Nitric Acid Boil Over - OOPS!

[orvi]

That was perfect. I actually understood it and it all made sense. Well done and thank you.

Now if you could just explain why a 24/40 joint wont come apart. The 24/40 connection between my boiling flask and my tee- spout appears to have welded together. lol. Not the end of the world, but I can't exactly hit it with a hammer to knock the glassware apart.

Never give the salts chance to access the ground glass joint. With great surface area of the ground glass, they could solidify, filling all gaps, tightening the joint and making it nearly impossible to dissasemble.
Basic solutions are another example - etching the glass slowly, tightening the joint together.

Basic thing you could do is grease joints with good quality silicon grease - but for distilling nitric acid, you cant do that. Nitric will decompose nearly any grease.
Greasing with concentrated sulfuric acid is advised instead.
Best solution is to use teflon joint spacers or lab grade teflon tape - but these are expensive. On the other hand, they will last for years

To dissasemble freeze joint, one of best things is ultrasonic cleaner. If not in hand, heating technique is very helpful. Heat gun or torch will do the trick. Always wear good and thick gloves when applying force to the freeze joints. Cracked glass in the palm and fingers with simultaneous applying good bit of force create very nasty cut, very deep, in a very bad place - lots of veins :/ big bad. Seen few times in my lifetime, not pleasant at all.

When trying to loosen it, not only try to "turn" it, or only "pulling" the pieces. Very good technique is (with thick gloves on your hands) slightly waggle the inner part from side to side, changing the directions of applied force and simultaneously pulling pieces apart. The waggling should be only very gentle, and it requires some skill, but it work wonderful

 

[Noggin]

I was once present at the moment of a boilover. It was rolling and I just turned the heat down (my old mantle without digital controls). The bubbling solution was teasing the bottom of the distillation column. Suddenly the vapor on the bottom lifted the whole mass and it just shot everything over nearly completely (thank you Keck, wherever you are).
Yes imo, you should pour back into your boiling flask and start over with a clean receiver. Sulfuric is hard on paper filters and can easily make an acid that's way harsher than nitric by itself. You will also create sulfates in solution which may be less soluble than the nitrates.
Nitric acid boils off at about 120-ish (technically should be less but I use 120 as guideline). You'll stay way below the angry boiling temperature of your sulfuric, which will cause bumping and boilovers. Hopefully you have an IR thermometer, and watch the temperature at your column. Covering the riser and column adapter with aluminum foil conserves heat and lets you keep temperatures lower.
Steel keck clips are worth investing in.
I've done several recoveries of nitric from my copper nitrate using sulfuric acid, so I'm familiar with the process. This is no joke, after your upper column temperature falls (because no more vapor is being brought up) you can turn off the heat and let it cool. When hot this stuff is savage.
There's a lot more to this that you may already know - I won't assume. Let us know if anything's unclear.

 

[Noggin]

Never give the salts chance to access the ground glass joint. With great surface area of the ground glass, they could solidify, filling all gaps, tightening the joint and making it nearly impossible to dissasemble.
Basic solutions are another example - etching the glass slowly, tightening the joint together.

Basic thing you could do is grease joints with good quality silicon grease - but for distilling nitric acid, you cant do that. Nitric will decompose nearly any grease.
Greasing with concentrated sulfuric acid is advised instead.
Best solution is to use teflon joint spacers or lab grade teflon tape - but these are expensive. On the other hand, they will last for years

To dissasemble freeze joint, one of best things is ultrasonic cleaner. If not in hand, heating technique is very helpful. Heat gun or torch will do the trick. Always wear good and thick gloves when applying force to the freeze joints. Cracked glass in the palm and fingers with simultaneous applying good bit of force create very nasty cut, very deep, in a very bad place - lots of veins :/ big bad. Seen few times in my lifetime, not pleasant at all.

When trying to loosen it, not only try to "turn" it, or only "pulling" the pieces. Very good technique is (with thick gloves on your hands) slightly waggle the inner part from side to side, changing the directions of applied force and simultaneously pulling pieces apart. The waggling should be only very gentle, and it requires some skill, but it work wonderful

Orvi's right on everything, but I've also got a couple items for thought.
Grease won't last very long against sulfuric acid. To get a tight seal you can consider sulfuric acid. It's got decent viscosity.
Also for the frozen joints, I use my squirt bottle and put a few drops in the joint. It will wick through the salts if the glass is warm (like 70-80 c is when I disassemble my apparatus). I can't stress the thick gloves part enough

 

[snail]

Lou recommended Krytox grease for the joints. Pretty pricey but you don’t use much. Being some sort of perfloropolyether compound I imagine it is pretty durable.