HNO3 the easy way

[kingspaz]

right, you are trapped in a desert and need a piss but don't want to lose the water. what do you do? you piss in a whole and put a plastic bag over it with a stone in the centre to make a cone. the water from the piss evapourates and condenses and can be collected with a cup underneath the bag. now try this with HNO₃ :)
this was originally thought of by simplyRED. all i have done is develop this a bit.
the idea is to take the mix you would normally distill containing H₂SO₄, HNO₃ and xHSO₄ and apply the desert survival technique.
it works because H₂SO₄ boils at a very high temperature compared to HNO₃. this means sulphuric acid evapouration will not be significant. i made an electric version of this principle by holding the acid container in a kettle to act as a water bath. the original idea was just to leave the kettle on but this didn't work because the water boiled too violently and the confinement of the main container inside the kettle created jets of boiling water <img border="0" title="" alt="[Eek!]" src="eek.gif" />
heres the pics to explain it better.
<img src="http://www.boomspeed.com/kingspaz/distillerdiagram.JPG" alt=" - " />
<img src="http://www.boomspeed.com/kingspaz/distiller.JPG" alt=" - " />
sorry if this post comes across as a bit confused but i'm really tired!
oh almost forgot, it does work pretty well too :cool:

[Mr Cool]

I would be better to lift the receiving jar out of the acid mixture, to stop it from heating up as much.

[kingspaz]

yes but i don't think it would make that much difference as this unit is designed to operate for a while so no matter how good an insulator is used between the collecting flask and the HNO3 source the heat WILL get through eventually. also it doesn't really matter because once the HNO3 is in the collection flask it gets trapped in a cycle of evapouration, condensation and returning to the flask.

[BrAiNFeVeR]

I took a shot at this too, but my results are not that good, mainly, I think, because I heated it too much. (didn't had much time)

I got a lot of NOx due to thermal decomposition of HNO3 (for pictures, look <a href="http://www.geocities.com/brainfevert/hno3.html" target="_blank">here</a>), a low yield and a relatively low percentage of HNO3.

I don't know how the water got in there, my NH4NO3 didn't contain much water.

[kingspaz]

the water came from decompostion of HNO3...2HNO3 ---&gt; 2NO2 + H2O + 1/2O2
i think thats right, some one correct me if its wrong please.

<small>[ January 01, 2003, 10:16 AM: Message edited by: kingspaz ]</small>

[simply RED]

The first time the distilator was tried using Ca(NO3)2, H2SO4 mix. The Ca(NO3)2 prills were crushed and then heat to drive off the chrystalohydrate water. Then mix with H2SO4 (the H2SO4 was 3/2 the calculated mass but i don't think it will matter if you make it stechiometric). Some mililiters of water were added to start the reaction.
After the distilation on the bottom was left unsoluble in water CaSO4.
The nylon is good to be substituted with glass, because it can rip if you distil too long.
At the end i made 1 liter HNO3 (suitable for RDX)
(in the experiment was wasted material for 1,5 liters :) )
Still don't know what is the optimal temperature for distilation...
My source says 85 degrees C is the optimal temperature.

<small>[ January 01, 2003, 10:38 AM: Message edited by: simply RED ]</small>

[THe_rEaL_dEaL]

Here’s an idea a bit off topic but still concerned with acid concentration/distillation.

This apparatus could be used to concentrate Battery Acid/Dilute H₂SO₄

You may think wow.... Big deal. What a waste of time.....but!

It could give an easy way of calculating the approximate percentage purity of the concentrated acid.

If the percentage purity of the battery/dilute acid used is known, then by finding the volume of the distillate, (mostly H₂O) the percentage purity of the concentrated acid can be found. Assuming that the density of water is approximately 1g/ml at 3.98^o C.

This could be useful to people who don’t have precise scales for density testing or a precise thermometer for testing boiling points. A measuring cylinder can be used instead.

Another idea :)

A hose connected through a hole at the bottom of the collection jar could lead distillate away to prevent water evaporating back into the ppe jar. Sit a second collection jar on the floor and the apparatus on a table so the distillate could drain through the hose into the second jar on the floor.

Back on topic :cool:

The hose idea could possibly be used when distilling out HNO₃ from a Sulfuric, Nitric, and Sulfate solution. A valve could be fitted to the hose somewhere close to the apparatus so that the distillate could reflux. Near the end of the distillation, the valve could be opened to drain the distillate. The small amount of nitric, yet to be collected would then flow straight into the second jar. This could prevent nitric being left behind in the still because the distillate nitric quickly passes through the hot collection jar and into the second, cooler collection jar. This could prevent reflux leaving nitric in the still and thus extracting the most nitric possible from the initial solution.

Hoses containers and valves would need to be made of a substance that can resist corrosion from concentrated nitric acid. PTFE and lab glass comes to mind.

Comments, Criticism, Suggestions?

[Mic]

I am questioning myself for the sort of plastic we can use for this method for producing HNO₃.

Is polythene suitable for HNO₃?
:confused:
Thanks

[stanfield]

yes, it resists a bit, but it will be eated after several distillations...

[A-BOMB]

I was thinking instead to plastic why not use a glass funnel? I thing it would be work better than plastic and would allow it to drip right in to the collector. Like in this drawing.

<a href="ftp://ewf:sd332gf@209.195.155.80/Hosted%20Images/New%20Folder/HN03.jpg" target="_blank">ftp://ewf:sd332gf@209.195.155.80/Hosted%20Images/New%20Folder/HN03.jpg</a>

<small>[ January 10, 2003, 09:51 AM: Message edited by: A-BOMB ]</small>

[simply RED]

The smaller the anagle of the collecting cone the bigger its surface, the fastest the speed of distilation.
The smaller the collecting glass, less acid will condense on it, the faster the distilation.
The higher the temperature the faster the ditilation but 90 degrees C is the upper maximum.

[mongo blongo]

I would go with the glass funnel idea. I was actually thinking of the same kind of thing. I would not want the plastic being eaten away and breaking when in use. The glass funnel would need a bit of sealing so the HNO3 wouldn't escape out of the sides. It would need some sort of venting to release pressure though.

[BrAiNFeVeR]

For the venting, I just made a tiny hole in the plastic, on the flat side of my big glass container.
So whenever pressure rises, and blows up the plastic a bit, it opens up the hole, and releasing the overpressure.

Has anybody had descent yield using this method ?

[knowledgehungry]

I tried this method and got a very clear liquid, I am positive that it was not highly conc. nitric because it didnt smell like nitric, fume like nitric or have the same density as nitric. I think either some ice leaked through my Al foil cone or moisture from the air also condensed on the cone. I think that it is the former because i got a far larger amount of the mixture than one would expect with condensation from air. I really like the idea for this method but it needs some fine tuning for me to get it to work.

[nbk2000]

Use a glass funnel with the stem flame sealed, or an old martini glass with the stem cut off, and place it over the mouth of the jar.

Rather than ice, which could leak water, use glycol and dry ice. This would be infinitely more efficient at condensing the nitric, with no risk of water dilution.

<small>[ January 10, 2003, 07:21 PM: Message edited by: nbk2000 ]</small>

[mongo blongo]

You might get a layer of frozen HNO3 on the funnel though and won't collect in the beaker.

[nbk2000]

Anything that might freeze on it will melt when you stop adding the dry ice. Plus, the constant immersion in the nitric "steam" will ensure that it doesn't freeze up too badly. After all, nitric doesn't freeze till about -50F, so just go light on the dry ice, eh? <img border="0" title="" alt="[Wink]" src="wink.gif" />

Also, Ye Olde Timey distillers that used this sort of arrangement, would suspend a smaller funnel underneath the point of the cone with a tube leading out so that the product was removed as soon as it was formed.

<small>[ January 10, 2003, 10:13 PM: Message edited by: nbk2000 ]</small>

[simply RED]

It is not need to make a small hole for venting.
The pressure in the vessel is equal to the pressure of the HNO3 vapours and the pressure of the air. The HNO3 condenses so its pressure does not matter.

[BrAiNFeVeR]

When you're constanlty standing near it, it wouldn't be needed to make that pinpoint hole, because then, you fill up on ice regulary, thus keeping the condensation rate high.

If, however, you're anything like me, you'd rather distill at a lower temperature (I used 60°C) and just use water instead of ice in the cone. Now I'm just looking for a system that feeds it water when it needs it to compensate for the evaporation ...

I'm getting off track there, the point was, if the condensation rate isn't high enough for some reason, you ARE getting overpressure, which bulges up the plastic, pouring over the water, and thus removing all means of cooling, and creating an ever bigger overpressure !!

In this case it would be better to evacuate a bit of HNO3 vapour, then to come back in a few hours later, finding a plastic balloon filled with HNO3 vapour ...

[nbk2000]

How about feeding polyethylene tubing of the right size to just barely be forced through the stem of the funnel, and having it wrap around the exterior of the cone (inside the jar), and the end coming back through the top rim of the funnel, to drain the flow of cooling water out into a sink? :D

Simple, and cheap. <img border="0" title="" alt="[Wink]" src="wink.gif" />

Also, it'd be advisable to have this running outside because of the highly toxic nature of NOx fumes. You could have a very small leak, but the extended length of exposure over the course of hours inside of a closed room could hurt you. May not kill you, but it could cause impairment and make you susceptable to lung infections you might otherwise not have gotten.

[DarkAngel]

<img src="http://entersection1.virtualave.net/Pictures/nitric.JPG" alt=" - " />
I tried something similar like on the picture only my heat source wasn't good enough so it failed.
It's made from 2 coke bottles, One with only the top and the second the top and bottom cut off.
The first bottle holds the collecting jar the condenser and the chemicals and the second bottle where the top and bottom are cut off is placed over the first bottle.One hole is punctured into the second bottle where a hose is inserted which let water flow away when necessary.
The only problem is that water leaks out through the space between the 1st and 2nd bottle so something needs to be find to prevent this.

<small>[ January 12, 2003, 11:35 AM: Message edited by: DarkAngel ]</small>

[Axt]

I think this method holds most merit as a vacuum setup, since the apparatus is so compact it could be easily confined inside a larger pressure vessel.

This could simply be done by using the glass funnel in the bottle and using a glass marble (or teflon coated bearing) in it to form some sort of check valve allowing pressure to equalise between the vessels, but sealing the pressure vessel from the acid.

The vacuum is easily created by fixing a large syringe, and drawing the air out through a valve. You can just use common copper pipe/valves/fittings for this as its not in contact with the acid.

Id post a picture but ive lost my motivation to do so :mad: .

Edit: Actually you can pollute your eyes at totse if you wish to view the PICTURE (http://www.totse.com/bbs/Forum19/HTML/004163.html) . They seem to allow you to post them.

[vulture]

A syringe for pulling a vacuum? :rolleyes:

Use your brains for gods sake. You'll pull a tiny weeny bit of vacuum in the beginning, but as soon as the nitric starts evaporating it will get back to 1 atm or higher.

You couldn't even use a vacuum aspirator, since this would draw all your nitric vapors out before they can condense.
That's why the vacuum connector is always connected to the distilling flask in a normal setup.

[Axt]

I think your wrong.

I believe it will form some sort of equilibrium at a certain heat and pressure, where the pressure will stabalise and vacuum can be maintained. The HNO3 going through the liquid/gas cycle will for the most part be trapped within the cylinder. After all, it is exactly the same as the methods above but working in a reduced pressure environment, even if the vacuum has to be "topped up" now & then. Though I couldnt think of an easy way of cooling the funnel.

And for the record, I know fuck all about vacuum distillations.

[vulture]

You're vaporizing HNO3, if you suck away HNO3 vapor more HNO3 will evaporate to compensate.

In a glassware distillation setup the vacuum outlet is positioned behind the cooler because most HNO3 is in liquid form there, so that you aren't simply wasting HNO3 vapor.

[Axt]

Acceptable loss.

If a pinhole was used through the bottle just under the funnel to allowing the pressure to equalise, which would allow you to cool the condensor (funnel) with water the losses will be minimal. After quality, not quantity.

[simply RED]

When you use this type of distiller, driving away the air will significantly faster the distilation.
Why?
The speed of distilation depends from the concentration of the HNO3 vapours. The more concentrated HNO3 vapours, the faster the process.
immagine the next example:
You have isolated your distiller from surrounding atmosphere. In one moment the pressure inside is reduced 2 times. The HNO3 then begins to evaporate quickly and fills the space with denser fumes. Until the mols of the evaporated HNO3 is equal to the mols condensed HNO3.
The pressure inside will not be equal to the atmospheric pressure because the aparature will be isolated (sealed well). The pressure inside will depend from temperature.

[Axt]

Yep.. Ive convinced myself enough that itll work, and well enough to try.

Ive began on a pressure vessel (steel), 12"x18"x5mm. this assumes I can get hold of one of these (http://www.steps-to-memories.com/Glass/fsg2643.jpg) to make use of the volume.

I was under the impression that not terribly much vacuum is needed to prevent the decomposition of HNO3, What vacuum should it be run at. Is it a case of "the more the better" (more the faster)?


Take a look here (http://ww1.altlist.com/~52497/rogue.altlist.com/images/vacuumstill.jpg), tell me what wont work before I get too far into it.

[kingspaz]

Axt, shouldn't the vacuum pipe go into the HNO3 vessel and not the oil bath vessel?

[Axt]

Originally posted by kingspaz
Axt, shouldn't the vacuum pipe go into the HNO3 vessel and not the oil bath vessel?

No, mainly because I wont be able to do it. Its so much easier working with steel. Im assuming here that the temp. difference between the "condenser" and oil bath will be enough that the small amount of HNO3 vapor to escape through a pinhole near the cone will be negligible.

[nbk2000]

I'd raise the receiver for the nitric up out of the oil so it's not heated as much, making it easier to keep it condensed. :)

[simply RED]

Which plastic is resistant from heat nitric acid (100 degrees) 98% concentrated?
It must be resisitant form mixed acids too.
PVC?

[blindreeper]

I think polytetrafluroethylene would hold up. But it may be hard to get. Don't quote me on this but PP (polyprypolene sp?) may be resistant and it is available in some products such as watering cans where the PP can be around 5mm thick and you can mould it with heat.
But the best bet would be PTFE

[Axt]

A wine glass could be used to bring the collecting vessel up out of the nitrate/acid mix. Not sure if it will be any cooler, but in the very least it will stop the collecting vessel floating around.

I was thinking of using these - http://www.bestcontainers.com/drum-liners-heavy-duty--ptfe--drumright-tm--teflon-r--liners.html for the acid/nitrate, that way you could use steel to make the correct sized jar for the glass cone to sit on, but they are bloody expensive.

[Mr Cool]

Axt, while your diagram is nice, this topic is called "HNO3 the easy way"!!

Would it not be easier and more effective to buy some glassware?

[simply RED]

1. Never use oil bath. Sometimes the glass brakes. If hot nitric acid mixes with oil, it will be a huge blast and fireball.
2. Do not use vacuum if you distill in quantities less than 2 liters HNO3 per cycle. If the condenser is near the acid (or acid - nitrate (tested with Ca and Pb nitrate). The speed is fast enough.at 80-100 C.
3. If you use vacuum, make the vacuum in the distilation vessel, this will speed up the process.
4. Make the condenser(the upper (wineglass) part) form a bottle, cut it from the middle and fill with ice. Use plastic cap to secure the bottle. No matter tiny holes absolutely no HNO3 vapours escape.
5. Use medicine syringe with attached hose to drive off the k.HNO3.

No matter with vacuum or not this is easier to make and cheper than normal distiller. Plus it never needs vacuum pump to work all the time.

[vulture]

1. I always use an oil bath, because otherwise you're mainly wasting energy on evaporating water.
Just heat up the oil slowly and make sure the temperature difference doesn't get too high.
You could always use synthetic non-flammable motor oil.

3. Ofcourse, in the distilling vessel the nitric is mainly in fluid form, so it won't get sucked away like the vapour. That's exactly the problem I'm trying to point out with your setup, because there isn't enough separation between the distilling and evaporating vessel, thus you're sucking away a great deal of nitric acid vapor.

5.Medicinal syringes will melt to goo in contact with hot nitric acid.


Glass distilling setup works perfectly for nitric even without vacuum. Looking at the construction Axt is going to make I have my doubts about it being cheaper. I got my whole setup for 100€.

Use teflon grease to cover your plastic. It's relatively cheap (12€/500g) and you don't need much.
I found it in the automotive supplies section of a big supermarket.

[nbk2000]

Using water, instead of oil, is the only sane thing to do.

RTPB "Plan for Failure".

You must assume that the flask will implode while drawing down the vacuum, and that it will happen at the worst possible moment.

Imagine hot, concentrated nitric acid oxidizer being explosively mixed with a hot hydrocarbon fuel by a vacuum implosion. Hot oxidizer...hot fuel...BOOM! Cooked vulture. :p

If it's water, instead of oil, worst thing that happens is a big mess and a lot of dilute acid to be cleaned up, not a flaming fireball.

Better yet, use sand, since it's inert and a solid.

[Axt]

Buy glassware! .... :confused: It is much easier for me to make whats in the picture then to somehow aquire a glass distillation setup.

Im not sure how stupid im going to sound by saying this, but is it possible to draw such a vacuum from the chamber so that heating isnt even necessary? at what pressure? that would solve many problems.

[Milamber]

If you did that, the problem is that the receiving vessel would ALSO be at a pressure that low, meaning that the acid in there would evaporate too (or, more to the point, would not condense) without being put in a cooling bath, which is sort of difficult if using the jar-in-a-jar setup described above. It could work using a real still, but you'd need to immerse the receiving flask in a cooling bath and you'd need a vacuum of around 20 torr (assuming a BP of 122*C for 70% nitric, and 25*C as room temperature) - which means a good aspirator or a pump. Problem there is unless you have REALLY good cooling, there's still gonna be a lot of vapour from the receiving flask, which would be happily sucked up by the vacuum source. The aspirator would probably suck a lot of nitric fumes down the drain with the waste water, while a pump could suffer severely from exposure to the fumes.

[simply RED]

Axt, do you need so much acid? :) Without vacuum it works fast enough, try it to see.
Syringe is not even touched from cool nitric acid in any concentrations. Never tried to displace HNO3 hot.
Axt's construction is not wrong. Only the recieveing glass may not touch the hot acid. The idea here is to make the vacuum once, and not use a vacuum pump working all time.
This of course is near(near absolutely) impossible to make at home... It needs perfect sealing.
If all the time vacuum pump is used, HNO3 vapours will escape.

HNO3 in the receving vessel will be cooler, not only that, it will be (97%) which evaporates slower than the acid in the H2SO4 mix. (with vacuum or not no matter).
Don't know for the others, but for me buying glasswere is not posiible. Thats why i make such constructions. This costs absolutely nothing to be made and works much better than non-vacuum device.
Where do i know about the shattering glass! Yesterday the jar shattered while distilling :)
before that, i had never thought what bath to use. (i was using water when the jar shattered, and of course with water nothing happened). (happily the distilled acid survived).

I never had any instruments to measure temperature vacuum and so on.
(now i have digital multimeter "Lamar" for 9 dolars which measures temperature with probe.)

What do you want.... 1 liter sulphuric acid 98% - 2,5 dolars. Ca(NO3)2 -5 kilos - 2 dolars. No funds or time for complicated devices....

[Axt]

Im finding it hard to get my head around this, does that mean to create a vacuum of 20 torr one would have a pressure of 559 psi pressing on the outside of the vessel?

1 atm = 760 torr = 14.7 psi.
760 / 20 = 38
38 x 14.7 = 558.6

It was always assumed that the HNO3 would continue to evaporate from the collecting vessel, but once vapourised it should condense and fall back into it so it will either be in the air, on the condensor or in the collecting vessel at any one time in the cycle. the lower surface area of the collecting cylinder compared to the acid/nitrate will also lower its evaporation.

[Mr Cool]

I'm not quite sure what you mean there Axt... even with a full vaccuum in the vessel, you would only have a net pressure of 14.7 psi on the outside of the vessel. The atmosphere can't exert any more than atmospheric pressure.

(20 / 760) * 100 = 2.6% of atmospheric pressure inside, = 0.38 psi.

(14.7 psi outside) - (0.38 psi inside) = 14.32 psi net pressure on the walls of your container.

:confused:

[Axt]

Correct .. in that im talking crap.

If it was 1 atm inside the vessel it would be 558 outside the vessel to have the vacuum ratio im after.

I was finding it really hard to get a mental picture of how much that really is - thats the way I reasoned with it.

Meaning to create a vacuum of 0.38psi one would have to exert the force necessary to compress 558psi.

[Tuatara]

Axt, you still seem rather confused. The ratio is irrelevant - only the absolute pressures matter. Example: say you were using a piston pump to create the vacuum, and that piston had an area of 1 square inch. If you had a perfect vacuum (0psi) on the low pressure side of your piston, and atmosphere on the other side, then the force needed to hold the piston still would only be 14.7 pounds-force. As you can see, the ratio of zero to 14.7 is infinte, yet the force is still only 14.7 lbs

[Axt]

I did spend last night banging my head against the head of the bed reciting how stupid I am.

Does this mean I could have just used the syringe to begin with.

[bobo]

In the place where I work, there is often a full 10l jerrycan of used piranha standing around because no one likes to haul the stuff away:D This typically means about 65% sulfuric, a lot of water, some H2O2 and NaS2O3 used to neutralize it.

I want to make some nitric acid and think this source of acid is far cheaper than buying sulfuric. now I know that even weeks old, neutralized piranha is evil (I cleaned a bathroom with it. When a liter of piranha met the fungi and shit behind the toilet it bubbled and the trusted smell of piranha fumes became so strong I decided to open all windows). If they see me hauling the chemical waste no one would think of theft:D

Would this be a good idea? I have no idea of the interactions of the other chemicals with fertilizer KNO3 prills let alone the mixture CA, NH4, K + NO3.

[knowledgehungry]

If you boiled it down the H2O2 should decompose and the water should boil off. Im not sure about the NaS2O3 though.

[bobo]

If NaS2O3 is indeed what remains - this stuff SHOULD be added in far less than stoichiometric amount to neutralize piranha. If you add much, a slab of sticky slurry will remain on the bottom. Pouring out the fluid and adding water to this slurry will lead to 'the fumes' coming at you. I cannot figure out a good reason for this.

[densest]

Just a thought about used piranha solution - you could do a couple of things to it:

try mixing a small amount of it with a cold solution of urea - the H2O2 should oxidize the urea (maybe even to HNO3?) In larger quantities be sure to do this slowly and keep the mixture cool. Other organic materials would probably work as well, but there is a danger of explosion if you add a solid or more than a little liquid at a time.

try stirring it with a stainless steel or nickel spoon - this should catalyze the breakup of H2O2 without getting much
random metal in the solution

BTW, according to some graphs (google for nitric acid synthesis or production) with any reasonable concentration of H2SO4 in excess (say 50%) shifts the anti-azeotrope point significantly towards 90% HNO3. Thus a vacuum might not be necessary except to get the last 10% water out.

Sodium bisulfate or aluminum sulfate powder should work as a source of H+. They're much easier to get than H2SO4.

[vulture]

Sodium bisulfate or aluminum sulfate powder should work as a source of H+. They're much easier to get than H2SO4.

Sodiumhydrogensulfate will react acidic, but Aluminiumsulfate will not, since the Al3+ ion is very slightly acidic and the SO4- ion is very slightly basic.

And sodiumhydrogensulfate is not acidic enough (in solution) to produce HNO3 from a nitrate, since HNO3 is a strong acid and HSO4- is not.

[ossassin]

Would anyone recommend fastening the funnel/martini glass to the beaker, or would resting it on top be enough? How much pressure would the reaction create?

[simply RED]

In my last experiments i use duct taped (one layer) funnel to a 3 liters jar. The jar is cut near the top so a higher surface of the funnel could be used as a fume reciever.
The reaction produces no pressure. The best resaults come from distilling Ca(NO3)2 fertilizer or NaNO3 + k.H2SO4. Maybe NaNO3 is the best choice.
The acid is collected in 800ml jar inside the big one, put over another jar to insure low heat transfer.
All heat on sand bath at 100 degrees celsius.
At the end of the distilation (500-600ml acid collected(hours are needed)), after colling the system, the 800 ml jar is extracted with "jar catcher" and put immediately in a bucket with water bath.
After this, all the acid is immediately "converted" into RDX with hexamine dinitrate.
Here lies the big problem. With no acetic anhydride the yiled is not perfect...

(the reaction produces "very low pressure" as said upper, it is done on atmospheric pressure)

[al93535]

I get quite nice, very high purity clear HNO3 from very simple distillation. I use a large pickle jar, set inside it a small cup upside down and a small mayson jar right side up on top of it. I then add about 300ml 95% H2SO4 and either appropriate ratios KNO3 or dilute nitric. I went to the good will and bought a coffe machine for 5 bucks, disassembled it and got the hot plate out. I set the filled pickle jar on top of the hot plate, and turn it on (gets to 55 to 60 degrees). I used no water or oil bath, like last time. I used another hot plate last time and set to 75 and got yellow nitric from decomposition. So this way I get no decomposition and pure clear HNO3. I then use 3 mil thick plastic sheeting from home depot to lay over the top and make an inverted cone into the mayson jar, and fill with ice water. This plastic sheet stands up excellent for up to 5 distillations. I got about 75ml HNO3 for 9 hours running time. I can take pictures if you guys want. The coffe hot plate I think is a great idea. What do you think? Also, with a real distillation set-up what kind of results do you get, if anyone here is using one? Time for how many ml's? Thanks for all the great information guys. ;)

[Mr Cool]

Simply RED, could you tell me the width of your funnel, roughly what surface area the acid/nitrate has, and how long it takes to collect that much acid (500-600mL)?
I've recently acquired a nice big funnel, so this method may now be practical for me to distil useful amounts of acid until I replace my condenser.

Edit: al, I never bothered to time my distilations, but I generally distilled at the rate of about 3-4 drops a second. You can do it faster with more vigorous heating, but then you'll probably get more decomposition. I found that when distilled at 1atm at this rate the acid was barely yellow, and good enough for respectable yields of RDX.

[Mendeleev]

I found that 1 layer of saran wrap holds up just fine to hot nitric vapors for at least one 12 hour distillation. Also, about distillation being slow, how the hell do they do it in industrial plants? I mean they have to operate on thousands of liters a day output, so how is it that they can distill so quickly, if they have to keep the heat/vacuum at a certain point, otherwise the water or other contaminating liquid will distill over?

[simply RED]

The active funnel surface is about 3-4 square decimeters. The evaporating surface is lower. It distills at a rate about 2 drops a second. Maybe slightly slower. 4-6 hours for 400-500 ml. Maybe slightly faster.
400 ml jar is better for recieving than 800 ml.
Use the highest possible surfaces and make higher quantity at one time.
90-100 degrees is optimal if the condensed acid and the "mother liquid" are separated (no heat transfer).
With real setup you get nothing without vacuum. (the vacuum also needs dehydrating of the circulating air)
The big jar can be cut with nichrom red hot wire (in order to place the funnel inside, it cranks exactly where the wire was.

[rikkitikkitavi]

dont worry mendelev , that is why they have guys like me...

no , but seriously it is not easy to tell how a process behaves on larger(industrial scale) compared to the lab. How many times havent I got in discussions with lab people about reactions that are almost impossible to scale-up?

they recyce any decompositon products, better temperature/pressure control (withint mbar and tenths of degress C) , controlling power input and flows e t c . It is actually not so difficult... :)

/rickard

[ossassin]

I like the coffee machine hotplate idea. I'm going to look into that.

[simply RED]

Never let the collecting vessel touch the hot mother liquid.
In one of the last tries, it accidentally happened and the yield was zero because of eveporation.
Use a jar with alluminium foil "funnel cap" letting the acid inside, not letting the fumes outside.

[Centimeter]

I used brainfever's method however I used a hollowed out lightbulb as the vessel for holding cool water. I can then use a slow syphon to replnish the cold water. Using this method I collected about 7 mL of slightly yellow acid with a density of about 1.43 g/cc. I distilled at about 65-70*C for 2 hours. I used KNO3 and ROOTO Concentrated H2SO4. Why did I collect a slightly yellow acid at such low temps? Is it good enough quality for making RDX?

Centimeter

[Mendeleev]

I have actually stopped using brainfevers method :) . Instead, I took two wine bottles, and joined them with piece of plastic hose I bought at Lowes. I then inserted the plastic hose into a larger diameter plastic hose, the edges of which I heated with a propane torch until they were very soft, at which point I ziptied them very tightly, effectively forming a water jacket and a condenser.

I poked two holes in the top and bottom of the improvised water jacket, and inserted a length of hose in each one. The wine bottle screw on caps were made out of some unknown metal so I just melted a thick layer of aluminum onto them, so that the oxide coating forms and protects the rest. I am going to see if plumbing solder works just as well, as it is much easier to melt. You could do it with a match. The holes in the wine bottle caps through which the plastic hose was put were sealed using melted paraffin.

This rig in my opinion is much better as it allows proper cooling of condensation medium and receiving flask, plus it is vacuum compatible, just poke another hole in the cap of the receiving wine bottle, and insert a hose connected to the vacuum source. Make sure the condesner hose is much lower than the vacuum hose so that you don't suck away any nitric acid. I have not tested vacuum, but I have successfully distilled water, and I just recently distilled about 100 mL of HNO3, only 100 mL though, because it is a bit slow :mad: trying to keep the temperature no higher than 65 to prevent decomposition. I hope to soon rectify the rate problem by constructing a vacuum aspirator. A water bath was used for the distillation. I have pictures of the rig, but they are about 2048 x 1600, so I need to edit, so as not to kill the forum's bandwidth.

This rig cost me about 92 cents, because I took the wine bottles out of the recycling, and the rest was about 30 cents for the smaller hose, 35 for the larger one, and about 10 or 20 cents per ziptie. And it is completely OTC. Not bad eh :D?

[aikon]

I collected about 7 mL of slightly yellow acid with a density of about 1.43 g/cc. I distilled at about 65-70*C for 2 hours. Is it good enough quality for making RDX?
Centimeter

Maybe the acid will work but you'll need more than 7mL to get an acceptable yield. The color by the acid is caused by the acid breaking down to NO2. A light yellow color is ok, but a reddish brown or pink acid shouldn't be used. You can try to add a litte bit of urea to it. For RDX you need nitric acid with next to no water in it to avoid the nasty side reactions producing toxic fumes.
Your acid is more likely to produce these side reactions.

[vulture]

You could try treating your acid with O2 gas under pressure for a while. O2 produced from H2O2 would be fine, as a bit of moisture is even beneficial in converting the NOx back to HNO3.

Slight, bright yellow color is normal for highly concentrated HNO3. My vacuum distilled stuff is a bright yellow, but you can perfectly see through. The NOx content is very low, under vacuum it almost immediatly turns colorless by giving away a few bubbles of yellow NOx.

Nothing like the red gas/destillate I got under atmospheric pressure.

[SantasL.Helper]

What would happen if you would, considdering you are using a triple or double neck distilling flask and a normal setup without vacuum, let oxygen flow into the distilling flask (not through the solution, just into the flask) at the same time you are distilling your nitric?

[0EZ0]

SLH, what are you hoping to achieve by doing so? Allowing atmospheric air to come into contact with the contents of the distilling flask would completely kill the distillation unless it was forced in with a high positive pressure. Having an open recieving flask would allow some of the HNO3 to escape as vapour unless the vessel is sufficiently cooled. The resulting concentration of the product may also diminish with extended distillation cycles as it would pick up moisture from the air.

Just "allowing" the contents to come into contact with bottled or chemically produced oxygen would probably do little to remove any discolouration of your nitric. The best method is probably prevention with vacuum equipment of alternatively very low distilling temperatures over extended periods.

[Mendeleev]

Here are the pictures of the still. The first one is one of the earlier ones, before I made the second hose connection to the water jacket, and in the second one, you can see the joint is pretty crude. I had expected the tubing would melt, but it burned instead. However it got soft enough to effectively apply a zip-tie. The metal screw-on caps can be made nitric acid proof through either melting on a layer of aluminum foil or folding several layers of saran wrap which is very resistant to nitric acid, and melting that on. A gentle flame must be used for the saran wrap so that it doesn't decompose. The whole still is made airtight by melting either paraffin or saran wrap around the hole through which the tubing is inserted into the cap. :)

[nbk2000]

How wonderfully Lo-tec, Mendeleev! :)

Stuff like this makes the oppressors disdain of ever gaining total control over their herd of sheeple. :D

[al93535]

Using brainfevers method of distillation, I aquired HNO3 with a purity just under 100% anhydrous. Pure anhydrous hno3's density is 1.5129 and I measured mine at 1.512432 after a double distillation at 60 degrees. Quite nice I must say, thanks brainfever for the wonderful method. I used a pickle jar, two tiny mayson jars, the corner of a gallon zip-lock bag, and the hotplate from a coffee machine, which regulates at 60 degrees. I get pure colorless acid I love to just look at it. With a double distillation I can produce about 200 ml in 3 days. Two days to get about 125 ml each day of 95%, then one more day to double distill that. Also the last distillation goes much faster then the first two that produce the HNO3. :D I plan on making some more RDX!

[nbk2000]

How on earth did you measure 1.512432? That's very precise for a kitchen chemist...

[al93535]

NBK: I used a grain scale for gun powder, it measures down to a tenth of a grain. One tenth of a grain = 0.00648 grams. I used a 1ml dropper, I then added 1 ml of distilled water noted the level, and weighed it until I got exactly 1 gram. I then weighed one ml of the acid at 20 degrees. To be sure of accuracy I also weighed 10 ml, and it only varried by .0008 grams. :D

++++++++++

Good thinking! :) NBK

[PeterB2]

Ok, after a few small scale tests, I amped this one up a bit.

I used ~350 g of cruddy, black drain opener sulfuric acid. Assuming 95% purity of the acid, I started with 332.5 g H2SO4. I used 288.2 g NaNO3. In a old steamer/frier I kept a water bath at about 80-85 C through the whole procedure. For the condensing cone, I used a zip-lock bag corner with an aluminum cone (for safety) inside that which held the salt/ice bath (which I replaced periodically).

After about 12 hours, I collected about 45 mL of bright yellow, see through nitric acid in my glass condesation collector cup. Even assuming a 100% purity, I got only about 68.4 g (estimated based on pure HNO3 density; haven't measured the actual density yet) out of a calculated theoretical yeild of 213.6 g product. Thus, the yeild is only about 32%.

Why are the yeilds so bad even with a relatively high temp and long distillation?

[Emil]

Sounds like quite a bad yield given the amounts of pre cursors used.

The only thing that could be your problem there is purity of your HS2O4 or your Nitrate. With drain cleaner, never assume concentration as it could be a lot worse than you expect. There are endless amounts of different brands out there and some are reported to be of much more use than others. May I ask what brand of drain cleaner it is??

I noticed a very sly piece of information recently with a certain drain cleaner I was looking at. Sure on the bottle it said "Contains 96% sulphuric acid."
But then if you check the box the bottle it's in, it says >51% sulphuric acid. A further check on an internet safety sheet left me with the knowledge that it was full of all kinds of inhibitors and other crap.

I've yet to try my first distillation, but I have all the gear ready, just waiting for some spare time. I'm really looking forward to trying it though. Got some holidays coming up very soon so I'll be planning to try then.

[Masonjar Chemist]

The bad yields are due to the design of the distillation set up. The "collector" being inside of the reaction vessle means that the distillate will coninualy re-evaporate and condense. A band-aid fix would be to create a stand so that the collector is above of the mixed acid as was stated earlier in this thread I believe (my apologies if you already knew this). The only true way of getting better yeild would be useing a conventional "still".

The brand of drain cleaner that I personaly use (liquid lightning drain opener)is black and "cruddy" so I doubt this is the problem.

[PeterB2]

Yes, I did raise the collector above the acid mix with a solid glass cylinder about 1 inch high to try to correct this problem. I waited several hours after cutting off the heat source in an attempt to allow any vaporized acid to condense before I collected it.

In the end, I think I'll just have to save up to get a nice distillation setup. Has anyone seen the glassware for sale on sciencefair.com? Looked like a nice rig to me.

The brand of sulphuric acid I used this time is call "Floweasy Drain Opener" made by Jones Stephens Corporation. According to the MSDS, it is 94.19% H2SO4 by weight.

[rangegal]

How does a still for under $150 sound?

I don't mean to give them free advertising or anything, but I think this is rather relevant. You should check out www.unitednuclear.com. They have RB flasks, liebig condensers, glass tubing, corks, and stands.

You'll need to wrap the stoppers in Teflon tape to protect them from nitric acid though (I can't personally vouch for this idea yet, but totenkov can).

I'm pretty sure you could even use their handpump vacuum filtration kit to make it a vacuum still. That is of course if it can hold up to nitric acid vapor, which I will find out when I get one.

I'm getting a still from them soon, along with some other glassware.

I'll post about how it goes.

[PeterB2]

I tried wrapping rubber stoppers in Teflon tape. Maybe I didn't do it well enough, but it tends to seep through the cracks and get at the rubber soon enough.

If you want to use a distillation setup for nitric, you really need to go for an all glass setup.

I think it's been pretty well established that the plastic in the hand pumps will not stand up to nitric very long unless you have several traps to neutralize the acid.

How about using an all glass apspirator instead? The additional advantage is that the fumes get instantly diluted and washed down the drain. pelletlab.com sells a nice all glass aspirator for under $10. They also sell glass retorts.

[rangegal]

Thats a pretty nice website! Wish I would have found them earlier. Now that I've seen their prices, unitednuclears look pretty bad...

I don't see the glass aspirators though... maybe they discontinued them?

[PeterB2]

From the main menu, click "Filtering Kit" under "Filtration". Should be right there for $6.95. You'll also need the adaptors and tubing.

[megalomania]

In my experience United Nuclear is very pricy, but at least they still sell to individuals, and based on the press they are not fedgov affiliated. Of course they were raided once, so who can say if they won't sell you out to the gestapo thugs the next time they get raided.

[rangegal]

Ohhh now I see it. I guess their search function doesn't work. Thanks PeterB2. I don't get how I would measure the vacuum though, since if the vapors will eat a hand pump, wont they eat any sort of valve or gauge I hook up?

BTW I notice their chemicals aren't badly priced either! (from what I have to compare it to) Their nitric acid is nearly half as much as that Trinity Lab Supply site somebody made a thread about. Not that I'm going to just go buy some nitric, because whats the fun in that?

United nuclear also has a lot of stuff that other sites like pelletlab don't, such as their (limited) pyrotechnic chemicals, isotopes, and aerogel (which I need for my heater/stirrer project!). And I have to give them props for their hydrogen car conversion thing, that is if they ever release it.

[Azido]

I'm in the process of building my own vacuum distillation rig, primarily from Vinyl Plastics and glass.

I built an aspirator, from a bit of T joint for 10mm vinyl tubing. I filled with epoxy filler and drilled a 4mm hole right through and a 4mm hole for the vacuum hookup.

Cost me about $6 for the aspirator and 30 NZD all together.

I'll post more pictures and maybe even a nice Documentary thread when (if) it works. :)

But yeah, the aspirator works, and for cheap. If it is a bit.. makeshift?

[Emil]

As far as what Nitric acid reacts with, I think it's quite hard to determine exactly. I gather that it attacks most materials, but how harshly is the true question. With Infomation on this type of topic hard to find it doesn't make it easy. I'm not sure with plastics how violently it attacks them, of course some more than others.

The only true safe material for use with Nitric is glass, metals are obviously a no no, so a glass aspirator is really an ideal way to go.
Of course it all depends on your situation as to whether a water fed aspirator is any good. If you have mains water pressure at hand then you are ok, but not everyone does.

Given my situation, I'm actually looking into electric vacuum pumps at the minute. You can get hold of some really nice ones, but of course the main problem being that you have to find one which is not made of metal parts. Luckily I have came across a nice range of pumps which are made of different plastics and teflon/ptfe parts, which are meant for increased chemical resistance.

Of course this type of pump comes at a price, not hugely expensive, but I know some people are all for cheaper alternatives and improvisation.

Besides all this, I really doubt that nitric acid attacks any plastics so tremendously that your unable to temporarily hook up a gauge to pull off a reading.

[PeterB2]

I dunno...one time I tried to put a little of my nitric acid in a plastic soda bottle (PET) to see if it would be suitable to store it in. It's not...it turned it white within a matter of seconds, and I didn't want to find out what would happen next.

[Charles Owlen Picket]

Many, many "plastics" today are made to be "bio-degradable". That often means that they are designed to break down and contain organic materials. That's a prescription for frustration. Don't forget that you are dealing with a heat issue as well.

[megalomania]

Acids also attack materials differently depending on concentration. I posted some links to chemical compatibility charts several months ago... Some chemical engineering reference books should have an extensive list. A google search for "chemical compatibility" + your material is a good way to find out.

I don't think most people go around with broad incompatibility knowledge in their heads. This is the kind of thing you have to look up in reference works.

[gaussincarnate]

Some of the best materials for nitric acid are 304, 316 stainless, bronze,
Al2O3, Teflon, Viton, and Ti. So sayeth the Cole-Palmer compatability database. They list a few more, but most of them are not exactly what I would call common consumer products. I would also like to assume that any other metal that can be passivated would be effective, which is more than likely why titanium is on this list.

I know that anondized aluminum has been discussed here to some extent, but it seems almost ideal. The only problem I could think of for some of these materials is their activity with nitrogen oxides or the danger assosiated with heating materials like Teflon.

[Setharier]

I saw a video making nitric acid from KNO3 and H2SO4 heating. 97.7% of you knew this, but question I would like to ask is, do the KNO3 need to be pure or very pure, does it matter if it has some "extra fertilizers" in it? We have here plenty of KNO3 available but in most cases it has impurities like cement etc. random sh*t in it. My Chem Supplier could deliver all of these in lab purity but price is what it is(11€ for 500g, bloody heavens and quite same stuff in 25kg bags for about same price in agristore).

I so wish we would have equal shop in EU like United Nuclear is. After hours of searching our country sites for lab stuff, ending with empty hands, I just open UN site, click once and got EVERYTHING glassware I would probably ever need in my lab life in front of my eyes. That's one more reason for move to USA as soon as it's phossible for me.

[ChippedHammer]

Its relatively easy to purify KNO3 by recrystallization, not that that's needed if you are distilling the HNO3. Straight fertilizer grade is suitable most of the time.

I'm still collecting my lab gear, I now have a complete quickfit glass distillation setup. I just need to turn a few stoppers and thermometer adapters out of my PTFE barstock.

[Cobalt.45]

To expand on gaussincarnate's earlier post, here is a link to a page on compatibility of concentrated nitric acid (and other chemicals) with various types of material, about 42, IIRC: http://www.coleparmer.com/techinfo/chemcompresults.asp

The following are deemed “Severe Effect, not recommended for ANY use”:
ABS plastic
Acetal (Delrinr)
Aluminum
Brass
Buna N (Nitrile)
Carbon graphite
Carbon Steel
Carpenter 20
Cast iron
Copper
CPVC
EPDM
Epoxy
Hypalon R
Hytrelr
Natural rubber
Neoprene
Nylon
Polyetherether Ketone (PEEK)
Polypropylene
Polyurethane
Silicone
Tygon R

Considered “Good - Minor Effect, slight corrosion or discoloration”, are:
ChemRaz (FFKM) (a high-temperature perfluoroelastomer)
Hastelloy-Cr
Noryl R (alloy of polyphenylene ether (PPE) and polypropylene (PP))
PVC

Said to be “Excellent”, are:
304 stainless steel (food service, often)
316 stainless steel
Bronze
Ceramic Al203
Fluorocarbon (FKM)
Kalrez (O-rings, seals)
Kel-Fr
PTFE
PVDF (Kynar®) (tubing)
Titanium
Viton R (available as tubing in at least two different hardnesses)

Glass wasn't listed, but is obviously an "Excellent"-type material.

Various other materials are listed as "C = Fair -- Moderate Effect, not recommended for continuous use. Softening, loss of strength, swelling may occur."