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BerthelotOnCrack
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[*] posted on 1-7-2021 at 03:05
Safety measures for working with NO2


Hello nitration experts,
I'm going to make some fuming nitric acid for nitrocellulose by distillating a mix of sulfuric acid and potassium nitrate. I'm aware this will produce a fair amount of NO2, which is really toxic.
My question is: even though I will do it outside, do I need to wear a respirator ? I do have the right filter, but should I use it ?

Excuse me if it sounds like a silly question but I have never worked with large quantities of NO2 and everywhere I read on it it says that it's a really nasty gas, so I prefer to ask.
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Oxy
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[*] posted on 1-7-2021 at 05:33


Do it with ventilation and preferably with scrubber (u can use 10-15% NaOH). Gas mask can be useful but if reaction will go smooth then scrubber should be enough.

Do not overheat the reaction as it will produce much of nitrogen dioxide

[Edited on 1-7-2021 by Oxy]
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BerthelotOnCrack
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[*] posted on 1-7-2021 at 05:57


Quote: Originally posted by Oxy  
Do it with ventilation and preferably with scrubber (u can use 10-15% NaOH). Gas mask can be useful but if reaction will go smooth then scrubber should be enough.

Do not overheat the reaction as it will produce much of nitrogen dioxide


Ok ventilation, would a fan be enough ? I'm in a totally opened space, I can afford to spill some NO2

Also I have already set up a trap but the NaOH + water solution tends to reflux in the distillated acid...

Finally, should I protect the apparatus from light ? I have heard that nitric acid was sensitive to light, but to which extent ?
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Herr Haber
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[*] posted on 1-7-2021 at 08:38


It's not a silly question if it prolongs your life.

The thing is that you shouldnt get any "fair amount" of NOx if you do it right. If you have time and plenty of ice for cooling doing it slower will *always* be better than faster. Plus, doing it faster gives you acid that is more red than white which is not desirable in most cases.
Forget the NaOH trap especially if you are outside. Put on the mask anytime you can though. If you've got a fan and can use it to push vapors away then by all means do it (change fan when the blade becomes yellow)

You will get some NOx while distilling but nowhere near what you'll get say... if your cellulose is contaminated with some fat.
I never thought it necessary to protect the apparatus from light. First, I can turn of the light in the room I'm distilling acid, second half of the apparatus is covered in Al foil.

One suggestion: if you voluntarily waste a few ml of HNO3 by allowing a reaction to heat up or by introducing impurities you'll have a clearer idea what is acceptable, what should be immediately crashed into water and what would require you to flee immediately.




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[*] posted on 1-7-2021 at 21:07


nitric acid reacts with UV light. I would guess to some extent that would happen in normal sunlight.
As for how hazardous is NO2, the STEL is 5ppm.
For comparison HCN and HS is 10ppm.

The problem is that it forms nitric acid in your lungs, which as you can imagine is bad for you.
People who live in major cities eventually get emphysema from NO2 as do industrial workers exposed to it.
It causes chronic damage.
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[*] posted on 2-7-2021 at 05:56


If you can guarantee always being upwind then it's very safe
If you get a whiff of NO2, even enough to make you cough a little - you'll be ok
I'd have the fan behind me blowing towards me while I'm facing the experiment which is downwind of me.




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BerthelotOnCrack
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[*] posted on 2-7-2021 at 07:57


@Herr Haber
@Sulaiman
Thanks for these valuable indications, I will buy a big fan and do it on windless day, keep the temp at 83°C and cool the recieving flask.

Just a question about the respirator... I am used to it for acid vapors and chlorine because when the filter is dead you just can't breath, so there is no ambiguity about when to change it, however for CO and NO2 there is a precise operating time, which is for my filter 20mn... do I really have to use it *only* this much ? How do you cope with the number of filters you need for longer expositions ?

@macckone
I intend to cover everything with Al foil
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[*] posted on 2-7-2021 at 11:50


The ratings on filters are pretty conservative.
The time is at the maximum concentration rating of the filter.
It isn't exactly linear because CO2 is also acidic from the filter's viewpoint.

As others have mentioned, doing it outside and avoiding the cloud is generally sufficient.
Be aware of the suction vortex created around a stationary object near clouds.
Ie. the campfire smoke always blows towards you.

With nitrocellulose, you can be close by but for more advanced nitrations, you want to put some distance between you and the reaction.
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[*] posted on 16-9-2021 at 19:26


NO2 fumes will take your breath quick. Be careful. I've been making small quantities of WFNA lately, and pull vacuum through a trap, and the exhaust vent on my vacuum pump is vented outside through a hose. Believe if I had a glassware episode during this particular distillation, I'd grab my dog and flee. Worry about cleanup when i could breathe.................



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[*] posted on 28-9-2021 at 05:16


I plan on making fuming nitric acid soon myself. However I will be doing so outdoors as I cannot install a fume hood in my apartment.

What I am also interested in is getting a respirator as well. I did see the 3M filters that are rated for acid vapors. I'm doing research on this myself as there are multiple ratings depending on what it's for. Some are for solvents like acetone, xylene, and toluene, while others do work for acids and nitrogen compounds.

I also am thinking of possible military surplus gas masks (albeit you need to be careful and make sure the filters still work. Many are old and some just have filters for show) as the military often tries to protect its soldiers from as many things as possible, while civilian respirators are more specialized.
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[*] posted on 28-9-2021 at 07:06


I would not trust old military masks and especially their filters. You can buy new mask with brand new filter for ~100 euro.
Until you have full specification of the filter you can't be sure that it will protect you against NO2. Actually not all filters are suitable for that.
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[*] posted on 28-9-2021 at 07:08


ManyInterests, a respirator is good but only as additional protection. We should not rely on a respirator when planning experiments because something could change and the gas concentration can jump in one moment. If your experiment was planned good the respirator will protect you in this case. Otherwise, you have risk because in any case, the more concentration in the air - the more concentration in your lungs. Filter doesn't isolate you completely.
Breathing of NO2/NO in amateur settings is usually not fatal but it is the experience that should be avoided. It damages your lung structure and makes it more sensitive to bronchitis etc.
WFNA doesn't create any appreciable amount of NO2 but it fumes by itself which is also bad. You can get it without vacuum if your starting material and apparatus are clean and you keep a proper speed of distillation. But breathing of fumes of dilute boiling HNO3 is also bad, believe me. But not anything as bad as NO2 - the sensation it creates is most unpleasant, it is probably knife-like, you feel like your lungs get something you are unable to breathe out.
There are a lot of threads about scrubbing of nitric oxides here and a lot of people shared their experience and ideas and some people reported success of complete elimination of nitric oxides. If you look at my short report about making WFNA you will see that I did it inside without any fume hood. I don't recommend doing it this way, of course (also it was not my first experiment with NO) I just want to say that the most important thing is planning.
Do some experiments with distillation not so toxic but just a very smelly compound to check your system for any leaks.
Pay the greatest attention to clamping and fixing everything on a stable stand. The mechanical stability of your system is much more important than the quality of your gas mask. Think about parts you will connect/disconnect also in case of a run-away situation. Make yourself familiar with the "suction-back" properties of NO2 - the worst enemy of any inexperienced NO2 chemists.
Play a bit with NO2 by generating it with Cu or Fe + HNO3 reaction. Take your time to understand what is it that are you working with, make you secure and comfortable. NO2 is a nice-looking gas that could be a pleasure to work with.

Also, if you are not comfortable, try to do distillation in 2 steps. Get HNO3 first and then concentrate it. This will lower the risk.

[Edited on 28-9-2021 by teodor]

[Edited on 28-9-2021 by teodor]
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[*] posted on 14-10-2021 at 19:58


I actually forgot to answer this more thoroughly.

Quote: Originally posted by BerthelotOnCrack  
Hello nitration experts,
I'm going to make some fuming nitric acid for nitrocellulose by distillating a mix of sulfuric acid and potassium nitrate. I'm aware this will produce a fair amount of NO2, which is really toxic.
My question is: even though I will do it outside, do I need to wear a respirator ? I do have the right filter, but should I use it ?

Excuse me if it sounds like a silly question but I have never worked with large quantities of NO2 and everywhere I read on it it says that it's a really nasty gas, so I prefer to ask.


Holy hell is it nasty. When I made nitrocellulose with drain opener it was not bad and not noticable, but right now I have nitrocellulose nitrating with purified H2SO4 and despite using a very small amount (35 grams of KNO3, 110 H2SO4, and 3 cotton balls). The gas it released is unbelievable. I felt it in my lungs and I had to leave my apartment (I did it on my balcony, but I left the balcony door open and the gases all flowed into my apartment instead of outside.

I should also mention that I kept the mixture ice cold the whole time. The temperature never went above 25 degrees Celsius. What I did was put the sulfuric acid in a beaker, placed the beaker in a bowl full of salt water, and froze it in my freeze overnight. The ice was rock solid and the acid was as cold as it was going to get. I added the KNO3 slowly, around 7 grams at a time and let my stirbar mix it into the solution, though I sometimes sped things up a bit with my thermometer.

It isn't bad and it isn't the worst thing to happen... I used impure KNO3 and it was really, really bad. I couldn't take a full breath of air without coughing a bit (I was outside) that it really, REALLY made me apprehensive of doing this without a respirator. I was able to go the gym the next day and do my usual intense workouts and did hours of cardio without issue, so I am not concerned with long-term damage.

Currently I will not do any more nitrations, no matter how small, without a respirator. I will also do my nitrations again on my balcony away from the door and with all windows closed to prevent any gas entry into my apartment, also while wearing a respirator the whole time.

I won't get an old military respirator, but a commercial one that is rated for various chemical work. It's worn by people who work with the stuff on a large scale, so it should be able to handle any quantities an amateur does,
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[*] posted on 14-10-2021 at 21:31


Be careful after being exposed to things which may cause pulmonary edema. Any physical effort is not advised as it may be a trigger to start it happening. This should be taken seriously, you may read about it in almost any medical paper.

You may easily create a scrubber system which can greatly decrease the amount of released gas. If the reaction is done in a controlled manner it can be clean and safe. Respirator will not always help you. 3M and other PPE equipment producers advices to not use gas masks for NO2 but to use air supply. This thing is really toxic and really underestimated by amateurs
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[*] posted on 14-10-2021 at 22:00


Quote: Originally posted by Oxy  
This thing is really toxic and really underestimated by amateurs

I may underestimate the danger,
but has any amateur chemist suffered death or chronic harm from NO2?
I doubt it.




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[*] posted on 15-10-2021 at 01:34


Those who died will not admit.

This forum is not the whole world. I've read some medical reports about NOx poisoning and people get heavily poisoned with the stuff.

It's much more toxic than for an instance HCN

https://www.chem.purdue.edu/chemsafety/chem/PoisonGasTable.h...
https://www.cdc.gov/niosh/idlh/10102440.html
https://www.cdc.gov/niosh/idlh/74908.html
https://www.cdc.gov/niosh/idlh/intridl4.html

Of course - HCN acts much faster but NO2 should be taken very, very seriously.
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[*] posted on 15-10-2021 at 22:01


Quote:
You may easily create a scrubber system which can greatly decrease the amount of released gas. If the reaction is done in a controlled manner it can be clean and safe. Respirator will not always help you. 3M and other PPE equipment producers advices to not use gas masks for NO2 but to use air supply. This thing is really toxic and really underestimated by amateurs


After doing some reflection. I decided that I needed more than a respirator. So what I'm going to be doing is not only do what I originally planned by sealing off my nitration setup in my balcony (and keep the door and window closes as much as possible, except to let the power cord in) but I am getting an personal air purifier with a hose attachment. What I plan on doing is getting a longer hose (I'll need to search for a compatible hose) and place the purifier in my apartment while wearing the mask on the balcony. This will let me breath clean air from the apartment while working with these dangerous chemicals. It isn't perfect and pretty improvised, but it's far better than what I have previously done.

The mistake I made with nitrating with pure H2SO4 is the last time I'm doing that. I know that when I have HNO3 to work with, it's going to be even worse. I will not risk getting pulmonary edema or any other condition. I know the stuff I work with doesn't go that big, but holy hell, I cannot believe the fumes that stuff made.
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[*] posted on 16-10-2021 at 03:34


NO2 can, I believe, be bubbled through H2O2 solution to be recovered as dilute nitric acid.
I've not tried so I don't know how quickly the gas can be absorbed,
maybe others here can advise.
Also, it would be less hazardous/noxious for your neighbours.

PS also not done yet, (like so msny things)
I intend to try to use or store (almost) all by products of my experiments.
Worth thining about?




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[*] posted on 16-10-2021 at 06:29


It is better not to bubble NO2 but just allow it to pass over water. It very eagerly reacts with water and bubbling is not necessary. Bubbling will cause suck-back, so for bubbling 2 bottles should be placed in a line.
After the NO2 trap, NO trap could be placed also (FeSO4 solution).

For de-gassing of the air in case of an incident keep a spray bottle with water.

The ideal weather would be a rainy day.

[Edited on 16-10-2021 by teodor]
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[*] posted on 16-10-2021 at 07:24


Quote:

For de-gassing of the air in case of an incident keep a spray bottle with water.


Hold the phone, you can do that?! That could have saved me so much trouble. The way the ventillation works in my apartment is all air ends up in my bathroom, and there was a super faint smell of NO2 there. Not bad, just really faint. I was hoping that just turning the fan on would eventually get rid of.

Just after you said that I sprayed the entire bathroom with a sodium carbonate solution. Made the floor slippery, but nothing that wiping it dry can't handle.

I'm going to need a bigger spray bottle now. I feel stupid not thinking of that. You've probably saved my lungs at a future date.

Edit: Wow. After spraying the more poorly ventillated parts of my apartment the air has never been fresher! This is just awesome.

[Edited on 16-10-2021 by ManyInterests]
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[*] posted on 16-10-2021 at 10:34


If you prefer you can use also an ammonia solution. But when I see brown gas leaking into my lab I always spray it with just water. It works well also with HCl and H2SO4 vapors.

[Edited on 16-10-2021 by teodor]
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[*] posted on 19-10-2021 at 18:02


I have some household ammonia that I got. The manufacturer's description was that it was a 6% solution with the remaining being water (no other detergents or anything) I initially got it to try to use it to make ammonium picrate. But at this point in time I think I need a higher concentration of ammonia for that synthesis, and I am having questions to wonder if it is worth it to try.

Either way, can I use that specific concentration in a spray bottle or so I need to dilute it further?
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[*] posted on 19-10-2021 at 20:40


6% ammonia sol. should be fine. But expect to see lots of ammonium nitrate/nitrite particles. This will be similar to the reaction of ammonia gas and hydrogen chloride, which was often used as a smokescreen. I personally just use water and leave the area after a gas leak. But if you do use ammonia since it is slightly more effective, it is probably best to do this in a garage or somewhere that won't need to be kept dust-free.

[Edited on 20-10-2021 by Triflic Acid]




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[*] posted on 19-10-2021 at 22:49


The thing is. The reason why I had to spray my bathroom is because when making nitrocellulose I was doing it on my balcony because while in previous times I did it in my apartment with all my windows (and balcony door) open, using pure H2SO4 for some reason released so much gasses it was terrifying.

But... I forgot to close my balcony door. The way my apartment is ventilated meas if I open my balcony door all the air will come in through there. Meaning my balcony would be a great fumehood... if I wanted to flood my apartment with toxic gasses.

I've ordered a breathing apparatus (not a gas mask) that has a hose attached to the mask. I can put the filter away from what I am mixing and I will be getting a small fan to blow away any fumes from me (And my filter) for future nitrations, which will need to happen outdoors... with my apartment door closed. I will not have any more of these incidents. I realize that there is no respirator rated for either nitric acid or sulfuric acid because these are inorganic acids.
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[*] posted on 26-10-2021 at 18:31


OK so I believe I've solved my fuming problem in the simplest and cheapest way possible (it is also effective so I can't complain). Beyond doing everything on my balcony with the doors sealed. I bought a fan from a 2nd hand store and set it up to draw the fumes away from me while I work on the stuff.

To test it, I made another batch of nitrocellulose with my pure sulfuric acid and the results were just amazing. While I did have a dust mask on. I didn't smell anything beyond a brief moment where I caught a tiny sniff and then it went away as my fan did it's job. This was by far the easiest and least smelly nitration I ever did. I hope it does the same when I make picric acid, ETN, and RDX. Ditto for making sure no NO2 enters my apartment when I distill for HNO3.

My next project will be my first hydrazine sulfate. Hydrazine is ultra toxic and I will set the fan to maximum to make sure no fumes come my way.
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