mekanochemical
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Hydrochloric acid separation
Hello, i want to separate hydrochloric acid from floor cleaner. It is composed by hydrochloric acid (in label said 33%), dodecylbenzenesulfonic acid
and pH controller. Is it possible to collect the hydrochloric acid just by distillation?
Muriatic acid is a crap to find (can buy 1l per month and you may receive a police visit)
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annaandherdad
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This same topic was the subject of a recent thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=154136
and there are probably more that can be found with the search engine or google.
In that aforementioned thread, it is stated:
"10 M HCl is placed in one container, in the other it is filled with distilled water. After several weeks, one container should contain pure 5 M HCl.
"
I would like to point out that the container, initially containing pure water, does not necessarily end up with half the initial M of the acid.
Equilibrium is reached when the concentration of acid in both containers is equal. The concentration at equilibrium depends on the initial amounts
in the two containers (acid in one, water in the other).
(I am assuming that any impurities in the initial acid are too small to affect the simple equilibrium condition I am stating. That may be true for
the hardware store HCl I can buy, but it obviously depends.)
If we are given the initial concentrations and masses of the liquids in the two containers, then we have enough information to determine the
equilibrium concentration. However, we do not have enough information to determine how much of the acid at that concentration resides in the two
containers. To know that we need an extra information. For example, the assumption that only HCl is transferred from one beaker to the other, not
H2O, gives a unique solution for the masses of acid in the two containers at equilibrium (because in that case the masses of water in the two
containers are the same initially and finally).
I do not know if it is reasonable to assume that only (or mostly only) HCl is transferred, but if the vapor pressure of the HCl is higher than that of
the H2O it would be logical. Surely it depends on circumstances (temperature etc).
Also there is some inefficiency because the container itself contains some HCl vapor which is presumably lost when the container is opened. This
loss could be minimized by lowering the temperature just before opening the container.
In this process the concentration of the purified acid can be greater than 1/2 the concentration of the initial, impure acid, in fact there are ways
of getting it quite close to the initial concentration of the impure acid (as close as you want, in principle).
Any other SF Bay chemists?
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mekanochemical
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I saw this post and my initial idea came from it, but here the floor cleaner has dodecylbenzenesulfonic acid (a soap that apparently retard the
hydroclhoric reaction), and my question is more if the dodecyl can mess the distillation or something else
thanks
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Sulaiman
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I would try distillation,
but as the HCl:Water azeotrope is twenty point two percent,
the first Hydrochloric acid to come over will be extremely concentrated,
including {I believe} HCl gas, which will not be condensed,
so you need to either
absorb the HCl gas {either complicated, or a risk of suckback}
or
dilute your hydrochloric acid to twenty percent before starting the distillation,
you will collect twenty percent hydrochloric acid,
which is concentrated enough for most purposes,
and easier to store than thirty three percent.
Don't be greedy, leave about five percent of your boiling pot contents un-distilled,
to reduce the risk of contaminating your distillate.
CAUTION : Hobby Chemist, not Professional or even Amateur
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j_sum1
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Dilution and distillation is the way to go IMO. If you dilute jusy below azeotrope then you get a bit of water / dilute acid first and then HCl of
known concentration. Your overall yiels will be greater and 20% is good for most purposes anyway.
The two container equilibrium method is interesting. Tupperware is ideal for this. To maximise yield and rate, make both containers shallow with a
large exposed liquid surface. Keep the head space as small a volume as possible to minimise loss. I don't think there is a huge amount of water
transfer. But do be aware that the entire internal surface gets coated with condensed acid. It gets everywhere if you are not careful.
Edit
I should add that if you need stronger than azeotropic HCl, you can easily fortify it usung HCl gas from concentrated sulfuric acid and table salt. It
is no trickier than ammonia production but you do need to watch for suck-back.
[Edited on 23-11-2019 by j_sum1]
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draculic acid69
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What country do you live in where hydrochloric acid is hard to get or a possible thing that police would be interested in?
Do u have swimming pools in your country? If so hydrochloric acid is available
Do u not have hardware stores either?
Any way just drop a heap of Al foil into your directly hydrochloric acid stuff in a bottle with a hose coming out of the top and lead the gas
generated into cold water.do this outside.way better than distilling water and dealing with HCL filling the room corroding everything.
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mekanochemical
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Live in Brazil, the problem is cocaine refiners... any chemicals used to refine/produce drugs are restricted
will try distillate the floor cleaner, lets see what happen
thanks to all
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mekanochemical
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Update:
Tried with 2 different brands with different formulations, both with same results. I put 100 ml on distiller, the cleaner boiled around 97°C (i am at
700m at sea level) and take 25 ml in receiver until the boiling start to foaming a lot, becaming impraticable to continue. On the distilled a slight
smell of hydrocarbon and in the boiled liquid a strong smell of chlorine... the soap block the separation.
will need another source
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Pumukli
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Maybe you should try the suggested two pot method! It does not require distillation only time.
It would not only give you very pure HCl but we -readers- may learn the outcome of the experiment and learn something useful! Which would be more than
brainstorming, which would be practice!
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draculic acid69
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Yes the twopot method might be the way to go or try what I suggested.distilling is not the best with hydrochloric acid.
[Edited on 23-12-2019 by draculic acid69]
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mekanochemical
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will try the two pot, thanks
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mekanochemical
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and here we go
1l of stone cleaner diluted in 1l of water on pink bowl and 750ml of distilled water in the purple bowl
and I measured the pH of distilled water and marked in lid
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Tellurium
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Very interesting to see, how it turns out. But why did you dilute your HCl? Because the more concentrated it is, the more HCl will escape. As it has a
positive azeotrope at 20,2% I think not much will happen with the 33% Acid diluted to ~16,5% at all. I would stick to the concentrated stuff, because
in my experience concentrated HCl has a lot of HCl fumes escaping and HCl with <20% concentration did not seem to fume at all.
[Edited on 29-12-2019 by Tellurium]
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mekanochemical
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I diluted by some precaution regarding detergent fraction... if runs well will try with pure cleaner (i have one more bottle here)
pure is a very thick liquid (like a hand dishwashing detergent), it might not work well
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draculic acid69
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The thickness of the liquid shouldn't be a factor with regards to how this works. And Have u tried dropping a small ball of Al foil into some straight
stone cleaner? U should get a large evolution of HCl gas after about a minute unless the other chemicals hinder this.
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mekanochemical
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will try later, thanks
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mekanochemical
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updating: I changed the detergent by the concentrated on 31/12 and keept the diluted to... cleaning 
today I measured the pH from distilled water, 2,8 (10 days later)
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CharlieA
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I would not expect the detergent to be very volatile; especially to affect the outcome of the "2-pot" method. Note that I have not checked the
volatility of the detergent. If there is one thing that we can do on this forum, it is to speculate about anything and everything whether we have
actual knowledge and/or experience about the subject.
Good luck with your endeavors.
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mekanochemical
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just to close the subject... after 50 days, the pH decreased to 2,6 and stopped, probably the cleaner has less acid than expected...
the good thing is that in this period i found a place that sell acids close to my work 
thanks to all that help me on this job
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draculic acid69
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If u tried the Al foil method u would have been done 49 days ago.
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SWIM
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Saturating the cleaner with NaCl may prevent the foaming so you can just distill it.
This works for many surfactants.
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