A team of researchers is turning to fungi to develop an environmentally friendly recycling process to extract the precious metals cobalt and lithium from tons of discarded batteries.
![[Aldo Lobos Three strains of fungi capable of recycling cobalt and lithium from rechargeable battery waste. [Courtesy: Aldo Lobos]](https://www.hayadan.org.il/images/content3/2016/09/NM252fungi1-500x464.jpg)
Rechargeable batteries that power smartphones, cars and tablets don't last forever. Spent batteries end up in landfills or incinerators, a fact that harms the environment, and in addition, they still contain valuable materials. Now, a team of researchers is turning to fungi to develop an environmentally friendly recycling process to extract the precious metals cobalt and lithium from tons of discarded batteries.
"The idea for our development came from a student who managed to extract a number of metals from alloy waste left after smelting processes," says the lead researcher. "We saw the significant increase in the amount of smartphones and all other products that run on rechargeable batteries, so we shifted our focus in that direction. "The demand for lithium metal is increasing rapidly, and it does not make sense to continue mining it from new lithium sources," explains the researcher. Although this is a worldwide problem, the US is a leader in the production of waste electronic components and it is not known what the recycling rate of this type of waste is. It is likely that most of the waste ends up in landfills, where it slowly decomposes and seeps into the soil, or is transported to incinerators, where it is burned and creates toxic exhaust gases that reach the air.
Although there are other methods for separating lithium, cobalt and other metals, they require the use of high temperatures and harsh chemicals. The research team is developing a safe method for such separation using organisms that exist in nature - fungi, in this case - and transferring them to an environment where they can do their work. "Mushrooms are a very cheap workforce," explains the lead researcher. The researchers, from the University of South Florida, chose three strains of fungi that have been shown to be effective in extracting metals from other types of waste products. "We believed that the mechanism should be similar, and if we find that it is indeed the case - these mushrooms could enable the extraction of lithium and cobalt from batteries that were thrown into the trash." In the first step, the researchers disassembled the batteries and disintegrated the cathodes. Next, they exposed the resulting mixture to the mushrooms. "The fungi naturally produce organic acids, and these are able to eat the metals," explains the lead researcher. "Using this method, we can extract the important metals cobalt and lithium from battery waste. We are trying to reach a situation where we can recycle the full amount of metals that were in the battery."
The results obtained so far show that using oxalic acid and citric acid, two of the organic acids produced by the fungi naturally, enables the recycling of up to 85% of the lithium and up to 48% of the cobalt. Gluconic acid, on the other hand, has been shown to be ineffective in extracting these metals. At this point, the metals lithium and cobalt remain in the medium of the liquid acid, and the researchers are now focused on developing a method to extract the two metals from this mixture. "We have several ideas on how to do this, but we are already responsible for a tremendous progress - finding the way to extract metals with the help of mushrooms."
