Sciencemadness Discussion Board

Nitric acid questions

Murcury - 26-8-2020 at 06:44

Hello all. Thank you for letting me in! I have started collecting computer parts to extract precious metals. I have decided that making my own nitric acid is the way to go. Buying it is so costly, about $140/gallon and the chemicals used to produce it are really cheap, $16/gal H2SO4 andb$20/55lbs NaNO2.
I’m not looking to make gallons, however, I would like to have it on hand so I don’t have to wait on a project for the nitric.
I have some labware I’ve collected over the years. I have a collection flask, condenser, the elbow that goes on the collection side, a heater/stirbar... and a box of other things.

My questions are.....

On the boiler side, do I need a thermometer for distilling nitric or sulfuric acid? Or can I get away with just a 75 degree adapter without a thermometer port?

For a boiling flask... does round bottom or flat bottom matter? And I was looking at 1L.... but noticed a lot of people are using 500mL... is a 1L overkill?

If I do go with a thermometer ported elbow, what gasket material will actually survive nitric? I see some things telling me Viton will not... but that is what comes with that piece.

I’ll post a picture of the exact equipment I have when I get home this evening.



pantone159 - 26-8-2020 at 06:47

I am pretty sure you need sodium NITRATE (NaNO3) not sodium NITRITE (NaNO2).

Murcury - 26-8-2020 at 07:00

Dang fat fingers.... I meant nitrate not nitrite. “Chilean nitrate” to be exact.

Syn the Sizer - 26-8-2020 at 07:23

For nitric acid, a 75° adapter should be fine but make sure the 105° adapter has a vacuum takeoff port or your receiving flask is at least 2 neck lots of NO2 gas will be produced, if you are using a thermometer adapter viton is the seal you want it is a fluoropolymer. But honestly I wouldn't use a thermometer. For reaction flask, if you plan on pulling a vacuum a round bottom is a must, flat bottoms will most likely implode. Flask size is just preference for the most part, I mean don't use a 1L flask to distill 100mL of liquid, I think 1L is fine.

You don't want leaks so grease all your joints with sulfuric acid, most normal greased will get eaten by and contaminate your acid. If you are routing the NO2 produced into a secondary vessel to produce dilute acid be sure to use suck back prevention of some sort.

An alternate method will save your sulfuric acid by using sodium bisulfAte in place of the acid.

Murcury - 26-8-2020 at 07:40

The 105 I bought does have a vacuum takeoff. I was smart there! I’ll would sodium bisulfate be cheaper? Maybe because pool season is ending I can get a deal. I was planning on making about 500mL at a time then diluting down to about 35% for most things.
I never considered porting the gas to make more... that’s a great idea... what type of suckback prevention?

And.... should I be pulling a vacuum? I hadn’t planned on it....

Herr Haber - 26-8-2020 at 08:01

If you've never done this distillation before a thermometer would help.

But if you watch enough videos, understand what you are doing AND if you are REALLY patient you can just very SLOWLY crank up the temperature and collect pretty pure acid.

A nice touch to help with the escaping NOx is to submerge your collection flask in ice water. I've seen a suckback in a vessel that was producing NO2, that should tell you how much it loves water so take Syn's advice seriously.

@Syn: in my experience grease will simply converted to CO2 by hot nitric acid vapor :)

JJay - 26-8-2020 at 08:08

If you do use a thermometer, it's a good idea to use a glass thermometer well - a rubber or plastic thermometer adapter will be damaged by the nitric acid vapors and will probably not surive one distillation.

Tsjerk - 26-8-2020 at 08:20

Of course learning how to do a distillation is priceless, but for dissolving metals from circuit boards you can just dissolve the nitrate salt in diluted sulfuric acid to prepare the nitric acid in situ.

How are you planning to do the extraction?

[Edited on 26-8-2020 by Tsjerk]

Murcury - 26-8-2020 at 08:37

I need nitric for aqua regia. And I’ll also be using it to remove silver from keyboard mylars. And test for gold and silver.
The materials are mostly gold plated pins and foils. I was going to use copper sulfate cell to strip the gold From the pins and AP for the foils then AR to clean up.

Tsjerk - 26-8-2020 at 09:13

If you add sodium chloride to the sodium nitrate/sulfuric acid you get a mixture of aqua regia and sodium sulfate.

The sodium sulfate shouldn't interfere downstream.

Murcury - 26-8-2020 at 09:41

I’m going to use sodium metabosulfate to precipitate the gold.
Using the above.... can I use that for spot testing for gold?

Syn the Sizer - 26-8-2020 at 11:00

Quote: Originally posted by Murcury  
I’ll would sodium bisulfate be cheaper? Maybe because pool season is ending I can get a deal.


I guess it depends where you live and OTC availability. Drain cleaner grade sulfuric acid is harder to find in my city than bisulfate.
Quote: Originally posted by Murcury  

I never considered porting the gas to make more... that’s a great idea... what type of suckback prevention?

And.... should I be pulling a vacuum? I hadn’t planned on it....


I like to use 2 flasks an empty one in the middle and the ice water in the last flask.

I should have worded the vacuum comment differently. What I meant is if you ever decide on pulling a vacuum on the flask during a different reaction you will want RB.
Quote: Originally posted by Herr Haber  
@Syn: in my experience grease will simply converted to CO2 by hot nitric acid vapor :)


Interesting, I am always concerned about contamination, but that does make sense.

Murcury - 26-8-2020 at 11:29

Ok.... how do you post pictures here?

Tsjerk - 26-8-2020 at 12:15

If you click on preview post you can upload files. If it is an image the forum software will recognize it as such. Just make sure the size of the image fits the normal width of the screen. You can check by clicking preview again.

Murcury - 27-8-2020 at 01:08

This is the acid. Walmart has it for $16.
And the fertilizer is $20.
57B27E91-1043-4F8C-AF67-E9F038345FE7.jpeg - 537kB

85112D8C-B11B-4D99-8214-B1F3367B56FB.jpeg - 213kB

woelen - 27-8-2020 at 01:23

If you have NaNO3, then the simplest is to dissolve this in concentrated hydrochloric acid (30% or better). If you can get conc. H2SO4 then I'm sure that you also can get conc. HCl.

Use HCl of high concentration, the higher the better. Dissolve the NaNO3 in boiling hot water, to make a really concentrated solution. In 100 ml of boiling hot water you can dissolve well over 150 grams of NaNO3. Add this solution to 150 ml of ice cold conc. HCl. A lot of NaCl will precipitate and you get aqua regia (with some left over NaCl/NaNO3 in it, which does no harm). What you get is not the optimum aqua regia (it will be somewhat low in nitrate), but it will be good enough to dissolve the metal. It is better to have sufficient acid in it than having a high nitrate content with only little acid.

Do the addition of the hot solution of NaNO3 to the acid outside. Because of the high temperature of the NaNO3-solution, the solubility of the HCl will decrease and you may get a lot of fumes of HCl. You don't want those fumes inside. For this reason it is best to make the acid as cold as possible. Freezer-cold (-18 C or so) is best.

[Edited on 27-8-20 by woelen]

Murcury - 27-8-2020 at 03:58

That is way easier for AR! But processing the mylars I think nitric would be the best bet still right?

Herr Haber - 27-8-2020 at 11:25

Yes

You could literally distill RFNA (which would be ideal for all the organics) and use it directly in a reaction vessel with your broken up cpu's, memories, pins etc.
No storage, no worries.

Though it wont dissolve gold it might dissolve other metals that you are after so their recovery can be another issue.
You'll end up with gold in gunk.

I dissolve silver in a reaction vessel and have a lot of gunk at the bottom of it after a couple uses (I just leave it there to collect).
All the gunk is not gold unfortunately. After emptying the reactor as much as possible I treat this gunk with concentrated or fuming acid episodically. When done, the volume is usually much lower.

Murcury - 28-8-2020 at 04:19

I was told I could possibly buy the couple pieces of labware I need to finish my distillation setup here. I’ll look around for that. Hopefully I can get some of these projects done soon!

Thank you for helping me figure out the best route.

B(a)P - 28-8-2020 at 13:15

Avoid plastic joint clips, nitric acid destroys them. You might get one distillation out of them, but then they just disintegrate.

IrishJeremy - 30-5-2021 at 11:29

I'm currently making some fuming nitric acid, I'm using a brand of drain cleaner sulfuric acid that is new to me and things are going REALLY slowly. The bottle of acid mentions that it contains inhibitors, does anyone know what they might be, and if they might be interfering in the acid production process? It's about 17c outside today so I'm also concerned that the issue might be the temperature. I have the reaction flask sitting in a hot water bath with my hotplate under it. I'm using kno3 as my nitrate salt. Any help would be greatly appreciated, thanks!

ManyInterests - 31-5-2021 at 18:00

Quote: Originally posted by IrishJeremy  
I'm currently making some fuming nitric acid, I'm using a brand of drain cleaner sulfuric acid that is new to me and things are going REALLY slowly. The bottle of acid mentions that it contains inhibitors, does anyone know what they might be, and if they might be interfering in the acid production process? It's about 17c outside today so I'm also concerned that the issue might be the temperature. I have the reaction flask sitting in a hot water bath with my hotplate under it. I'm using kno3 as my nitrate salt. Any help would be greatly appreciated, thanks!


From what I've seen in the videos by the CanadianChemist using drain cleaner grade sulfuric acid will not affect your final product that much. They've all used that stuff and the results worked just fine. The inhibitors will be left behind in the waste after the distillation is done.

I could be mistaken about that. Anyone with any experience can maybe correct me? NileRed and Nurdrage also have videos on fuming HNO3 but they used 98% H2SO4.

I don't know about the heat outside, but I don't think it is that much of an issue. I purified some sulfuric acid today by boiling it. It was roughly that temperature as well and it did not affect my end product. I have some extremely pure H2SO4 in a nice erlenmeyer flask

KNO3 will work fine. I don't think the actual type of nitrate matters that much so long as you're using a fairly pure nitrate.

I think you'll need more heat to make the reaction work. I've seen oil baths instead of water baths. I'll post some videos that should aid in the process.

While I am at this I have a question about the bottles for storing fuming nitric acid. Can I store them in a tinted liquor bottle? It isn't borosilicate or chemistry grade, but will the nitric acid attack the glass bottle?

Fyndium - 1-6-2021 at 08:01

Using calcium nitrate causes a solid mass of calcium sulfate formation. Adding even quarter of water soluble nitrate makes it's extraction after reaction 10 times easier.

LabDIRECT - 3-6-2021 at 05:15

I second the Calcium Nitrate - definitely better. But we can probably get you ACS grade 70% Nitric acid for about the same price and with much less effort. LabDirectLLC.com - send me an email at richard.carboni at labdirectllc.com and I'll make sure to do whatever we can to help out a first time customer

ManyInterests - 30-5-2023 at 21:34

I decided to bump this old thread because I have some questions regarding making nitric acid.

In times past, I played it by ear, since I couldn't control for temperature. Now I got a thermometer adapter and a clairsen adapter, I decided to try it out and set my temperature at no more than 90C. But I am not seeing that much acid coming over. Does making WFNA normally take this long? Or is simply the acid cooling down too quick and returning to the flask?

For a note, it is currently in process?

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