I sort of feel bad about raining on the parade of the person distilling isopropanol in his garage earlier, but it really is dangerous.

But most of us chemists also need to be reminded of it. To the point that someone had to write a paper whose entire point is “don’t distill isopropanol”.

Please, don’t do this thing.

The issue with isopropanol peroxide formation is that exposing it to air – even when just using it, like when you’re cleaning parts – starts the process. The air in the head space of your containers is also enough to form them over time. You don’t necessarily need to see solids in the containers for it to be dangerous, since they’ll crystallize out as you concentrate the solution during distillation.

It’s also a numbers game. It probably won’t explode the first time you do it. But there’s a chance each time. Do it enough, and you’ll have an incident.

There are chemical reductants that can clear peroxides. For industrial scale isopropanol distillation, I’m not sure what they use. It may be that they just never distill down to the point that peroxides concentrate to a dangerous level.

I love EnF. But I assure you, organic peroxide formers are scarier.

No no no no no.

I’m a chemist. Organic chemistry PhD, now a process chemist in the industry. I do this for a living. Do not distill isopropanol that’s been exposed to air for any meaningful length of time.

Isopropanol slowly reacts with oxygen in the air to generate peroxides that, when you concentrate them down, EXPLODE. Source. Sorry, not an open access journal. But please take my word for it.

Unless you have a way of confirming the peroxide levels in your isopropanol are near zero, do not concentrate it down by distillation. You’ll blow up your glassware, which will probably expose what you’re distilling to your heat source, which will generate a secondary fireball.

PLEASE do not do this.

Admission: I stole it.

qntm’s cool science fiction stories are my favorite.

Worse: your sleeper ship arrives at what should be a pristine planet. But FTL capable ships beat you there. And they ruined the planet over a few thousand years. And now they’re sending out refugee ships of their own.

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.

The small beings are being brought to the slender building of magic!

1. Hack together a proof of concept
2. Works well enough that management slaps a “done” sticker on it
3. Pile of hacks becomes load bearing
4. One or two dependencies change, the whole thing falls over
5. Set evenings and weekends on fire to fix it
6. Management brags about moving fast and breaking things, engineers quit and become cabbage farmers and woodworkers
7. New graduates are hired, GOTO 1

Yeah, that sounds like seizing Russian assets and selling them to the west with more steps.

I’m late to the party but I use a WhamBam build surface on my Ender 3 V2. Absolutely a game changer. Wipe it down with high-percent isopropanol or acetone between prints and it works every time. Sticks like glue when hot and just pops off with zero effort once it cools down.

Not affiliated, just love the thing. https://www.whambamsystems.com/products/235-x-235-kit-with-pre-installed-pex-build-surface

It’s a consequence of the terminally-online brain rot idea that if you do not explicitly state that you are against a bad thing, you must be actually a huge supporter of it. Or that if you do explicitly state that you are against a bad thing, the fact that you didn’t mention a different bad thing means you are a huge supporter of it. Ad nauseam.

A single AA battery is going to discharge itself just sitting on the shelf over a decade

Beats me. I’m just a chemist who managed my facility’s NMR magnets (built like MRIs but with different electronics for chemical analysis) for a few years. We had to pull some stunts to keep those magnets alive sometimes, but it was always a matter of how soon, not if, a shipment of cryogens would arrive. Can’t imagine trying to keep MRIs from quenching in a war zone.

No idea, but if it were up to me I’d spend that rationed power on ventilators and such keeping patients alive. Losing cryogens stinks, but you can top them off without any power as long as you have stock or deliveries. And I’d rather a magnet quench than have to explain to a dead person’s family that their loved one’s life was less valuable than some helium and a chunk of ceramic.

The cryogens boil off at a pretty consistent rate no matter what, but the recovery/recompression systems do require power. So once power is cut, any boil off isn’t recovered.

Superconducting magnets (like in MRIs) can run effectively forever when at the right temperature. Turning them off requires a complex process of draining off that current slowly and carefully so that the magnet isn’t damaged. Hard to do on a normal day, and profoundly harder if there’s no power.

It is infinitely remappable. To anything you can program in with a Shortcut, which is a ton of non-trivial stuff. Which they said explicitly.

So many people in this thread saying “who cares it’s just a button” without having any idea what it actually does.

Want the mute switch behavior? Well that’s the default thing the button does and you can use it without looking at it.

Want to program the button to do like literally anything? You can do that. For example:

• Launch the camera app, or any other app
• Control your smart home accessories
• Toggle Do Not Disturb, or another focus mode
• Run a command on a remote server via ssh
• Start recording audio in case you’re around cops doing cop stuff
• Or anything else you can program in with a Shortcut