How to make Sodium Chlorate by Electrolysis of salt water?

[gary350]

I have a power supply for electrolysis of salt water brine, variable 3v to 6v up to 30 amps. Cathode is stainless steel, anode is carbon rods. Carbon rod surface area 42" sq. the Stainless steel cathode should be 21" sq. Salt is pure 100% salt dissolved into distilled water. I have been making saturated salt wrong. Today I learn saturated salt is, dissolve pure salt into 150°f water cool to 100°f pour into the 2 gallon brine tank. I find conflicting information about brine tank temperature some say, 40°C, or 60°c to 90°c, or 113°f. I Brine tank was 4.71volts 12.5amp running for 12 hours. Brine tank was 70°f and 12 hrs later 90°f. Lots of chlorine gas, hydrogen gas and oxygen comes from the brine tank no problem with 8'x8' door open. Sodium chlorate is suppose to fall out of solution below 40°C. I cooled 1 pint of brine water down to 0°f for 8 hours and no sodium chlorate fell out of solution. Something is wrong???

 

[sophiecentaur]

@gary350 Firstly, I really appreciate the intelligible circuit diagram you've given us., Too few of those around on PF!!

I know very little about electrolysis and my only experience was to try it with spent fixer from film developing. The place where I worked had loads of the stuff so I thought "money makes the world go around ...". I have to say, I came to it quite unprepared and all I ever got was a thin white film (silver, assumed) on the cathode, followed by horrible stains and warm water. I varied the volts but don't remember the current. This was pre-internet so information was not easily available.

From the vigorous activity you report, you are obviously electrolysing something so your circuit must be connected properly.

I did a quick search and a question about cathode material seemed worth asking. There was mention of titanium in one of the videos. Are you sure SS is suitable (at least the alloy you are using)?

 

[Borek]

Today I learn saturated salt is, dissolve pure salt into 150°f water cool to 100°f pour into the 2 gallon brine tank.

Could be that's just a lousy wording, but no, varying temperature is not what makes the solution saturated. You need to be sure there was an excess of salt present during dissolution.

 

[gary350]

Could be that's just a lousy wording, but no, varying temperature is not what makes the solution saturated. You need to be sure there was an excess of salt present during dissolution.

This is Google definition of saturated salt. To make a saturated salt solution, add salt to water and stir until no more will dissolve, and solid salt remains at the bottom. You can heat the water to dissolve more salt, stirring until no more dissolves, and then let the solution cool to create a saturated solution.

Today I made saturated salt. Dissolve as much salt as I can to 2 gallons of 70°f water. Heat water to 150°f dissolve as much salt as I can. Cool to 70°f again you have saturated salt.

I have been doing electrolysis for 6 hours, 4 amps at 4 volts. Electrolysis is no longer causing green color water and no excess chlorine gas.

I also learned I am using the wrong salt. A cooking show claimed canning salt is pure 100% salt but that is wrong. Kosher salt is 100% salt. When I heated canning salt to 150°f it turned dark dirty brown color. After 6 hours of electrolysis dirty waster has become clear. Maybe I should dump my salt water and start over???

 

[Borek]

stir until no more will dissolve

Yes, and that's what your original post was missing. You mentioned just dissolving and varying the temperature, there were not a single word about the excess left.

Kitchen salt is technically never 100% pure (actually 100% pure NaCl would be costly as hell, analytical methods can detect ppm level contaminations - and 99.999% leaves place for 10 ppm of other substances, removing them would probably put us in k$ per gram range).

We are most likely talking about several tenth percent of other substances. If the solution gets dark my bet would be on dextrose, used sometimes as a stabilizer for the added iodide.

Still, at these levels of contaminants I would expect the solution to behave as if it was just NaCl.

Sorry, I don't know the chemistry behind the chlorate synthesis good enough to be able to help. The general mechanism is chemically obvious, but apparently there are fine prints at work and of these I known nothing.