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Re: Aquatic Plants Digest V2 #770
> Date: Sat, 14 Jun 1997 02:05:08 +0400
> From: vahe at arminco_com
> Subject: New type of DIY CO2 proposed
> I am thinking of designing a new type of DIY CO2 setup: using a bottle with
> dilute muriatic acid and pieces of marble in it. This should be cheap and
> can produce lots of CO2. Since marble is rather dense, and
> one can use very dilute acid, it can be set up so that the reaction will
> last for quite a period of time.
> Anyone would like to experiment with this setup? Any other ideas?
> - - Vahe
I haven't done this, so what follows is mostly speculation on my part...
I suspect that you may be able to make this work, but the working system
would be fairly "high tech". If you were to build it as a batch process
(add chips and acid once a month and let 'er rip) that you'll get a very
high rate of production initially, declining to very low rates as the
acid is nuetralized. The time necessary for the system to get depleted
would be difficult to predict.
You might get more regular production by dripping the acid through a
column containing chalk or limestone chips. That way the CO2 production
would be controlled by the drip rate. It might be tough to regulate
the drip rate as low as you want it. The process will start having
problems as chips dissolve and the column compacts, leading to the
formation of channels though the column. That might be fixed by
adding an inert framework to keep the chips apart... Oh well. I guess
that's what experiments are for.
The results will depend a lot on the kind of "marble" chips you use.
What you need is a rather pure CaCO3 with a very consistent grain size.
True marble is rarely pure; it and many kinds of limestone will contain
insoluble material that may accumulate and armor the remaining part of
the grains. Dolomite is probably not as good as limestone because
it is less soluble. Chalk is probably the best bet.
Anyway, I think its interesting. Maybe I'll give it a try.