New Polymer Easily Captures Gold Extracted From E-Waste
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New polymer easily captures gold extracted from e-waste:
A new study led by Yeongran Hong of the Korea Advanced Institute of Science and Technology involves a chemical with an impressive affinity for gold. Subject some circuit boards to an acid treatment to release its materials and this stuff will gather up all the dissolved gold. And after it lets go of that gold, it's ready to be used again.
The researchers' gold-scrubber is based on an organic compound called a porphyrin. Linked together in a polymer, it possesses lots and lots of little pores that, energetically, want to host a metal atom. That's the kind of structure chemists look for to help with recycling.
The researchers put their polymer through a number of different tests to work out which metals it worked best on and how much it could capture. It's most effective with a small number of precious metals, most notably gold. In fact, compared to the number of pores in the polymer, they found it was capturing about 10 times as many gold atoms. For other elements like platinum, each pore only hosts one atom (responsible atomic social distancing, shall we say). But gold atoms seemed to make a party at each pore.
That behavior was verified by measurements and explained by some modeling. The researchers found that the polymer would interact with the gold atom-aided by ultraviolet light-and hand it some electrons, which happens to make it possible for more gold atoms to join in a clump. Sure enough, repeating the test with varying amounts of ultraviolet light had an impact, although capture was still quite high even without it.
Journal Reference:
Yeongran Hong, Damien Thirion, Saravanan Subramanian, et al. Precious metal recovery from electronic waste by a porous porphyrin polymer [$], Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.2000606117)
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