"The idea first came from a student who had experience extracting some metals from waste slag left over from smelting operations," said Jeffrey A. Cunningham, Ph.D. and the project's team leader.
Cunningham's team is developing the environmentally-safe way to do this with organisms found in nature -- fungi in this case -- and putting them in an environment where they can do their work.
"Fungi are a very cheap source of labour," he pointed out in his work to be presented at the 252nd National Meeting & Exposition of the American Chemical Society (ACS).
To drive the process, Cunningham and Valerie Harwood, Ph.D., both at the University of South Florida, are using three strains of fungi -- Aspergillus niger, Penicillium simplicissimum and Penicillium chrysogenum.
The team first dismantles the batteries and pulverises the cathodes. Then, they expose the remaining pulp to the fungus.
"Fungi naturally generate organic acids, and the acids work to leach out the metals," Cunningham explains.
"Through the interaction of the fungus, acid and pulverised cathode, we can extract the valuable cobalt and lithium. We are aiming to recover nearly all of the original material," he added.
According to the results, using oxalic acid and citric acid, two of the organic acids generated by the fungi -- up to 85 per cent of the lithium and up to 48 per cent of the cobalt -- from the cathodes of spent batteries were extracted.
ACS, the world's largest scientific society, is holding the meeting here from August 21 to 23. It features more than 9,000 presentations on a wide range of science topics.
