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Cake day: July 15th, 2023

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  • Drawbacks are mostly the economics of it. You have to convince people to put time and energy into turning waste into monomers. If the monomers you get from crude oil are cheaper, you’ve got an uphill battle.

    The catalysts can be complex, but the good ones are really simple. The zinc one in this article is pretty easy to understand. Ours was an organic molecule, but a really abundant and cheap one. (We could easily recover and re-use the catalyst, too, which I also doubt most of the metal salt catalysts are capable of). Part of the project was optimizing that catalyst. We found ones that worked a little better, but were like 10x as expensive. So we just used a little more of the simple one and figured out how to use it over and over.


  • I worked on a similar (but competing) technology to this one for a few years. Depolymerization is absolutely the way forward for most polymer recycling.

    For most uses, manufacturers want plastic that’s colorless and has good physical properties. Melting down clear plastic can work, but it degrades the polymers in hard-to-control ways. And if there’s any pigment in the plastic, forget about it.

    If you break down polymers into their constituent monomers, you’ve turned a polymer process into a chemical process. Polymers are hard to work with. Chemicals are, comparatively, pretty easy. You can do a step or two to extract all the color and impurities, then re-polymerize the cleaned up material and get plastic that’s indistinguishable from brand new.

    If your depoly process is good, it can distinguish between different polymers, so you can recycle mixed waste streams. Ours was even pretty good at distinguishing nylon from PET, which I sorta doubt the zinc process will be. But hey, more competition in this space is gonna be good for the world.



  • becausechemistry@lemm.eetoMicroblog Memes@lemmy.worldOutstanding idea.
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    9 months ago

    clearing the launch tower during a test launch with an experimental rocket that has no payload and no humans aboard is success

    managing to get into the right orbit without aborting using a rocket that’s launched since the 60s and is lit with giant matchsticks is success

    You, an idiot: “these are comparable”


  • I don’t think articles like this help that situation. “Plastic isn’t actually recyclable” is a pretty dangerous mind virus that’s basically already running rampant.

    Pyrolysis isn’t perfect. But it is absolutely better than throwing plastic in a landfill, and can handle otherwise impossible-to-recycle mixed feedstocks.

    The process I worked on recycled PET while leaving the other materials in the mix untouched, ready to go through a different specialized process. That was kind of the whole point of it. Those sorts of technologies are harder in the sense that the tech is more sophisticated, but realistically doesn’t cost more to run once you have it going. The future isn’t all doom and gloom. That’s why I hate these “don’t bother recycling” articles.





  • Plastic that’s got a lot of color (especially black) is very, very hard to recycle. Getting the color out so you can make like-new, colorless plastic makes the economics pretty much impossible.

    Should recycled plastic that isn’t colorless be accepted? Yep. But basically every manufacturer that uses recycled plastic only accepts colorless stuff. Even if they’re going to turn around and dump a bunch of pigment and dye into it! (Or especially if they’re going to do that. They have specific color targets.)

    So, for now, if you buy something that’s made from recycled plastic but isn’t clear and colorless, that plastic is now outside of the recycle-able ecosystem. It’s a bummer.

    But there are ways to get around that coming online. One is to turn the plastic polymers back into monomers (the building block molecules). It’s sometimes easier to separate out the pigments and dyes once you have a chemical soup of monomers instead of a block of plastic. Then you take the purified monomers and repolymerize them. Bam, you have recycled plastic that’s nearly indistinguishable from new.

    I worked on a chemical recycling / depolymerization project for a couple of years. That tech is currently being scaled up into a big plant that’ll actually churn out like-new plastic from really crappy input material. Pretty exciting stuff. (As long as the business and engineering guys running the project now don’t ruin it.)


  • becausechemistry@lemm.eetome_irl@lemmy.worldme_irl
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    9 months ago

    Not… really? Like, nobody strung up Washington for being a tyrant. Cromwell ruled England, Wales, Scotland, and Ireland until he died. Castro ruled Cuba until he died. Stalin was one of Lenin’s lieutenants, and ran the Soviet Union until he died.

    The French Revolution (of 1789, the big one) was infamous for this. The original batch of revolutionaries were mostly liberal-ish nobles and lawyers. The second wave (of what the original guys considered to be street trash) sent many of those guys to the guillotine if they didn’t get out of town fast enough. The third wave sent a bunch of second wave guys to the guillotine. Et cetera, until Napoléon grabbed the reins.