Sciencemadness Discussion Board

Sodium hypochlorite cooling cell.

Chemgineer - 11-6-2022 at 15:49

I've recently bought a beer line flash cooler second hand from a pub/bar and I was wondering about using it to cool some copper coils to keep a salt water solution cold.

I would then use a suitable anode and run electricity through it whilst keeping the cell very cool and maybe produce sodium hypochlorite.

If I was to do this do you think the copper cooling coils would work ok as the anode? I would probably use platinum titanium substrate for the anode.

Johnny Cappone - 11-6-2022 at 18:42

Quote: Originally posted by Chemgineer  

do you think the copper cooling coils would work ok as the anode?


You meant "cathode", I assume.
If so, although it will work, I would prefer not to use the cooling coil as an active electrode, although it would still need cathodic protection and so would still have reactions happening on its surface, albeit at a much lower intensity.

On the other hand, using it as a cathode will certainly protect the metal, while submerged, against oxidizing species in solution. In any case, it appears that the production of hypochlorite in a single vessel is somewhat ineffective, as it tends to be oxidized to chlorate at the anode. In fact temperature is a key factor in this reaction, but I'm not sure if it alone is enough to promote the formation of hypochlorite in a configuration that would usually tend to produce chlorate.

Chemgineer - 13-6-2022 at 07:57

Thanks, yes I did mean to say cathode for the copper coils.

I had read if the reaction is kept below 60 deg C then chlorate should be avoided however I should perhaps read into this some more before bending my copper tubing!

B(a)P - 15-6-2022 at 16:39

Copper will work as a cathode.
Chlorate formation in a call like you are describing is more efficient at higher temperates, but still occurs at lower temperatures. Certainly above 40 deg C you will get plenty of chlorate formation.
The article 'Disinfection of Water' in the following link seems to indicate 30 deg C will prevent chlorate production, though with a dilute salt solution.
Link
I have run chlorate cells at a temperature that is just warm to touch and still had plenty of chlorate formed, unfortunately I have never measure the temperature, so I can't give you anything more specific.