Side project: Isopropyl distillation from resin printing rinsing
Side project: Isopropyl distillation from resin printing rinsing
Edit: Deleting this post. It's starting to get controversial, but that's OK. Not what I planned on, but whatevers.
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.
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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.
Sounds like fun! Got to go get a still though.
Please, don’t do this thing.
As a quick addendum, I am finding that with extremely dirty isopropyl the resin will clump up into tiny blobs during heating and boiling. This makes for easier cleanup and it kinda looks cool.
I am wondering if I can leverage this as an intermediate cleaning step between full distillations. While putting containers of contaminated isopropyl in the sun for a few days may have a similar effect, it wouldn't hurt to try and speed that process up.
TLDR for anyone reading: Do not do this!
There is a very well laid out reason by @becausechemistry@lemm.ee in this thread, but suffice to say this is dangerous to an extreme and is not worth the risk to save a little money.
How much $ you saving (or any other motivations)?
Don’t have frames of reference so perhaps what proportion less are you paying by doing this?
Assuming it’s no small sum/% given risks called out by you and a couple others. Glad you got a discussion going so you can give it all more thought!
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Yo, this thread caught my eye, but because it’s deleted, it’s unclear exactly what it’s about. Can someone summarize exactly what I’m to avoid?
Don't distill your own isopropanol in your garage/yard. Simple as that.
That is shocking because many articles on the internet suggest this, and I myself have been distilling IPA for years.
Not trying to challenge or argue, but I’m just surprised and a little embarrassed.
Can anyone comment why this hasn’t been a problem for me? Is this a matter of potency? Or number of cycles of distilling?
Do you take any steps to clean the wash before boiling it? Filtering or anything like that?
I've had some success using aluminum sulfate to precipitate resin out of the wash based on this guy's work: Recycle Isopropyl Alcohol FAST! | Recovering IPA From 3D Printer Resin Wash
I haven't tried distillation... as you say, it's risky.
What does your waste look like after distillation? And... what would you think about using an alcohol still for this, instead of lab glassware?
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Have you tried using typical water filters and letting the alcohol filter through? I suppose it wouldn't remain as pure as distilling, but might be mostly reusable while posing no immediate fire hazard.
I have considered vacuum filtration using celite and powdered carbon, but the materials cost would start to exceed the cost of the IPA. Standard activated charcoal would filter the IPA, but purity is a goal of mine. (Molecular sieves would be a much better option in regards to filtration, I believe.)
TBH, this is within my tolerance for risk and just one of several sub-hobbies that involve potentially dangerous processes. (Nothing illegal, of course.)
What I do is just expose the dirty isopropanol to sun or UV in general - the resin will precipitate. Then just filter it out and you have clean isopropanol.
That shouldn't produce clean isopropyl, but rather, isopropyl with fewer polymers and the only resin you are curing with the sun is what is settling to the bottom, TBH. However, your process is good if you only use a batch of IPA for resin washing and eventually dispose of it.
If you were to spray that isopropyl on some glass, it will leave residue of some kind. The more you use the isopropyl without distillation, the more contaminated it will get with other solvents and photoreactors.
My goal is to produce pure IPA that I can use across my hobbies.
I see, to be honest I have not checked how clean it actually is. It is visually transparent, as opposed to the used one, but you are probably correct.
It may be worthwhile checking this out as an alternative: https://hackaday.com/2022/10/12/toilet-paper-tube-pulls-dissolved-resin-from-ipa-cures-it-for-disposal/
A BIT?!!! oh fuck no
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You deleted your comments but not the post 🤪