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Researchers have used fruit waste to extract precious metals, opening the door to more sustainable battery production.
The idea that an electric car, for example, is intrinsically greener or more eco-friendly, has its dangers. What are the sources of the electricity it consumes? How are its batteries manufactured? Opting for the development of renewable energies is one part of the equation; the other is that the manufacturing methods of electrical vehicles (EVs) become more sustainable. And batteries are at the heart of this technology. Right now, they make up a third of the cost of an electric car. Finding alternatives to current materials or recycling them would be two of the basic approaches to achieving green credentials. So far, high-temperature treatments have been used to reuse the precious metals in batteries, with the drawback of generating toxic gases. However, a group of scientists at Nanyang Technological University in Singapore is turning to a solution that uses fruit peels to reuse the precious metals in old batteries. In this way, they can leverage organic waste while recycling them. In other words, a way of applying the principles of the circular economy.
In recent years, chemical treatments have begun to be used on old batteries, which are shreded and reduced to a paste known as black mass. The acid bath allows the most valuable materials to be extracted, but it is still not a very eco-friendly solution. The researchers at Nanyang, on the other hand, have used oven-dried and ground orange peel, together with citric acid, to extract compounds such as manganese, lithium, cobalt, or nickel with an efficiency of 90%. This is equivalent to the results obtained with hydrogen peroxide, one of the most commonly used acids in the recycling process.
The researchers point out that one of the keys lies in the cellulose in orange peelings, which is transformed into sugars when subjected to heat during the extraction process. It seems that other antioxidants such as phenolic acids or flavonoids, also present in the waste of oranges, also help to optimize the process. One of the advantages of the new method, besides its low price, is that the resulting residues are non-toxic.
Frequently, this type of technological project works in a laboratory environment but then fails to transition into industrial production. However, developers have already created functional batteries from recycled materials that show a similar charging capacity to the original devices. They are now engaged in process optimization to improve the performance of recycled batteries further and optimize their production on a large scale. Technically, orange peelings are one of the options, but it might be feasible to use other vegetable waste, which they are already studying. Also, they are exploring the possibility of applying this innovative method to batteries of various types, including lithium, iron, and phosphate.
If you want to know more about recycling organic household waste, you can check out this article we published some time ago about house hacks with eggshells. In any case, whether with initiatives on an industrial or domestic scale, it is clear that the circular economy, which advocates zero waste, is destined to play a crucial role in the sustainability of the economy over the coming decades.
Source: Science Daily