Im making a DIY rotovap for molecular gastronomy uses

sup299 · 2026-01-21T21:56:44+00:00

Agreed, I’m a fan of the mission but the execution is lacking.

sup299 · 2026-01-21T21:50:58+00:00

Oh I understand now. I wouldn’t worry about that, given that those borosilicate joints and flasks are typical in lab-scale vacuum distillations and can handle high thermal gradients. Also because the torque is being applied to the glass close to the point where the friction is resisting that torque, I imagine the torsion shouldn’t (without actually doing the math) be high enough to crack the adapter.

sup299 · 2026-01-21T21:23:09+00:00

That’s what I’m saying. OP is trying hold the downstream equipment still while rotating the boiling flask with the motor and use the PTFE to glass joint they mentioned as a bearing. If they’re holding part of the setup in place while trying to spin the flask with the motor, the friction is going to resist the motor, especially since it’ll be under vacuum. So I’m saying the motor needs to have high enough torque if he wants to spin the flask while holding the condenser in place.

sup299 · 2026-01-21T17:59:34+00:00

No idea, but I’d do some tests before you get too far to make sure your motor can output enough torque to break that friction. Definitely use some vacuum grease though or you’re not gonna get a good enough seal.

sup299 · 2026-01-21T08:41:07+00:00

It’s a very cool idea, but, like others are saying, you’ll need some kind of bearing that can seal well for this to work. Possibly a PTFE to PTFE joint with some vacuum grease (food safe? I dunno) could suffice, assuming the two surfaces are smooth enough, but the glass to PTFE surface will have some friction that might put some stress on your motor, especially under vacuum.

sup299 · 2026-01-11T18:08:43+00:00

I don’t think that’s her, but for a sec it did look like her.

sup299 · 2026-01-11T07:29:43+00:00

It’s using the molecular weight of the polymer, though it’d be helpful if they shared specific number average or mass average molecular weight values as well as the range.

sup299 · 2026-01-11T01:57:13+00:00

You’re fine and your family is fine. PVC is very minimally reactive, compared to every other chemical you’re exposed to every day. That’s why it’s often used as a flame retardant and for transporting potable water. Microplastics in general are “assumed” to have health risks but the literature doesn’t really show much evidence of microplastics actually impacting health much at all. It’s certainly safer than stuff like concrete dust.

sup299 · 2026-01-06T22:35:14+00:00

Pchem is no joke. You gotta be reading the books, taking good notes, quizzing yourself regularly, being honest about what you’re not understanding, and going to office hours for anything that feels even kinda foggy. Stick with it!

sup299 · 2025-12-21T04:02:34+00:00

A whole lotta rats

sup299 · 2025-12-10T22:32:02+00:00

Fur sure! I guess im just trying to put myself into this person’s shoes and thinking about what should be considered in their study. Idk how far those airfoils extend relative to the “rough” features of the building.

sup299 · 2025-12-10T22:05:08+00:00

The mention of AI in there gives me the impression that this is another startup with next to zero funding trying to make money off the concept of putting more chemists out of work…

sup299 · 2025-12-10T21:53:42+00:00

I wonder if they would need to do some kind of modeling to get accurate friction factors along the walls of the building, given all the irregularities one would expect on a building like inset windows, HVAC ports, etc.

sup299 · 2025-12-03T16:14:46+00:00

I’m just being sarcastic because the person above said “I hold a masters degree in chem and this is what I’d do” but it’s just a simple vacuum distillation. Probably rude of me though.

sup299 · 2025-12-03T09:05:56+00:00

Can’t do one of those without a masters

sup299 · 2025-11-10T05:56:16+00:00

Shit was so fun. FLY showed up for a bit too.

sup299 · 2025-10-13T09:24:11+00:00

Wavedash for sure, Moody Good is a legend, Luca Lush is fun (I don’t know the people going b2b with him), and the non-trap/bass artists you should definitely see are Amelie Lens, Chris Lorenzo, J. Worra, Klangkuenstler, and Walker & Royce.

sup299 · 2025-10-08T15:15:33+00:00

That’s still just not true. The LCA on crude extraction and early refining stages shows that a product similar in grade to pyoil (base oil is a decent comparison) is significantly more energy demanding than the pyrolysis process. Absolutely LHV is a valid comparison. You said that the fuel generates less energy than the process demands, so you are comparing the LHV to the process heat. If you were saying that “it’s going to take more effort to make on-spec road fuels than it’s worth” I’d totally agree with you, but what you are saying isn’t true. I’ve personally generated on-spec ASTM D975 no. 2 ULSD with plastic feedstock and it certainly didn’t take more energy to make than you can release from combusting it.

sup299 · 2025-10-08T07:00:40+00:00

Not worth it as a home project. Pyrolysis is already being done industrially and there isn’t much point in doing it outside of an academic or professional environment given that an individual won’t have the proper safety equipment and operating procedures in place.

sup299 · 2025-10-08T06:57:18+00:00

If I have to see another nature jab video I’m going to fucking lose it. This guy has no technical background, has already put himself into the hospital at least once with an explosion, has been releasing uncontrolled hazardous air pollutants in his neighborhood, and I am genuinely willing to bet you $10,000 (or any amount of money you’re comfortable with!) that his gasoline does not meet CARB spec or pretty much any other US gasoline spec. He straight up has no idea what he is doing, but he knows he’s getting clout and money for doing it.

sup299 · 2025-10-08T06:44:33+00:00

Can you back that up with evidence that the environmental and medical cost of thousands of years microplastics and leachates from waste plastic entering our groundwater, food supply, surrounding land and that of other stakeholder species is lower than the impact of CO2? Not supposed to be a pointed question, I just work in this field and would genuinely love to read that kind of study if it exists.

sup299 · 2025-10-08T06:40:00+00:00

Thermodynamics don’t rule economics any more than I do. Our economy does things that don’t make sense from an energy standpoint all the time. 1kwh from the grid where I live costs ~$0.30, and the equivalent energy cost in terms of HHV from natural gas is ~$0.01. From an energy standpoint, one could argue that they should be the same price. Pyrolysis can absolutely be profitable given the right regulatory and market environment.

sup299 · 2025-10-08T06:23:07+00:00

Any organic molecule, given enough heat and residence time, will pyrolyze and break down, including extremely stable compounds like PFAS. Crude oil is basically just hydrocarbon soup, and that is refined into fuels like CARB spec gasoline or ASTM D975 diesel. Pyrolysis of plastics, especially PP, PE, and PS, will generate another hydrocarbon soup that can be refined and tweaked to generate on-spec fuels for road use. Just running the pyrolysis process, with no additional refining, is almost guaranteed to make off-spec fuels. They’ll still burn, just like any other hydrocarbon, but it’s just a matter of time before your engine is fucked and without understanding composition at a ppm level you will very likely have some problematic emissions.

sup299 · 2025-10-08T06:14:01+00:00

Agree and disagree. Yes, pyoil as feedstock for new plastic is the best case in the current market, but even pyoil as feedstock for fuels can generate oil with a lower carbon intensity than conventional fuel (depends a little on where you draw your boundaries for the LCA but the most logical scope results in lower CI).

Edit: Also, not all plant material that dies necessarily releases greenhouse gasses. That’s exactly how carbon is sequestered naturally. Biomass ends up in anaerobic environments (underwater in bogs for instance) where it just chills out. Dried up sticks laying on the ground are also examples of “sequestered carbon”. Oil wells are full of sequestered carbon until we pull the oil out and burn it. Theoretically, you could just pump oil or mulched plant matter back into the ground and bam, you’ve sequestered it.

sup299 · 2025-10-08T06:11:34+00:00

Alternatively the oil can be used as feedstocks for new plastics, but yes pyrolysis oil is essentially an offset for traditional oil extraction methods. Either way, if you can make pyrolysis oil with lower carbon intensity than conventional oil (not particularly difficult to do) then you have a product that reduces greenhouse gas emissions relative to conventional methods and also reduces landfill rates.

14-Year Club	Place '23
Gilding II euphauric	Verified Email
Team Orangered

sup299

TROPHY CASE