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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
concentration high.
> 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.
> optimal
> 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
> cathode.
Probably.
As mentioned by someone else, oxalic acid is very toxic, and
not to be handled carelessly.
--
Paul Sears Ottawa, Canada