Applied Science - 2012-01-23
In previous videos, I used supercritical CO2 to dry my homemade aerogels. This time, I soaked the aerogel in methanol, then raised the temperature and pressure of the methanol itself to make it supercritical. This allows the gels to be dried without an additional solvent exchange into CO2. The downside is that it requires a chamber full of methanol at 460*F and over 1200 psi, which is a much bigger hazard than using CO2. The aerogels dried with methanol shrank less than the ones dried with CO2, but there was still a lot of cracking, and I have yet to create a high-quality monolith.
Think I could do it with supercritticial water?
What a coincidence 8 hours ago, probably not, since at least finished aerogel dissolves. There is a chemical way to waterproof it (probably after completion), but i don't know when in the process those things will take effect. The purpose of using methanol is to dry it out completely
That would be absolutely awesome but depending on the type of aerogel, I've read water can compromise the gel. The gel is covered in -OH groups that cause the gel to quickly dissolve in water but apparently if you replace the -OH groups with some hydrophobic -OR group then it could potentially work. Not sure though.
Haha, nice touch @ 2:11 It's like "if this thing blows up it will vaporize this whole shop but remember, always wear eye protection". Maybe we see more FPGA stuff in the future. Or stainless steel high vacuum parts turning in your nice lathe. Doesn't matter much because your experiments are always interesting, just keep it safe :)
You're an inspiration
Your experiments (or fiddling around if you will since you aren't actually doing science normally) reminds me of the stories I read about 17th century legends who's work our world is based on today.
if i recall correctly - hi pressure deepfrying is patented by KFC. that makes it very rare outside KFC's shops.... their HP fryers were the only safe design for many years. great videos, i love them. keep it up :-)
Protip, you should actually understand what he's doing before posting criticisms. He isn't using the torch to find leaks, he is using the torch to heat the vessel. A side effect of using the torch is being able to identify leaks right as they happen. The application of soap water in this case would have been the wrong tool.
"I ended up using a torch, if there was a slow leak it would ignite and I would detect it right away if there was a big leak ummm that could be a problem" hahahahaha You are awesome! Keep up the good work!
As for your cracking, try to create a tool to heat the chamber more evenly at a more controlled rate of increase and see if it helps control the cracking. Also try heating to your hold temperature at different rates and see if a specific rate of increase helps. Also try using a silicone mold for your media. The melt point of the silicone should be around (2,577°F) but I think the structure of the silicone would stay intact during the process and is known to be highly resistant to the methanol.
i work with simple chemical pumps and ive noticed the aluminium pump bodies on methanol pumps react and build up with an ashy compound
"A little more dangerous". My, how delightfully understated.
High pressure frying is done on a comercial scale. Every KFC has a couple of pressure fryers in back. They're an off the shelf item. :-)
Another fantastic video. :) If you get chance take a look at the videos from NurdRage. Some interesting stuff there. According to Wikipedia - One of the drawbacks of methanol as a fuel is its corrosivity to some metals, including aluminium. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminium from corrosion: 6 CH3OH + Al2O3 → 2 Al(OCH3)3 + 3 H2O
I love these aerogel videos!
Baking in a pan with fat is a "no go" to divers at great depth, if my memory serves me well, the main reason being the toxicity of the fumes, the chemistry of the increased temperature on the other hand also raised some issues.(caused by the reduced cooling effect of water wich boiles at a higher temperature)
It looked like it was filmed in the early 80's
What about extremely high pressures for frying food with carbon dioxide..no caloric enrichment and no toxicity...from the CO2...
It's a typo, thanks for catching it. It would hydrolyze to aluminium oxide and methanol.
I read about special sugars that, when added to water, raise the boiling temperature of water to a point where you can get the maillard reaction, i.e. you can deep fry food in water with these sugars...
No. That would be awesome, though!
Bravo. Any tips on making the very different but supposedly easier Aeroclay?
All I've been able to tell from reading around is:
Clay + polymer + vacumn and then freeze to dry. Easiest available polymer seemed like gelatine?
Have ingot the process right? What vacuum pressure might I need?
If anybody reading this has any idea at all please comment. This aerogel video is the best inspiration so far to show that it's been possible to do this at home.
I’m sure you guys have figured it out by now but. The powder residue is obviously the remains of your aluminum screen. The combination of heat, pressure and chemical exchange may be the result. While the melt point of the screen should remain around 1200 F in normal atmosphere the pressure and chemical composition of the environment inside the chamber allows it to be more fragile and susceptible to the conditions. Stay safe M
Hmm, good point. Your right, I can't think of any aluminium salts that are black. The aluminium alloy theory is a strong possibility. There are alloys containing lithium, mercury, copper, palladium, cobalt, iron, magnesium and those are just the ones I can immediately think of. On a slightly different thought I also vaguely wondered what the effect of heating the PTFE tape wrapped round the threads to such high temperature would have?
Back in the 1970s? there was an experimental racing car that had chassis tubes made of such thin metal it needed to be pressurised to cope with it's loads without catastrophic buckling.
I'm wondering if an aerogell like substance could be cast inside thin walled foil cylinders, perhaps hold onto some of the pressure from supercritical drying, and produce the same kinds of hoop stresses. low mass, but high rigidity struts etc
the aluminum reaction could also explain your water being pitch black when extracting the caffeine. i'd not recommend trinking too much of that caffeinated aluminium :D
"as you can see there's still a lot of cracking involved" *voice cracks*
I can't think of any aluminium salts that are black; they are all white/colorless. Also, aluminium methoxide (Al(OCH3)3) would hydrolyze in moist air to give aluminium oxide and water. I must admit I'm clueless as to what the "soot" could be, but one possibility is that it comes from some other metal used in the aluminium alloy. That would be a place to start.
Thanks for doing these videos for us. It is very cool stuff. Stay safe M
@Fast2405 At those temperatures and pressures it's even possible, that the methanol attacks the metallic Al to form all sorts off components. e.g hydrocarbons, carbon, hydrogen and as you pointed out correctly Al(OCH3)3 and some Al(OH)3
Awesome! :) Have you thought about installing a fume hood?
some of the aluminium methoxide may have also turned into aluminium hydroxide and methanol when exposed to the moisture in the air.
I was gonna suggest you changed your molding technique, but you already will, i was thinking the pressure to release the gel from the syringe actually fractured the gel, and these fractures only showed until you dried it. >.< so i think. Good luck in future experiments very informative, Thumbs up.
I think the black powder is aluminum oxide and carbon from the metanol (termite reaction)
Not sure, but from looking at an Ellingham Diagram, aluminum metal will reduce silica. The thermodynamics say yes, the higher temperature probably helped the kinetics. Is that right thinking?
Deep frying under high pressure is called broasting. Some restaurants do that with fried chicken, and it's really good.
Have you tried applying the blowtorch to a finished piece of aerogel? Being made of silicon or ceramic, I'm curious what would happen to it.
Nothing, really. Aerogel (and ceramics in general) are thermal insulators. If you get the temperature high enough, it will sinter, but nothing spectacular. You can find other videos on YouTube of people putting torches to aerogel.
@bkraz333 thanks, is stainless steel right? Im from Argentina and I tring to figure out how I suppose to make my supercritical dryer for aerogel production without killing myself in the process! I planned to make it with stainless steel 316 or 304 pipe fittings but if is a way to make a bigger dryer with other components will be great. thanks and keep working, you great!!
I love science! Can I ask what state you live in? How did you get the tetramethyl orthosilicate?
Are you related to Bill Nye? Thanks for the informative, and sometimes dangerous, scientific experiments. Keep up the good work and making science interesting and fun.
Great video Ben. I'm interested on using supercritical co2 to extract oil from algae. Just wondering if you tried this experiment before. Thanks.
Hey Ben, how do you know that pipe can handle the pressures you are placing it under?
When I was young I recall the old woman who ran the local KFC fried the chicken in a pressure cooker. Go with the vacuum experimentation.
great job man! I see you changed de preassure vessel from the original's aerogel.org pipe fittin design. what kind of pipe did you use? is inox steel?
Nice project.
Not sure if you T fitting was safe to use at the pressures you were working with...
if there was a slow leak and it ignited you wouldnt know because methenol burns with a clear flame! (you can only see the heat haze)
Super-hot, pressurized flammable toxic gas? Sounds safe ;)
Don´t forget to put an open flame next to it just to catch any leaks.. haha that made me chuckle
I think the black/grey stuff is aluminum carbide
But wouldn't it then only react with the outside coating? And since there is an absence of air in the pipe the aluminum wouldn't have any O2 to react with halting this reaction fairly quickly?
Why wouldn't you just freeze the methanol to get the water out of it?
Same thing you do to make a more pure form of hydrogen peroxide, just put it in the freezer, the water freezes, take the ice out!
i like your scale. also, what material did you use to make the chamber?
"High pressure frying" was used by "that fried chicken chain" to cook chicken much faster back in the 1930's.
Super critical methanol ate your aluminum? Science! Aluminum is actually fairly reactive, but it's oxide layer on the surface is typicality impermeable, the nonreactive CO2 didn't do anything but the methanol must have done the job. I wonder how deep super critical CO2 penetrates, and if it can carry things with it... perhaps a coloring agent. hmmm
You know typical steel vessels lose their structural integrity and weaken @ 350F. I would wrap your tank w kevlar or not really push that vessel to its max psi anymore. Thanks for yr post, did you happen to try decaffinating coffee w high pressure water after being subjected scfe?
@jonsith3103 - 2014-09-22
Methanol reacts with aluminum, yes. Worse at high temperature. That is why it is not recommended to use an aluminum tank when making biodiesel. That and it is susceptible to NaOH as well. Thanks for posting video!
@gt.7092 - 2017-04-03
Jon Sith we don't care that you're smart, fuck off.