported to date in polymer membranes, ”they added. “By combining polymer synthesis, material characterization and computer modeling, we discovered the origins of this remarkable behavior: sodium interacts strongly with these specific chemical sites, slowing it down considerably, while lithium does not interact, leading it to cross the membrane. more freely.

In other words, while in typical membranes sodium crosses faster than lithium, the new model exchanges it to make lithium travel faster because sodium binds to crown ethers and delays their movement. Such a discovery could prove to be important for lithium mining, as it would capture larger amounts of ore in the filtration process.

While synthetic membranes are already a popular method of water purification – especially in seawater desalination – the team says existing models are unable to separate some contaminants.

“Today’s membranes were not designed to treat highly contaminated water and lack sufficient solute-specific selectivity to access these processing possibilities,” they say. “The development of membrane materials to achieve higher specificity using easily treatable chemicals will be crucial in advancing this frontier. “

The future of membrane technology

According to the team, their technology also has the potential to extract lithium from water generated in the production of oil and gas for batteries. Indeed, wastewater from the oil and gas industry often contains high concentrations of lithium, but it has so far remained unexplored. The research team found that a week of water from hydraulic fracturing in the Eagle Ford Shale in Texas could produce enough lithium for 300 EV batteries, if only it were tapped. As such, advancing the technology towards commercialization is the next step for the team.

“As the project evolves, we seek to further improve membrane selectivity for target molecules, such as lithium, by varying the structure / chemistry of polymers and by uncovering the mechanisms underlying the selectivity in such areas. such systems, ”they said in an email. “This will guide the design rules for new synthetic membranes that rival the specificity of biological membranes. Advances to commercialization rely on this and the ability to mass-produce optimal polymer chemistries in the form of thin, flawless membranes.

If scaled up to commercial levels, the technology could certainly open the door to larger supplies and lower costs for lithium. As the world is currently only able to tap a small portion of its lithium supplies, technologies seem to have the potential to join in and expand our offering, and US universities are not the best ones. only to seek ways to rationalize water-based technologies. lithium extraction.

In June this year, researchers at the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia announced that they had developed a way to extract lithium from seawater in a more cost effective than existing methods. The team deployed a “solid state electrolyte membrane” and designed an electrically driven continuous membrane process to enrich the lithium found in seawater samples 43,000 times. While the structure has holes large enough to allow lithium to pass through, other minerals and ions are trapped. Any residual seawater could also be used in desalination plants to provide fresh water.

Solutions such as these are certainly needed as the global demand for battery materials is set to increase as we turn to cleaner storage and transportation alternatives. An article published in 2020 by the New Statesman said global demand for lithium is expected to more than double by 2024, with electric vehicle production increasing from 3.4 million vehicles to 12.7 million in 2024. With demand Increasingly, developing low-cost and efficient methods of operating in currently inaccessible sources would change the face of the industry and bring us closer to a battery-powered future.

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