idrbur
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there is anyway to prevent carbon electrode from corrosion during electrolysis.
My carbon electrode corode vigorously during the electrolysis of h2so4 . So there is anyway to prevent it from corrosion.
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phlogiston
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Filling up the pores with linseed oil or paraffin helps, at least for chlorate cells. Not sure if it does any good in the case of other electrolytes
though.
Ideally, submerge the carbon electrode in linseed oil and apply a vacuum to get as much of it into the pores. Remove excess and allow to cure for a
few days in air.
[Edited on 10-7-2015 by phlogiston]
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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aga
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Reduce the voltage to 3~6 volts.
Higher voltages will eat the electrodes very fast.
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idrbur
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And what about the oil that will get mixed with the solution.
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idrbur
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And what about the oil that will get mixed with the solution.
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papaya
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For H2SO4 you better use lead as an anode, graphite (which I suspect usually is not at all graphite, rather highly compressed dust of carbon from
other sources) is not suitable here. You must chose materials on purpose -for example to electrolyze alkali solutions stainless steel (even plain
iron) will stand up very well, nickel will be probably the best, for chloride containing solutions near neutral pH only platinum, graphite (with some
erosion) and special metal oxide anodes will work.
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AJKOER
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Recently, I made CuSO4 via electrolysis of aqueous MgSO4 using one Carbon electrode sitting in a funnel with filter paper half submerged in the aq
MgSO4. A Copper electrode was placed outside the funnel in contact with the solution (in essence, I have a membrane). The carbon electrode quickly
fell apart, but the carbon mess was contained in the funnel, allowing pure CuSO4 formation outside. I repeated the experiment with better results
replacing the carbon electrode with stainless steel.
To apply to your H2SO4 electrolysis, use a large mouth glass funnel with say grounded glass (or sand as the membrane) in place of filter paper (which
would be attacked by the H2SO4).
In other words, you may be able to work even with a corroding carbon electrode through containment.
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MeshPL
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Coat graphite with lead dioxide. Or just use lead as mentioned before.
You can also try with different H2SO4 concentrations. Higher MAY help reduce corrosion, but it may do exact opposite.
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battoussai114
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+1 Vote for a lead electrode. AFAIC the whole point of H2SO4 being made with the lead chamber process back in the day was the fact that lead resisted
the corrosion.
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deltaH
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Lead oxidises rapidly in sulfuric acid when used as an anode. This is the basis of one-half of the lead-acid battery in your car. The half reaction
is:
Pb + SO4[2-] => PbSO4 + 2e[-] E° = +0.3588V
or more appropriately written as:
Pb + HSO4[-] => PbSO4 + H[+] + 2e[-]
Sources:
https://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page)
https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery
Aside: The other half reaction is the reduction of lead dioxide to lead sulfate.
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idrbur
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Thanks guys .
I think i can try the filter paper idea because it will be more convenient for me.
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