huegene83 - 23-11-2017 at 11:12
Hi,
for an experiment (preparation of glyoxylic acid from oxalic acid) I intend to build an electrolysis chamber. This electrolysis chamber needs to be
divided by an ion exchange membrane. Like so many, I intend to save some money and use a reverse osmosis membrane from a used water filter. I figure
that i might act as an anion ion exchange membrane and get the job done.
I think it must be able to act as an anion exchange membrane, because it lets water pass through it.
Am I all to wrong about this or should this be possible?
macckone - 23-11-2017 at 17:13
It might work. Reverse osmosis membrane may actually be too small of a pore size for a particular process. In this process the divider should work
if it resists the sulfuric acid.
Melgar - 28-11-2017 at 09:51
Reverse osmosis is the opposite of what you want. It allows neutral molecules through, but not ions. If you want to be cheap, then use a piece of
thick, durable fabric. If you want the best membrane that money can buy, the Nafion line of membranes can meet your needs.
[Edited on 11/28/17 by Melgar]
huegene83 - 6-12-2017 at 04:13
Thank you very much,
I have done the experiment already and I can confirm the suspissions. With 24Volt supplied to "the cell" with 35cm² surface of the membrane, I got
200mA tops (it startet out at 50mA and grew to 200mA within a minute).
As to the fabric, what do you think about "infusing" the (cotton) fabric with a solution of cation exchange resin dissolved in acetone (and
evaporating the acetone afterwards)?
(this may seem pathetic to you but I could efford the nafion membrane. I am more curious about what hack I could get away with)
Important P.S.:
A stoichiometric mixture of hydrogen and oxygen is very capable "to run away" at roomtemperature. I was lucky the cell did not blow and the hose
connectors where pointing away from me! I did not see that coming. Also interestingly, there was a faint red glow of the gas mixture ~200ms prior to
the ingnition.
Melgar - 8-12-2017 at 16:27
If you're going to be doing this regularly, you probably should have some Nafion membrane, as your control. So you can test other materials against
it, and then use the Nafion results as your "ideal" results. Otherwise, you might not have any idea what type of performance is good, and what isn't.
Ion exchange resin is crosslinked. You can't dissolve it in acetone or anything else. However, if you have styrene sulfonate and divinylbenzene, you
could make your own membranes.