Sciencemadness Discussion Board

Concentrating Sulfuric Acid through Boiling

AndrewOfWallachia - 5-12-2023 at 00:34

For context I live in probably one of the shittiest countries in EU for acquiring chemicals so... Let's say that I managed to use 3% H2O2 to clean the shitty (probably, hopefully) ~15% Sulfuric Acid drain cleaner either that or used the Copper Sulfate or Oxalic Acid method and now I have a hopefully pure solution of who knows how much Sulfuric Acid in water. Now, in theory I can concentrate that to around 96% Sulfuric Acid by just boiling away the water... but is there any way to tell when I've finally reached the azeotropic Sulfuric acid so that I know to stop boiling? Thanks in advance and screw the idiots who made these dumb restrictions.

greenlight - 5-12-2023 at 02:57

If you have a pure solution of sulfuric acid in water at a low concentration then there are two observations that can be made to indicate that the majority of the water has been removed.

~98% sulfuric acid boils at 330 degrees Celcius so when white fumes are appearing and you are getting close to 300°C in temperature you are close.

A visual observation that can also be used is placing a glass lid over the heated acid solution and checking for water condensation on the glass surface. I used to use this method with moderate heating until the majority of the water was removed indicated by minimal condensation on the glass lid, then the temperature increased to 300°C to finish.

j_sum1 - 5-12-2023 at 04:19

I encourage you to search for posts by ave369. She became quite the expert at this process - which she called "boiling the bat". IIRC, she devised quite a few tips and tricks.

AndrewOfWallachia - 5-12-2023 at 05:59

Quote: Originally posted by greenlight  
If you have a pure solution of sulfuric acid in water at a low concentration then there are two observations that can be made to indicate that the majority of the water has been removed.

~98% sulfuric acid boils at 330 degrees Celcius so when white fumes are appearing and you are getting close to 300°C in temperature you are close.

A visual observation that can also be used is placing a glass lid over the heated acid solution and checking for water condensation on the glass surface. I used to use this method with moderate heating until the majority of the water was removed indicated by minimal condensation on the glass lid, then the temperature increased to 300°C to finish.

For the process to be complete let's say I want like 95% Sulfuric Acid, would I need to get close to 300 C? My hotplate can only reach 200 C plus I am worried that the glassware might crack if I get it that hot, also the risk of having Sulfuric Acid hot enough to ignite things spilling around

Sulaiman - 5-12-2023 at 07:14

200oC should bring concentration to about 80%
https://www.sciencemadness.org/smwiki/index.php/Sulfuric_aci...

RU_KLO - 5-12-2023 at 08:56

Maybe instead of drain cleaner you could start with battery acid. Usually is quite pure and 30 - 33% concentration.

and for heating, using a camping stove + sand bath?

dont forget to add some boiling stones. Sulfuric acid at that temperatures is quite bumping.

I think that clean sand is used also.

(Note: never performed sulfuric acid destilation, but seen videos)





[Edited on 5-12-2023 by RU_KLO]

leau - 5-12-2023 at 09:47

Stoneware:

https://www.marketsatshrewsbury.com/blog/stoneware-care/

heated slowly will work much more safely than borosilicate glass as the references explain :cool:

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leau - 5-12-2023 at 10:06

Stoneware can be acid resistant :cool:

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AndrewOfWallachia - 5-12-2023 at 14:42

Quote: Originally posted by RU_KLO  
Maybe instead of drain cleaner you could start with battery acid. Usually is quite pure and 30 - 33% concentration.

and for heating, using a camping stove + sand bath?

dont forget to add some boiling stones. Sulfuric acid at that temperatures is quite bumping.

I think that clean sand is used also.

(Note: never performed sulfuric acid destilation, but seen videos)





[Edited on 5-12-2023 by RU_KLO]
For distillation I'd need a temperature of around 337 C, my hot plate can only reach 200 C. Also are you sure battery acid/electrolyte the type you can buy in a bottle from a car shop is that concentrated in the EU? I've heard EU regulations only allow up to 15%.

RU_KLO - 5-12-2023 at 18:33

Yes, battery acid is approx 30%. but from google yuasa.de
Sulphuric acid is now classified as a regulated substance (Annex I of the regulation). As of February 1st 2021, members of the public who wish to acquire, possess or use sulphuric acid with a concentration of more than 15% will need an official licence. Thus, in order to buy a motorcycle battery with a separate acid pack, consumers will have to apply for and receive a valid official licence before purchasing, for which up to approx. € 2,000 will be charged.From the cut-off date (February 1st 2021), it is considered an offence to possess or use sulphuric acid with a concentration of more than 15% without a valid official licence. This also applies to bottles of battery electrolyte that have not yet been filled into a motorcycle battery.

so it seems that you need a permit to buy battery acid in the EU. ( because its concentration).


[Edited on 6-12-2023 by RU_KLO]

Rainwater - 5-12-2023 at 22:03

Quote: Originally posted by RU_KLO  
Thus, in order to buy a motorcycle battery with a separate acid pack, consumers will have to apply for and receive a valid official licence before purchasing, for which up to approx. € 2,000 will be charged.[Edited on 6-12-2023 by RU_KLO]


Slow down, dude. Just looked it up.
Its bad, from my prospective across the water, But not that bad.
https://www.gov.uk/government/publications/licensing-for-hom...
They want 39 euro, a background check, and to know your reason.
Your a student or hobbist. Show them an organization work area.
Clean setup, safty gear. The ability to safety handle the hazards and quantities ordered.
If you don't have a way to vent nitrogen oxides into unpopulated areas,
do you need to risk your negibors?

My gun permit cost more than that. And there was a background check there to.
Attachment: duediligencechecks.pdf (89kB)
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Read about it here. Not really that restricted. Mostly common sense.
Not quite sure why all the genital mutilation stuff is in there but hell if they beat that
thing so hard its deformed, not allowing them to purchase dangerous compounds
may be the right call.

If you're going to study this, and you need a permit. Order it.
If they say no, find out, politely, why. And what could you do to change their mind

you dont need 5 kilos of oxidizer to study an experiment. I got the same 100ml of
nitric i been using for 2 years. Recycled it almost 40 times now.

If you're going to learn to refurbish old batteries or work in that type of industry.
Show them that. You'll get your permit for the acid.
If your going for a bs in chemistry that will go a long way in producing valid
arguments.

[Edited on 6-12-2023 by Rainwater]

Texium - 6-12-2023 at 08:25

Quote: Originally posted by Rainwater  
Quote: Originally posted by RU_KLO  
Thus, in order to buy a motorcycle battery with a separate acid pack, consumers will have to apply for and receive a valid official licence before purchasing, for which up to approx. € 2,000 will be charged.[Edited on 6-12-2023 by RU_KLO]


Slow down, dude. Just looked it up.
Its bad, from my prospective across the water, But not that bad.
https://www.gov.uk/government/publications/licensing-for-hom...
They want 39 euro, a background check, and to know your reason.
Your a student or hobbist. Show them an organization work area.
Clean setup, safty gear. The ability to safety handle the hazards and quantities ordered.
If you don't have a way to vent nitrogen oxides into unpopulated areas,
do you need to risk your negibors?
That’s the UK. They aren’t in the EU anymore and these regulations were implemented post-Brexit, so the rules may be different.

Sulaiman - 6-12-2023 at 11:04

Quote: Originally posted by AndrewOfWallachia  
Let's say that I managed to use 3% H2O2 to clean the shitty (probably, hopefully) ~15% Sulfuric Acid drain cleaner...

Sulphuric acid drain cleaner is normally 95%+ so that it can destroy (mainly by dehydration) organic matter.
Have you actually tested the concentration?

AndrewOfWallachia - 7-12-2023 at 02:27

Quote: Originally posted by Sulaiman  
Quote: Originally posted by AndrewOfWallachia  
Let's say that I managed to use 3% H2O2 to clean the shitty (probably, hopefully) ~15% Sulfuric Acid drain cleaner...

Sulphuric acid drain cleaner is normally 95%+ so that it can destroy (mainly by dehydration) organic matter.
Have you actually tested the concentration?

I tell you, and assure you, the crap that I have is so impure it's borderline impossible to test the concentration with the tools at my disposal, furthermore, I don't live in the Home of the Free, Land of the Brave * distant screaming eagle cry* where I can find such nice things, I have to put up with the shit of the EU regulations, which clearly state that any commercially available product containing sulfuric acid, can not be above 15% concentration.

Sulaiman - 7-12-2023 at 03:05

Just to be sure..
Pour a little of the acid onto some sugar or tissue paper,
- see if anything happens.

AndrewOfWallachia - 7-12-2023 at 06:03

Quote: Originally posted by Sulaiman  
Just to be sure..
Pour a little of the acid onto some sugar or tissue paper,
- see if anything happens.

First thing I did was the sugar test, the sugar was blackened but only a weak exothermic reaction, and no 'tower' formed, I then also tried paper towels, it burned through them but took a long time to do so.

Sulaiman - 7-12-2023 at 07:11

Then it is MUCH more than 15% - my guess would be 85% to 95%

Test by density
or
Do a quick/approximate titration...
measuring cylinder accuracy should be adequate for an approximate calculation
or
Measure BoIing point
(BE VERY SAFETY CONSCIOUS)

PS usually boiling near concentrated sulphuric acid will destroy any organic additives/inhibitors,
so hydrogen peroxide is not required.
Adding peroxide will dilute the acid, requiring additional boiling,
not a big problem but why add any if not required.

Try a boiling point test to both estimate concentration and test if peroxide will be needed.
A test tube heated by a candle (or small spirit lamp) is adequate.
Again, be careful, boiling sulphuric acid is VERY prone to violent bumping.

So far (only three times) I've not had a borosilicate rbf (cheap Chinese type) fail due to distilling sulphuric acid.
I used the open flames of a small/portable tabletop butane stove with the rbf a few cm. above the flames.
I made a windshield/chimney using an old tinplate biscuit tin.

[Edited on 7-12-2023 by Sulaiman]

Grizli7 - 14-12-2023 at 10:59

If your heater does not give out more than 200 degrees, you will not be able to get more than 78% approximately. 75% 187.8 degrees. 80%
210.2 degrees. In addition, with low heater power, you will have heavy losses. Well, to determine that the receipt is - take ten militers into a syringe, weigh, divide ten and look at the density table. Try to make useful acquaintances in galvanic production.