Innovations in Chemistry
An eco-friendly approach to lithium extraction from saltwater promises a more sustainable future for battery production.
Lithium-rich brine in an evaporation pond in the Atacama desert, Chile
Image Credit: John Moore/Getty Images
The demand for lithium due to its critical role in rechargeable batteries, essential for electric vehicles and renewable energy storage, poses significant environmental challenges. However, a new sustainable extraction method harnesses solar energy to not only recover lithium but also generate fresh water, fundamentally transforming the lithium mining industry.
Most lithium is currently sourced from subterranean brine deposits in the Andes, where it is concentrated by evaporation in open ponds over extended periods. This traditional method necessitates large volumes of fresh water and can lead to detrimental effects on local water supplies as fresh water is drawn from nearby aquifers to replenish the drained brine reservoirs.
To counter this, researchers are developing innovative direct lithium extraction methods. A promising technique, pioneered by Yu Tang and colleagues at Lanzhou University in China, proposes a system that generates fresh water, potentially reversing some of the environmental impacts associated with lithium mining.
This method utilizes a specialized manganese oxide that possesses two advantageous properties: it effectively converts sunlight into heat and selectively binds lithium ions. In the designed system, brine or seawater flows over a sun-exposed layer of manganese oxide. As sunlight heats the oxide, water evaporates, allowing lithium ions to attach to the material. Once saturated, an acidic solution is used to release the lithium for further use while the manganese oxide can be reused in the system.
The innovative design of this process means it operates within a sealed system, allowing the evaporated water to condense and be collected. Initial tests of the prototype demonstrated successful lithium adsorption and release cycles, yielding water that complies with World Health Organization drinking standards.
Ugo Bardi, a researcher at the University of Florence in Italy, praised the approach, stating, “It is very clever.” In theory, it could offer a much more sustainable lithium source. However, he also raised concerns regarding the material’s longevity and effectiveness in real-world applications, questioning how many extraction cycles it could endure.
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