3 replies to this topic

[frosty90]

Hi all,

Any oxidiser except KNO3 is effectively completely unavailible commercially for me. I have to make do with what I can synthesise myself. I have made chlorate before using electrolysis with graphite anodes, it works brilliantly, but I became fed up with the errosion of the anodes, which puts an incredibley fine graphite into the solution. So I have purchased a commercial gold-plating platinum plated mesh anode and a stainless steel cathode. The stainless steel cathode has what appears to be a stainless steel strap spot welded to it to make the electrical connection. Heres the weird thing. At the point where the strap leaves the solution, the part exposed to the 'air' above the electrolyte is going brown/corroding. The part submerged is fine though. What is going on? This looks bad. Could it be gaseous chlorine? or something more complicated? more to the point: can itbe stopped?

Jesse

[Arthur Brown]

I'm not sure that ss is fully up to duty as cathode. Most of the successes I hear of have CP Titanium cathodes.

There is massive web literature about the electrochemistry of chlorate cells and some reported successes with perc cells.

[lavenatti]

Corrosion on steel cathodes in cells I have run always occurs just above the surface of the liquid. I have used PVC sleeves (just a small PVC pipe) filled with hot glue to cover this area and extend below the water. It solved, well minimized, the problem for me. I'm sure something similiar will work for you.

I've found treating the graphite (welding) electrode with linseed oil reduces their rate of wear significantly. I just soak for a few days, wipe off the excess and leave to dry for about two weeks before using. Graphite can be easily removed from the solution using a funnel with a few cotton balls stuffed into the bottom. I use a 2 liter soda bottle with the bottom cut off and a few holes drilled in the cap. 3 cotton balls stuffed into the neck will remove all the graphite and leave you with a crystal clear solution. It takes a while to filter through so support it well and just leave it over night. These are all pretty common solutions I found online, hope they help.

[digger]

P.S. Stainless steel is prone to corrosion from brine. It is called chloride stress corrosion, it is form of electrolytic crevice corrosion. I would not choose stainless steel in a chloride environment. We use titanium for greater than 50ppm chloride duties.