Plato - 11-12-2002 at 08:07
I am trying to produce water with a Ph of 2.5-3.0 via hydrolysis but I can't seem to get the water lower than 3.8!
Advice?
-Plato
madscientist - 11-12-2002 at 13:31
Via hydrolysis of what?
Hydrolysis...
Plato - 12-12-2002 at 10:37
I have a container of water set up in which I insert two electrodes and run current through the solution. Around one of my electrodes is a permeable
bag in which I collect the water with the low Ph. The main bucket contains the high Ph. I split the water with the current.
madscientist - 12-12-2002 at 11:36
What is the solution?
Solution...
Plato - 12-12-2002 at 13:09
The solution is water that contains a little bit of salt for conductive purposes.
Ollie Snowie - 16-9-2003 at 03:58
"a little bit of salt for conductive purposes"
The reason why electrolysis of salt solution in the type of cell you describe produces acidic water is because electrolysis of salt solution yields
chlorine, and in your setup, this will dissolve in the anolyte and make it acidic. You need to use more salt. Also, chlorine water does have a limit
to its pH, so you might have to use a different salt altogether to reach the pH you desire.
What do you want this acidic water for?
[Edited on 16-9-2003 by Ollie Snowie]
vulture - 16-9-2003 at 06:03
If you're using NaCl, you're also producing NaOH, which prevents your pH from dropping too low.
[Edited on 16-9-2003 by vulture]
Ollie Snowie - 17-9-2003 at 10:12
I think the permeable bag is meant to stop the NaOH from getting to the acidic water. Try using something like an unglazed plantpot instead of a bag.
You could also replace the catholyte with fresh brine every now and then to remove the NaOH.
vulture - 17-9-2003 at 10:29
OH- and H+ are almost equally agile. A common membrane that will allow H+ to pass will also pass through OH-. Only highly specialized membranes would
allow that.
Furthermore, by separating H+ and OH- you're creating quite a potential difference. Using a higher voltage might improve "yield".
Theoretic - 7-10-2003 at 06:31
I wonder what happens when a current with a voltage not big enough for electrolysis is run through, say, a NaCl solution (with inert electrodes of
course, since oxidation of Fe at the cathode is energy-producing)?
overseer - 31-12-2003 at 07:45
In my opinion, Ollie Snowie has the point. If the purpose would allow for that, a better result would be obtained with a sulphate salt. Once the water
is acidified, the dilute acid thus formed can simply be concentrated by boiling.