Mold, the type that grows on everyday foods like bread, could be used to recycle valuable metals out of rechargeable batteries, according to USF researchers.
Aldo Lobos, a USF graduate student in microbiology, Jeffrey Cunningham, a USF professor in civil and environmental engineering, and Valerie Harwood, a USF professor in integrative biology, are working on research that may provide a more environmentally friendly method for extracting lithium and cobalt out of old batteries.
Cellphones, laptops, portable recorders and many other devices most students use in their daily lives, use rechargeable batteries.
When these batteries get old and are recycled, the current processes for obtaining two major substances from the cathodes in the batteries – lithium and cobalt – are not necessarily environmentally friendly.
Lobos used hydrochloric acid or nitric acid to extract lithium and cobalt from a cathode to measure the content of both substances inside of the cathodes of mobile phone batteries. He had to contain the fumes from the acid under a fume hood as it worked to extract the materials. The idea is, Cunningham said, to find a way to not have fumes like those released into the atmosphere.
The research is studying three different mold species with the ability to create different acids that can get the lithium and cobalt, both valuable metals, out of the battery in a less harmful way, according to Cunningham.
The acids produced by the molds, Lobos said, come from them feeding off of a carbon source. The acids are those found in normal foods, like citric acid and lactic acid. The acids from the molds dissolve the lithium and cobalt to get them out of the battery.
“The motivation is that pretty much every electronic device now has a rechargeable battery in it,” Cunningham said. “… Lithium ion batteries don’t last forever. So, eventually you’ll end up with a battery that doesn’t charge anymore but, number one, we don’t want that battery to end up in a landfill or an incinerator where it would potentially do environmental harm and, number two, we don’t want to waste the valuable lithium and cobalt that are locked up in that battery.”
The research took about eight months to get going, as Lobos was busy fixing equipment to be used for the research. Then, he said, he could start his work with the mold species. The research has made strides in measurements for acid production, growth of the organisms and metal toxicity have already, according to Lobos. The toxicity is key, Cunningham said, because of potential harm to the mold.
“They could essentially be poisoning themselves by doing their job,” Cunningham said. “So, we need to find out: is that a problem, are lithium and cobalt toxic to the fungal strains and, if so, can the fungi build up a tolerance to those toxic metals.”
Cunningham said literature by others suggests the fungi can build up a tolerance. Lobos’ tests so far, Cunningham said, have shown that lithium tested in the strains so far has not appeared to be toxic. That is one thing still being researched.
Cunningham also wants to look at targeting the production of certain organic acids by the mold species, as some of the acids are more effective than others in extracting the lithium and cobalt. So far, extraction rates have been relatively high, Cunningham said, but they aren’t at 100 percent yet.
The research was funded by the National Science Foundation via a grant. That grant just ran out, but Lobos said the team has been able to stock up on materials to carry on in answering the questions they have now. Cunningham said they will need to secure other sources of funding to carry the research forward after that.
Challenges to the research weren’t just in the form of Lobos needing to repair equipment before it could be used. The mold also needed a lot of time to grow and, due to the aerobic environment the mold requires, there was always potential for contamination. Some other challenges have been orders of mediums to grow the fungi on that, after a month of testing and ordering a new batch of mediums from a different company, Lobos found were faulty.
“So, you know, sometimes even when you do everything right, there are challenges,” Cunningham said.
The research has gotten attention and was among 17 of 9,000 presentations highlighted at a meeting of the American Chemical Society, where Cunningham presented the research. Lobos has also presented the research at a meeting of the American Society for Microbiology.