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Re: Carbon dioxide generation by electrolysis of oxalic acid
- To: Aquatic-Plants at actwin_com
- Subject: Re: Carbon dioxide generation by electrolysis of oxalic acid
- From: Paul Sears <psears at nrn1_NRCan.gc.ca>
- Date: Wed, 9 Sep 1998 09:13:13 -0400 (EDT)
- In-Reply-To: <199809081948.PAA04461 at acme_actwin.com> from "Aquatic Plants Digest" at Sep 8, 98 03:48:01 pm
> From: Denis Daly <dalymob at bigpond_com>
> Subject: Carbon dioxide generation by "electrolysis?" of Oxalic acid (ethanedioic acid)
> A friend seen a CO2 generator in a hydroponics shop that was
> supposed to work on electrolysis of Oxalic acid.
In priciple, this could work O.K..
-OOCCOO- -> 2CO2 + 2e- Anode reaction
2H+ + 2e- -> H2 Cathode reaction
I haven't been able to find the standard electrode potential
for the anode reaction, so I don't know how well it would proceed
in competition with the other possibility:
4OH- -> 2H2O + O2 + 4e-
Keeping the pH low would help, as would keeping the oxalate
> The salesman trying to sell my friend the commercial product
> claimed that it could be turned on and off by turning on or off
> the DC supply to the electrolysis cell.
That is how it would work.
> Has anyone got any ideas of what the catalyst could be,
I would start with sulphuric acid, to keep the pH low and
hence the OH- concentration _very_ low. Don't use hydrochloric acid -
you would get undesirable anode reactions.
> cell voltage (I could find that by using a variable power supply)
It will be only a very few volts.
> and whether stainless steel would be suitable for the anode and
As mentioned by someone else, oxalic acid is very toxic, and
not to be handled carelessly.
Paul Sears Ottawa, Canada