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Author: Subject: Sulphur Trioxide and Oleum Using a Box Oven - Illustarted Practical Guide
PHILOU Zrealone
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[*] posted on 7-8-2015 at 01:57


NH4 persulfate may burn or explode because of the peroxydic link (molecule contains oxydiser and reducer).

Also to take into account:
NH3 + SO3 --> NH2-SO3H
and maybe
2 NH3 + SO3 --> NH2-SO2-NH2 + H2O (sulfamide)
and related polymers (imidodisulfamide, trisulfimide... and from memory a hexamethylene tetramine related compound with strong curarisant (curare like) effect).


[Edited on 7-8-2015 by PHILOU Zrealone]




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[*] posted on 8-8-2015 at 21:42


Thanks for the article,
I wanted to try this one, haven't got around to it, don't like the exposure, and I only wanted it to remove the 2% of water in my concentrated h2so4 to increase yields in one of my experiments.

In the "The SO3 / H2O system" part of the article it states:

"If one tries distilling sulphuric acid with b >> a, initially a dilute acid distils, with the fraction of the SO3 progressively increasing until the maximum boiling point at 337C of the liquid/vapour azeotrope of 98%/2% H2SO4/H2O is reached. After this no further concentration in the SO3 component can be obtained. Hence distilation can not be used to prepare oleum/SO3."


Then in the "The SO3 / H2O / Na2SO4 system" part of the article, it states:

"We can say that the addition of Na2SO4 to H2SO4 breaks the azeotrope."


1) So if I wanted just 100% h2so4, I could slowly heat up sodium bisulfate up to 780 degrees without a cut, while condensing and collecting the runoff.

Or

2) could I take a liter of h2so4, add x amount of sodium bisulfate, heat until approx. 20ml of h20 comes over, then triturate, and use, or continue heating to remove more water?

I'm not sure how the formula would go, and I'm not sure if this isn't all gibberish, I'm tired, and feel lame, but I still want to get to 100% acid.

Comments?



[Edited on 9-8-2015 by shadow]
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chloric1
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[*] posted on 9-6-2023 at 09:40
Regeneration of bisulfate


If you clean up and crystallize your sodium sulfate byproduct, would you get sodium bisulfate if you added dilute sulfuric acid? Or is the bisulfate only made by partial neutralization? I should know this and my intuition tells me it’s so but I wanted to verify. Because it would be a great alternative than just “Boiling the BAT”.



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[*] posted on 9-6-2023 at 10:09


Quote: Originally posted by chloric1  
If you clean up and crystallize your sodium sulfate byproduct, would you get sodium bisulfate if you added dilute sulfuric acid?
Yes, you would.

Also, I just went and fixed all the broken image links in the OP by changing the HTML formatting to bbcode.




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chloric1
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[*] posted on 9-6-2023 at 12:35


Thanks! I was thinking that. You see in certain applications, sulfuric acid is actually CHEAPER than sodium bisulfate! Let me elaborate. That’s not based on chemical weight but on acidity. Sulfuric acid is at least twice as acidic as sodium bisulfate. That does not factor in the fact that the strength of that second hydrogen is barely more than the first hydrogen off of orthophosphoric acid.

I started anodizing aluminum using a 20% sodium bisulfate solution whereas I discovered I only needed 11% sulfuric acid and hence that option is cheaper yet more hazardous.




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