Extracting rare earths from e-waste.

Our highly technological world would be inconceivable without rare metals such as scandium, yttrium, lanthanum, neodymium, or terbium. Key to the digital age, these so-called rare earths are the basis for future technologies, such as the engines in electric cars or generators in wind turbines.

However, many of these raw materials only occur in small quantities in nature and are difficult and costly to mine. This makes it all the more important to recycle these rare metals and return them to the materials cycle.

One potential source of raw materials is e-waste. So far, however, we are lacking suitable recycling processes that filter the substances out of disused smartphones, for example, or discarded energy-saving lamps.

A team at Helmholtz center Dresden-Rossendorf led by Franziska Lederer, a microbiologist from Freiberg, is currently researching innovative biotechnological processes that can achieve this goal. She has found one approach using bacteriophages, which are viruses specialized in infecting bacteria. With access to a library of these bacteriophages, which have fragments of proteins known as peptides attached to them, she can identify peptides that will bind selectively to given metals. This is because the surface of some peptides is a perfect fit for the surface of certain metals.

The question is: which peptide fits best to which metal? When a match is found, the researcher binds the appropriate peptides – without virus – to magnetic carriers. She aims to use this method to extract the rare earths from complex particle mixtures such as electronic scrap and thus recover them in an environmentally friendly manner.

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