Discolouration of electrolyte

[pyrogenius007]

Hello, I had successfully made a batch of Barium Chlorate with very good results, however, when I tried to repeat the same I noticed that the electrolyte is turning black, what could be the reason for this ? I am using the same batch of Barium Chloride which I dissolved in distilled water. I am using an mmo anode (the same which I used for the previous batch ) the anode has been used only twice before, this was my third batch, I am using an SS plate for the cathode, I have replaced the old cathode and now I am using a new one cut from the same sheet that I had used previously. What could be the reason of discoloration of the electrolyte ? can anybody please tell me how to rectify this problem ? Regards.

[SeaMonkey]

Did you replace the stainless steel cathode on account of erosion

or deterioration? What was the amount of current applied to your

cell?

 

Discoloration generally indicates that one of the electrodes is eroding

and losing small particles into the liquid.

 

Erosion is very common when using Graphite Anodes and in order to

minimize carbon contamination of the electrolyte the cell current must

be reduced. Running a cell at lower current level will increase the time

needed for the chemical processes to complete but it will extend the life

of anodes considerably and keep contamination levels low.

Edited May 30, 2020 by SeaMonkey

[pyrogenius007]

SeaMonkey, Thanks for your reply. I changed the stainless steel cathode, in fact I do it after every run since they show some signs of corrosion. The anode does not show any signs of erosion. The anode is rated for 10 Amps. I have a d.c. converter which gives out a fixed supply of 5 V and 10 Amps. The same setup worked fine with my previous two attempts. I was wondering as to what I did wrong which caused a failure in this attempt and wanted to get advice from members who have more knowledge in this subject so that I can either avoid or introduce new methods which will give the desired results.

[Mumbles]

Has anything else changed, like electrode spacing?

 

When you examine your electrodes from the electrolysis that didn't go well did you notice any extra corrosion on the SS cathode? You might be able to figure out where it's coming from at least. If it's not significantly discolored or corroded, I'd expect the black particulates unfortunately probably came from the anode. I really hope that's not the case though.

 

One of the most common causes for anode degradation tends to be pushing it past it's limits. You may want to check the current density you've been putting on the anode. If it's consistently been high, maybe the anode has just hit it's limit. The other thing to look into is your connections. If the connections are not solid and secure, some power sources could cause extra energy to be pushed through the system causing it to over do it, even if you think you're fine.

[SeaMonkey]

Do you have a way to vary the current from your supply and to measure

it while the cell is in operation?

 

I too fear that it may mean that your Anode is eroding as Mumbles suggested

above.

 

I run my cells at from two to four Amperes. The process takes longer but that

is fine with me since I'm not in a great hurry to produce chlorates.

 

My power supply is a Regulated Switching Supply with provision for setting the

Output Voltage and the Maximum Current Output.

 

Are you experienced with hooking up power supplies such as this one and

could you use a digital meter such as this one to set voltage and current

for your cell?

 

Or a switching supply such as this one which is a single unit?

Edited June 1, 2020 by SeaMonkey

[pyrogenius007]

Mumbles, Thanks for your reply. The spacing between the electrodes was not changed. I was using the same cell I had used before. I checked the anode and cathode, the anode seemed to be fine, I mean no visible corrosion though at one spot there seemed to be some slight discoloration, the whole anode is pitch black whereas one spot had a somewhat bluish color, the titanium core is not exposed, just the small circle of discoloration. The cathode however was completely corroded. In fact, even during the previous two batches which went off well the cathode had corroded, the top portion which was not immersed in the electrolyte was pitted and rusted. As for power supply I am using a d.c.converter with a fixed output of 5V - 10Amps. The anode is rated for 10 amps. The connections are secure, I check them every time I start a fresh run. When the cell is running I have no way of checking the output. If you have any suggestions please let me know. Also let me know if it is o.k. to use graphite substrate lead oxide anodes, they are cheaper and I think also suitable for chlorate cells. Thanks

[pyrogenius007]

SeaMonkey, Hi, Thanks for your reply. I do not have much knowledge about electronics or chemistry for that matter, I am an accountant. I do try to read some stuff about the two subjects, but, since I have not studied these subjects right from basics I find it difficult to comprehend the advanced topics. I however read topics related to pyrotechnics and whatever doubts I have I post questions on this forum. I know the basics of pyrotechnics e.g. fuel, oxidisers etc., I mainly concentrate on the guidelines regarding safety, i.e not mixing chlorates with sulfur, wetting untreated magnesium, ramming certain mixtures etc., I started off by making traditional Indian fireworks like rockets and fountains. My first foray into stuff like mines, mortars, colored stars started after I read a book by Tom Perigrin titled Introductory Practical Pyrotechnics which opened a whole new world of pyrotechnics to me. It was in this book that I learned about the role of various chemicals, techniques, items and tools required for making fireworks. As far as electronics are concerned I can ask my son who is an automation engineer to help me out. I will ask him if he can reduce the voltage and the amperage from my current d.c converter. From what you have mentioned about running the cell at a lower level,is it o.k. if I run it at say 3.5 v and 6 to 8 amps ? The d.c converter I am using has a output of 5V / 10 amps. My anode is rated for 10 amps. Sorry for the long winded reply, I just wanted to tell you where I stand regarding my knowledge of electronics and chemistry. I am willing to learn from all available sources. Thank you.

[SeaMonkey]

It is very strange that your Stainless Steel Cathode is corroding and eroding to

such a great extent. For my Cathodes I use ordinary steel plate which works

well but it does require careful attention to assure that it doesn't rust either

while in use or between uses. Probably the best metal for the Cathode is

Titanium; it is most recommended by those who do a lot of Chlorate work.

 

It is good that you have a Son who may be able to help you with monitoring

Voltage and Current at your Cell and who may be able to devise a way for

you to adjust the Voltage to control the Cell Current.

 

Are you in a hurry to make your Chlorate? Or would you mind if the process

went along more slowly for a couple of weeks to a month?

 

I like to use lower current levels of two to four Amperes because though the

process takes more time it is a gentler operation with little heating of the

cell and much less chance of leakage or splashing electrolyte, The Cell

doesn't require as much checking of electrolyte level and it can run

unattended for a week without fear of catastrophe.

 

The main reason though for the lower Current levels is because I did

use Graphite Anodes exclusively for years. If pushed too hard with a

higher current the Graphite erodes greatly and the electrolyte quickly

turns dark black with heavy carbon contamination. At low current

levels the contamination is much, much less and barely visible.

 

I now have an MMO Anode which I'll use when I next run my cell to

see what I've been missing. I may never go back to using Graphite

again!

 

Once you have the ability to adjust the Cell Voltage and Current with

measurement then you'll be able to decide how hard you want to push

your Cell; you'll see how changing the driving current to your Cell affects

heating and bubbling and you will be able to set it for whatever condition

looks best.

 

Have you seen the NurdRage videos on how he made his Chlorate Cell

and how well it worked?

 

Make Chlorate by Electrolysis - The Basic Guide

 

Make an Electrolysis Box

Edited June 2, 2020 by SeaMonkey

[kingkama]

The colors or the contaminations of electrolyte are collateral in the process, if you are making directly potassium chlorate you will recristallize the crude product to get rid of chloride and hypochlorite so at the end this is a no problem. My electrolyte is usually from light green to dark brown or black. I used to make pbo2 electrode who released a good reddish brown tint. The only way to have a pure electrolyte is by MMO or platinum anode and titanium cathode.

[pyrogenius007]

SeaMonkey, Thanks for your reply. I will start working on my power supply and find out a way to adjust the power output. I am in no hurry to make my chlorate, I am willing to wait, my only concern is that the cell should run properly and there should be no damage to my electrodes. When I purchased my anode I specifically asked the manufacturer as to its rating, he told me that it was rated for 10 amps. he also assured me that it would work well with a 5v, 10amps. d.c converter. As for the cathode I had a ss sheet with me, I think it is of food grade, it is quite thin, maybe about 1mm or less. As for titanium cathode, most of them are meant for industrial use and are sold in bulk, getting one or two strips is quite difficult, the same goes with anodes, I have to purchase whatever the sellers have with them. It takes a lot of hunting around to find a manufacturer who has some spare electrodes for sale. I forgot to mention, I check the Ph levels every 12 hrs., it is alkaline, never crossed over the midway levels to indicate that it was acidic. It was always around 7 to 8 on the color indicator When operating the cell I noticed that it gets warm, not hot but warm. To be on the safer side I immerse the cell in a tub containing water, after sometime the water gets warm but never too warm or hot. Yes, I did see the video by NurdRage and also several other ones. In fact, I made my cell based on these videos. I relied on the anode suppliers assurance and went in for the high current, since everything went well during the previous two runs I felt that everything was o.k. Well, I guess this is one more lesson I have learned, read more and when in doubt take advice from pros. .

[Mumbles]

This is a little off topic, but barium chlorate cells are known for low current efficiency. Does anyone know why? Does more chlorine escape? Do the intermediates not convert as easily?

 

I'm just thinking a little bit about why this cell seems more corrosive. I agree that if you can get Titanium, it might hold up better as the cathode.

[SeaMonkey]

The attached document Electrochemical Preparation of Barium Chlorate from Barium Chloride

is a detailed analysis which may answer the questions of efficiency.

ba_chlorate_prep.pdf

Edited June 3, 2020 by SeaMonkey

[SeaMonkey]

Pyrogenius,

 

Could you tell me more about your Power Supply like the Model No.

and who it is made by? I'd like to see if I can find information on how

it is designed and built.

 

There are problems which can develop in DC Power Supplies that

can affect their output purity. It may be a long shot but the extreme

corrosion of your Cathode which mysteriously just began after two

successful runs could mean that your Power Supply has developed

a problem.

[pyrogenius007]

SeaMonkey, The converter I purchased has no brand name, model or serial number on it, it only has a sticker on which the current input and output are mentioned, it is made in China. As for the cathode I had mentioned that I had to change it after every run, I ran the cell twice before and each time there was corrosion on the cathode, only the top portion which was not in the electrolyte was corroded.

[SeaMonkey]

Yes, thank you. I see now that I had that wrong.

 

Corrosion in the space above the electrolyte is quite common actually

due to the Chlorine gas and electrolyte spray. So would you say that

the Cathode corrosion in your case goes beyond what would normally

be expected in that chemically hostile space above the electrolyte?

 

Is there a vendor on-line who might have an offering of the same Power

Supply and might have a description of its characteristics? A vendor such

as Banggood or some other, maybe EBay?

 

Or maybe not. If you purchased it locally from a shop then it may be more

difficult to discover what it is. Only the owner would know.

 

Is your Power Supply in a case which covers the Electronic Circuitry?

 

This question may seem strange but since your problem is so unique:

 

Is there any possibility that the Polarities of the Connections to your Cell

during the most recent run were reversed? That the Cathode was possibly

connected to the Positive Output of the Supply?

 

When unusual problems such as yours are encountered one of the first

considerations is whether the Power Supply is working properly and whether

the connections to the Cell were properly Polarized.

[pyrogenius007]

SeaMonkey, In my previous runs the portion which was not in the electrolyte was pitted and rusted. The portion immersed in the electrolyte only had a very thin layer of a whitish substance, but, there was no sign of any kind of rust or pitting. As far as BangGood goes many of my friends say that it is not reliable, neither the products or the service. EBay does not operate here. Amazon is the only on-line vendor I have to rely on. I guess I will have to purchase a good standard unit which is used in labs or industries, they are expensive, but they come with full details. I make sure that all connections are secure and the polarities are correct, I double check them. My main concern is if there was some mistake on my part or if there was some equipment failure, either way I have to find out the reason and rectify it. This time it was only discoloration but if it results in something dangerous it will be something I would definitely want to avoid.

[SeaMonkey]

Yes, that part of the Cathode above the electrolyte would be

exposed to electrolyte spray and Chlorine Gas. In most cells,

unless some sort of protective coating is applied, this sort of

corrosion is quite common.

 

The thin layer of whitish substance on the surface of the

immersed Cathode might be Barium Hydroxide which is

produced there by the electrolysis. It does in some cases

precipitate as solid particles until it is either reacted with

Chlorine or goes into solution.

 

There may not be anything at all wrong with your Power

Supply. The only way to know for certain though would be

to evaluate its output with a Volt Ohm Meter to assure that

it is outputting Pure DC and that it is Regulating the Output

Voltage properly.

 

Good. I was sure that you had the polarities correct and that

your connections were secure.

 

Have you tried your Anode with other electrolytes since the

discoloration episode?

 

If you were to electrolyze an electrolyte of Salt Water would

it discolor the same as your attempt with Barium Chloride?

 

It doesn't seem to be a mistake on your part but there must be

a reason for the discoloration. In most cases the discoloration

is due to Anode deterioration. Could you perform another test

with it to see if it discolors Salt Water?

Edited June 5, 2020 by SeaMonkey

[pyrogenius007]

Yes, I too had this idea of trying it with salt water and finding out the result. I think that running the cell for about 24 or 36 hrs., should give me some indication as to whether the same problem persists. If it still goes on then I will have to consider replacing the anode or maybe even the power source. I have checked the power output with a Volt Ohm meter, it is giving out the correct output.

Replacing any or both of them may resolve the problem, but, I am still curious as to what went wrong.

[SeaMonkey]

Thanks for testing your Power Supply. A power supply that tests

good is surely not the problem.

 

As you test your Anode further you should find out whether it has

lost any of its integrity. The 24 hr. to 36 hr. test run should be long

enough to evaluate its condition.

 

Since my own experiences are with Graphite Anodes exclusively,

because I haven't used my newly acquired MMO Anode yet, I'm

learning as much as you are from this very interesting problem.

[pyrogenius007]

I am glad that this discussion has opened up new thoughts as to what could have been the problem, they are a big eye opener for me. Hope these discussions will be of use to other enthusiasts who want to try their hand at electrolysis. One more thought, could the electrolyte be contaminated ? Though I have taken care in the preparation of it there is always scope for human error. I will carry out one run with salt water and let you know the results. Thank you for having taken the time and effort to help me with my problem. Thanks,

[SeaMonkey]

Good question. If you still have the discolored electrolyte an analysis

could be done to identify the nature of the discoloration.

 

Or, some could be filtered to try to isolate the particles which are causing

the discoloration.

 

If you knew precisely what the black substance was then it would shed

much more light on the problem.

 

You're quite welcome! It has been quite fascinating trying to imagine what

has happened.

[pyrogenius007]

I will start my cell today and wait for 24 hrs., minimum to see the results after which I will post the outcome.

[pyrogenius007]

SeaMonkey, I ran the cell with salt water as electrolyte for 24 hrs. there was no problem whatsoever. I think the discoloration was due to contamination of the electrolyte. That seems to be the only possibility.

[SeaMonkey]

Well, that is very good news! Your Anode appears to be in good condition.

 

If you still have the discolored electrolyte it may be possible to heat the

solution, treat it with a small quantity of Activated Charcoal Powder well

stirred and then filter it. This technique is used often in Chemical Processes

to remove discoloration and it is effective.

 

If not, then the problem will remain a mystery unless it happens again.

 

Any thoughts on what the contamination might have been?

Edited June 9, 2020 by SeaMonkey

[pyrogenius007]

If the discoloration occurs another time I will treat it with activated charcoal powder. As for the reason of contamination I am still not sure, it could be due to the distilled water I used or the container in which the electrolyte was prepared. Another strong possibility is the cup in which I weighed out the barium chloride, I use the same cup for weighing other chemicals too, maybe some other chemical could have either remained in the rim of it or the plastic may have reacted to some chemical. Anyway it still remains a mystery as to what went wrong. From now onward I will use only glass containers for measuring, mixing etc., and make double sure that they are clean.