Thursday, December 01, 2011

Nanotechnology could make battery recycling economically attractive

Batteries are an integral part of modern life – just go ahead and count the batteries that you use yourself in your watches, computers, cell phones, cameras, alarm clocks, flashlights, toys, remote controls, power tools, cars, boats and so on. You'll come up with a staggering number. And chances are that your batteries are disposable, so you throw them out with your garbage when they are empty. Add to that the batteries used by industry, hospitals, public transport, the military etc and you get several billion batteries that are bought every year, a roughly $50 billion market.
Many batteries still contain heavy metals such as mercury, lead, cadmium, and nickel, which can contaminate the environment and pose a potential threat to human health when batteries are improperly disposed of. Not only do the billions upon billions of batteries in landfills pose an environmental problem, they also are a complete waste of a potential and cheap raw material.
Unfortunately, current recycling methods for many battery types, especially the small consumer type ones, don't make sense from an economical point of view since the recycling costs exceed the recoverable metals value. Therefore, recycling companies only take up spent batteries if someone pays for their service. In Switzerland, for instance, the purchase price of batteries up to a weight of 5 kg contains the cost for the battery's disposal which finances the entire recycling process.
The economic recycling problem is particularly serious in developing countries like India where, so far, economic interests supersede environmental obligations. This situation makes the development of economically interesting battery recycling technologies quite an urgent issue.
"Most of the reported process for the recovery of metals from the spent batteries focuses on production of metal salts/oxides/ferrites," Akash Deep, a scientist in the Biomolecular Electronics and Nanotechnology Division at the Central Scientific Instruments Organization in Chandigarh, India, explains to Nanowerk. "Steps involved in these technologies include ammoniacal or acidic leaching, precipitation, solvent extraction, and thermal treatment. Generally the recycling of lead-acid, lithium ion and rechargeable Ni-Cd batteries is given more importance. But, in reality, the relative consumption of alkaline Zn-MnO2 batteries is much larger."
Deep and his team carried out research to address the recycling of consumer-type batteries. Reporting their findings in a recent issue of Environmental Science & Technology ("Recovery of Pure ZnO Nanoparticles from Spent Zn-MnO2. Alkaline Batteries"), they describe the recovery of pure zinc oxide nanoparticles from spent Zn-Mn dry alkaline batteries.


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