so lately i came to a need to conecntrate 30%sulfuric acid to get 95 or even better the 98%
what i'm planing to do is to fill a 1000ml wide beaker with 750ml of the 30% and put it in a hot sand bath and boil it ,could it work?
i've watched a few videos on youtube and in one of them (by nile red) he tried to "clean" a drain cleaner 95% sulfuric acid and the boiling didn't go
well at all it bumped a lot ,you can find the video Here
i'm worried that that will happen and spill everywhere
is there anyone who tried it before ?
what are your thoughts? aga - 16-11-2016 at 10:58
Boiling sulphuric definitely works.
Yes, if any can spill out, it will, and wreck whatever it touches, so you need to be certain that cannot happen.
The hardest part is deciding exactly when it's 'done'.
The idea is to wait until you see dense white fumes leaving, which look slighly different to the water vapour that leaves before it.
If it's brown drain cleaner, you can add 3% H2O2 and stirr to remove the brown colour.arkoma - 16-11-2016 at 18:49
after a few close calls in other areas, i've become somewhat more cautious. no hot acid mishaps, but have had a near thing
with a fire and one time had boiling ethanol bump and fountain up my 300ml vigreaux and blow the thermometer adapter out. etoh hit the ceiling and it
hit the ceiling. I had naked incandescent bulbs way too close. fortunate the gremlims were just pranking and not firebombing.
that said, wack a earthenware plate with a hammer for boiling chips and USE them. i'd not fill anything more than half full, tops. use a single eye
110hotplate outside. fuck a sandbath--too long to heat up and TOO LONG to cool' oil bath big nono, even break fluid. boilover into that ya might as
well run 50 feet and then look back.
if 50 % reduction ain't fuming, do two batches and combine.
WEAR A FACE SHIELD AT LEAST
H2SO4 is unforgiving at battery %'s. instant painful charring of flesh
have large box baking soda handy with the top tore off. also a gallon sat solution soda.
Your post asked for others thoughts, these are mine; i've had enough near misses to quit being cavalier. sulfuric acid is no joke......
i
[Edited on 11-17-2016 by arkoma]mayko - 16-11-2016 at 21:11
I think Ave369 is our resident expert on concentrating sulfuric acid. I'd start with this thread of hers:
Thanks to you all
Now reading ave369's post i don't think i'll reach the 95+ concentration by simply boiling it i'll have to do a distillation at 300+° C
But i'll figure m'y setup out to do that
Thanks again.ave369 - 17-11-2016 at 12:47
My setup works in two parts. Part one is simply boiling. It concentrates the acid to 70-80%. Part two is insulated distillation with a specifically
designed condenser. It works like a charm.aga - 17-11-2016 at 13:50
Personally i find that sulphuric acid is boiled down with no difficulties if put it in 250ml beakers, usually 4 at a time, on a hotplate, then boil
until dense white fumes are seen.
Bumping and/or difficulties have not been seen here.
Well, apart from the fumes.Tsjerk - 17-11-2016 at 22:29
Ave369 concentrates her acid by just boiling, no distillation involved. You may use a short, insulated "column" of sorts to minimize losses through
splashing and inefficient separation of water from acid, although at near azeotropic temperatures the boil off will be very acidic anyway.
[Edited on 18-11-2016 by Tsjerk]CHEMxpl - 18-11-2016 at 02:10
okay so i've tried to simply boil the sulfuric acid down using a hotplate with some boiling stones and at the bigining it all went great but as it
approached the higher concentrations the boiling died down quit a bit and i was taking samples (with all the safty gear on)
and when the boiling slowed down it was around the ~85% concentrations (i tested it by measuring it's density at room temp which was about 1.75g/ml)
and it took a while to get it well concentrated
the final yield was about 175ml of (93-96%) sulfuric acid (i started with 760ml)
note: sulfuric acid vapors where coming off te whole time Tsjerk - 18-11-2016 at 02:22
If the boiling dies down it means your hotplate can't give enough energy, maybe some alu-foil helps. Maybe your yield could go up a bit with a small
column, although it will take longer in that case. CHEMxpl - 18-11-2016 at 04:04
yeah i'll try that maybe tomorow and i'll see the results
do you think i should use a vigreux colum for that ?
and i'll go get a heating mantel(should be much hotter) and try to just dirrectly distill the sulfuric acid
Tsjerk - 18-11-2016 at 05:59
I think a vigreux would be too long because the temperatures are quite high, you would need very good insulation. I think a couple of glass adapters
stacked on top of each other would be sufficient.
If you are going for distillation be careful with high temperature gradients as they can crack your glass. CHEMxpl - 18-11-2016 at 06:41
yeah for sure i have good quality borosilicate glassware so as long as i heat it slowly and gently it will be okay
now i'm just going for the simple distillation cuz using a colum i think would be very time consuming
so the the yeild should be aroung 165ml of consentrated sulfuric acid per (30%)720ml bottle
i'm gonna go ahead and distill ten of them to get a reasonable amount of sulfuric acid if it all goes well with the simple distillation and the new
heating mantle works !
thanks
Maroboduus - 18-11-2016 at 10:47
One of those full coverage spherical mantles would be great for this. More heating area and minimal thermal stress from temp gradients on the flask.
Glass-col makes upper covers for RBFs as well, so you can just put one on along with your regular mantle for total coverage.
At least one poster on this site used a hot air gun to make a hot air mantle of sorts. This kind of rig could be modified to heat the entire flask
and the distillation head as well. The guns are cheap, and even the cheapest of them are advertised as going to 500C.
CHEMxpl - 18-11-2016 at 23:57
yeah thanks for that
i't sounds a cool idea i'm sure i have and old heat gun somewhere in my house it's quite old but i'll try it
the heating mantels are really expensive but i guess it's worth it.ave369 - 20-11-2016 at 02:31
note: sulfuric acid vapors where coming off te whole time
The very point of my condenser setup is getting rid of vapors. With it, I've been able to concentrate sulfuric acid in a tiny apartment without a fume
hood. If vapors bug you, use my setup.CHEMxpl - 20-11-2016 at 04:03
I'm doing this outside and it's away from anything that is easily corroded
So for now i'm okay
But in case i ever moved inside i'll use your setup
Thanks a lot! AJKOER - 20-11-2016 at 12:29
Some boiling of the not so concentrated H2SO4 is likely performed without incident.
I would recommend an experiment of adding Na2SO4 to the hot solution and freezing.
The sodium sulfate is not very soluble (due to the sulfate ion in excess) and the question is would any Na2SO4(H2O)9.H2O form on cooling? In general,
the second water here represents the water of solution as distinct from the pure attached water to the sodium sulfate.
I would expect some loss in yield, but if successful, likely a much safer route.
[Edited on 20-11-2016 by AJKOER]CHEMxpl - 20-11-2016 at 21:26
I watched a video on YouTube where battery acid got boiled until white fumes were seen but that acid contained sodium sulfate and upon cooling the
concentrated acid it crashed out of solution.
Since i want a pure concentrated acid i dont want to add any contamination. i'm lucky cause the acid that i used doesn't contain any contaminants ,
and conc H2SO4 is really hard tout filtre.
and loss will occure no matter what method you use
[Edited on 21-11-2016 by CHEMxpl]ecos - 23-11-2016 at 06:39
yes i did but that time i tried it i didn't have a powerful enough heating mantle so it worked but was very long
i've ordered a new better one on ebay and i'm waiting to get it then i'll concentrate it buy distilation
nurd rage built his own mantle but i decieded to zkip that hastle of building my own
thanks
