Sciencemadness Discussion Board

best route to WFNA

BerthelotOnCrack - 14-1-2023 at 17:44

Hello, I have a few questions about HNO3
I decided I wanted to purify my nitic acid as much as possible. I already dried it using sulfuric, it's density indicates >99% but it's so orange (picrel) that I know there is still a lot of nitrous oxides in it, which I want to get rid of.

So the plan is to let the RFNA vent in 0.2 atm (aspirator pump) to let the oxides go away. But for future synthesis I would rather directly produce WFNA, so here is my problem and question:
I don't have that much sulfuric around so I use a mix of sodium bisulfate and KNO3 to produce my nitric. Is it of any use to vacuum distill with this reaction ? I mean the temp used is higher than regular synthesis because you have to melt the bisulfate, I'm thinking the vacuum may have a very low impact on HNO3 decomposition

nitric.jpg - 617kB

Rainwater - 14-1-2023 at 18:56

Setup a reflux apparatus and boil.
Soft vacuum will speed up the process.
It will discolor again on storage,
i find bright light / sunlight will accelerate decomposition

Edit:
Check your local laws, its illegal where im at

[Edited on 15-1-2023 by Rainwater]

BerthelotOnCrack - 14-1-2023 at 19:08

Quote: Originally posted by Rainwater  
Setup a reflux apparatus and boil.
Soft vacuum will speed up the process.
It will discolor again on storage,
i find bright light / sunlight will accelerate decomposition

Have you tried this with fuming acid ? Cause I did and I find it only works with azeotropic nitric

Rainwater - 14-1-2023 at 20:25

Ya. Anytime i deal with making nitric acid i use a water aspirator
with baking soda to help keep the stink down.
It speeds up the distillation, lowers boiling point, helps limit decomposition
and makes the process a lot less orange.
The orange is just NO2 gas contamination, short of making explosives,
it shouldnt effect anything but the looks

Junk_Enginerd - 15-1-2023 at 01:32

Related to this, I have a question... If you have RFNA, but it's not maximum concentration, and you want to increase the concentration, what's the right route? Heat it mildly and bubble air/oxygen through it? That dissolved NO2 isn't just a waste product, right? So if OP wants more nitric acid, the hypothetical best route should be to add some water and convert the NO2 contamination to more nitric acid instead. Am I correct in this?

Sure, it might be easier to just remove the NO2, but just for the sake of discussion and me learning...

Rainwater - 15-1-2023 at 04:06

If you wanted a slightly better yield, i believe adding water and bubbling air would react the NOx gases to produce more acid

BerthelotOnCrack - 15-1-2023 at 05:11

Quote: Originally posted by Rainwater  
Ya. Anytime i deal with making nitric acid i use a water aspirator
with baking soda to help keep the stink down.
It speeds up the distillation, lowers boiling point, helps limit decomposition
and makes the process a lot less orange.
The orange is just NO2 gas contamination, short of making explosives,
it shouldnt effect anything but the looks


Ok thank you, I will vacuum distill
Do you keep the same temp as for a regular distillation ?

Rainwater - 15-1-2023 at 16:31

https://www.sciencemadness.org/whisper/search.php
You should search for your answers
Have you considered how you're going to store the wfna?
Its like fresh wine. It will.make your bottle go pop

BerthelotOnCrack - 15-1-2023 at 22:44

Quote: Originally posted by Rainwater  
https://www.sciencemadness.org/whisper/search.php
You should search for your answers
Have you considered how you're going to store the wfna?
Its like fresh wine. It will.make your bottle go pop


I have searched already for my specific reaction and I didn't find much, that's why I made a new thread
Well I guess the storage is not different than for RFNA which I already posess. That amber glass bottle with a ptfe cap should handle everything