HNO3

[Mic]

Hey I'm planing to build a distillation apparatus for nitric acid and I have a question: can I use Al tubing without problems ? :confused:

If no, what can I use exept of glass ? thanks <img border="0" title="" alt="[Wink]" src="wink.gif" />

[BrAiNFeVeR]

You can only use Al tubing if it is very pure, any impurities will compromise your destillation setup and fill your lab with HNO3 fumes.

The other material choice would be PTFE ...

There is a very interesting topic on HNO3 destillation here:
<a href="http://www.roguesci.org/cgi-bin/ewforum/ultimatebb.cgi?ubb=get_topic;f=15;t=000023" target="_blank">http://www.roguesci.org/cgi-bin/ewforum/ultimatebb.cgi?ubb=get_topic;f=15;t=000023</a>

And this is my page on this experiment:
<a href="http://www.geocities.com/brainfevert/hno3.html" target="_blank">http://www.geocities.com/brainfevert/hno3.html</a>

<small>[ January 06, 2003, 12:37 PM: Message edited by: BrAiNFeVeR ]</small>

[ShockWave]

Hey brainfever, your way of getting the HNO3 is great, but are you using plastic from just a normal plastic or something? doesn't it melt ?

[zylion]

Better use highgrade stainless steel, it cools better and does not get soft en bend. Turning a coil of it won't be such a problem I think.
problems occuring with distilling at normal pressure (760 mbar??) is the forming of the red dreaded gas, that can be minimized by vacuumdistillation(aspirator type) and collecting the nitric acid in a supercooled (&gt; -28 centigrade formed by dry ice and rubbing alcohol or aceton)flask. Placing the nitric acid in the freezer keeps it longlasting. The collected nitric acid will be of +98% strenght as long as the xNO3 was dry and the sulphric acid was of &gt;98%

<small>[ January 06, 2003, 02:14 PM: Message edited by: zylion ]</small>

[knowledgehungry]

Brainfever clear HNO3 is perhaps the most beautiful thing i have ever seen. That is a great method im gonna do it tonite in my dreams most likely.

[PyroTech]

Brainfever I really like your methode but isn't it a waste of time?
You can buy HNO3 &gt;98% I guess it's cheaper than spending/wasting all that H2SO4, but that's my opinion. I'm going too try it though, just for fun, might give me some more experience with chemicals.

[knowledgehungry]

Where can you buy 98% HNO3????
I'm sure that it is not cheaper than using sulfuric, i can get my H2SO4 for 7 dollars for about 4 L, and a 50 lb bag of kno3 for 40 bucks s/h included.

[ShockWave]

Pyrotech, do you mean HNO3 from FLEX ?
Or are there more company's that sell 98%HNO3 ?

[Sparky]

Brainfever, that seems like a very good way to make nitric. Reminds me of a solar still to seperate salt from water and such. Very scalable since you can pump hot water into a large tub and don't have to have a heat source underneath.

[Aaron-V2.0]

That is a great way for distilling HNO3! Because 1) An average Joe will have all the parts for the setup (Aside from the chems.) 99.99% of the time. And 2) A stainless steel pot setup in a backyark doesnt look as suspicious as an all glass distillation setup.

This is definately on my list of things to do now. :D

Though I'm still going to get a condensing tube from <a href="http://www.sciplus.com" target="_blank">www.sciplus.com</a> along with more glassware. :)

Also, just a thank you to everyone who has synth's public that show the use of XNO3 in place of HNO3, it's a real wonderful deal for those who cant obtain Nitric.

[zylion]

Try Firm Boom in Meppel, or J.T.Baker in Deventer you Dutchies among us. J.T. Baker doesn't sell it off the shelf, I think it has to be ordered. I couldn't find it in their catalog.
The best way in my opinion is to distil it with the usual method.
Following the procedure in Uncle Fester's Homemade Workshop Explosives is top off the bill. It produces the fuming WHITE nitric acid.

[simply RED]

Yeah, nice, nice!
Brainfever did you try to make nitrocellulose with the acid.
The speed was so low because of the mixture that does not produce precipitate, the low "s"(don't know the word) (cm2) of the collector(nylon) and the relatively low temperature.

[megalomania]

Out of all the posts from the other server while the board was closed, and only this one has any value... anyway I have brought it over to continue the discussion.

[Mic]

I will be trying Al tubing, Stainless Steel Tubing, PTFE and I will be trying others. In other words, I will be testing which works the best for me and I will tell you guys. :rolleyes:

Anyway I can't do it right now because I (well.. my parents :o ) don't want to do that inside my house and here it's very cold and there is very much snow. So I have to wait to this summer to test it. <img border="0" title="" alt="[Frown]" src="frown.gif" />

[Mendeleev]

BrainFever, the procedure for distillation on your page is so simple and ingenious I am kicking myself in the ass for not thinking of it myself ;)! I think this is definately the procedure I will use, considering it is a much cheaper alternative to buying a 5L distillation apparatus for $350.00. Anyway, I saw you used a rather small beaker in a slightly larger beaker. I was going to supersize this procedure and use a 5 gallon (18.9L) pot, with a 1000mL beaker inside. The pot is about 40 cm in diameter and I doubt that saran plastic wrap will hold such a large amount of ice :mad:, so I was wondering I you know any other materials onto which nitric acid will condense, but much stronger, like industrial grade. I was thinking of using a conical metal pot top, but this wouldn't be good for two reasons, 1. it isn't clear, so I wouldn't be able to see inside and monitor the experiment and 2. the nitric acid would corrode the metal. Also does anybody know which metals nitric acid does not corrode :confused:? I think stainless steel was mentioned?

Thanks

[blindreeper]

While it is simple it is no where near as effective as a proper still. I think its jsut an experiment, probably best not use it if you are really serious about nitric distillation.

[photonic]

I thought that Teflon was the only sort of plastic resistant to Nitric Acid? Why don't the fumes eat through the plastic(low purity?)? Also, could you use a sheet of Aluminum foil in place of the plastic sheet?

[Mendeleev]

Yes, blindreeper you are correct it isn't nearly as effective, but right now I live under the oppressive household of two asshole parents who are highly suspicious, and they are both scientists with Ph.D's so if I buy something like a distillation rig, they will be really pissed. I was thinking of buying one anyway for $350.00 and having it delivered to my friend's house, so my parents wouldn't know, but in the meantime, I am forced to stick with improvised methods that might unfortunately seem a bit kewl... Sorry. Also when you said it was not as effective as a proper still did you mean in terms of concentration or yield?

[blindreeper]

I think yeilds and concentration.

[Mendeleev]

Well for the time being I am forced to stick with the pot method :( untill I get order the rig to my friends house. So... in the meantime I thought up a method to supersize this distillation. Use a large metal pot like the one I am, instead of saran wrap use a clear plastic shower curtain, and attach it to the pot using zip-ties. On BrainFever's site, he got half a test tube of clear HNO3 with density 1.5 g/cm3, from a pretty small beaker, so that means >90%, which is good enough for all my purposes I think: NG, TNP, RDX, and guncotton. Furthermore if he got that from that tiny beaker I think my 5 gallon pot should fill up the 1000 mL beaker with > 90% HNO3. After I get my apparatus delivered offcourse I will move on to bigger things hopefully. I was thinking some of those new superpowerful explosive like the ones mentioned in the medina post under the high explosives section, hexanitrobenzene, would be really cool :D. It would also take a huge chunk out of my budget :mad:.

[0EZ0]

Actually, yield and purity would not suffer as much as you think. The rate of distillation is very poor though. You can produce small amounts of very high purity nitric acid if you are willing to heat the apparatus for a few days at low (50-60oC) temperatures. You get minimal loss from decomposition due to the low temperatures. If you use high concentration (+98%) sulfuric acid in the procedure, then the end product is highly likely to have a concentration of over 95%.

I thought the original idea was rather ingenious. It uses readily available materials for construction and gives quite good results considering it's simplicity.

There is not really much point in investing in a large capacity laboratory still unless you intend to use it regularly and for other applications as well. A small capacity (think 500ml distilling flask and 250ml recieving flask or smaller) will do you more than fine for most needs if you do want one. You can't really store large amounts of high grade nitric for risk of contamination and it's subsequent deterioration. Distill it as you need it.

[wrench352]

Ok,Im sure this has been done to death somewhere else,but I have waited forever to try this synthesis,and I would like to post my findings.
Using Brainfever's method I first did a "dry run" in my kithen using a water bath,and for safety reasons,electric heat.However I ran into several problems when I took the still outside.
First I thought the temp I was shooting for was 80 C When in fact the temp I needed was 65 C.Next problem I had was the heat source,an electric hotplate,which when trying to get to a specific temp is tricky at best.However I found it easier actually to get it to 65 C.(as it pertains to my first synthesis the temp unfortunately hovered around 85 C,although if it matters the out side temp hung around 10-15 C).In addition I found oil heats up more rapidly than water and does not dissipate it easily.
Next I mixed 940 gms H2SO4 w/ 455 gms KNO3,although a large yellowish gas plume appeared,I was disappointed I did not get the dark red plume Brainfever got,but I think its my vessel size which I figure to be + - 14.6 liters.The initial process was rushed due to my inexperience with the process coupled with a healthy respect for NOx.Also the process was interuppted twice causing a release of NOx which of course would lower yield.
The end product is about 100ml of crystal clear (I presume) crap.That I will try and reuse at a later date.How can I anylize the end product for purity?
Incidentely the first go round I used ACS grade H2SO4,the next go round I will be using drain cleaner as it is much cheaper.
my next batch of synthesises will be KNO3+H2SO4 redux,NH4NO3+H2SO4,ACS H2SO4+ACS 70% HNO3,to determine best yeild.I think the most interesting experiment will be the NH4NO3 as all equiptment and chemicals will be purchased at walmart.

[Mendeleev]

Those aren't too bad results considering you had errors such as temperature control and interruption. Anyways I found out I can use a stainless steel pot, heres a website which gives the corrosion resistance of some common metals, to just about all chemicals: http://www.srcoils.com/corros.html

[wrench352]

Hmmm,my first attempt with the NH4NO3 was a total failure unlike the KNO3 the yeild was terrible,yellow and the collection jar contained a large amount of sediment.Also at the rate Im goin through H2SO4,I am going to forgo the ACS H2SO4/HNO3 for now,and am goin to concentrate on the KNO3 and ramp up production.Question?In regards to my first go with KNO3,I forgot to mention my HNO3 fumed.

[Mendeleev]

Your HNO3 should most definitely fume! Nitric acid has relatively weak intermolecular forces, and thus a higher vapor pressure, hence the fuming. If it fumes it means that it is above 80% concentration. I don't know why you haven't heard of it mentioned before, I always see references to "fuming nitric acid". Anyway that means you have good results :D. I had a question as to what kind of hot plate you used, was it a laboratory hot plate or a regular kitchen plate like those sold at Wal-Mart? The reason I ask is that I have a regular Wal-Mart plate, because it was cheap, about $8.00, and I have heard that such kitchen sources let the heat fluctuate, so that it becomes very hot then stops, then hot, etc. Also did your distilling container touch the bottom of the pot with the water bath, or was it suspended in the water? Thanks.

Edit: Oezo, would I really have to heat the apparatus for 2 days? I was hoping for 8 hours for 1L of hno3 :(. Could I do it in shifts, like 8 hours one day, then 8 hours the next?

[wrench352]

In regards to the fuming issue: Doh!I was mistaken and will edit that,Ive been very excited lately, as this is my first real research,and it slipped my mind.Thank you Mendelev,for the reminder.I put the cart before the horse there.First go round must have produced some good shit huh?
My hot plate for the time being IS a walmart special(should have a hotplate stirrer by May).Indeed they are hinky, tempermental things,but although it seems settings vary from unit to unit I was able to keep the temp fairly stable(I monitored constantly) and with both units(yep,Im gonna run two at once) Im using I can pin it to 65C fairly easily.The water baths I originally wanted were out of season so I improvised and am supporting the vessel on a 6" deep stove chrome plate reflector bowl.I know what your thinkin,convection but its immersed in an gallon of mineral oil.Also original temp testing in water showed it wasnt an issue.Looks like rain and Ill double check.Next go round Im gonna keep the temp real low and really let it go, 36 hrs.
You showed me I need to go through the research once more before I start again.(My old lady is gonna kill me,ha!).Thanks again this is what peer reveiw is all about I reckon.

[Centimeter]

Although this doesn't precisely fit in this thread, the title is generic enough that it should work. I mixed 250ml H2SO4 and 365g KNO3 and distilled under a vacuum. As you can see, I added quite a large excess of sulfuric acid. Theoretical yield is around 150ml fumming HNO3, however I was only able to get about 50ml of ~90% HNO3. I drove the reaction as hard as I could but that was all I could possibly squeze out of the system. I raised the vacuum to about 100 torr but nothing. I raised the temp to just under 80*C but nothing. The combination of a vacuum of 100 torr and 75*C should have been more than enough to drive the reaction forward if it was at all possible. Further more, such a large excess of H2SO4 should have pushed the equilibrium of the reaction in favor of HNO3 production. Is 30% theoreticle yield realy the best one can get out of HNO3 distillation? Perhaps I am doing something wrong?

[Marvin]

Keep the vacuum as low as possible.

My gut reaction is that your end point is far too low, maybe by as much as 100 degrees. Sulphuric hangs onto nitric in a similar way it hangs onto water, you have to drive it off and force the reaction forward. Excess sulphuric certainly helps reduce the temperature, which is probably why you got any yeild at all at these low temperatures, as will use of vacuum. My own experiments without vacuum left the sulphate/bisulphate salt molten at the end, not unlike the old industrial process, I was using slight excess sulphuric as would be needed to form pure bisulphate.

[nbk2000]

Vacuum is dangerous, though, unless you're equipment is in good shape, because if the reactor implodes, there's going to be nitric acid sprayed everywhere.

[Centimeter]

If I rase the temp any more, the nitric will decompose and I will get red nitric acid. I thought that the entire idea of using a vacuum was to lower the boiling point so that you don't decompose as much HNO3. If decomposition is not a problem, then why use a vacuum at all? I was under the impression that red fumming nitric acid was no good for nitrations. Well, I guess all I heard was that it's bad for RDX synthesis, and I assumed it was bad for other explosives too. Other than when nitrating hexamine, why wouldn't the dissolved NO2 result in a better nitration, after all we use sulfuric acid to protonate the nitric anyway?

[tmp]

Point well taken, NBK2000. This is why I stay away from any glassware
labeled "BOMEX". It doesn't take heating too well either. I was purifying
KClO4 in a beaker made of that shit-glass and it developed a hairline
crack while it cooled. BOMEX has its place for measuring and mixing but
don't use it for heat or vacuum applications. I use KIMAX filtration flasks
for vacuum applications - they're designed for that.

Centimeter, even 75 C seems too high for concentrated HNO3 vacuum
distillation. You need a lower vacuum, but as NBK2000 has already pointed
out - BE CAREFUL !

[Mendeleev]

I have never had heat trouble with bomex, like boiling sulfuric acid repeatedly in the same beaker. But it is pretty shitty quality, with gas bubbles from the glassmaking. I have tested by bomex erlenmeyer flask in 720 mm vacuum and it was suprisingly fine, but the only vacuum application for which I recommend consistent use is a bong. This job it performs quite nicely. The problem with using a very strong vacuum when boiling a nitric/sulfuric mixture is if it is too strong you either won't condense your nitric or everything in your receiver will boil away. To prevent this you could circulate -20 C IPA (-20 C is about the limit of a typical freezre on max) using a device such as this:

http://www.rhodium.ws/chemistry/equipment/convective.circulator.html

[Centimeter]

For some reason my posts are taking a very long time to actualy show up. I think it us because I am a newbie. Anyway, in case anybody missed my previous post, I was wondering why red nitric acid is a bad thing. Also tmp, I was wondering the same thing; so what is Marvin talking about? I use second quality bomex myself and I haven't had any problems...yet. The guy that sold it to me said it would be fine for use in a light vacuum. Perhaps a way to increase the integrity of a bomex distillation set up would be to use smaller boiling and collecting flasks. I can not and will not use a vacuum greater than 100 torr to distill nitric acid. I guess I will just distill at high temps and then redistill if neccesary. Although I have also been getting bad yields in distilling slightly dillute nitric acid as well. I start out with 100ml 68% HNO3 and end with around 25ml 98% nitric acid after two distillations. I just can't squeeze out anymore without decomposing the nitric acid. Perhaps I can take two fractions. One will be what I can get while avoiding decomposition and then the other will be high temp distillation to recover as much of the nitric as I can. What kind of yields do you guys get when distilling from xNO3/HNO3 plus H2SO4?

[Isotoxin]

I am getting ready to distill some nitric as soon as I get my vacume aspirator. I however have a few questions. With it I can have a reduced pressure enviroment and with my 300mm liebig and ground glass setup I hope to distill ~500ml of white fuming nitric acid from H2SO4 and KNO3. I have ~30L of 30% H2SO4 so I will concentrate it to ~94-98% and then add the correct amount of KNO3.

Can someone show me the compleat equation of the reaction of H2SO4 and KNO3 so I can work the stoich?

I currently get my KNO3 in 100g jars for 2$USD at a local shop. I have heard you can get it in large bags for fertalizing but I checked Home De' Pot and nothing. How can you convince the farmer warehouse type places to sell to you?

[Marvin]

If you can use the equation to work out the materials you need you should be able to balence the equation in the first place.

Either way its irrelavent. If you use theoretical amounts the temp at the end will be very high and a lot will decompose, or your yeild will be tiny if you stop distilling at a low enough temperature to prevent this.

Use the suggested amounts, or a larger excess of sulphuric if the temp is still too high. You can always use the residue for lower grades of nitric.

[Pb1]

The equation is:
KNO3 + H2SO4 -> HNO3 + KHSO4

If you use equimolar amounts of each chemical, you will end up with a solid cake of potassium bisulfate before all your nitric acid is out, so you have to add extra sulfuric acid.

[knowledgehungry]

Red Nitric Acid just doesn't give as good yields for certain things, I am not sure why. Red Nitric Acid will work however for almost all nitrations, just not as effeciently.

[Centimeter]

Red nitric acid can make a run-away nitration more likely...take for example RDX production. Based on my experimentle data, it would seem that the H2SO4 is only donating one H+ ion. To test this, I ran a distillation using 1mol H2SO4 per 1mol NH4NO3. I used 300ml H2SO4 and 400g NH4NO3. At first I tried without a vacuum, knowing that I could purify it with urea. For some reason, I could not get the damn thing to distill over. Thus I put on an aspirator and began distilling at maybe 130*C. The product was quite yellow, but it was easily purified with urea. From the reaction, I obtained ~100ml of 87% HNO3. At least I think it's 87%. I assume that the addition of urea will change the density/concentration ratios, however considering it was such a small amount of urea it should be negligable. I could titrate it...but I don't want to. If the H2SO4 did indeed only give up one H+ ion, this would equate to aprx. a 50% yield. From what I observed in the boilng flask, I would have been hard pressed to squeeze any more nitric out. Based on these results, it seems clear to me that the H2SO4 is not giving up both H+ ions. Is there some way to instigate the H2SO4 to give up that second H+ ion short of cooking the crap out of it?

[knowledgehungry]

No, equilibrium favors the HSO4- ion forming over SO4 -2. The only way I can think of changing the equilibrium would be to cook the hell out of it, if that would even work.

[Marvin]

Red nitric acid contains NO2 and HNO2, these have a tendency to destructivly oxidise. Whats more when they oxidise, they produce NO, which is regenerated by the nitric acid, the reaction ends up being autocatalytic.

It is possible to go all the way to neutral sulphate at high temps with an alkali nitrate but the temps are rather high and the acid impure. Industrially it was continued to only slightly beyond the bisulphate stage so the molten mass could be poured out.

[Centimeter]

How come everyone's posted procedures assume that the H2SO4 gives up both H+ ions?

I still have the left overs from the ammonium nitrate + H2SO4 distillation. Would it be such a bad idea to add 100ml 70% HNO3 and use it to distill again? This would help to squeeze out even more HNO3 from the solution and it should result in a more concentrated product. I guess I will try it and report back the results. This time I am going to just bubble dry air through the acid. I don't like the idea of nitrourea being produced.

Edit- I got back 82ml of the exact same concentration of HNO3...which is some what surprising. I did however get a chance to test the use of dry air w/o adding urea. The acid was quickly converted into a crystal clear liquid. From what I observed, it worked just as well and rapidly as urea.

[Gleng]

I assume that nitric acid higher 70% will fume. It gives nitric acid at around this concetration and contains less NO2. Simple distillation 120g NH4NO3 per 100 ml H2SO4 will work.

H2SO4 + NH4NO3 -> HNO3 + (NH4)2SO4 , distillation below 300 degrees
You will need a stirrer to distill again and maintain the temperature between 96 and 120 degrees . This gives a good result slight red fuming nitric acid higher 95% and contains less NO2. 100 ml 70% HNO3 per 150 ml per 98% H2SO4 will work.


When giving measurements, you must always specify the unit of measure to be used.

'temperature between 96 and 120 degrees'...is this using &deg;C or &deg;F?

[Gleng]

This are the specific temperatures to the distillations.
HNO3 70%, 122 - 300 °C
HNO3 80%, 95 - 120 °C
HNO3 95%, 86 - 95 °C
I`m planing to design a diagram which will give more information to the apparatus.

[0010110]

When I distill nitric I use a homemade still that I made from 2 jars and a light bulb instead of the plastic as mentioned earlier in this thread. I got the idea from a show about drug addicts smoking out of a light bulb! Any ways I usually distill around 180 deg F. The nitric that I got has a density of around 1.42 g/cm3. which I believe is around 70% concentration. I used KNO3 as my nitrate salt. the heat source was a hot water bath. the still produced around 1-2ml/hr. i was pleased with the nitirc it produced i have done this method many times.

[The_Duke]

Yeah, there is already a "diagram" in the first volume of Urbanski....

That and your figures are WRONG!:rolleyes:

[Gothy]

In general, I would say that it isn't necessarily 70%+ conc. if it fumes. I mean, I have some 62% which I usually buy at the local beautyshop. And it fumes alright. It isn't much anyway, but white fumes slowly rise from the bottle.

And I also have a very basic question which I have thought about for a while. Please be patient with me if I come out as a total retard:

The thing that puzzles me with distilling NA, from a low concentration NA and H2SO4, is the water in the solution. Why isn't it evaporated along with the NA? I know that H2SO4 chemically bonds with water, but than what the heck is going on with the fact that you can concentrate weak sulphuric acid by boiling off the water?
I don't understand why the water isn't evaporated in the NA distilling process, when it is in concentration of H2SO4.

I didn't want to start a new thread with this, since it might be seen as a n00b question.
And it really annoys me that this is my first question ever, since I don't see myself as a chemistry-dunce

[megalomania]

Any simple distillation (the separation of two or more liquids by boiling) will always produce vapors of all components. The degree to which those components are vaporized is entirely dependent on their respective boiling points. The greater the gap between boiling points, the less of the higher boiling liquid you get in the distillate.

For example, sulfuric acid boils at 290 C, whereas water boils at 100 C. Compare that to ethanol which boils at 78.5 C. Notice the temperature gap between boiling water and boiling sulfuric acid is considerably greater than the temperature gap between boiling water and boiling ethanol.

The closer in boiling points a mixture is, the harder it is to separate by simple distillation. Sulfuric boils at such a high temperature that water can be substantially removed by boiling with very little sulfuric acid distilling over.

To answer your question more specifically, you do get a lot of water distilling over when you concentrate nitric acid. If I remember correctly the maximum concentration of nitric acid you can get with simple distillation is 67-70%. Distilling under reduced pressure not only helps prevent thermal decomposition of your distillate, but it can also widen the gap between boiling temperatures with some substances.

[Gothy]

Sorry about that, I somehow got myself to believe that the boiling point of NA was 120 celsius... Doh. I can see now that is is fairly close to ethanol i.e.
So anyways, if you were to distill NA by simple distillation, the only way to get it concentrated would be by the nitrate salt and SA way yeah?

And on the sidenote: When lower conc. NA and conc. SA is mixed, the water will get an increase in boiling point because of the SA right? Otherwise I can't see the point in that method

[megalomania]

You can achieve anhydrous conditions, or near enough anhydrous, by distilling concentrated nitric acid with concentrated sulfuric acid. I don't have any numbers handy, but there are many recent patents (last 20-30 years or so) about doing this. The sulfuric acid acts as a dehydrating agent trapping the (small amounts of) water. The good thing is the sulfuric acid can be reconcentrated and used again and again.

[Enkidu]

The reason you can't concentrate Nitric Acid to 100% using simple/fractional distillation in and of itself is that Nitric Acid forms an azeotrope with water at ~68% by weight. According to answers.com, an azeotrope is a liquid mixture of two or more substances that retains the same composition in the vapor state as in the liquid state when distilled or partially evaporated under a certain pressure.

Mega is right, the closer the BPs of two liquids are, the harder they are to separate. That's where fractional distillation comes in. However, azeotropes are impossible to separate by distillation alone. That is the theory of denatured alcohol (ethanol/methanol azeotrope). Sulfuric acid also has an azeotrope with water. It's at 98%. That's why you can boil the water off car battery acid (~35% conc. H2SO4) up until it hits 98% but no further.

The reason that you had 120&deg;C stuck in your head, Gothy, was because that is the BP of ~68% conc. HNO3.

At least that's the way I understand it.

[Khalnath]

No, equilibrium favors the HSO4- ion forming over SO4 -2. The only way I can think of changing the equilibrium would be to cook the hell out of it, if that would even work.

Sulfuric acid gives up its first H+ ion much more readily than the second. In fact, due to the common ion effect, basically all of the H2SO4 will convert to HSO4- before any of the HSO4- will give up the second H+ (technically it will happen an insignificant amount, but not enough for even the pickiest chemist to care). If those H+ ions are being sucked out of solution somehow (reacting with something, for example), both H+s will come off and react, but the second set will do so more slowly and this will certainly affect your reaction rate, but probably not your actual products unless the sulfate ion is somehow undesireable.

H2SO4 is a strong acid that will fully dissociate into H+ and HSO4-.
HSO4- is a weak acid that dissociates in an equilibrium. The presence of H+ already in solution (from any source) greatly inhibits its dissociation as a result.

[Aristocles]

SHIT!

I have spent over eight fucking hours trying to distill HNO3. Without doubt it can be done sans vacuum, but I sure as hell did not succeed. I painfully watched the temperature! But after five and one half hours I decided to up the temp a bit. I finally got some distillate to come through but merely a few drops. After a little over eight hours I shut it down.

I spent all that damn time in a freezing fucking garage with the window and door open, as well as a fan going, and a small ceramic heater. It was 13F when I finished rinsing off the glass (in cold ass water).

The real bitch was hoisting that siphon bucket over and over ad fucking nauseum...

Despite some really nice looking vapors, I ended up with drops...

Shit... I am TIRED

[Charles Owlen Picket]

SHIT!



Let's take it from the top.....was your distillation rig TIGHT? The design is also meant to run downhill...your temp on the first attempt should be fucking hot. Let it be a less efficient distillation at first but a workable one...you will find the best temp in time. What was the heat source? Did it heat the whole of the flask? What was the ratio of solid nitrates or 70% HNO3 to H2SO4 ?
The run for a 1/3 filled liter flask should take about an hour. Most of the time you can pull about 300ml of 1.52 for your hassle.

[Aristocles]

Let's take it from the top.....was your distillation rig TIGHT?

Charles, I think it was. Here is how it was set up: 1000 ml RBF with Ace 24/40 and 10/30 head, thermometer was inserted at the 10/30 end via a teflon plug (just wrapped tape and then shoved until it seemed reasonably seated). Pyrex Liebig condenser was joined to the head's 24/40 joint, then a curved adapter, and lastly a 500 ml receiving RBF. I teflon taped every joint. After 5-6 hours I did notice some condensation leaking through a couple of he joints, I nigger rigged further taping. (I even noticed some very small white NOx fumes escaping. Maybe not sealed well, but it's about as good as I can do, I think...

The design is also meant to run downhill...your temp on the first attempt should be fucking hot. Let it be a less efficient distillation at first but a workable one...you will find the best temp in time. What was the heat source? Did it heat the whole of the flask? What was the ratio of solid nitrates or 70% HNO3 to H2SO4 ?

It was downhill at an angle but I assume it could be sharper? Better quantify the minimum angle for me. :) That was a definite fuck up. I got no results until I cranked up the heat. I mean zilch, nothing but a receiving flask with vapors. After I turned up he heat I could clearly see vapor passing across the condenser but it was still pitiful, re: the product. The heat source was a hotplate with pretty good heat adjustment. I heated a pen of vegetable oil and slightly suspended the RBF above it the bottom of the pan. No, as to heating the whole, the 'liquid' was just under the oil. I believe this was another fuck up. I should have wrapped it in glass wool? Explain, Charles. I used a 6/5 (ml to g) ratio of H2SO4 to KNO3, respectively.

The run for a 1/3 filled liter flask should take about an hour. Most of the time you can pull about 300ml of 1.52 for your hassle.

Certainly screwed the pooch on this one... Damn, Charles these creaky bones feel that cold this morning. All those years of lifting heavy weights combined with being off the juice for a year, have almost wrecked me. :D

[Aristocles]

Post whoring... mea culpa

Something else entered my mind: refluxing.

I noticed a significant amount of this... from prior threads it would seems indicative of not distilling rapidly enough. Advice? As I stated earlier should I wrap the exposed part of distilling flask in glass wool?

[Charles Owlen Picket]

If you noticed ANYTHING leaking from the joints of the glass...that's most likely your issue. However, let's define some of the parameters......"downhill" would be about at 10 degrees. The thing doesn't have to be extreme but must allow for gravity to let fluid roll with ease.

What's taking place is the heat is producing gas...the gas condensing and forming fluid... that fluid rolling;condensing, into a collection flask. Often the flask is maintained at a substantially lower temp (water bath or stronger). The distillation rig MUST be air tight for these reasons.

The level of reactant must be such that it CAN boil - therefore that flask must be a least one third or more empty (half is much better and 2/3's is great). Try water at first. Knock over plain water! If you succeed, your rig is set up fine. I still do this. I use Vodka. I need ethanol so I use cheap Vodka to determine if I have everything set just fine - then I knock out about two or more runs of HNO3 with solid nitrates. I am interested in efficiency and can sometimes get as much as 300ml anhydrous nitric from 365 H2SO4 and my solids. But this is achieved through very careful temp control. Trial runs allow the user to test temp with a thermometer and mark on the hot plate what is the settings needed. For nitric, I use a jump from 80-90C to 110 and back. But you CAN have a result from a simple boil.

I'm too old to lift heavy anymore. I also have bits of metal in me. I know about cold mornings and getting in gear (no pun intended). Give it two years. The receptors will need that much to regenerate from any long term juice especially orals. Always keep your sense of humor. The biggest joke is when we take ourselves seriously.

The Teflon taping was probably the culprit. When you (African-American)-rigged the thermometer. But ANY steam, smoke, what-have you, must be eliminated. The portion for the connection of the vacuum tube is OK but before that...make it snug......NOT too tight. That's why it's good to use a very light coating of chemistry glass joint compound. If you don't have it try a tiny bit of vasoline. Any more than a tiny bit will yellow and contaminate. Don't snug dry joints with the force of the Gods.

[totenkov]

Maybe I didn't read correctly, but what amounts of reactants did you use? If you're using to little, its possible that there simply isn't enough HNO3 fumes to condense, hence the yeild you got.

I would try using much large amounts of reactants and like Charles mentioned, cook the crap out of it at the beginning. Then as the distillation continues, slowly start letting the temp fall (a few degrees every few hours).

Also, about reflux, its a good idea to wrap aluminum foil around the neck of your flask to avoid this, a couple turns is all you will need to make sure the fumes actually get into the condenser.

Let us know how it turns out!

[Aristocles]

The forum has been down, thus I did not have the benefit of this wisdom.

BUT SHIIIIIIIIIIIIT

I cranked up the heat. And guess what? I am (thank God!!) standing sort of to the side and back a bit from my setup, when I hear a loud noise... the thermometer blew off. I know it sounds comical but as that MASS of fumes came forth I saw my life pass before my eyes. I bolted out the door, hell for leather.

I really ceased to process data at that point and had no real idea if my rig had fallen and been trashed... all I could do is stand back and watch fumes pour out the window and door. Did I mention that I am completely paranoid about being exposed to NOx fumes, in any fashion, let alone getting a lung full.

So after a couple of minutes, I decide that it's a must that I get the burner turned off. I take a deep breath, run in, turn it off, and run back out. After a couple more minutes I do the same for the siphon hose.

After around 20 minutes I decide it has cleared out... surprisingly nothing is broken. I'm as nervous as a pregnant nun while simultaneously being pissed that I have failed again. (Bordering on giving up the hobby, even if I survive this) So, I tear down the rig and commence the cursory clean up. Lo and behold, I have a few cc's of nitric in my receiving flask!

So, I am thinking, if I live this might be a lesson learned... then, of course, as I am taking the hoses off my condenser, I managed to take the condenser tip off with one of the hoses... damn...

I cleaned up and came home...

Totonkov: My reactant ratio is 6:5... thanks for the encouragement but I have, at least mostly, failed again.

Charles: I guess it would have helped if I had read the thermometer tip in your last post, before I started :D

Sheez... I almost started singing "Nearer my God to Thee" when I saw that thermometer blow out and all the fumes...

addenda: Should I make some sort of tiny stopper for thermometer to go through? I don't see how, it's an awfully small joint. The still head is an 'Ace' 3-way distillation adapter, the top joint is 10/30 for a thermometer (other two are, of course 24/40).

[megalomania]

Reminds me of the time I had the same thing happen with a runaway nitration :) I held my breath, ran back into the rapidly spewing cloud to grab my gas mask, then after donning the mask went in again to begin emergency ventilation and clean up. It's funny now, not so funny then...

[Charles Owlen Picket]

NOx is quite deadly but the human has to actually get a lungful first. The body recoils at the gas. it's actually very unnatural to breath that shit unlike carbon monoxide; you KNOW when you're getting a whiff of NOx. Many a lad has gotten just a wee taste of the gas and lived to speak of it's disgusting presence. It's good to recognize danger but in proportion to it's reality.... Aye, you're a better man for having seen the gas as she is. You can cope with a disaster of that nature.

Everyone has a story to tell of the 1st time they had to deal with NOx. I basically don't do most nitrations indoors for that reason. Plus it's easier to use natural materials like snow if I'm outside. The only thing I have to cope with outdoors is UV and that's not too difficult.

[Emil]

I'll be attempting my first HNO3 distillation in a few days which I am really looking forward to after all this time. After finally collecting up a nice amount of labware and gear needed to try it, I have just a couple of small questions at this time.

Is it best to thoroughly mix the KNO3 into the HS2O4, just like you would with a normal salt acid mix?? I ask this as I didn't want to waste any just from a small error like this. I was going to mix them in a normal beaker until the KNO3 had all dissolved, and then pour it into the RBF.

Also Charles, I see you are doing your distillations at normal atmospheric pressure. What are your views on vacuum distillation?? I have an awesome new vacuum pump (Teflon coated parts) which I got hold of. Do you do yours without a vacuum because of the hassle of doing it with one, or because it is not really needed, possibly bubbling dry air through with the addition of urea after obtaining your nitric to purify?

Tonight I am going to do a distillation like you mentioned with water, just to see if my rig is all ok. This will really help to show me any little problems I might encounter before trying with HNO3. Any feedback would be great.

Please don't think I haven't read through plenty of the HNO3 threads, I have. It's just with so many different accounts from people encountering problems and some having none, it's nice to get another persons point of view.

[Charles Owlen Picket]

YES! Mix your materials first to a completed solution, then begin. IF you have a vacuum, you will have greater efficiency over all. IF you can do so without damage to the pump, etc; by all means it's a much more efficient system. I use normal pressure out of necessity and I have a great deal of materials and a damn fine condenser. Efficiency is improved with a vacuum.

I frequently will distill ethanol (via Vodka) with the distillation rig prior to anything else as it works the bugs out of the set-up and let's me gage the hot plate temp. It has really paid off as it tells you a lot of things about the system. Every time you set up a system of glass; there are variables, etc. It can be done indoors and is clean. It's a very fast method to determine if everything is set to go. Making a mess with acids is a big chore. A watch your distillation; don't walk away from it for very long. Issues may arise that you can clear up IF you see them coming.

I once used a aspirator that kicked back water (due to poor inconsistent water pressure) and it made a mess. I also had a pump that I got as lab surplus and it died on me. If I had a good one; I'd use it.

My magic ratios are 690-700gr H2SO4 to 600gr KNO3 (or a little less if using Na or ammonium nitrate): from this expect between 285-300ml anhydrous HNO3 before pulling the system down. Don't let it run till dry. Let your condensation continue even after the "heavy" flow.
I have also experimented with cooking down surplus sulfuric (drain opener) & it wasn't worth the hassle. The only thing that is worth the time is to really dissolve the solid nitrate in the sulfuric first. That, without question improves everything. I always think about the process; I don't simply dump things into glassware and expect fine results.

As long as we are asking questions here - I have one. I have heard this question asked before and perhaps Mega could answer it......if Urea contains more nitrogen than other solid nitrates why couldn't Urea be used in a solid nitration? What are the foundational aspects of solid nitrate nitrations (as this seems to be the core issue)? Why do some aliki metal nitrates like CaNO3 make for poor nitration while Na does so well?

[Emil]

Tonight I decided I would give my HNO3 distillation a go. Last night I did a test run with water and all was well. My Rig was setup nicely, vacuum pump was working lovely, so I was quite optimistic about trying for some HNO3.
To start of with I cut the reaction down to 175gr Sulphuric to 150g KNO3.

It's late here so I got annoyed and gave up for tonight (work tommorow), but the problem was actually quite a basic one, not even to do with the distillation.

There I was with my magnetic stirrer adding my KNO3 to my Sulphuric, happy as Larry, when all of a sudden my stir bar stopped spinning. Confused, I fiddled with the stirrer and try to move the spin bar thinking it had just moved out of place or got lodged, but I got nothing. I thought the Magnetic stirrer/Hotplate had given up on me. I decided to determine if it had so I grabbed another beaker with water, placed in a spin bar and turned it on. It worked fine in the water.

My KNO3/HS2O4 mix was actually reasonably flowing, any ideas on why it would no longer spin in the mix? OK it's obviously less flowable than water but it was not solid in any form which is why I was very confused when it just stopped. Could it be a crappy stirrer/Signs of it being passed its best?

You may be looking at this post thinking, so whats the big deal?
Well the problem is without the magnetic stirrer, KNO3 is VERY hard to get to dissolve. Just using a glass rod stirrer was not working well at all and would of taken me a long time.

I personally would prefer to use AN as the salt, but for me it is hard and expensive to get hold of. I don't want to be going through kilos of AN for
HNO3 production, but KNO3 I'm not bothered about. This has annoyed me somewhat as It's not even an interesting problem to discuss in the scope of chemistry. Any ideas Charles?? I know you've got a magnetic stirrer/hotplate.

[Charles Owlen Picket]

Yes indeed. It's the density of the solution and -- you're right; it's just too thick. Actually the stir-bars need to be big ones (like the 600's or the ovals). Otherwise; I'd stir it by hand at room temp and -(neat trick)- make SURE your solid nitrate is really fine. Use an old coffee bean chopper or an old blender. Blenders are actually very useful and can be used for all sorts of things.

Many people find that Na nitrate is a better bet that potassium nitrate and they usually prefer ammonium nitrate the best (this is a real opinion issue). Calcium nitrate is generally considered to be a poor choice (I'm not sure as to the chemistry in that issue) however remember that the source can "coat" the prills with clay OR the actual salt may be so contaminated with crap (seriously, there can be real contaminants in it).

Note that NaHO3 is very hygroscopic and that grinding it up in a coffee bean mill can show if there is a bit of moisture there. Frankly, if I grind the nitrates prior to mixing, I can get it done by hand after about 3-5 minutes. I had two stirrers and one had a hot-plate as part of it. The hot plate put more ROOM between the magnet and the stir-bar unit (!) and was always less potent than the simple design (the old bastard burned out on me too). Stir it by hand at first. It will be OK. And attempt to find one of the BIG stir-bars. They are expensive but there is an alternative. There is a large oval magnet used in veterinary applications to keep a cow's stomach free from metal bits. You'll find them at the feed store and they can be coated with PTFE or whatever.

[Aristocles]

Charles seems to be equipped with a helluva a lot of 'practical wisdom' (praxis). ;)

I stir mine by hand, takes me about 15-20 min. I use a bit more H2SO4 than you. My KNO3 is Spectracide Stump Remover. Seems reasonably ground to me, but of course could be finer, it's something to consider. Maybe I'll put some in my handy dandy rock tumbler...

I was going to post this last time, but didn't. 'Pour' is not a word I'd associate with getting that sludge into the RBF.

I wish you all the best and hope you succeed.

I may try again tomorrow, myself.

[Hinckleyforpresident]

A few days ago I vacuum distilled some white fuming nitric from anhydrous ammonium nitrate and 93% sulfuric acid (rooto). I used 480g of ammonium nitrate and 420ml of 93% sulfuric acid.

I used a home made vacuum pump (a converted air compressor) to pull a 60 torr vacuum, distilling the nitric at 30oC. The final yield was 200ml. I suspect I could have gotten more out of it, but I grew tired, and as soon as it cooled to room temp (and without vacuum) the ammonium bisulfate immediately crystallized making further distillation difficult.

The distilled acid had a density of 1.49-1.51g/ml (98.6-100%). The yield was 80%.

By the way folks, I encountered no leaks while this doing this indoors. I simply ran the exhaust line from the vacuum out a sealed window about 15 feet into a bucket of NaOH solution. No HNO3, no NOx, no nothin' inside :D!

[Aristocles]

A few days ago I vacuum distilled some white fuming nitric from anhydrous ammonium nitrate and 93% sulfuric acid (rooto). I used 480g of ammonium nitrate and 420ml of 93% sulfuric acid.

I used a home made vacuum pump (a converted air compressor) to pull a 60 torr vacuum, distilling the nitric at 30oC. The final yield was 200ml. I suspect I could have gotten more out of it, but I grew tired, and as soon as it cooled to room temp (and without vacuum) the ammonium bisulfate immediately crystallized making further distillation difficult.

The distilled acid had a density of 1.49-1.51g/ml (98.6-100%). The yield was 80%.

By the way folks, I encountered no leaks while this doing this indoors. I simply ran the exhaust line from the vacuum out a sealed window about 15 feet into a bucket of NaOH solution. No HNO3, no NOx, no nothin' inside :D!

My 'mityvac' arrived in the mail today. I think I'll give it a go. I need to figure out setting up a trap or two for it. It appears that they fix it as a basic siphoning set up... this toy claims to be able to hold a decent vacuum, we'll see

I have read that 30-50 torr is sufficient for NA. Is this the correct formula for conversion: in. Hg x 25.4 = torr or mm Hg

[Hinckleyforpresident]

I have read that 30-50 torr is sufficient for NA. Is this the correct formula for conversion: in. Hg x 25.4 = torr or mm Hg

Yes. It's just a unit conversion.

[Charles Owlen Picket]

Aristocles: if it works well, give it a review! I for one am interested in getting something other than a aspirator. I've tried a few little vacs and they didn't hold up past about 4-6 labs. At the half dozen mark they started getting some bad joo-joo due to the acid. If the thing works well (especially after a FEW tries) write some feed back: product name, cost, performance levels setup, components, design, etc.

[Dr. M]

Charles (and others using pumps for pulling high-vac) -

I'm sure it wouldn't be all too hard to rig up an acid trap in-line between the apparatus and the pump; all one needs is a canister which will resist vacuum-implosion, two microporous plugs (e.g. cotton or glass wool, steel wool would work in a pinch; hell, a coffee filter cut to size would probably be ideal) and a filling of prilled sodium hydroxide; calcium carbonate would probably do in a pinch.

In a very rudimentary process flow diagram:

Distillation App. --> Hose --> Trap --> Hose --> Vac --> Exhaust

It's a lot cheaper to change out lye crystals and a short length of PVC than it is to repair a vacuum pump, agree? Furthermore, if the trap is set up with sufficient absorptivity, the vacuum pump exhaust should be completely non-offensive.

[Emil]

Sucess! At last, tonight I had a sucessfull Nitric distillation.

24/29 Quickfit Rig:
2000ml Boiling Flask
500ml Receiving Flask
520ml Condenser
Anti Bump Bent adapter.
Bent adapter with Vacuum take off.
Cole-Palmer Vacuum Pump with Teflon tubing

After having some difficulties with my KNO3 (possibly due to an impure product) I decided to give some AN a try. The AN, like my KNO3, was ground using a coffee grinder to a nice fluffy powder.
175g H2SO4 with 150g Ammonium Nitrate was used for this distillation and it was done with a vacuum pump. The exhaust was run outside the door into a bucket of water, and heating via a portable gas stove. I do have an electric hotplate, however I must admit I don't like using it. I find it takes a long time to heat up your materials.

At first I was actually slightly confused. I had left my mix of AN and Sulfuric overnight in the RBF due to having to cut my experiment short the night before, and my initial thought was that the mix had taken in some water (both being greedy with water). I applied the heat and it started boiling nicely. I don't have a measurement because I don't use a thermometer in my rig. The nitric started coming over and it was so clear, I actually thought I was just distilling over water. How wrong was I! There was no nox build up inside my rig and after checking the product in the receiving flask, I realised it was heavily fuming. I turned it all back on and continued.

15 minutes later I had collected 70ml of white fuming nitric acid with a tiny yellow tint. It fumes alot! Tomorow I will measure the density and post the results. It might be slighty lower concentration than what could be attained due to the fact there could of been a slight bit of water introduced over night. However I am really happy with the yield!

The main thing is that everything works well, my rig is working beautifully, and now we just have to hope my vacuum pump will live through the nitric acid fumes. It is meant to be a chemically resistant one with mostly teflon parts, so we'll have to see.

[Charles Owlen Picket]

Excellent job! Now if you experiment with ratios vs. temp ranges and time lines you will find optimum for specific materials. I have always wondered at HNO3 productivity levels utilizing a variety of supplanted solids.

I used to keep my distilled HNO3 in a large heavy glass bottle with a glass stopper and refrigerate it. I would use .5 gram of Urea to 100ml of acid and all trace of yellow would leave after a week. However, that is not a necessity. {I have used this to maintaining acid density over the course of a year. If you put a lot of work into distilling acid, you may want to keep what you've worked at.}
I still wonder if Urea could function as a solid nitrate... No one has ever written on that subject, that I could find.

I once lost some glass due to using too high a heat source. It focused heat in one area and not all around the container. I got a crack and it spread. This occurs if the fluid is dense and cold (H2SO4) & sudden heat is not spread over the whole of the container. I only use a hotplate that is a fairly decent quality now as I got so damn angry at my impatient attitude; I didn't have to loose that tapered flask.

[Emil]

Now that would be interesting if urea could be used as a solid nitrate. I have plenty of it that could be used for nitric production, if it were possible. It's also dead cheap and easy even for me to get hold of.
Worth a try, maybe I shall give it a go when I get some spare time.

Yes, at the minute I have my distilled HNO3 in an Amber Pyrex bottle, chilling in the fridge, all covered up from any light. Hopefully this will stop any significant breakdown.

Luckily the heat source I use doesn't just focus heat on one part. It is a portable stove which takes small gas bottles, and is much like a ring on a cooker, which gives a reasonably wide flame. I would definitley hope not to crack any of my rig, as I have already cracked a glass aspirator and that was bad enough. The only problem with glass aspirators is they have a weak point, and that is the part where the stem thins down before expanding back out. The silicone hose was quite a tight fit and when I pulled it off.. *Crack*

It doesn't help that I have a cluttered lab which needs sorting out.

[Aristocles]

Well, Well

It worked out much better for me this time. Not too efficient but much better...

Rigged things up yesterday, but had a problem with my trap. Bad seal... kept losing pressure throwing water back into my receptacle. So, I repeated this fuck up several times for sheer fun (masochistic that way, I guess). Actually, I got pissed and abandoned it.

Went home got a 2-necked round bottom flask and a couple of rubber stoppers. Having no proper tools, I took my pocket knife, sat there watching "House" and bored the holes.

Went in the next morning to my setup. Connected the 2-neck, pumped the mityvac up to around 24 in. HG, and turned on the hotplate.. The vacuum pump held pretty well although I had to give it a pump now and then. Did my best to keep the heat regulated, well considering my thermometer was in half from being hurled against the ceiling, in my last disaster. I had to depend on keeping the temp of the oil within reason using a candy thermometer and understanding the transfer fairly well.

My setup was 24/40 throughout. I used 3.37 mol H2SO4 and 1.63 mol KNO3. I let it go for 1:55... yield was 50 ml.

So it was a learning exercise, but it worked. I put the nitric acid in a volumetric flask with a glass stopper and stuck it in the fridge.

One thing that stuck me was the near implosion of the hose, from the vacuum adapter to the trap. It was almost "sucked" together. I am assuming I need a stronger hose material....

Truthfully, I am quite pleased. If I had not been worn down from hoisting that five gallon bucket of water virtually over my head and then leaning carefully over my rig to dump it into the supply bucket, I could have extracted significantly more, I presume, based on the drips. (Had to do that every six minutes and thirty seconds) Lazy...

No dark fumes (NO3?), much easier to get it dripping nitric, and overall a success.

[Emil]

Well done, glad to hear of your sucess. It's extremely enjoyable when everything goes to plan. It's not failing that is the frustrating part of chemistry. It's more the waste of valuable chems and the unecessary clean up that you create for yourself.

Thats interesting that you mention the "hose imploding". I have exactly the same thing occur when I have my vacuum turned on. I'm not sure if this is meant to happen or not, but the hose I am using is proper 3/8 tygon tubing. However it is very soft and collapses easily. If that's the case then I will have to get a suitable hose for the vacuum part. The main reason I chose the tygon tubing is becuase I know alot of silicone and rubber based hoses will breakdown from the HNO3 fumes.

Like you Aristocles, I saw no NOx fumes what so ever during the whole distillation, which I was pleased about. Before beginning the experiment I was a bit cautious and slightly worried about NOx escaping from my rig and me breathing some in. I had the gask mask at hand, but luckily did not have to use it.

Next I plan to sort out my KNO3 troubles. It would be and ideal salt to use, because I can get so much of it for great prices. I can personally get hold of 25kg's of KNO3 for the same price I could attain 3kg's or AN or Na.

When I distilled I didn't find it necessary to cool the recieving flask, or insulate any of the distilling flask. Just the cooling of the condenser was enough for the entire procedure to run smooth. I was distilling at roughly 2drops a second.

[Charles Owlen Picket]

Charles (and others using pumps for pulling high-vac) -
I'm sure it wouldn't be all too hard to rig up an acid trap in-line between the apparatus and the pump; all one needs is a canister which will resist vacuum-implosion

This is a very logical concept. I like it! It makes sense and is not expensive. :)

[Emil]

Good thinking, an acid trap may save alot of problems occuring. However "canister" sounds a rather brief description.
I'm not to sure what you mean by this....

Wouldn't the trap have to have some type of filter to prevent any of the harmful fumes travelling through the pump?

It also couldn't obstruct the vacuum flow too much, otherwise this would lower the performance.

[Aristocles]

Well I tried Sodium Nitrate tonight, not bad coulda used some habanero sauce... ;)

Anyway, I tried 2 mol H2SO4 (assuming it's > 99%, it's not) and 2 mol NaNO3 (assuming it's > 99%, might be), rather poor choice considering things. To wit, the fact that I poorly crushed the prills. (I ended up with a bunch of locked NaNO3 in my boiling flask.)

I was amazed at the clean nitration as well as the 'clean' distillation. Sodium Nitrate seems to work GREAT! Set it up... of course I broke a 500 ml two-neck I was using as a trap. So I quickly grabbed a three-neck and an extra stopper, filled the superfluous stopper hole with silicone rubber, jammed it in, and let it set up a moment.

I cranked up some heat and walked over to pump up the mityvac. I pumped it up to a bit over 25 in. Hg. I learned something at this point. The mityvac will hold a vacuum and it is a fine little tool but at 25 in. Hg and above, it deposits some fluid into the receiving flask. :( But being hard headed, I let it ride with a smidge of water. In less than an hour, I had roughly no fluid left in the boiling flask, and a nice, albeit small, amount of nitric acid in the receiving flask.

The temperature stayed very low- the temp of the oil stayed around 75-80C- and I could have gotten significantly more had I done a better job on the ratio of H2SO4 and NaNO3 and crushed the prills better. That SN was nice to behold boiling away at such a low temp, virtually no visible fumes, very clean. My reward was a bit over 100 ml. of nitric acid.

So, I now know:

1)SN (I cannot 'say' enough good about it) is the go for me.

2) Keep the mityvac just below 25 in. Hg.

Getting that clump of shit out of bottom of the RBF took SEVERAL washes and time!

Nothing new for many but quite new for moi...

[Charles Owlen Picket]

80 C is generally what I use. I also am a fan of boiling stones as I jumped to a 2 liter and with each of my runs - I try to better 350ml acid distilled. At one time I actually filled a dark amber gallon acid jug with my efforts and refrigerated it for about 6 months. Upon opening; it was fresh and delicious as the day it was distilled...... ~-= Ahhhhh=-~

[ETCS (Ret)]

My experience with Calcium Nitrate (solution grade prills) and commercial 93% Sulfuric Acid has been without disappointment.

I use a bottle (glass or teflon) with a screw cap and fill the bottle to near capacity with the Calcium Nitrate prills and shake them down to get good settling. Then I pour into the bottle the Sulfuric Acid to just cover the prills and screw on the cap to keep air/moisture out. The reaction begins immediately but as it takes quite a long time for the prills to convert to Calcium Sulfate and release the Nitric Acid I set it aside in a dark cabinet for a week or two.

When all is finished the Calcium Sulfate will have settled to the bottom and the bottle will contain a clear liquid above. When the cap is removed you will see instantly that you have fuming Nitric Acid (with perhaps a bit of Calcium Nitrate in solution) which works very well in all of the nitrations I've attempted (nitrosugars, nitrostarch, nitric esters) without any additional processing or distillation.

For those who require the purest product simply pour the liquid into your glassware, decanting to leave the calcium sulfate precipitate in the bottle, and distill away. You'll find that there is very little residue left behind.

[Charles Owlen Picket]

For those who live within the USA this is quite important. The availability of calcium nitrate will continue (TTBoMK) as the Fertilizer Institute has begun a co-ordinated effort to minimize the packaged bag availability of ammonium nitrate and shift to bulk vehicle delivery in accordance with the Be Aware America campaign.

The Fertilizer Institute as many know is the corporate entity of the mfg associations as an umbrella organization of firms that manufacture chemicals, etc and have been working with the fedgov to minimize impact to agri-business from various political agenda. Chuck Shumer (D-NY) attempted to actually BAN ammonium nitrate when he was told that such a move would destroy American farm production (and it's impact on our economy would be devastating).

However such things would come frequently from the likes of urban dwellers who "know not what they do". Calcium nitrate is a common fertilizer available as 40-50lb bags at about $14 per unit. However various patents illustrated it's use in explosive materials so it's really "six of one, half dozen of the other" for the likes of Mr. Shumer.

[Dr. M]

Good thinking, an acid trap may save alot of problems occurring. However "canister" sounds a rather brief description.
I'm not to sure what you mean by this....

Wouldn't the trap have to have some type of filter to prevent any of the harmful fumes traveling through the pump?

It also couldn't obstruct the vacuum flow too much, otherwise this would lower the performance.

I say "canister" because it leaves a lot of room for creativity regarding the vessel one might use to contain the prilled base.

The absolute requirements would be:
1 - Gas-tight seal on all fittings/joints used to construct the canister;
2 - Chemically inert with regards to the filler material (i.e. doesn't dissolve in contact with NaOH);
3 - Resistant to reasonable vacuum pressure;
4 - Sufficient volume to contain enough filler material to be effective.

I would envision that schedule 40 or 80 PVC or ABS pipe with appropriate fittings would fit the bill quite nicely. All one would need is an end fitting suitable for attachment to the vacuum take-off from the distillation apparatus (i.e. a stepwise series of reducers taking 2" PVC pipe down to 3/8" I.D. vacuum line), an appropriate length of vacuum-resistant tubing with I.D. to match your reducer fitting, a length of PVC pipe (say, 2" O.D.) which will hold a good handful of NaOH - 6" should do more than nicely, and another reducer fitting which will run from the PVC acid trap to the vacuum pump. It would, of course, be prudent to plug both adapter ends properly with glass wool or similar inert packing to keep particles of NaOH from entering your pump or flowing back into your distillate. Cotton could be used in a pinch, but may deteriorate on the acid-input side over time whereas glass wool would more than likely outlast the chemical trap's absorbent capacity.

Acid vapor is so well absorbed by loosely-packed NaOH that, provided one packs the setup well enough that there aren't any large direct paths through the absorbent, not a single wisp of acid vapor will survive to the vacuum-demand side of the trap; your pump will thank you. The restriction to vacuum flow is negligible - manually packed prilled NaOH will provide more than enough slowly meandering passages to allow a full-rated vacuum to be quite efficiently established.

And as one final bonus, after sufficient usage (quite some time, I'd imagine), the NaOH should be converted largely to NaNO3; in essence, recycling your acid trap after numerous distillations should give you a distillation all its own. After each usage, one could simply detach the trap and dry it in a suitably warm place to eliminate any bulk water resulting from the NaOH + HNO3 ---> NaNO3 + HOH double-displacement, in order to avoid an eventual NaNO3 slurry.

[Emil]

Well, I had an interesting experience tonight. Having tried both Potassium and Ammonium nitrate for Nitric acid distillation, I thought it was time to try some Sodium nitrate.

Being fed up of paying high prices to suppliers, I dug around for a source of a cheap nitrate and have recently had a good find (or so at least I thought). £3per kilo, labelled in the garden shop as "Nitrate of Soda", I looked up the MSDS to find it contains 97% Sodium nitrate. It however doesn't list the other 3%. Now me, not thinking the 3% could be of any interferance what so ever, was suprised to find that actually it was a big problem.

As always with nitrates, it was finely ground using my trusty coffee grinder.. no probs. I measured out my Sulfuric acid and began addition of the nitrate like usual. Straight away I noticed that my NaNO3 was not dissolving how I visioned it to. I expected it to be like my AN. Thinking possibly it may just take slighty longer than AN I continued to add.

After 5 mins I started to notice something was not quite right. The mix was hardly fuming like it would with the AN or PN. It also had a slighty different smell (not that I was purposley sniffing the vapours given off, but we all get a whiff). I stopped my magnetic stirrer and thought it was time to grab my glass rod. However I noticed the Nitrate had clung together in about 20 seperate lumps and formed hard clumps of nitrate. They were also quite big.

It just was not dissolving, and after this discovery I dumped the reaction.

What I would like some advice on is my nitrate. Could that 3% really be that much of a substantial problem?? If so what do you recommend, that I purify my nitrate via the hot water and filter route?? Any of you guys had this problem before with a nitrate which wasn't "Pure"???

Any comments would be most helpful, as I am still a little puzzled.

[Darkover]

I've been testing extractions using calcium nitrate, as ammonium nitrate is no longer available here. Other than you need to use an excess of drain cleaner ( I use an extra mol as a general rule) as calcium nitrate is double by weight per mol. It extracts very nicely, at 27 inches of vacuum it boils at 30-33C.

I get my "double salt" fertilizer in prills that I cook at 250C (at 45C the prills melt and form a liquid) till all the water is gone and its a solid again. Once cool it goes into a food processor and ground to fine powder that sieves through a screen to make sure its all very uniform.

This was 164g of calcium nitrate with 100ml drain cleaner and produced 36ml of clear colorless nitric acid. This is less than a mol, previous extracts have made 54ml per mol of nitrate. Normally I heat my acid to 280C to dry it, this was a test with my new vacuum acid bottle with gauge. This gave me some insight on the strength of the raw drain cleaner I use and let me test to see if the vacuum bottle removed the acid from the air stream going to the vacuum pump. Clearly I need to use more acid, however the final product is beautiful even if there is waste in the extraction.

My extractions are done in a water bath, as only 33C is needed to bring the nitric to a rolling boil in this setup water boils at approx 50C so the water bath is held digitally at 42C to keep water from distilling over.

The pictures show the slurry before extraction, I mix this in the 1L flask nitrate first then acid. As I was pouring the slurry into a funnel and into the glassware long ago. I had 2 tiny drops of mixed acid too small to see hit my arm above my gloves, I couldn't even see the drops on my arm looking down, but it felt like red hot needles being driven into my arm, and holding a funnel of mixed acid I had to sit there and grit my teeth while I finished pouring... Mixing happens IN the bottle now. I've read on these boards about people asking how they get the yellow off there whole hand or some such, after nitric. My first question would be more like where's the painkillers.

The vacuum bottle during operation, this was filled with water with a large excess of sodium bicarb, the brass fitting going into the bottle was green from corrosion and the bicarb-water was colored the same. The brass fitting leaving was only a bit dark colored, this is exactly what I was hoping for. Very little acid vapor is reaching the pump.

The picture with the dangerous looking orange gas is after the pump and is at standard atm, this serves as a trap for compressor oil that is aspirated out. As the gas passes through the pump its heated beyond 100C decomposing the nitric gas that wasn't condensed or neutralized in the vacuum bottle. The end of this tube leads waaay outside.

Next is the leftover scum picture, this is the junk your gonna be scrubbing outta your glassware when your done, a dozen rinses and good shaking with a gloved finger plugging it and it comes clean.

Finally the completed acid, at less than a mol (36ml) but perfectly clear and colorless it sits beside the freezer nitric, with the slightest tint of yellow (was working out the bugs on the homemade digital hotplate from wallmart parts) from a previous extraction and not used up.. yet.

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