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Tarnished Cathode

karlkoehkarlkoeh Posts: 8
in Electrophoretic Tissue Clearing (ETC)
After about 2 days of ETC at 30V and 45-50ºC the cathode is completely black. I'm assuming this is platinum sulfide (correct?). Has anyone found a good way to clean the electrodes in-between runs? For that matter, does this tarnish affect the outcome of ETC? I have notice no issue with black particles depositing on my sample as long as I keep the voltage low (~30V or lower). However, I haven't been doing this very long.

So far, I have tried filling the chamber with 70% isopropanol and placing it in a ultrasonic bath for several hours. This mildly cleaned the electrodes. I also tried this silverware cleaning trick, but to no avail:

http://scifun.chem.wisc.edu/homeexpts/tarnish.html
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Comments

  • joelrosienejoelrosiene Posts: 63
    I have noticed this. I must say that I have also noted no (or at least minimal) effect of this on the electrical end. Voltage and amperage remain constant from day one (with no tarnish), all the way up until day 3 or 4 (fully black cathode). I would assume that if this process were to interfere with the electrical properties of your chamber, it would do so by increasing resistance, and my amperage would have changed.
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  • FabioFabio Posts: 62
    As long as there are no changes in amperage and water hydrolysis is happening, I suppose its fine.
    If you want to get rid of the black deposits, you can try to circulate mild sulfuric acid (0.5-1M) through the chamber.
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  • joelrosienejoelrosiene Posts: 63
    Fabio is right - of course those deposits will probably just come back on your next run...
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  • KatherineHolzemKatherineHolzem Posts: 21
    I have also noticed the tarnish... surprisingly Tarn-X does take it off with a gauze pad. I don't know what this stuff is, and I have had to clean things regularly to not get too much buildup in solution or on my tissue.
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  • arvidarvid Posts: 9
    I get the black tarnish at the cathode as well, it's a little sticky, but I can easily wipe it off - To me it looks like burned SDS, and I'm thinking it might be a matter of temperature i.e. the electrodes themselves getting too hot and "burning" the SDS - what do you think?

    I'm working right now on trying to optimise the chamber for cooling the cathode, contrary to my belief it seems that turbulent flow is a much more efficient cooler than laminar flow, supporting the idea of some breakwater used by someone at forum (can't find the post right now sorry^^)

    I'm new to electrolysis, but as far as I understand it hydrogen is produced at the cathode, and since there is plenty of oxygen it will react momentarily producing water and heat.. That could mean that constantly bubbling the solution with say nitrogen could permit higher voltages and faster clearing - ok, I'm just speculating here, will report if I test it :)
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