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.

 

[gary350]

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.

I built it and it works. I had to watch several videos and read several instructions to finally learn and understand how this works. Lots of information is not complete they don't explain in details I need to learn how this electrolysis works.

1. Bring 2 gallons of distilled water to a boil then and 8 lbs. of Kosher salt. Stir well only about 75% of the salt will dissolve into the hot water. When liquid cools to 70°f pour water and salt into plastic brine tank.

2. When brine is at 70°f turn on the power supply. Set to 4 amps DC and 7 volts DC. When electricity is turned on the load will pull 7 volts DC down to 4 volts DC. There should be several lbs. of salt in the brine tank that never dissolved.

3. Let the electrolysis brine tank run at, 4 VDC 4 amps for 18 hours. Keep watch on voltage about every 30 minutes volts will drop to 3.9 volts turn the variac up to keep volts at 4 volts. As sodium chlorite is slowly replaced with sodium chlorate voltage continues to drop and amps will stay at 4 amps for a while.

4. In about 16 to 18 hours electrolysis is getting very near being finished. Brine tank has 42 carbon rods, anodes surface area of all 42 rods is about 44 sq inches. Cathode surface area is 50% less than the anode. Stainless steel anode has a surface area of 21 square inches. Stainless steel metal plate needs to be bent into a C shape to expose electrolysis to both sides. When voltage starts slowly going up and amps are slowly going down almost all of the sodium chloride has been replaced with sodium chlorate. When volts are up to 6 volt and amps are down to 2 amp its time to stop. Brine will look dark gray dirty color from the carbon rods. If there is any salt = sodium chloride in the bottom of the brine tank remove it or add more water then turn on electrolysis again for 30 more minutes.

5. About 24 hours later brine will look clean all the carbon falls to the bottom of the tank. Syphon off the clean brine and filter dirty brine through a paper coffee filter.

6. Boil away the water. As water volume is reduced that forces sodium chlorate out of the solution.

My power supply is over kill it is 1200 watts and I only need 16 watts. It is nice to have 100% control of voltage and current.

 

[sophiecentaur]

I built it and it works.

Good one. I'm impressed. What exactly did you want to do with the stuff? More experiments? It's banned as a weedkiller and I remember playing with a Chlorate and sulphur mix which you could ignite (bang!!!) when hitting it with a hammer. Not the best explosive though.

You've obviously gone to a lot of trouble with this project so could it be a "just because it's there" venture?

 

[gary350]

Good one. I'm impressed. What exactly did you want to do with the stuff? More experiments? It's banned as a weedkiller and I remember playing with a Chlorate and sulphur mix which you could ignite (bang!!!) when hitting it with a hammer. Not the best explosive though.

You've obviously gone to a lot of trouble with this project so could it be a "just because it's there" venture?

I though it would be a fun project, it was very educational. I wish I had taken a real chemistry class in college not a general study chemistry class. I also need some weed killer.

 

[Mayhem]

How are you identifying chlorine gas? For the record, producing 'lots of chlorine gas' is a serious safety hazard in itself! Anyhow, by smell, slight yellowing of the brine?

I am no expert, but the chemistry suggests your reaction may be too cold.

Chlorate is supposedly formed from hypochlorite (which is an aqueous speciation of chlorine) at hot conditions. In fact, hypochlorite is produced at low temperatures exactly to avoid forming chlorate.


You said your bath temp was like 90 °F (~30 °C). Wikipedia says this reaction happens at > 60 °C. That said, you are producing gases which only become less soluble at high temps.

I trust your intentions are pure but producing chlorine gas at home is inherently dangerous.

 

[gary350]

How are you identifying chlorine gas? For the record, producing 'lots of chlorine gas' is a serious safety hazard in itself! Anyhow, by smell, slight yellowing of the brine?

I am no expert, but the chemistry suggests your reaction may be too cold.

Chlorate is supposedly formed from hypochlorite (which is an aqueous speciation of chlorine) at hot conditions. In fact, hypochlorite is produced at low temperatures exactly to avoid forming chlorate.


You said your bath temp was like 90 °F (~30 °C). Wikipedia says this reaction happens at > 60 °C. That said, you are producing gases which only become less soluble at high temps.

I trust your intentions are pure but producing chlorine gas at home is inherently dangerous.

I am doing this outside in a small 8'x16' shed with an 8'x8' door. We seldom have a day with wind below 10 mph. My industrial chemistry book says brine tank is 113°f.

 

[gary350]

I am doing this outside in a small 8'x16' shed with an 8'x8' door. We seldom have a day with wind below 10 mph. My industrial chemistry book says brine tank is 113°f. Industrial chemistry book also says, 4 vdc and .3 amps per sq in on the anode. Anode is 44 sq in. 44 x .3 = 13.2 amps. A can not figure out how to get 4 vdc at 13 amps? At the moment the circuit is doing 4 vdc 2 amps. More than .3a per sq in eats up the carbon rods. NO load on power supply meter reads 7 vdc.

 

[gary350]

http://www.chlorates.exrockets.com/remove.html

 

[gary350]

Power supply wire is 30 amps. I used an electric skillet to keep brine at 140°f. Wires to the carbon rods are 4 amps 2 wires in parallel = 8 amp but after about 18 hours of electrolysis stainless steel wires are burned up. I had to replace the 4 amp wires and about 22 hours later they are burned up again. I put all the brine in 1 quart glass jars 24 hours later sediment settled to bottom brine was clean. I washed everything clean. Brine is still in glass jars. I made 2 gallons of chlorine bleach that I could have bought at any grocery store. I think maybe this project is finished. If I decide to make sodium chlorate I can buy 1 gallon of bleach at Dollar store. Bleach is a good weed killer, so is salt. 50 lb bags of salt are $5 each.

 

[oz93666]

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???

Have you callculated how much chlorate you have made in theory by knowing how many coulombs have passes ... it will take a long time to create enough to precipitate out ..
Dark solution maybe from carbon electodes particularly if harvested from batteries... titanium mesh electodes would be better (cheap on eBay) ... low resistance and almost as good as platinum

 

[gary350]

I rebuilt power supply for 30 amps. Replaced carbon rods with stainless steel gravy stir and stainless steel scrubbing pads. After 2 days of setting in 1 quart jars brine is clear yellow color. I poured brine through a filter into the tank. Tank is setting in electric skillet. Brine temperature is 140°f. Power supply is set for 12 amps and about 4 vdc. It took 2 minutes for brine to become brown gravy at the negative terminal. I wonder if brine is contaminated from all the other experiments I did? Maybe I should pour out the brine then buy a gallons of bleach at a grocery store.? Negative terminal needs to be a different material.

 

[Mayhem]

It sounds like your problem isnt electrochemical but simply chemical.

You are generating chlorine which is the precursor to your target product.

How is the pH? Chlorate forms from chorite under warm alkaline conditions.

 

[gary350]

I don't know the pH I have not tested it. What should the pH be?

A few days ago I sprayed brine on neighbors fence. Today vines, stickers weeds, poison ivy, Kuclebur weeds, are dead. There must have been 1% sodium chlorate among the 99% sodium hypochlorite. 10 years ago when sodium chlorate was still available at Farmers Co-op 1 table spoon in 5 gallons of water will kill any thing.

Next time I am at the grocery store I will buy 1 gallon of sodium hypochlorite. I will test carbon rods again on the negative terminal.

 

[oz93666]

I rebuilt power supply for 30 amps. Replaced carbon rods with stainless steel gravy stir and stainless steel scrubbing pads. After 2 days of setting in 1 quart jars brine is clear yellow color. I poured brine through a filter into the tank. Tank is setting in electric skillet. Brine temperature is 140°f. Power supply is set for 12 amps and about 4 vdc. It took 2 minutes for brine to become brown gravy at the negative terminal. I wonder if brine is contaminated from all the other experiments I did? Maybe I should pour out the brine then buy a gallons of bleach at a grocery store.? Negative terminal needs to be a different mat

View attachment 367121

This is definitely due to the steel electrodes ... even stainless will react .
This is what you need for all electrolysis....
https://www.ebay.co.uk/itm/30367903...YMGWM0&hash=item46b4ae474f:g:GcoAAOSwtnFcdxr-
space them close together to keep resistance (hence heat) low .

 

[ldanielrosa]

I have not made sodium chlorate, but I have done potassium chlorate. Simple reason is feeding it.

Sodium chlorate is too soluble with respect to sodium chloride. Separating the two will be a bit more tedious than I wanted to commit to. However potassium chlorate has very poor solubility and it falls out of solution easily, while potassium chloride sits near the top of the tank in a perforated cup.

Yes, you will need one of your electrodes to be carbon or lead dioxide or platinum or MMO on titanium. You will also benefit from adding a small amount of potassium dichromate to the soup. Some of this I learned at and some at https://woelen.homescience.net/science/chem/exps/miniature_chlorate_cell/index.html

 

[oz93666]

I have not made sodium chlorate, but I have done potassium chlorate.

Yes potassium chlorate is a much nicer choice , it's not hydroscopic ... I asume this is wanted for use as an oxidiser in makeing rockets or whatever ... with sodium chlorate the rocket mix can quickly become a sticky mess

 

[gary350]

Yes potassium chlorate is a much nicer choice , it's not hydroscopic ... I asume this is wanted for use as an oxidiser in making rockets or whatever ... with sodium chlorate the rocket mix can quickly become a sticky mess

I have no interest in, rockets, or fireworks.

Sodium Chlorate is a very good weed & grass killer it even kills bamboo & trees. 5% pure sodium chlorate is good enough to kill plants. Yesterday I learn swimming pool supply sells sodium hypochlorite 5 lbs. for $4. So far I can not fine electrodes larger than 2"x4" any where & prices are $20 to $40 each. I also lean I can buy 1 lb. of 100% pure sodium chlorate for $20. This could still be a fun $4 project with swimming pool supply.