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posted by Fnord666 on Monday June 29 2020, @06:32AM   Printer-friendly
from the all-that-filters dept.

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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  • (Score: 2, Interesting) by Anonymous Coward on Monday June 29 2020, @06:56AM (2 children)

    by Anonymous Coward on Monday June 29 2020, @06:56AM (#1013993)

    The gold recovery is of course a click-bait story. But I wonder how usefull it will be to use this to recover metals from polluted soils or just throw sea water over this stuff to collect the gold (and other metals) from that.

    Another things is, looking at the periodic table, the efficiency of recovered metals seems quite random, why is this? Would be interesting to see if things can be tweaked in favour of other/specific elements.

    • (Score: 4, Insightful) by ledow on Monday June 29 2020, @01:06PM (1 child)

      by ledow (5567) on Monday June 29 2020, @01:06PM (#1014048) Homepage

      Quite:

      "The researchers say the polymer costs about $5 per gram to produce, and that gram can capture $64 in gold. And since the polymer can be reused, it would be considerably cheaper than that over time, adding little to the overall cost of a recycling operation."
      "Although other tests showed that 99 percent of gold can be scavenged in about 30 minutes."

      So, if that were true, I guarantee you that those same researchers would be taking that stuff home, or feeding in old e-waste junk into the lab even on a weekend. 99% of the gold in 30 minutes making a 13x profit from feeding in junk, and is reusable? Even with the unspecified extra costs, I'd be literally dumpster-diving to feed that beast.

      Recycling isn't profitable until someone offers you money for your waste rather than charges you to take it away. It's that simple. At that point, you know it's profitable, viable, sustainable.

      Until then, it's all just snakeoil, or requires so much extra (collection, sorting, filtering, acid-baths, heating, etc. etc.) or so many subsidies that it's basically pointless.

      There's a reason you're asked to cherry-pick paper, glass, etc. from your rubbish and give it to someone - that's the only bit that's vaguely recyclable, and even then, that someone is not only paid to do it (by your local government), they are subsidised (by your national government), and you are charged too (in the form of local taxes).

      • (Score: 0) by Anonymous Coward on Monday June 29 2020, @03:22PM

        by Anonymous Coward on Monday June 29 2020, @03:22PM (#1014112)

        "The researchers say the polymer costs about $5 per gram to produce, and that gram can capture $64 in gold. And since the polymer can be reused, it would be considerably cheaper than that over time, adding little to the overall cost of a recycling operation."

        The article conveniently omits all details on the "acid treatment" to dissolve the gold which is the first step of the process and is done before the polymer is used.

        Gold is notoriously unaffected by most acids. It will dissolve in aqua regia: a mixture of concentrated nitric acid and concentrated hydrochloric acid. This is phenominally nasty stuff and will be consumed by the process.

  • (Score: 1, Funny) by Anonymous Coward on Monday June 29 2020, @11:32AM

    by Anonymous Coward on Monday June 29 2020, @11:32AM (#1014017)

    Find people who shit gold and then tap into their sewage pipe.

  • (Score: 0) by Anonymous Coward on Monday June 29 2020, @01:17PM

    by Anonymous Coward on Monday June 29 2020, @01:17PM (#1014051)

    ‘Junkyard Gold Rush’ starring Yeongran Hong and Parker Schobble

  • (Score: 4, Interesting) by hendrikboom on Monday June 29 2020, @05:27PM

    by hendrikboom (1125) Subscriber Badge on Monday June 29 2020, @05:27PM (#1014170) Homepage Journal

    There was a company that replaced old carpets in dentists' offices for free, and was quite profitable.
    It made its money by mining the old carpets for gold. Yes, god dust from fillings ended up sequestered in the carpets.

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