Lithium-rich brine from an evaporation pond in the Atacama Desert, Chile
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The extraction of lithium for batteries, essential for the electric vehicle movement and renewable energy utilization, poses significant environmental risks. Nonetheless, innovative solar-powered techniques for generating fresh water and lithium might improve sustainability.
Currently, most lithium is sourced from subterranean salt lakes in the Andes. The brine undergoes a concentration process through evaporation in outdoor ponds for several months, followed by the extraction of lithium carbonate, which consumes a substantial amount of freshwater. Additionally, when salty water is removed from the reservoir, freshwater from the surrounding rock can trickle down to fill the gap, leading to a decline in the water table, highlighting the negative impact of mining on water availability.
Numerous research initiatives are exploring Direct lithium extraction methods that bypass field evaporation. A notable approach, developed by Yu Tang and her team at Lanzhou University in China, has successfully generated usable freshwater and allowed for recovery back into the underground aquifers.
The team utilizes the unique structure of manganese oxides, which exhibit two crucial characteristics: they can convert a significant amount of sunlight into heat and selectively bond with lithium ions.
In their method, a thin stream of salt or seawater flows over a layer of manganese oxide exposed to sunlight. As the sun heats the material, water evaporates and lithium ions adhere to the oxide. Once these layers are saturated, acidic solutions can extract the ions, enabling the reuse of the material.
This process operates within a sealed environment that captures and condenses evaporated water for collection. The research team has tested small prototypes that successfully completed five cycles of lithium adsorption and release, with the collected water meeting the World Health Organization’s drinking water standards.
According to Ugo Bardi from the University of Florence, Italy, the approach is “very clever.” He suggests it could potentially offer a more sustainable lithium source.
“The paper appears credible,” Bardi notes. “One possible concern could be the material’s stability. How many cycles can it endure under real-world conditions?”
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Source: www.newscientist.com
