Diablo
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Silica sol gel as salt bridge
In the production of silica aerogels the first step is to produce a sol gel, a gel made of silica whos pores are filled with whatever solvent it was
made in. I bet that this would make the perfect salt bridge, stable and chemically inert for various electrochemical processes. I won't be able to try
this for a long time, but thought I'd post it anyway.
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elementcollector1
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Anyone got some of this stuff? It probably wouldn't work for sodium hydroxide production, though, because sodium silicate would be formed.
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Diablo
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If you have or can make tetramethyl orthosilicate, or the ethyl version it should be easy to make.
Edit: Also if you have silicon tetrachloride then you can make tmos by alcoholysis.
[Edited on 14-7-2012 by Diablo]
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kristofvagyok
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Blame me if I am wrong but a SALT bridge contain ions what can move in it while the electrolysis goes.
But! When making a silica gel (sol-gel process), then this gel will contain mainly alcohol, some water and a lot of amorphous silica.
As far I remember pure water and even alcohol conducts electricity really bad.
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Diablo
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After the gel is produced one would exchange it into water with a dissolved electrolyte multiple time to remove the alcoholand add mobile ions.
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Swede
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In my other thread, I'm playing with boehmite (al oxide hydroxide) gels... would these be suitable for your intended application?
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Diablo
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Since it is pretty inert it would probably be suitable as a salt bridge in most applications such as making sodium hydroxide from NaCl, but if making
sulfuric acid from a sulfate I would be worried that some of it would dissolve.
Edit: Also alumina sol gels seem quite easy to prepare http://www.aerogel.org/?p=1017
[Edited on 16-7-2012 by Diablo]
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daragh8008
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I have tried to make silica gels from teos on a number of occasions and while the chemistry and prep are quite straight forward I found that the gels
normally (sorry always) collapse on drying. I think you would need a supercritical dryer I you wanted form the stable porous gel. Prior to drying they
have they are like a really weak jelly and any attempts to move wreck them. Swede, I have also just started working on boehmite sols and have a few
small successes with them. I have been able to make a freestanding porous boehmite film and on monday I will be calcinating it to try for a porous
alumina film. I'll post a description and results on your tread when I get my camera charged.
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Diablo
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The supercritical drying process produces aerogels.
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