Sciencemadness Discussion Board - Make plastic explosive out of ETN/PETN & EDGN

Make plastic explosive out of ETN/PETN & EDGN

Ankit1612 - 14-5-2023 at 08:11

Hi guys,
I have Recently synthesized some PETN & ETN.
Now, I want to make some Plastic explosive out of it. I don't have any binder, so I decided to use EDGN as binder!
Can someone mention it's characteristics like sensitivity, detonation, velocity, etc?

B(a)P - 14-5-2023 at 12:40

EGDN

[Edited on 14-5-2023 by B(a)P]

OneEyedPyro - 15-5-2023 at 21:27

Quote: Originally posted by Ankit1612

Hi guys,
I have Recently synthesized some PETN & ETN.
Now, I want to make some Plastic explosive out of it. I don't have any binder, so I decided to use EDGN as binder!
Can someone mention it's characteristics like sensitivity, detonation, velocity, etc?

I'd expect relatively high sensitivity straddling the line between primary secondary depending on the ratios used. I'd also expect poor handling properties without the moldability and sticking characteristics of something like C4, if you get it to a decent density expect a VoD around 8,000ms with very high brisance. Again it all depends on ratios and density.
EGDN is a pain to work with in my experience, just too toxic and easily absorbed by skin for my taste.

Ankit1612 - 16-5-2023 at 09:34

Earlier i've tested 80/20 PETN/NG plastic explosive it worked very well!

The one in which NG was used, it was smelling very bad, also i suffered from headache.
After making it, i Detonated it within 2 Hours.
I made another batch and stored it for 2-3 days, and then detonated but it did'nt detonate. It had been insensitive!!

So thought can i use EDGN with same ratio.
It might work better.

OneEyedPyro - 16-5-2023 at 10:53

Quote: Originally posted by Ankit1612

Earlier i've tested 80/20 PETN/NG plastic explosive it worked very well!

The one in which NG was used, it was smelling very bad, also i suffered from headache.
After making it, i Detonated it within 2 Hours.
I made another batch and stored it for 2-3 days, and then detonated but it did'nt detonate. It had been insensitive!!

So thought can i use EDGN with same ratio.
It might work better.

Did you properly deacidify everything? It shouldn't spontaneously decompose or smell bad.
EGDN is really no better than NG as far as I'm concerned, it's even more toxic and annoying to work with but has very similar explosive properties.
I'd recommend just sticking with NG if you insist on having a composition with no inerts.

Binders like PIB can easily be found at any hardware store and nitromethane can generally be used in place of sensitive explosives like EGDN or NG.

Microtek - 16-5-2023 at 11:55

If you add a little NC to your NG (and maybe some acetone to help with colloidonization), you will probably get a more cohesive product. You still need gloves to handle it of course.

ManyInterests - 17-5-2023 at 00:26

There was another thread where someone mentioned TNF (trinitrofructose) that was a resin like energetic that could could be used as a binder as well. I was thinking of going that route and see if I can make a shelf-stable plastic explosive that can last a while. Sometimes that is an experiment in itself.

I was also thinking about doing the same with DEGDN, since it is less sensitive and less volatile than EDGN (but has the disadvantage of being hygroscopic).

Microtek - 17-5-2023 at 12:41

Nitrosugars have very poor stability. Nitrated sugar alcohols are OK (mannitol and erythritol are examples of sugar alcohols), but if you are looking for storage stability, nitrosugars are not the way to go.

Herr Haber - 17-5-2023 at 17:53

Quote: Originally posted by OneEyedPyro

Did you properly deacidify everything? It shouldn't spontaneously decompose or smell bad.

Specially after two hours. This would have me very worried.
Better lose a bit of product and wash it correctly than lose your appartment, a limb, etc.

ManyInterests - 22-5-2023 at 18:13

Quote: Originally posted by Microtek

Nitrosugars have very poor stability. Nitrated sugar alcohols are OK (mannitol and erythritol are examples of sugar alcohols), but if you are looking for storage stability, nitrosugars are not the way to go.

Ahh, so in that case if I do make a bit of TNF it should be for immediate use. I gotcha.

ManyInterests - 23-5-2023 at 19:28

Oh there is something I wanted to mention. I did read in a book of making methyl nitrate plastic explosive using methyl nitrate (not something I wish to make soon for obvious reasons!) and nitrostarch.

I remember that nitrostarch was used in some applications during WW1 for use as a grenade filler. Obviously to make sure it is pure not only would recrystalization be necessary, but also refluxing it with absolute (or near absolute) ethanol to remove the impurities.

Would nitrostarch be able to fully absorb something like EGDN or DEGDN? Making a sort of gelignite?

Microtek - 23-5-2023 at 23:45

Yes, I would think so. Not as well as NC I'm sure, but you could doubtlessly do it.

Herr Haber - 24-5-2023 at 12:56

I dont think methyl nitrate plastic explosives is a good idea though it sound appealing.
First, for a non rational reason I'm about as afraid of methyl nitrate as I am of TATP.
Second, it's high volatility guarantees your material will not remain plastic for very long probably giving you a nice headache along the way. NG on the other hand...

I wondered for a long time how would nitrostarch fare compared with NC mixed with NG or EGDN.
I'm very curious about the differences in viscosity / fluidity and how you can toy with that with more or less nitrostarch, different N % etc.
Unfortunately there's relatively little data on nitrostarch compared to other common EM.
You mention nitrostarch used in grenades. I was also used in demolition charges in WWII which... well seems kinda odd for a country like the US to produce when you have other EM's that are simpler to synthesize, handle and package.

ManyInterests - 24-5-2023 at 19:09

Quote: Originally posted by Herr Haber

I dont think methyl nitrate plastic explosives is a good idea though it sound appealing.
First, for a non rational reason I'm about as afraid of methyl nitrate as I am of TATP.
Second, it's high volatility guarantees your material will not remain plastic for very long probably giving you a nice headache along the way. NG on the other hand...

I wondered for a long time how would nitrostarch fare compared with NC mixed with NG or EGDN.
I'm very curious about the differences in viscosity / fluidity and how you can toy with that with more or less nitrostarch, different N % etc.
Unfortunately there's relatively little data on nitrostarch compared to other common EM.
You mention nitrostarch used in grenades. I was also used in demolition charges in WWII which... well seems kinda odd for a country like the US to produce when you have other EM's that are simpler to synthesize, handle and package.

The ultra high volatility of methyl nitrate is also a major reason why I am steering away from it, too. I got more to say on that, but I have other questions to ask (I thought about starting a thread, but I think you might be able to provide an answer).

I actually saw several videos on making methyl nitrate on YouTube and I've seen people use concentrated nitric acid and at least one guy who used just a nitrate salt (KNO3) along with sulfuric acid.

This did get me asking... in what circumstances would a nitration work fine with the dilute nitric acid made by adding a nitrate salt to sulfuric and in what other circumstances is an azeotropic nitric acid absolutely necessary? I mean one reason I decided to go the nitrate salt route for my picric acid (and if I ever had to make more picric in the future I'll be doing so that way as well) is the problems I had doing it with nitric acid.

There is someone who posted a video on YouTube where he made TNT using regular 95-98% sulfuric acid (it was slightly discolored I find, meaning he probably didn't fully clean and/or concentrate it from drain opener) and ammonium nitrate. It was the first video of its kind where I saw the whole process (which seemed simple, except for the purification. This guy was THOROUGH in purifying his TNT!). This is not something I was expecting, since on an industrial level I did read that it was made using Oleum and pure WFNA, which are really strong ingredients, and in the lab it can be done with regular azeotropic sulfuric acid and near pure WFNA. I never realized that it could be made with a simple nitrate salt. Yet the guy in the video did it with ammonium nitrate, something I was surprised to see happen with something like TNT.

https://youtu.be/uwASaAqyuAk

This is the video BTW.

So this does make me want to know when using nitric acid in a nitrating mixture absolute necessary vs using a nitrate salt. I've seen NG and EGDN (and I assume DEGDN would work fine with 70% nitric acid, too. Ditto for TEGDN if I can find TEG). I do have all the books that you recommended, and I should read them sometime (if I wasn't busy with other stuff).

So far the only thing I have seen that absolutely requires WFNA is RDX.

But getting back on methyl nitrate. There is a guy on YouTube who did make it and give it a thorough smacking with a hammer and... surprisingly resilient to going bang on the first few blows. This was quite surprising to me. I am not going to think that it is something normal, since the last thing I want is to make a bit of the stuff and think 'haha! I can handle this like crap' and end up losing my hands.

https://youtu.be/MlOtTWVSChI

This is the video.

If I ever did make methyl nitrate it would be for immediate use, or use within the next day or two. The one thing that I learned from all the reading and research over the years is that if there is an energetic material that has been known for a very, very long time and was able to be mass produced, but hasn't, there's probably a good reason for it.

The only exception I guess is ETN. ETN has been known for a long time, but getting erythritol was super expensive until the last 20 years or so, and all niches in civilian and military sectors were fulfilled by long-standing stuff like PETN.

Microtek - 24-5-2023 at 23:20

TNT can easily be made with 96% sulfuric acid, and I've done so myself many years ago. The main reason oleum is used in some industrial processes is AFAIK that you can do it as a one pot reaction, since the SO3 reacts with byproduct water to form more H2SO4. The pushes the equilibrium further to the product side of the equation. In the end it becomes more economical to do it that way. In this video he used about 600 g H2SO4 to make less than 75 g TNT/DNT mix. From crystal morphology it did look pretty pure, but without a melting point analysis, it is difficult to tell.

When you add a dry nitrate salt to sulfuric acid, you do not make azeotropic (68%) nitric, but rather fuming nitric (ca. 95%). The drawbacks of this method are mainly the much higher viscosity which can make proper mixing difficult, and that some nitration substrates are destroyed by sulfuric acid. As a rough rule of thumb, nitramines are not suitable for mixed acids, but nitrate esters are.

Oh, and methyl nitrate is actually less sensitive than NG, but I agree that the volatility makes it impractical.

[Edited on 25-5-2023 by Microtek]

B(a)P - 25-5-2023 at 02:11

Quote: Originally posted by Microtek

TNT can easily be made with 96% sulfuric acid, and I've done so myself many years ago. The main reason oleum is used in some industrial processes is AFAIK that you can do it as a one pot reaction, since the SO3 reacts with byproduct water to form more H2SO4. The pushes the equilibrium further to the product side of the equation. In the end it becomes more economical to do it that way. In this video he used about 600 g H2SO4 to make less than 75 g TNT/DNT mix. From crystal morphology it did look pretty pure, but without a melting point analysis, it is difficult to tell.

When you add a dry nitrate salt to sulfuric acid, you do not make azeotropic (68%) nitric, but rather fuming nitric (ca. 95%). The drawbacks of this method are mainly the much higher viscosity which can make proper mixing difficult, and that some nitration substrates are destroyed by sulfuric acid. As a rough rule of thumb, nitramines are not suitable for mixed acids, but nitrate esters are.

Oh, and methyl nitrate is actually less sensitive than NG, but I agree that the volatility makes it impractical.

[Edited on 25-5-2023 by Microtek]

I believe oleum was also used to allow reaction conditions that were conducive to maximising the yield of the 2,4,6 isomer.

ManyInterests - 25-5-2023 at 04:31

Quote: Originally posted by Microtek

Yes, the viscosity is definitely an issue. When I tried to make ETN with potassium nitrate it was the worst synth I've done with it. Of course this was probably compounded by the fact that I didn't fully grind my KNO3 to a fine powder (which I do now) and not give it a 2nd drying in the oven to drive off any moisture it might have collected in storage... and the fact that after adding I put it in the freezer for a while, which gave it a jelly-like consistency that made things far harder to work with.

I did find interesting that adding a nitrate salt makes it so much stronger than I thought. I thought it would be far more dilute. But I did remember on an other thread that RDX (I know, I am mildly obsessed with getting that energetic out of my bucket list!) that making RDX in mixed acids is not viable, and I realized that it isn't a viable way of doing things.

But that being said, I think I might still give more nitrations with a nitrate salt a go to see how it would turn out. I think it might be more economical in some applications, since I want to make some smokeless gunpowder and NC is a pretty big component of that, and I will need quite a bit of that. I think it would be more economical to use nitrate salts for that purpose.

Herr Haber - 25-5-2023 at 05:53

Quote: Originally posted by ManyInterests

This did get me asking... in what circumstances would a nitration work fine with the dilute nitric acid made by adding a nitrate salt to sulfuric and in what other circumstances is an azeotropic nitric acid absolutely necessary?

Azeotropic nitric acid is 67-69%. The rest being H2O
With the nitrate salt, assuming its dry and you're using 96% H2SO4 you have 4% H2O.
Now, which one is dilute ?

Back to your question. Nitric acid will always be better than a nitrate salt IMO. You can use a nitrate salt if you need more concentrated acid, if heat is not an issue and well often if you accept to sacrifice some yield. Picric acid is a good example.
Some nitrations reportedly work with 10-15% acid

Quote: Originally posted by ManyInterests

There is someone who posted a video on YouTube where he made TNT using regular 95-98% sulfuric acid (it was slightly discolored I find, meaning he probably didn't fully clean and/or concentrate it from drain opener) and ammonium nitrate. It was the first video of its kind where I saw the whole process (which seemed simple, except for the purification. This guy was THOROUGH in purifying his TNT!). This is not something I was expecting, since on an industrial level I did read that it was made using Oleum and pure WFNA, which are really strong ingredients, and in the lab it can be done with regular azeotropic sulfuric acid and near pure WFNA. I never realized that it could be made with a simple nitrate salt. Yet the guy in the video did it with ammonium nitrate, something I was surprised to see happen with something like TNT.

Well, consider your own skills now. You are beyond TNT.
What would be the point for you to "just make" TNT ? I know I would enjoy every step in the nitration, the purification, the isomer separation etc. I actually need a bit of mono-nitrotoluene ! Red water is a pain though...

Anyway, you can skip a lot of what you read about this synthesis. Reverse engineering a few procedures you read to fit what you have at your disposal shouldnt be hard. Here's the thing: the more liberties you take, the more your yield will suffer.

Quote: Originally posted by ManyInterests

So far the only thing I have seen that absolutely requires WFNA is RDX.

Pretty much.

Quote: Originally posted by ManyInterests

But getting back on methyl nitrate. There is a guy on YouTube who did make it and give it a thorough smacking with a hammer and... surprisingly resilient to going bang on the first few blows. This was quite surprising to me. I am not going to think that it is something normal, since the last thing I want is to make a bit of the stuff and think 'haha! I can handle this like crap' and end up losing my hands.

Probably explained in Tome II or in a topic somewhere here. Or both

One interesting experiment requires: an anvil, a hammer, two drops of NG or other, a piece of paper.
The drop on the piece of paper will always be easier to detonate.

Quote: Originally posted by ManyInterests

The only exception I guess is ETN. ETN has been known for a long time, but getting erythritol was super expensive until the last 20 years or so, and all niches in civilian and military sectors were fulfilled by long-standing stuff like PETN.

The first part of your reasoning was correct. There are many good reasons for example why not to load an artillery shell with NG based explosive but that same NG can help make the propellant.
A good reason for staying clear of methyl nitrate is... do you feel comfortable distilling an explosive ?

ETN as you say didnt get that much attention. We hadnt yet enslaved bacteria to produce erythirol back in WW2 !
ETN's melting point is also not desirable for the military or civilian sector.

[Edited on 25-5-2023 by Herr Haber]

ManyInterests - 25-5-2023 at 08:06

Quote:

Azeotropic nitric acid is 67-69%. The rest being H2O
With the nitrate salt, assuming its dry and you're using 96% H2SO4 you have 4% H2O.
Now, which one is dilute ?

Wow! I was REALLY off with that. It also gets me thinking... since one issue I had previously is consistently making WFNA (I did make it a few times, but for some reason it isn't consistent. Maybe it's because of moisture drawn into the nitrate salt that I didn't dry immediately before then and/or the sulfuric acid doing the same, which means I would need to reboil it to make sure it is as dry as possible), or that I simply couldn't control for temperature previously (I will cover this later).

But I do remember that adding a bit of ammonium nitrate (for best results, but potassium or sodium nitrate will work in a pinch) to the WFNA will make for a better RDX yield. Now that I learned that adding a nitrate salt to sulfuric acid basically makes a super concentrated nitric acid, I thought... what if I make 90% nitric acid. would A: Redistilling the same acid with more nitrate salt result in a dryer end product, or B: just adding more ultra acid help in making it more concentrated?

I hope that my (near) future nitric acid distillations will work better. I learned somethings over my previous attempts. That A: The stuff needs to be pure (there might have been some carbonate contamination in my sodium nitrate that was causing issues), B: the stuff needs to be as dry as possible, and C: The stuff needs to be as cold as possible. I got much better results when I cooled down the sulfuric acid as much as possible beforehand, as well as cooling down the nitrate salt, and I also made sure that the water going through the condenser is also as ice cold as possible.

But I was unable to control for temperature since I didn't have a proper thermometer adapter. I got a new joint that will allow me to put in a 240mm ground glass thermo adapter (wrapped in teflon tape for a good, non-acid seal) and be able to monitor the temperature more accurately. The adapter goes half-way in my 1 liter boiling flask and quarter-way in my 2 liter boiling flask.

Is this sufficient depth for still getting a good reading on the temperature? I want to make sure it comes over at the right temperature, which I saw previously as 85 to 90C, am I correct here?

Quote:

TNT wasn't on my radar, though seeing the process done (I am a very visual person and like seeing things be done to make sure I get everything first. You know this by now) was interesting. The only really interesting thing about the video is seeing how he did all this with just a nitrate salt. That was my sticking point.

I might make TNT just for the hell of it in the future, but probably not as much the guy is making. What I might be interested in in making the intermediary product: DNT. I did hear that DNT makes for a burn regulator in smokeless powder and is used in some rifle powder compositions.

But other than that, I actually find TNT to be... boring. I mean it is the benchmark by which all other energetics are judged. An energetics connoisseur being obsessed with it is like a car enthusiast being a little too into Toyota Corollas and Honda Civics. Too boring. :p

Quote:

A good reason for staying clear of methyl nitrate is... do you feel comfortable distilling an explosive ?

ETN as you say didnt get that much attention. We hadnt yet enslaved bacteria to produce erythirol back in WW2 !
ETN's melting point is also not desirable for the military or civilian sector.

I didn't think about the melting point being an issue. Now I know.

But for distilling it? Yeah that might run in a chemical plant, but at home I would be more doing it the simply way of very slowly dripping methanol into the nitrating mixture in an ice bath while mixing like there's no tomorrow.

Microtek - 26-5-2023 at 00:19

If you want to concentrate your nitric further, redistil it from more sulfuric acid (distilling from KNO3 or NaNO3 would be completely pointless, though Mg(NO3)2 or P2O5 can work - you need something that will scavenge the water molecules. Concentrated sulfuric is the most practical). You don't need a thermometer for this kind of distillation, just go pretty slow to avoid too much thermal decomposition (besides lowering your yield it will also dilute your nitric, since water is one of the decomposition products). If you want to really make a difference, distil under reduced pressure. This will make it possible to almost completely avoid thermal decomposition (because you are distilling at a lower temp), while the nitric is coming over at a reasonable rate.

HNO3 H2SO4 trick

Hey Buddy - 26-5-2023 at 18:40

I love nitric acid and I love PTFE. Here is one of those neat tricks. If you make some HNO3 and put it in a small mouth Erlenmeyer, you can lightly stretch PTFE tape over the opening and tape the circumference with electrical tape to hold it in place. You can heat the HNO3 and it drives water off through the PTFE and will bring HNO3 beyond azeotrope. A diaphragm concentrator. This is sort of a red neck engineering thing, so you have to play with a few types of PTFE and stretching and the temperature to get a good system. I havent measured the resulting HNO3 concentration because I havent taken a serious effort at it, but it works. Also works with concentrating H2SO4.

ManyInterests - 26-5-2023 at 18:51

Quote: Originally posted by Microtek

If you want to concentrate your nitric further, redistil it from more sulfuric acid (distilling from KNO3 or NaNO3 would be completely pointless, though Mg(NO3)2 or P2O5 can work - you need something that will scavenge the water molecules. Concentrated sulfuric is the most practical). You don't need a thermometer for this kind of distillation, just go pretty slow to avoid too much thermal decomposition (besides lowering your yield it will also dilute your nitric, since water is one of the decomposition products). If you want to really make a difference, distil under reduced pressure. This will make it possible to almost completely avoid thermal decomposition (because you are distilling at a lower temp), while the nitric is coming over at a reasonable rate.

By reduced pressure you mean to apply some vacuum to it? I am not sure if I have a pump strong enough for that, but my days of playing it by ear and eyeballing the flask at over. I need to monitor it very closely and not let it go above 90C. According to the wiki

Also you mentioned how water is a byproduct of decomposition? So that explains how water got into my acid.

Speaking of which, I've been making quite a bit of potassium nitrate and I am finding the yields to be weird... this is despite doing what I normally do with this stuff. I'm gonna make some nitric acid real soon just to see if I can make good nitric with it or not.

Microtek - 27-5-2023 at 13:11

Yes, a vacuum distillation is what I'm talking about. You don't need a very strong vacuum, just enough to reduce the boiling point of the nitric a little. I draw vacuum of about 0.5 bar when I distil nitric. I use an aspirator, which can draw down to about 0.02 bar at my tap water temperature. If you grease your joints properly, you don't need to run the pump all the time - I run it until I reach the aforementioned 0.5 bar, then close a valve in the vacuum line (before turning off the water, or water will get sucked back into the system). I have a low-pressure barometer installed, and it takes hours before I have to run the pump again, so usually one or two times is enough for a batch.

ManyInterests - 28-5-2023 at 21:33

I'll consider that. I have a very small (but disposable) air pump that I can use for that purpose.

But on an aside note, and maybe a bit off-topic, but I have quite a bit of HDN (hexamine dinitrate) that I want to use to turn into RDX. I initially dried it by putting it in a closed box with lots of calcium chloride near it. I am not sure if it absorbed more moisture since then, but I wanted to know if I can dry that stuff in the oven.

I know the melting point of HDN is around 170C, so I will of course not be heating my oven that high, but what I am thinking of doing is preheating my oven to 120C or so and then turning it off, then put a glass baking dish with the HDN near another glass baking dish with calcium chloride next to it and putting it in the oven as it is still hot, but cooling down. Is there any danger to this? Or will it help in making my HDN super dry for RDX synth?

Microtek - 29-5-2023 at 08:58

I have had some batches of HDN decompose from heating on a steam bath (which of course can't exceed 100 C at one bar), so I would recommend not drying it that way. I think that a hotplate set to 50 C, or a heating cabinet at the same temp would be a better option.

ManyInterests - 31-5-2023 at 07:10

I don't have a heating cabinet. I will find something. Maybe preheat the oven to only 75C before switching off? The temperature would be a bit too low to damage it. I will test it with a bit.

Right now I am having issues with my new setup for nitric acid. The adapter that I thought I could use was no good and I needed to use a Clairsen adapter with another 3-way on one side. I think I didn't put my thermoproble (I am using one of those small tiny ones for this) at the absolute bottom of the adapter, which I guess meant that once it got to 90 and started to climb, it condensed back into the flask. I was told that it needed to be higher up. Which I will do next time.

Microtek - 31-5-2023 at 08:17

The longer the distillation path, the more you will need to heat it to collect anything. This can be a problem with compounds that suffer from thermal instability (such as nitric acid). You can mitigate the problem by insulating the upper parts of you setup (wrap it with a cloth and use Al foil or a clothes pin to keep it in place). You can also shorten the path as much as possible by eliminating any extra joints between the boiling flask and the condenser. There really is no need for a thermometer (or probe) for this distillation.

ManyInterests - 31-5-2023 at 22:20

Quote: Originally posted by Microtek

The longer the distillation path, the more you will need to heat it to collect anything. This can be a problem with compounds that suffer from thermal instability (such as nitric acid). You can mitigate the problem by insulating the upper parts of you setup (wrap it with a cloth and use Al foil or a clothes pin to keep it in place). You can also shorten the path as much as possible by eliminating any extra joints between the boiling flask and the condenser. There really is no need for a thermometer (or probe) for this distillation.

OK so once again I would direct you to my thread in Beginnings.

I found a workaround that uses my old setup, but since I have a smaller thermoprobe, I was able to insert it in the small thermometer adapter hole. I wrapped it with copious amounts of teflon tape to protect it and seal the hole at the top. I did not see any gasses escape and after the distillation I washed it and removed the tape. It was intact. So I know this way I can measure the temperature while keeping a short path.

The only problem is, I got 75% nitric acid. Maybe it was because of the mishap yesterday (probably that) But I did see that nothing came over until the temperature reached 113. Maybe I kept the the small thermoprobe a little too high?

If you look at the picture, that little white thing in the adapter is the probe head. What do you think of the setup?

IMG_20230601_000549950_HDR - Copy.jpg - 1.9MB

Microtek - 1-6-2023 at 08:27

The setup looks fine, but add insulation as described above and preferably some vacuum if possible. Vacuum is obviously NOT possible with the improvised thermocouple adapter, but you could just replace that with a stopper (if you have one). PTFE tape is not great for vacuum seals, I would replace with grease (or old school conc H2SO4 if you don't have grease). Ideally you shouldn't see red NOx fumes in your boiling flask since these are a sign that your HNO3 is decomposing (though I have heard that a little is unavoidable if using nitrate salt and sulfuric - another reason I prefer to use 65% HNO3 instead of a salt).

ManyInterests - 1-6-2023 at 18:19

I wish I could use a stopper, but the joint that I have doesn't allow for it. I will see what I can do to make a small vacuum filter. I have a small tiny little air pump. It isn't much and is very weak, but it is cheap and I don't mind losing it if the acid vapors destroy it.

The thing is, I've ALWAYS seen red fumes when I power up my mantle. I think what I am going to do now is to gradually increase the temperature. Like start to make it go to 50C and gradually raise the temp until I set it to 85 or so.

Hey Buddy - 15-10-2023 at 14:38

Quote: Originally posted by Hey Buddy

I love nitric acid and I love PTFE. Here is one of those neat tricks. If you make some HNO3 and put it in a small mouth Erlenmeyer, you can lightly stretch PTFE tape over the opening and tape the circumference with electrical tape to hold it in place. You can heat the HNO3 and it drives water off through the PTFE and will bring HNO3 beyond azeotrope. A diaphragm concentrator. This is sort of a red neck engineering thing, so you have to play with a few types of PTFE and stretching and the temperature to get a good system. I havent measured the resulting HNO3 concentration because I havent taken a serious effort at it, but it works. Also works with concentrating H2SO4.

I must have been smoking crack when I wrote this. I somehow have a memory of doing this but recently I tried it and it doesnt work at all with HNO3. It does work with H2SO4. I dont know why I thought it worked on HNO3. Anyways, on standard ptfe, when its stretched NO2 goes right through tape so dont waste your time. I did however notice the NO2 slips through the PTFE with ease, like its not there. NO2 I believe is smaller than H2O. Not sure of HNO3 molecular size... it may be possible to pull H2O out in a reduced pressure distillation with PTFE membrane... need to experiment

[Edited on 16-10-2023 by Hey Buddy]