Hi all,
Currently I'm trying to coat the IrO2 electrode, which acts as anode, with a liquid Nafion Dispersion using a dipper. However, this coating does not work as chlorine is produced after 90-150min of electrolysis.
Up to the moment, I dip the anode for 5min in the 5%W/W Nafion dispersion, then I dry it for 5min at room temperature and for 30min at 80ºC. I repeat this process 5 times. However, as I mentioned above, the coat seems not to be sufficient stable.
The anode is a Ti mail substrate with an IrO2 coat. Maybe the mail geometry decrease the Nafion adherence?.
Thank you in advance.
If you need more information only say it.
Since the materials you are using ( Ti substrate, IrO2 electrode etc.) are not heat sensitive, I would suggest you try to heat treat the Nafion suspension ( or even diluted Teflon aqueous suspension) at 325C for few minutes. Tefon will sinter at this temperature and you may get a better adhesion. Without knowing how you are going to use this electrode and the purpose of the Nafion. this is what I can suggest.
The purpose of these experiments is to decrease the chlorine evolution reaction on the Ti/IrO2 anode. The Nafion is used for coating the anode as it is a cation exchange membrane that will prevent chloride presence on the anode surface.
Should I heat the Nafion suspension into any special atmosphere?
Any reference on making fuel Cell electrodes will give you details and other references.
Yes, I'm doing that right now but I've stability problems, that is, chlorine evolution appears from 90-150min of electrolysis. I'm looking for a method that holds on with the electrowinning conditions.
It would be useful to know full details of what you are doing and what you are aiming to get out of this.
Today, I've used a planar electrode, made of Ag, and it seems that the results obtained are very hopeful, they are very similar to those obtained with the membrane reactor I used previously.
In summary, I want to recover zinc from spent pickling baths. Currently, I'm looking for different ways to diminish the chlorine evolution reaction produced on the anode during zinc electrolysis in this media.
OK. You need to use an anode substrate that has high over-potential for Chlorine evolution. I don't remember off hand but one suggestion would be to use PbO2 coated graphite.
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