5 ms·

Vaporizing plastics recycles them into nothing but gas

56 points by bell-cot 2y ago

bell-cot 2y ago
A much better title: Newly discover recycling chemistry might solve the intractable problems of polypropylene and polyethylene
- thecosmicfrog 2y ago
  Thanks OP. I appreciate that Hacker News has rules on post titles so it's nice to see you self-correct in the comments!
  - PaulHoule 2y ago
    Notably the easiest way to not run afoul of those rules is to not modify the title even if the original title is bad. You do have to squash titles down to the 80 char limit and the same way to do that is delete words, preferable noise words like “very” or “novel” and past that more complex transformations where you maybe change a passive construction into a shorter active construction.
    - bell-cot 2y ago
      Yeah. Ars didn't have a good subtitle, so I futzed around for a minute trying to give a good 80-char summary. Then gave up.
- anticorporate 2y ago
  I agree. Wouldn't vaporizing anything recycle it into a gas, like, by definition? (If only temporarily.)
  - analog31 2y ago
    Yes, but what gas? Maybe the title should have said either "useful" or at least "harmless" gas. The gases that come from basic polymers could be comparable in those ways, to the original petroleum. They could even be reformed into new polymers, or used as fuel. By way of contrast: Vaporizing lead or mercury compounds, not such a good idea.
    - bell-cot 2y ago
      Tangential Safety Note: Metallic (liquid) mercury does evaporate at room temperature, or even far below that, at dangerously high rates. Unless you're eager for brain damage, never have an unseal container of that stuff around. And treat any spill - even "grandma's old thermometer broke" - as a for-real HazMat situation.
    - marcosdumay 2y ago
      Those gases are not "harmless" by any metric. They must be promptly used or they are a much larger problem than the plastics. But the GPs point seems to be that only those two specific kinds of plastic vaporize into those tractable gases. Most of them become all kinds of things, from wild poisons to chemical nightmares that will destroy your equipment.
PaulHoule 2y ago
My take. The current sense of a plastic waste crisis is that a certain fraction of plastic gets chucked outside and will find its way to the ocean where it will be mechanically broken down in harmful ‘microplastic’ and ‘nanoplastic’ particles. No form of recycling will work if people don’t use the bin. If, in the other hand, people throw the plastic in the trash bin it will be buried and spend a long time (100-10,000 years?) underground and will at least somewhat decompose. Any environmental threat is kicked far into the future. The trouble with chemical recycling is that it produces the kind of chemicals that come out of an oil refinery/petrochemical complex (which are used to make plastics) and those are all worth about 50 cents a pound.
- dflock 2y ago
  Burying plastics results in leaching phthalates, estrogen mimics and assorted other crap into the ground, and groundwater, in the near term, not the far future.
  - actionfromafar 2y ago
    Using less of it and standardazing on what kinds of plastic can be used + burn the waste seems the only reasonable solution to me.
  - Mistletoe 2y ago
    Not saying it is perfect, but modern landfills are sealed on the bottom. > Modern landfills are completely sealed to reduce contamination of the nearby groundwater. First, the ground is lined with clay. A thin layer of flexible plastic is placed on top of the clay layer. That allows the collection of leachate, the liquid that passes through the landfill and may draw out toxins from the trash. The leachate is collected though a drainage system that passes this contaminated water through pipes to a pool where it can be treated to remove the toxins before being released back into the environment. https://education.nationalgeographic.org/resource/landfills/# https://education.nationalgeographic.org/resource/landfills/...
  - testfoobar 2y ago
    How much of the decline in testosterone among young men may be attributed to the plastics? https://www.urologytimes.com/view/testosterone-levels-show-steady-decrease-among-young-us-men https://www.urologytimes.com/view/testosterone-levels-show-s...
deleted 2y ago
[deleted]
underdeserver 2y ago
Sounds promising, and plastic waste is a huge problem. But the article doesn't address the biggest issues: 1) Do you need to separate types of plastics or clean them before using this process? 2) What are the challenges to scaling this? (They mentioned that this is an issue but didn't answer the question)
- Sindisil 2y ago
  > 1) Do you need to separate types of plastics or clean them before using this process? The whole second section of the article discusses this process on mixed plastics, including: > Another test involved introducing different plastics, such as PET and PVC, to polypropylene and polyethylene to see if that would make a difference. These did lower the yield significantly. If this approach is going to be successful, then all but the slightest traces of contaminants will have to be removed from polypropylene and polyethylene products before they are recycled.
  - underdeserver 2y ago
    I guess it does hint that litter, food waste etc. are also problematic. Could be clearer though.
create-username 2y ago
plastic waste is usually vaporised in the recycling plants by setting the whole plant on fire https://time.com/6271576/recycling-plant-fire-indiana/ https://time.com/6271576/recycling-plant-fire-indiana/
orbisvicis 2y ago
Are propylene and isobutylene really in such high demand that this process is worthwhile, as opposed to chucking all plastics (without sorting) into a plasma gasifier, which for plastics generates just syngas? Out of curiosity, how often are new plastics invented, and how often are those plastics difficult to recycle? For example I'm finding that modern computer cables are sheathed in a much more durable (less brittle) form of plastic than those from 10+ years ago. Or is that just the addition of pthalates? Edit: plasma gasification does still produce tar, as per [1], but much less than standard gasification. There isn't much review on the effects of applying plasma gasification to plastics. 1. https://www.sciencedirect.com/science/article/abs/pii/S0956053X13004522 https://www.sciencedirect.com/science/article/abs/pii/S09560...
- bee_rider 2y ago
  Is there any downside to using a plasma gasifier? I still see a lot of plastics around, so I guess(?) additional solutions are needed.
- btbuildem 2y ago
  I think you could add energy costs to that equation to better answer your question
idunnoman1222 2y ago
If this approach is going to be successful, then all but the slightest traces of contaminants will have to be removed from polypropylene and polyethylene products before they are recycled. - well they tried
lsllc 2y ago
You may have seen on YouTube, various videos that come out of I think Pakistan of various "human powered" factories -- in many of them, they are recycling plastics into new products (I won't get into any of the safety [total lack of] or child labor exploitation aspects of this ...). In one particular video they were shredding all kinds of waste plastic (again, not even a dust mask) and melting it to extrude into thin strings that were then cooled and chopped up yielding bags of source material for new products. They were then taking these pellets and making "PVC water pipes" using a home-made looking propane powered extrusion machine. God only knows what kinds of plastic they were using but the pipes looked exactly like the ones you'd find at a Home Depot or similar store. Kudos to the ingenuity of the workers, but wow, I worry about the health implications not just for the workers inhaling the particles and fumes, but the end-users who are now drinking water through pipes made from who knows what plastics.

56 points by bell-cot 2y ago

A much better title: Newly discover recycling chemistry might solve the intractable problems of polypropylene and polyethylene

thecosmicfrog 2y ago
Thanks OP. I appreciate that Hacker News has rules on post titles so it's nice to see you self-correct in the comments!
- PaulHoule 2y ago
  Notably the easiest way to not run afoul of those rules is to not modify the title even if the original title is bad. You do have to squash titles down to the 80 char limit and the same way to do that is delete words, preferable noise words like “very” or “novel” and past that more complex transformations where you maybe change a passive construction into a shorter active construction.
  - bell-cot 2y ago
    Yeah. Ars didn't have a good subtitle, so I futzed around for a minute trying to give a good 80-char summary. Then gave up.
anticorporate 2y ago
I agree. Wouldn't vaporizing anything recycle it into a gas, like, by definition? (If only temporarily.)
- analog31 2y ago
  Yes, but what gas? Maybe the title should have said either "useful" or at least "harmless" gas. The gases that come from basic polymers could be comparable in those ways, to the original petroleum. They could even be reformed into new polymers, or used as fuel. By way of contrast: Vaporizing lead or mercury compounds, not such a good idea.
  - bell-cot 2y ago
    Tangential Safety Note: Metallic (liquid) mercury does evaporate at room temperature, or even far below that, at dangerously high rates. Unless you're eager for brain damage, never have an unseal container of that stuff around. And treat any spill - even "grandma's old thermometer broke" - as a for-real HazMat situation.
  - marcosdumay 2y ago
    Those gases are not "harmless" by any metric. They must be promptly used or they are a much larger problem than the plastics. But the GPs point seems to be that only those two specific kinds of plastic vaporize into those tractable gases. Most of them become all kinds of things, from wild poisons to chemical nightmares that will destroy your equipment.

PaulHoule 2y ago

My take. The current sense of a plastic waste crisis is that a certain fraction of plastic gets chucked outside and will find its way to the ocean where it will be mechanically broken down in harmful ‘microplastic’ and ‘nanoplastic’ particles. No form of recycling will work if people don’t use the bin. If, in the other hand, people throw the plastic in the trash bin it will be buried and spend a long time (100-10,000 years?) underground and will at least somewhat decompose. Any environmental threat is kicked far into the future. The trouble with chemical recycling is that it produces the kind of chemicals that come out of an oil refinery/petrochemical complex (which are used to make plastics) and those are all worth about 50 cents a pound.

dflock 2y ago
Burying plastics results in leaching phthalates, estrogen mimics and assorted other crap into the ground, and groundwater, in the near term, not the far future.
- actionfromafar 2y ago
  Using less of it and standardazing on what kinds of plastic can be used + burn the waste seems the only reasonable solution to me.
- Mistletoe 2y ago
  Not saying it is perfect, but modern landfills are sealed on the bottom. > Modern landfills are completely sealed to reduce contamination of the nearby groundwater. First, the ground is lined with clay. A thin layer of flexible plastic is placed on top of the clay layer. That allows the collection of leachate, the liquid that passes through the landfill and may draw out toxins from the trash. The leachate is collected though a drainage system that passes this contaminated water through pipes to a pool where it can be treated to remove the toxins before being released back into the environment. https://education.nationalgeographic.org/resource/landfills/# https://education.nationalgeographic.org/resource/landfills/...
- testfoobar 2y ago
  How much of the decline in testosterone among young men may be attributed to the plastics? https://www.urologytimes.com/view/testosterone-levels-show-steady-decrease-among-young-us-men https://www.urologytimes.com/view/testosterone-levels-show-s...

deleted 2y ago

[deleted]

underdeserver 2y ago

Sounds promising, and plastic waste is a huge problem. But the article doesn't address the biggest issues: 1) Do you need to separate types of plastics or clean them before using this process? 2) What are the challenges to scaling this? (They mentioned that this is an issue but didn't answer the question)

Sindisil 2y ago
> 1) Do you need to separate types of plastics or clean them before using this process? The whole second section of the article discusses this process on mixed plastics, including: > Another test involved introducing different plastics, such as PET and PVC, to polypropylene and polyethylene to see if that would make a difference. These did lower the yield significantly. If this approach is going to be successful, then all but the slightest traces of contaminants will have to be removed from polypropylene and polyethylene products before they are recycled.
- underdeserver 2y ago
  I guess it does hint that litter, food waste etc. are also problematic. Could be clearer though.

create-username 2y ago

plastic waste is usually vaporised in the recycling plants by setting the whole plant on fire https://time.com/6271576/recycling-plant-fire-indiana/ https://time.com/6271576/recycling-plant-fire-indiana/

orbisvicis 2y ago

Are propylene and isobutylene really in such high demand that this process is worthwhile, as opposed to chucking all plastics (without sorting) into a plasma gasifier, which for plastics generates just syngas? Out of curiosity, how often are new plastics invented, and how often are those plastics difficult to recycle? For example I'm finding that modern computer cables are sheathed in a much more durable (less brittle) form of plastic than those from 10+ years ago. Or is that just the addition of pthalates? Edit: plasma gasification does still produce tar, as per [1], but much less than standard gasification. There isn't much review on the effects of applying plasma gasification to plastics. 1. https://www.sciencedirect.com/science/article/abs/pii/S0956053X13004522 https://www.sciencedirect.com/science/article/abs/pii/S09560...

bee_rider 2y ago
Is there any downside to using a plasma gasifier? I still see a lot of plastics around, so I guess(?) additional solutions are needed.
btbuildem 2y ago
I think you could add energy costs to that equation to better answer your question

idunnoman1222 2y ago

If this approach is going to be successful, then all but the slightest traces of contaminants will have to be removed from polypropylene and polyethylene products before they are recycled. - well they tried

lsllc 2y ago

You may have seen on YouTube, various videos that come out of I think Pakistan of various "human powered" factories -- in many of them, they are recycling plastics into new products (I won't get into any of the safety [total lack of] or child labor exploitation aspects of this ...). In one particular video they were shredding all kinds of waste plastic (again, not even a dust mask) and melting it to extrude into thin strings that were then cooled and chopped up yielding bags of source material for new products. They were then taking these pellets and making "PVC water pipes" using a home-made looking propane powered extrusion machine. God only knows what kinds of plastic they were using but the pipes looked exactly like the ones you'd find at a Home Depot or similar store. Kudos to the ingenuity of the workers, but wow, I worry about the health implications not just for the workers inhaling the particles and fumes, but the end-users who are now drinking water through pipes made from who knows what plastics.