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Oxalic acid

Hi everyone!

Sorry, this is a quite lengthy message.

I would like to return do discussion of alternatice CO2 production
method that was discussed here a while ago, through electrolysis of
Oxalic acid. This method seems extremely attractive to me for several
reasons: high yield (theoretically, 88g of CO2 should be produced from
90g of Oxalic acid), low cost (Oxalic acid is used in industrial
quantities in dieing, bleaching, etc. and is quite cheap), and easy
electronic control over the process (since CO2 production is directly
dependent on electric current). Among the advantages should be listed,
perhaps, that this method is used commercially by the greenhouses,
which means it should be quite efficient. The disadvantages are, of
cource, toxicity and corrosive effect of the substance, but if proper
care is taken, its safe use can be provided.

To start with, I purchaced 2lb. of Oxalic acid (it costed me less than
$2) and made a simple elecroliser from plastic coffee can. I took two
stainless steel plates sized 2.5x6 inch, screwed them on a piece of
0.6 x 0.6 x 2.5 inch plexiglass bar, connected the wires, and attached
this to a coffee can cap. I poured water into the coffee can until
about half-full, diluted about two tablespoonfuls of Oxalic acid,
screwed the cap on, and connected to a current source producing 5
volts (I didn't measure the current). In the original report about
this method of CO2 production described in the archives on The Krib
some liquid catalist was mentioned, probably Sulfuric Acid, but I
didn't add it fearing that it would corrode the steel electrodes.
Afterswitching on connecting the current the electrodes immediately
started to bubble, but it seemed a little strange to me as the most 
active bubbling was on the outer side of one plate (not the side
facing the other electrode, but looking at the jar). There was also
some gas production on the inner part of both electrodes, but less. I
let the system run for an hour or two to see how it would behave. Now,
the strange part begins. The liquid has become brown after a few
minutes of operation and with time, it was turning darker and darker.
After two hours it was almost black, so I couldn't see the electrodes
through it. When I disconnected the current and took off the cap, the
outer part of the electrode, on which most bubbles were produced was
covered by bright lemon-yellow staff (apparently, it was Iron Oxalate
as it looked exactly like the staff I produce by reacting Iron Sulfate
with Oxalic acid - btw., by heating Iron Oxalate to about 600F
atomized Iron is produced, which can also be used for the plants). The
inner part of the electrode was also lightly covered with iron oxalate
and some black and much dencer staff (did not clean off easily) -
I could not figure out what it was. The other electrode was clean,
covered by a thin layer of whiteish staff, perhaps calcium carbonate
from the water.

Now, my only knowledge of Chemistry is from general education school,
and I need help to find out what to do next. I don't understand why
most of the iron oxalate was built on the outer side of the steel
plate, I wouldn't be that much surprised to see it between the
electrodes. I don't understand what is the black-ish deposit on the
inner side of the same electrode, and what colored the liquid into
dark brown - judging from color, it must be some Fe (III) salt, but it
is dilute, or colloid at worst, since it didn't set down at all by the
next date. All I could think of would be Fe (III) oxalate, but I know
nothing about its color or solubility of water, and I have no other

If there are people knowledgeable in electrochemistry, please give me
some advice on how this research could be continued. Apparently, the
method has no practical uses at this stage. First, would the addition
of sulfuric acid change the situation at all? Second, what material
could be used for the electrode to prevent formation of oxalate? Coal?
(it is hard to find a coal electrode of decent size to provide
sufficient current density). Would silver be of any use? (I cannot use
gold or platinum for this project :) Any advise or explanations are
very welcome.

Many thanks in advance,