22January2018

Fungi a Fine Fixer of Battery Recycling Issue

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The natural world has done it again, with fungi found to extract cobalt and lithium from waste batteries previously consigned to landfills and incinerators. 

Disposing of batteries is rarely the most environmentally friendly of activities, with the materials they are made from often having a long-lasting, damaging effect on the environment. 

However, maybe the environment itself can provide the solution to this problem, with a team of researchers suggesting fungi can be used to break up the waste in a safe, manageable fashion. 

Old batteries often end up in landfills or incinerators, with high temperatures or “harsh chemicals” used to break them down, leading to dangerous emissions being released into the atmosphere. 

Jeffrey Cunningham, of the University of South Florida, the leader on this project, is developing an environmentally safe way to do this with fungi, creating an environment for the work to flow. 

“Fungi are a very cheap source of labour,” he points out. “The idea first came from a student who had experience extracting some metals from waste slag left over from smelting operations. 

“The demand for lithium is rising rapidly, and it is not sustainable to keep mining new lithium resources.” 

Using three strains of fungi – Aspergillus niger, Penicillium simplicissimum and Penicillium chrysogenum – Cunningham and co think they’ve solved the problem. 

The team first dismantles the batteries and pulverises the cathodes, before exposing fungus to the remains. 

“Fungi naturally generate organic acids, and the acids work to leach out the metals,” said Cunningham. 

“Through the interaction of the fungus, acid and pulverised cathode, we can extract the valuable cobalt and lithium,” he said, though the result is the duo tied together in a liquid that is, as yet, inseparable. 

“We are aiming to recover nearly all of the original material,” said Cunningham, with further strains of fungi under investigation. 

More Information
ACS Fungi recycle rechargeable lithium-ion batteries

Abstract

A Novel Fungal Bioleaching Process for Recovery of Lithium and Cobalt from Spent Lithium-Ion Batteries 
R. Kumar1, J. A. Cunningham2
1Department of Chemical and Biomedical Engineering 
2Department of Civil and Environmental Engineering 
ramkumar1@mail.usf.edu" data-mce-href="mailto:ramkumar1@mail.usf.edu">ramkumar1@mail.usf.edu  

The growing application of rechargeable lithium-ion batteries is increasing the demand for lithium and cobalt, and disposal of these batteries at the end of their lifetime is also posing a big environmental concern. In this poster a novel biological process for separation and recovery of valuable metals such as Li and Co from spent lithium-ion batteries is proposed. Conventional processes used for recovery of valuable metals from solid wastes are pyrometallurgical and hydrometallurgical methods. 

Recycling by pyrometallurgical processes contaminates the environment due to the emission of toxic gases, and hydrometallurgical processes require rather extreme conditions of temperature, pressure, and chemical environment. Bioleaching processes have been gradually replacing hydrometallurgical and pyrometallurgical processes due to their higher efficiency, lower costs, fewer industrial requirements, and lower environmental impact. 

Compared to bacterial bioleaching, fungal bioleaching has the advantages of tolerance to low pH, resistance to release of more toxic metals, and better extraction kinetics. Fungal bioleaching has been applied for the extraction of metals from industrial solid wastes in many cases but it is yet to be applied for recovery of lithium and cobalt from spent Li-ion batteries. 

In this project, the bioleaching process will be carried out using three different adapted fungi(Aspergillus niger, Penicillium simplicissimum and Penicillium chrysogenum) to produce organic acids which include citric, oxalic, malic and gluconic acids during bioleaching. The objective will be the recovery of at least 80% of lithium and cobalt in organic acids excreted by fungi under realistic operating conditions. 

The dependence of key bioleaching performance aspects (production of organic acids, growth of fungal biomass, extent of extraction of target metals, and kinetics of extraction) upon operating conditions (pulp density, pulp composition, temperature, pH, carbon source, and reducing agent) will be investigated. It is anticipated that a 3% pulp density will produce the highest concentration of various organic acids, and as a result, the highest lithium and cobalt recovery will be achieved. 

The metal concentration at various stages of the process will be determined by Atomic Absorption Spectrophotometry (AAS) and organic acids will be analyzed by High Performance Liquid Chromatography (HPLC). It has been estimated that this process would lead to savings of approximately 20-40% overall costs at industrial scale due to lower capital and energy cost. The process will also help to curb the exportation of electronic waste from North America to China, Ghana, and other developing countries for disposal.

Source: Envirocentre - Fungi a Fine Fixer of Battery Recycling Issue

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