Supercritical CO2 is heavy like a liquid, with weird and useful properties(popula.com)
popula.com
Supercritical CO2 is heavy like a liquid, with weird and useful properties
https://popula.com/2019/01/29/saving-the-planet-with-co2/
56 comments
>My application was to use the sCO2 to solubilize organometallic precursors to deposit thin films on particles in a fluidized bed, and one of the best reasons for sCO2 was that the only likely contamination would be carbon (sCO2 is sometimes used to form carbides intentionally).
I understand some of these words.
Kidding aside, what was the goal of this endeavor? What is the end product?
I understand some of these words.
Kidding aside, what was the goal of this endeavor? What is the end product?
Let's guess. I'm going to say they are dissolving the 'precursors' into the co2, pumping it through the bed of particles with sufficient vigor to achieve 'fluidized' [1] state. As the supercritical co2 rises through the bed, the particles are dumping heat into it, ultimately flashing to vapor and leaving the solute (or at least the metallic part of it) behind as a thin film on the particle that did the trick.
This of course leaves the particle itself cooler, making it less likely to receive additional deposition and resulting in a more uniform thickness across the batch.
These coated particles are probably then going to be used as a catalyst in some other process.
[1] https://www.youtube.com/watch?v=My4RA5I0FKs
(alternate is that the the precursors themselves are the fluidized bed and the co2 is used to help move the coating from the donor to the recipient. If GP called them parts and not particles i would be more inclined to this option)
This of course leaves the particle itself cooler, making it less likely to receive additional deposition and resulting in a more uniform thickness across the batch.
These coated particles are probably then going to be used as a catalyst in some other process.
[1] https://www.youtube.com/watch?v=My4RA5I0FKs
(alternate is that the the precursors themselves are the fluidized bed and the co2 is used to help move the coating from the donor to the recipient. If GP called them parts and not particles i would be more inclined to this option)
Almost! Except for the flashing CO2 to vapor, I actually just had a filter at the top to keep particles from flying out but the reactor itself was at 5000PSI and I just used a backpressure regulator for the exhaust stream which was very little since basically every byproduct was a gas. But in backstory, I invented a process, particle supercricial fluid deposition (UMass Amherst previously demonstrated deposition onto wafers and I worked with them on it through STTR), which lets you put down conformal thin films onto particles as a protective coating.
https://www.brianneltner.com/thin-films
The key is conformal films and aspect ratio. If you're familiar with CVD, you might have encountered "duning" where film growth can produce unstable interfaces or find that a trench will get filled in at the top and leave a void underneath.
One common option is using ALD which uses alternating precursors so you can fully coat every surface of an arbitrarily high surface area material with a monolayer of your precursor, and then a second step converts that precursor to metal so you get atomically thick layers.
The downside of ALD is that it's quite slow in terms of growth rate because you can only grow one atom thick layer at a time. Additionally, the precursor has to have a vapor pressure high enough that the often solid precursors can actually be flowed through a reactor under vacuum. But it can get super thin films that can be conformal and which have incredible aspect ratios.
What I did was use sCO2 to dissolve chemicals like those ALD or CVD precursors in an "organic solvent" (sCO2 itself) to deliver it at super high concentrations to the reactor (at like 5000PSI) instead of at super low concentrations under vacuum. It stays supercritical through the full fluidized bed. But the reactor itself is hot so the precursors spontaneously decompose and do so preferentially on surfaces. But! The key difference is that because of the high precursor concentration, instead of the film growth rate being dictated by how fast precursor can get to the particle surface (diffusion limited) it's limited by how fast the precursor reacts on the surface (kinetically limited). The prior is notorious for unstable interfaces, the latter is much better because it's just growing at max speed at all locations simultaneously.
So the real difference is that it let me deposit thin films from a high concentration precursor stream.
My actual application was trying to coat copper flake with chromium metal to increase the oxidation temperature for use as a replacement to silver conductive pastes used in solar panel manufacturing. Silver was (might still be) like 10% of the total cost of making one, so this was of keen interest and would be pretty awesome. Ultimately, I was able to make it so that copper showed no oxidation at 300C over a minute while uncoated copper did show a lot of oxidation.
However, the amount of coating I needed to keep the oxygen away from the copper was too thick (or at least I couldn't make it thinner with that tech) and the chromium was expensive enough that it'd have ended up more expensive than just using silver.
So I moved on =) A project worth doing for sure, everyone I talked to about it simply could not guess if it would work. Sadly it worked but wasn't commercially interesting in the end.
https://www.brianneltner.com/thin-films
The key is conformal films and aspect ratio. If you're familiar with CVD, you might have encountered "duning" where film growth can produce unstable interfaces or find that a trench will get filled in at the top and leave a void underneath.
One common option is using ALD which uses alternating precursors so you can fully coat every surface of an arbitrarily high surface area material with a monolayer of your precursor, and then a second step converts that precursor to metal so you get atomically thick layers.
The downside of ALD is that it's quite slow in terms of growth rate because you can only grow one atom thick layer at a time. Additionally, the precursor has to have a vapor pressure high enough that the often solid precursors can actually be flowed through a reactor under vacuum. But it can get super thin films that can be conformal and which have incredible aspect ratios.
What I did was use sCO2 to dissolve chemicals like those ALD or CVD precursors in an "organic solvent" (sCO2 itself) to deliver it at super high concentrations to the reactor (at like 5000PSI) instead of at super low concentrations under vacuum. It stays supercritical through the full fluidized bed. But the reactor itself is hot so the precursors spontaneously decompose and do so preferentially on surfaces. But! The key difference is that because of the high precursor concentration, instead of the film growth rate being dictated by how fast precursor can get to the particle surface (diffusion limited) it's limited by how fast the precursor reacts on the surface (kinetically limited). The prior is notorious for unstable interfaces, the latter is much better because it's just growing at max speed at all locations simultaneously.
So the real difference is that it let me deposit thin films from a high concentration precursor stream.
My actual application was trying to coat copper flake with chromium metal to increase the oxidation temperature for use as a replacement to silver conductive pastes used in solar panel manufacturing. Silver was (might still be) like 10% of the total cost of making one, so this was of keen interest and would be pretty awesome. Ultimately, I was able to make it so that copper showed no oxidation at 300C over a minute while uncoated copper did show a lot of oxidation.
However, the amount of coating I needed to keep the oxygen away from the copper was too thick (or at least I couldn't make it thinner with that tech) and the chromium was expensive enough that it'd have ended up more expensive than just using silver.
So I moved on =) A project worth doing for sure, everyone I talked to about it simply could not guess if it would work. Sadly it worked but wasn't commercially interesting in the end.
Super interesting. Comments like this are what keep me coming back to HN.
Holy moly this is cool! Thanks for all the detail and the link to your blog post. The process sounds really cool, i bet it was awesome seeing it work the first time!
Also:
>Almost!
You’re quite generous with your knowledge and compliments haha!
Also:
>Almost!
You’re quite generous with your knowledge and compliments haha!
Thank you very much!
Exciting read!
Exciting read!
Thanks for taking the time to post this. It was a fun read.
Particles with thin films on them, of course.
Does cavitation depend on temperature in like submarines too?
CO2 is super weird. In a CO2 tank it's actually two-phase, CO2 gas and liquid in a steady state equilibrium that is exclusively a function of the temperature. Since the outlet was connected to the HPLC pump inlet, if the temperature between the tank and the pump head was exactly equal, when the pump piston draws liquid in it every so slightly reduces the pressure, which results in the liquid CO2 boiling inside the pump head producing bubbles that make metering the flow rate impossible.
So the cavitation in this case is indeed temperature driven (albeit indirectly) but it's really just a side effect of the pump type. A syringe pump style system just is well, a syringe, so the problem goes away.
So the cavitation in this case is indeed temperature driven (albeit indirectly) but it's really just a side effect of the pump type. A syringe pump style system just is well, a syringe, so the problem goes away.
Excellent use of the HPLC pump, we used to order them by the pallet.
Here's the phase diagram:
https://en.wikipedia.org/wiki/File:Carbon_dioxide_pressure-t...
I'm no engineer, but I like to work with engineers that are good at not just established "engines" but imaginary ones too.
I always thought any engineer should be able to understand this well-established graph just by looking at it, regardless of whether they had any ChE background.
Engineers already exposed to material phase behavior sometimes still take a little while, but there's not much there, it's a pretty straightforward graph.
Studying it alone should bring understanding, not of the full implications of the dynamic physico-chemical properties of course, just the states of matter that exist under the conditions indicated by the data.
Some engineers can never get this, I don't get that.
While I would prefer an engineer with an appreciation for what it takes to turn the imagination of some PhDs into apparatus capable of creating drawings like this, using commercially available components when possible, based primarily on drawings like this.
I'm no capitalist without other people's money (I personally owned two of the automated positive-displacement high-pressure [syringe] pumps), but a good capitalist to work with would have enough imagination for an intuitive understanding of the leverage used to assemble advanced equipment into money-making machines, when the majority of operators must accept the high-dollar components as unrecoverable costs.
Here's the phase diagram:
https://en.wikipedia.org/wiki/File:Carbon_dioxide_pressure-t...
I'm no engineer, but I like to work with engineers that are good at not just established "engines" but imaginary ones too.
I always thought any engineer should be able to understand this well-established graph just by looking at it, regardless of whether they had any ChE background.
Engineers already exposed to material phase behavior sometimes still take a little while, but there's not much there, it's a pretty straightforward graph.
Studying it alone should bring understanding, not of the full implications of the dynamic physico-chemical properties of course, just the states of matter that exist under the conditions indicated by the data.
Some engineers can never get this, I don't get that.
While I would prefer an engineer with an appreciation for what it takes to turn the imagination of some PhDs into apparatus capable of creating drawings like this, using commercially available components when possible, based primarily on drawings like this.
I'm no capitalist without other people's money (I personally owned two of the automated positive-displacement high-pressure [syringe] pumps), but a good capitalist to work with would have enough imagination for an intuitive understanding of the leverage used to assemble advanced equipment into money-making machines, when the majority of operators must accept the high-dollar components as unrecoverable costs.
I sort of agree, but I think you're too harsh. Having taught phase diagrams to freshmen, very smart freshmen, as with everything else it comes down to familiarity and practice. I tend not to look down on people for not knowing stuff they're not familiar with, I'm sure they could all get it with someone who can actually guide them through it.
But I do appreciate a simple, inexpensive design of course. But they're so hard for people to make if they don't understand the deep details of everything in the system, and once the knowledge is split between two brains then it's a lot harder to spot inconsistencies. But I also can hardly blame people for throwing in the towel on deeply researching the sheer vastness of the McMaster, Swagelok, and Digikey catalogs. Much less ASTM standards or the ASM handbook.
I work on building a lot of surprisingly easy things like electromagnets and battery charging circuits and low noise filters and precision temperature controllers and such like that in-house because it's shocking how bad and expensive stuff made commercially usually is. Just yesterday I was replacing a flow sensor in a water pump to water cool a vibrating scanning magnetometer my office mate designed. It's a fun line of work. I also do stuff on the side as a consultant along these lines to scratch the "let's make something people can use in industry" itch (http://neltnerlabs.com/).
But my biggest pipe dream for the past 9 years has been using AI tools to close the loop around synthesis and testing and predicting properties for heterogeneous catalysts. Equipment is a key part of that dream, sadly Google was uninterested (no ads?) and I've only ever found a handful of companies working on it all of which don't quite seem to get just how big a deal it is almost certain to be. At least the national labs are catching on.
But I do appreciate a simple, inexpensive design of course. But they're so hard for people to make if they don't understand the deep details of everything in the system, and once the knowledge is split between two brains then it's a lot harder to spot inconsistencies. But I also can hardly blame people for throwing in the towel on deeply researching the sheer vastness of the McMaster, Swagelok, and Digikey catalogs. Much less ASTM standards or the ASM handbook.
I work on building a lot of surprisingly easy things like electromagnets and battery charging circuits and low noise filters and precision temperature controllers and such like that in-house because it's shocking how bad and expensive stuff made commercially usually is. Just yesterday I was replacing a flow sensor in a water pump to water cool a vibrating scanning magnetometer my office mate designed. It's a fun line of work. I also do stuff on the side as a consultant along these lines to scratch the "let's make something people can use in industry" itch (http://neltnerlabs.com/).
But my biggest pipe dream for the past 9 years has been using AI tools to close the loop around synthesis and testing and predicting properties for heterogeneous catalysts. Equipment is a key part of that dream, sadly Google was uninterested (no ads?) and I've only ever found a handful of companies working on it all of which don't quite seem to get just how big a deal it is almost certain to be. At least the national labs are catching on.
> but I think you're too harsh.
What I found when I took thermo which is where you learn this stuff. Nothing really prepares you for the basic concepts before hand. So it's a steep hill to climb. I think some students get through it via rote memorization. Which means they don't actually understand it. I had to retake the first semester because I got a C-. Which was likely for the best.
I also think that thermo is somehow very deeply connected to how the universe actually works. And the next step down is a doozy. So it's difficult to explain it in terms of something familiar.
What I found when I took thermo which is where you learn this stuff. Nothing really prepares you for the basic concepts before hand. So it's a steep hill to climb. I think some students get through it via rote memorization. Which means they don't actually understand it. I had to retake the first semester because I got a C-. Which was likely for the best.
I also think that thermo is somehow very deeply connected to how the universe actually works. And the next step down is a doozy. So it's difficult to explain it in terms of something familiar.
I was super lucky that they were taught in freshman chemistry. It made it more familiar seeming later on I'm sure.
I agree about thermo, it has an unexpected amount of symmetry. It wasn't until my third time taking a thermo course that I think I really started to get it.
I had a professor that I just straight up asked "why?" and his response was "because sometimes we want to know numbers that are hard to measure so we come up with ways to represent them using things that are easy to measure". That is by a wide margin the most practically coherent reasoning for the importance of thermo I've ever gotten, and suddenly all the seemingly arbitrarily PDE manipulation made perfect sense.
Although I think the basics like "what is entropy" are pretty generally useful regardless of if you ever touch the PDEs or free energy equations.
I agree about thermo, it has an unexpected amount of symmetry. It wasn't until my third time taking a thermo course that I think I really started to get it.
I had a professor that I just straight up asked "why?" and his response was "because sometimes we want to know numbers that are hard to measure so we come up with ways to represent them using things that are easy to measure". That is by a wide margin the most practically coherent reasoning for the importance of thermo I've ever gotten, and suddenly all the seemingly arbitrarily PDE manipulation made perfect sense.
Although I think the basics like "what is entropy" are pretty generally useful regardless of if you ever touch the PDEs or free energy equations.
Differential forms in thermo can be an eye opener
I don't want to be harsh, I admire and want to recognize the creative designer.
I enjoy guiding people through unfamiliar things which I have experimented with, it's good to see the diverse ways to grasp the same fundamental concept. Some students are quicker than some degreed engineers.
You seem like a person that could make an outstanding collaborator, building systems unique to the direction of the project.
I'm glad you put your website here, I'll pick up the phone and give your company a call, there's not a more promising, businesslike way.
I like instruments also, and have more than one.
Testing pays the bills, see the message for the acetone user.
When retired it might be good to build some robotic type stuff, maybe in a capitalist venture to overcome financial limitations.
Or looks like things would be fine without any equipment, helping companies negotiate the byzantine ASTM process alone instead, just been invited to join the emerging cannabis committee as an independent voting member.
That's only about testing, but extraction operators might best benefit from more supercritical ability on their side, you could surely consider this yourself now since it's very uncommon to have experience safely handling this type equipment, especially as a researcher on an experimental basis. Haven't done EOR in years and this time it could be CBD oil.
Anyway, presenting some findings on heavy petroleum oils to my traditional ASTM committee shortly, they want to get it into the book as soon as possible because it could save operators millions across the board.
Started to meet with some AI people just over a month ago too, inviting them to the lab to see firsthand (& smell) the kinds of crude oil they have been modeling about, some engineers for the first time.
I enjoy guiding people through unfamiliar things which I have experimented with, it's good to see the diverse ways to grasp the same fundamental concept. Some students are quicker than some degreed engineers.
You seem like a person that could make an outstanding collaborator, building systems unique to the direction of the project.
I'm glad you put your website here, I'll pick up the phone and give your company a call, there's not a more promising, businesslike way.
I like instruments also, and have more than one.
Testing pays the bills, see the message for the acetone user.
When retired it might be good to build some robotic type stuff, maybe in a capitalist venture to overcome financial limitations.
Or looks like things would be fine without any equipment, helping companies negotiate the byzantine ASTM process alone instead, just been invited to join the emerging cannabis committee as an independent voting member.
That's only about testing, but extraction operators might best benefit from more supercritical ability on their side, you could surely consider this yourself now since it's very uncommon to have experience safely handling this type equipment, especially as a researcher on an experimental basis. Haven't done EOR in years and this time it could be CBD oil.
Anyway, presenting some findings on heavy petroleum oils to my traditional ASTM committee shortly, they want to get it into the book as soon as possible because it could save operators millions across the board.
Started to meet with some AI people just over a month ago too, inviting them to the lab to see firsthand (& smell) the kinds of crude oil they have been modeling about, some engineers for the first time.
Yeah, I have the deepest respect for the people who do a lot of AI. I took Ng's online course and know that I don't know a ton but I'm more a "learn the basics, read papers after that" kind of person so I just started trying to replicate papers after that a bit.
Now my problem is mostly that I just don't have the energy to scour the research journals and books to put together datasets worth training with (for heterogeneous catalyst performance). Same as everyone I guess. The algorithms don't seem that bad, albeit obviously I want to run it past some friends that do it before claiming anything since I know I'll do it badly and just not know, so maybe in a perfect world it's just a matter of needing more data.
I honestly think it will work because I with a human brain can look at trends in catalyst manufacturing methods and composition and guess at least reasonably locally what changes will do. The parameter space is just too big between atomic composition, preparation methods, support acidity, surface area, etc etc etc. I think honestly a computer could do it because it feels like a problem of fitting the data in my head enough to model it beyond super locally.
But every time I try to improve a catalyst I succeed, which I think says more about how poorly optimized we are today than it says about my cleverness -- literally almost any random change is likely one that is a variable no one has tried yet. It's an awesomely open feeling field, and more exciting now that biomolecules are getting thrown into the mix from fermentation facilities.
Now my problem is mostly that I just don't have the energy to scour the research journals and books to put together datasets worth training with (for heterogeneous catalyst performance). Same as everyone I guess. The algorithms don't seem that bad, albeit obviously I want to run it past some friends that do it before claiming anything since I know I'll do it badly and just not know, so maybe in a perfect world it's just a matter of needing more data.
I honestly think it will work because I with a human brain can look at trends in catalyst manufacturing methods and composition and guess at least reasonably locally what changes will do. The parameter space is just too big between atomic composition, preparation methods, support acidity, surface area, etc etc etc. I think honestly a computer could do it because it feels like a problem of fitting the data in my head enough to model it beyond super locally.
But every time I try to improve a catalyst I succeed, which I think says more about how poorly optimized we are today than it says about my cleverness -- literally almost any random change is likely one that is a variable no one has tried yet. It's an awesomely open feeling field, and more exciting now that biomolecules are getting thrown into the mix from fermentation facilities.
Venus' lower atmosphere is actually composed of supercritical CO2 at 90 atm and ~450°C which makes corrosion interesting[0]. sCO2's property of acting like a solvent works against us in this case. Copper grows a hair copper sulphide from the trace amount of sulfur dioxide and other sulfur compounds present. Hydrofluoric acid, even though it's present at part per billion concentrations, cause corrosion problems too. While we now have interesting silicon carbide integrated circuits like image sensors[1] and 555 timers[2] capable of operating at Venusian temperatures, it's challenging to actually use them on Venus because of corrosion of the bonding pads.
[0]https://www.researchgate.net/publication/325521557_Chemical_...
[1]http://kth.diva-portal.org/smash/get/diva2:1303493/FULLTEXT0...
[2]http://www.diva-portal.org/smash/record.jsf?pid=diva2%3A1317...
[0]https://www.researchgate.net/publication/325521557_Chemical_...
[1]http://kth.diva-portal.org/smash/get/diva2:1303493/FULLTEXT0...
[2]http://www.diva-portal.org/smash/record.jsf?pid=diva2%3A1317...
It's amazing how wide the applications of supercitical CO2 can be -- we used it as a solvent to extract high-value lipids from algal biomass at a biofuel company I worked for:
https://en.wikipedia.org/wiki/Supercritical_fluid_extraction
But it can also be used as a 'solvent' in non-toxic and low/no-water laundry systems:
http://e3tnw.org/ItemDetail.aspx?id=512
In addition to all of the benefits it can provide for energy-related pursuits as a working fluid.
https://en.wikipedia.org/wiki/Supercritical_fluid_extraction
But it can also be used as a 'solvent' in non-toxic and low/no-water laundry systems:
http://e3tnw.org/ItemDetail.aspx?id=512
In addition to all of the benefits it can provide for energy-related pursuits as a working fluid.
Super critical co2 is also used for caffeine extraction in coffee, and its safer solvent for cannabis extracts and concentrates. I would never buy cbd products unless they are lab tested with a GC for contaminates and extracted with co2.
Look into USP-grade acetone-extracted cannabinoids. Acetone is 100% VOC so it will evaporate away cleanly without needing a vacuum purge (I'd still heat it to 135F to boil off the acetone which boils at ~133F) and your body naturally produces it in small amounts, so a tiny bit of contamination isn't going to be likely to cause damage. It is cheap to obtain vs. compressed CO2 (the cost of the equipment required for CO2 extraction represents the bulk of the cost of the extract) so you'll also save money.
Many places that do CO2 extraction also don't use a closed-loop system, so many are just venting the CO2 directly into the atmosphere.
Many places that do CO2 extraction also don't use a closed-loop system, so many are just venting the CO2 directly into the atmosphere.
Take a look at the USP Acetone specification, it does not indicate definite ideal suitability for the task:
https://greenfield.com/wp-content/uploads/2018/11/Spec-Sheet...
This fungible specification has no specific limit for Diacetone Alcohol content, a common impurity and one which increases during storage.
Diacetone Alcohol is an industrial solvent with properties of its own, not nearly as low-boiling as Acetone. Clean Diacetone Alcohol will also show negligible Residue After Evaporation and Non-Volatile Residue under conditions of the tests, which report mostly solids content along with many higher-boiling liquid impurities but not components as moderately volatile as Diacetone Alcohol itself.
However Diacetone Alcohol can still be a significant component of the extract once the bulk Acetone has fully evaporated, depending on the conditions of the processing. Rotovap would help a lot and more than 135F would reduce residual solvent better from a viscous matrix.
The USP Purity minimum of 99.5 basically means that the water content plus any other chemical impurities such as Iso-Propyl Alcohol & Methanol (specified) and implying things like Diacetone Alcohol or Benzene, etc (but unspecified) must not add up to more than 0.5 percent.
You might even prefer to explicitly specify a maximum limit For some other target toxins, less than some low detectable amount if you were picky.
Some legitimate laboratories may not be able to detect the difference between Acetone which contains unlisted impurities and that where it is negligible.
Take a look at the associated weaselwords from legal:
https://greenfield.com/wp-content/uploads/2018/11/OVI-Residu...
Which references this as the closest applicable guideline, even though it was intended to apply to the residual solvent content of pharmaceutical products not solvents themselves:
https://www.uspnf.com/sites/default/files/usp_pdf/EN/USPNF/g...
Better than nothing but not as cautious as it could be. You may want fewer impurities than marginal drug companies anyway, you're allowed to do that. This particular supplier does look nicely better than marginal, which is good, with typicals looking well better than the limit.
Regardless with two lots of USP Acetone having apparently identically suitable certificates, one may result in its Diacetone Alcohol or other not-so-volatile components comprising a significant portion of the extract, while the other lot would not, under the same solvent-removal conditions which are excellent for the latter batch of Acetone having only the lighter impurities such as IPA & Methanol.
I would still want to test it myself first.
Source: pioneered laboratory techniques which some other testers and chemical plants eventually adopted years later, still state-of-the-art today, including this particular material. Certified billions of dollars worth of commodities like this, single-handedly more than some single petro-chemical companies can manufacture. Less than a year ago deployed a further advanced system with two backups for 100 percent uptime in a 24hr staffed operation, for when a big oil/chemical client has their ships come in, and it was Acetone. There is still no adequate publication within ASTM, been at it since dirt was rocks, and Acetone has been around even longer. Documentation not found elsewhere.
https://greenfield.com/wp-content/uploads/2018/11/Spec-Sheet...
This fungible specification has no specific limit for Diacetone Alcohol content, a common impurity and one which increases during storage.
Diacetone Alcohol is an industrial solvent with properties of its own, not nearly as low-boiling as Acetone. Clean Diacetone Alcohol will also show negligible Residue After Evaporation and Non-Volatile Residue under conditions of the tests, which report mostly solids content along with many higher-boiling liquid impurities but not components as moderately volatile as Diacetone Alcohol itself.
However Diacetone Alcohol can still be a significant component of the extract once the bulk Acetone has fully evaporated, depending on the conditions of the processing. Rotovap would help a lot and more than 135F would reduce residual solvent better from a viscous matrix.
The USP Purity minimum of 99.5 basically means that the water content plus any other chemical impurities such as Iso-Propyl Alcohol & Methanol (specified) and implying things like Diacetone Alcohol or Benzene, etc (but unspecified) must not add up to more than 0.5 percent.
You might even prefer to explicitly specify a maximum limit For some other target toxins, less than some low detectable amount if you were picky.
Some legitimate laboratories may not be able to detect the difference between Acetone which contains unlisted impurities and that where it is negligible.
Take a look at the associated weaselwords from legal:
https://greenfield.com/wp-content/uploads/2018/11/OVI-Residu...
Which references this as the closest applicable guideline, even though it was intended to apply to the residual solvent content of pharmaceutical products not solvents themselves:
https://www.uspnf.com/sites/default/files/usp_pdf/EN/USPNF/g...
Better than nothing but not as cautious as it could be. You may want fewer impurities than marginal drug companies anyway, you're allowed to do that. This particular supplier does look nicely better than marginal, which is good, with typicals looking well better than the limit.
Regardless with two lots of USP Acetone having apparently identically suitable certificates, one may result in its Diacetone Alcohol or other not-so-volatile components comprising a significant portion of the extract, while the other lot would not, under the same solvent-removal conditions which are excellent for the latter batch of Acetone having only the lighter impurities such as IPA & Methanol.
I would still want to test it myself first.
Source: pioneered laboratory techniques which some other testers and chemical plants eventually adopted years later, still state-of-the-art today, including this particular material. Certified billions of dollars worth of commodities like this, single-handedly more than some single petro-chemical companies can manufacture. Less than a year ago deployed a further advanced system with two backups for 100 percent uptime in a 24hr staffed operation, for when a big oil/chemical client has their ships come in, and it was Acetone. There is still no adequate publication within ASTM, been at it since dirt was rocks, and Acetone has been around even longer. Documentation not found elsewhere.
It's also being used as a solvent to make high quality cannabis concentrates and extracts in place of butane or alcohol that's more commonly used now. I haven't tried them, but I know the CO2 extracted products are being used more in edibles as toxic solvents aren't used in the extraction process.
Such extracts are too pure imo. Especially for edibles, I'd rather have an ethanol extract that got a run of related chemicals and some other stuff that came along for the ride... aka "flavor".
Super pure extracts that then have added back flavorings, or even blended concertos of specific chemicals, miss the charm and much of the value of taking the "light oils" off the plant. Flower is hard to fake, home extracts are easy to do, and who knows what's in that commercial oil, really?
Super pure extracts that then have added back flavorings, or even blended concertos of specific chemicals, miss the charm and much of the value of taking the "light oils" off the plant. Flower is hard to fake, home extracts are easy to do, and who knows what's in that commercial oil, really?
Ah yeah, the terpenes in the strains do more than add flavour too. Different terpenes in different strains have been found to have different effects in combination with the cannabinoids in the strain. I doubt re-adding terpenes and flavouring after the fact has the same effect. I suppose I have tried CO2 extract, I have tried the prefilled oil carts with the added flavour. I don't like them. The high from them feels weird and the taste isn't great.
Yes. The advantage as I've heard is that the extract is flavourless.
CO2 is also the best substance to inject into oil fields for enhanced oil recovery. It becomes supercritical at the pressures involved in the oil bearing formations and is more effective at sweeping recoverable petroleum than water or steam. The problem is sourcing enough CO2 near a field.
It's also a very convenient way for oil and gas companies to suck all the renewable subsidy money in the name of "carbon sequestration", when the reality is they're developing new ways to get even more oil and gas out...
I assure you, the decision is entirely economic on the production side. CO2 is fungible, no? (in regards to sequestration subsidies)
CO2 is indeed fungible. I simply suspect that a lot of companies are requesting government money to research and develop something that they would choose to research anyway even without government money. (because it increases oil production).
They get away with that because many governments don't have good tech advisers.
They get away with that because many governments don't have good tech advisers.
CO2 injection is not R&D, but established operating procedure. Its use can count to what determines recoverable reserves.
Applied Science has a great video (as all of his videos are) on supercritical CO2.
https://www.youtube.com/watch?v=-gCTKteN5Y4
https://www.youtube.com/watch?v=-gCTKteN5Y4
Codys Lab did a video as well; https://youtu.be/4Z-KbcLs-yo
Ben is a brilliant man with many fascinating and insightful videos.
It seems like this link from the article deserves its own front page story:
https://www.ge.com/reports/call-ecomagination-ge-building-co...
That's pretty neat.
That's pretty neat.
Martyn Poliakoff of Periodic Videos fame has done a lot of work with supercritical CO2, particularly in the context of more environmentally friendly organic solvents.
This 5 minute video provides an excellent summary: https://www.youtube.com/watch?v=yBRdBrnIlTQ
This 5 minute video provides an excellent summary: https://www.youtube.com/watch?v=yBRdBrnIlTQ
Some molten salt reactor designs were planned first with helium turbomachinery and later with supercritical CO2.
Also GE tried to sell gas turbines for ship propulsion. You get back some efficiency with a CO2 turbine running with the waste heat. Ship owners still like their diesels. Really long time between overhauls.
Also GE tried to sell gas turbines for ship propulsion. You get back some efficiency with a CO2 turbine running with the waste heat. Ship owners still like their diesels. Really long time between overhauls.
> Also GE tried to sell gas turbines for ship propulsion.
Pretty common for warships though, or at least that's my understanding. The Arleigh Burke class [0] is powered by GE gas turbines, for instance.
Though the requirements list for "large surface combatant engine" and "huge cargo vessel engine" are probably more than a bit different.
0: https://en.wikipedia.org/wiki/Arleigh_Burke-class_destroyer
Pretty common for warships though, or at least that's my understanding. The Arleigh Burke class [0] is powered by GE gas turbines, for instance.
Though the requirements list for "large surface combatant engine" and "huge cargo vessel engine" are probably more than a bit different.
0: https://en.wikipedia.org/wiki/Arleigh_Burke-class_destroyer
Yes. They pay little for fuel. Also afaik they do not use the waste heat. Though probably with the logistics train to some places the fuel can probably be expensive at times.
There used to be passenger ships with turbines too. They changed the engines to regular diesels at some point. https://en.m.wikipedia.org/wiki/GTS_Finnjet
There used to be passenger ships with turbines too. They changed the engines to regular diesels at some point. https://en.m.wikipedia.org/wiki/GTS_Finnjet
I think they actually do reuse the waste heat in a way, not via steam, but by being recuperated.
The other interesting thing is it can be used within a 100% carbon capture power plant that happens to generate more liquid CO2 which is inherently trapped within circuit of the plant. (and is presumably tapped off to sequester in places - this is said to be better than trying post collect and sequester the gas in a regular system).
https://en.wikipedia.org/wiki/Allam_power_cycle
https://en.wikipedia.org/wiki/Allam_power_cycle
Supercritical liquids are generally weird. H2O, for example, changes from being a polar solvent to a nonpolar solvent -- you can dissolve oil in supercritical water, and even burn it if you have a source of oxygen. It's also more corrosive -- which is relevant if you're considering using supercritical water in a nuclear reactor.
> even burn it if you have a source of oxygen
How does that work? What are the combustion products? The closest reference I could find is this, https://science.nasa.gov/science-news/science-at-nasa/2014/1... , which seems to be talking about something else.
How does that work? What are the combustion products? The closest reference I could find is this, https://science.nasa.gov/science-news/science-at-nasa/2014/1... , which seems to be talking about something else.
Easiest case of this: You have a tank of water and oil under supercritical conditions, and you pump high pressure oxygen gas into it. You get a "flame" around the intake, but unlike a regular flame (which is the boundary between fuel and the surrounding oxidizer) this is the boundary between the incoming oxidizer and the surrounding fuel.
The combustion products are the same as you would get in the absence of the supercritical water -- typically H2O and CO2 -- but they're all contained inside the supercritical water tank, which makes this very convenient for e.g. disposing of chemical weapons.
The combustion products are the same as you would get in the absence of the supercritical water -- typically H2O and CO2 -- but they're all contained inside the supercritical water tank, which makes this very convenient for e.g. disposing of chemical weapons.
I guess supercritical CO2 can be a decent refrigerant as well.
https://www.greenbuildingadvisor.com/article/a-heat-pump-usi...
https://www.greenbuildingadvisor.com/article/a-heat-pump-usi...
AFAIU it's quite common in supermarket/warehouse refrigerators and freezers. Apparently upfront cost is slightly higher, but the refrigerant is cheap and there's no risk the next iteration of the F gas legislation will make your investments a dead end. And of course the environment friendliness is important to businesses that are concerned about their image.
I spent a summer in college working in a chem laboratory with no air conditioning. Sometimes I would give the big standing CO2 cylinder a shake, and if I didn't hear any sloshing, I knew we were in for a rough day.
Holy moly, until now I had absolutely no idea about the existence of supercritical CO2. And now all the comments here are making me so incredibly fascinated and excited about the potential utilities for stored CO2. I am thinking not in terms of the science, but actually making a business case for CO2 storage beyond just CSR projects!
"GE has built a prototype which is small enough to fit on a desktop" - The linked page (https://tinyurl.com/y2s9z69d) claims 10 MW output - This is several orders of magnitude "north" from the reality (~ 15 kW).
From what I can gather, the chambers are quite small due to the pressure issues. This has the result of making aerogel, typically produced with supercritical carbon dioxide, come in comparatively small chunks, especially at the hobbyist level. It's a pity.
Nice! I was just wondering the other day with water having so many weird ice forms and what not what do we know about other common chemicals and their states of matter
Fantastic article, very well written and informative with lots of great links (e.g. diamond anvil).
sCO2 is also used for the production of aerogel: https://en.m.wikipedia.org/wiki/Aerogel
Link doesn’t display on mobile devices.
It worked pretty well, though I had to stick a TEC on the pump head. $5k instead of $100k+ for a high pressure syringe pump.
My application was to use the sCO2 to solubilize organometallic precursors to deposit thin films on particles in a fluidized bed, and one of the best reasons for sCO2 was that the only likely contamination would be carbon (sCO2 is sometimes used to form carbides intentionally).