A Chloralkali Cell - Diaphragm Electrolysis ep2
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- Опубліковано 16 вер 2024
- We do our best to make a final, comprehensive video on the diaphragm chloralkali process by building a cell capable of making moderate quantities of sodium/potassium hydroxide.
This particular cell is capable of converting sodium chloride into sodium hydroxide at a current efficiency of 15-20%. At one amp of current (and a voltage of about 6-7 volts), we generate about 50g of NaOH per kWh, and under my price for electricity, that comes out to a production cost of $5 per kilogram of NaOH (a profitable process if all I need is NaOH solution rather than the solid stuff).
The cell will be useful in the future for the production of sodium hydroxide, potassium hydroxide, chlorine, hydrogen, and possibly hydrochloric acid eventually.
Watch the rest of the series here:
• Diaphragm Electrolysis
Watch my other videos on electrolytic sodium hydroxide here:
• Making Sodium Hydroxide
• The Chloralkali Proces...
• Sodium Hydroxide - Dia...
Excellent progress. I purchased a stainless dog dish for my negative and placed the sealed pot inside it currently have produced a half gallon of sulfuric acid and magnesium hydroxide
A stainless dog dish is a great idea for a cathode/container! Good to hear the process worked for you.
@@ScrapScience
Stainless steel works good as a cathode, carbon works good as an anode.
Acrylic is good with chlorine.
(I have tried all this)
Overdone?! I love to watch every of your videos because I like to learn from you too ! Never boring with you my honest meaning :)
Your video gives a good background on the color-alkali process. I wished I would have seen it 25 years ago. I was once given the task to determine if a cheaper grade of NaOH could be used in my companies industrial processes. I knew nothing about the chlor-alkali process but, had to figure the difference between the more expensive Mercury grade and cheaper diaphragm grade caustic. All I was give was obsolete specifications for a material we were buying which was referred to as “Rayon grade” NaOH. The specifications were old and no one knew why that specifications chosen or what a different grade would do to our various processes. Rayon Grade specs were looser than mercury cell but, tighter than diaphragm cell product.
I determined that for some of our processes Mercury cell grade was necessary, but for most of our other processes the cheaper diaphragm grade purchasing wanted to use would be fine.This was because in some cases diaphragm grade contained too much residual salt and iron which would interfere with processing and contaminate our final products.. I talked to several different suppliers. None had even heard of Rayon Grade and they all said that diaphragm cells could not produce the quality of NaOH we needed. One of the suppliers I contacted said that they had completely switched to a newer membrane process which was able to provide the high-quality I needed. for a price similar to diaphragm grade. Now all of the Mercury plants have been shut down and diaphragm plants have mostly switched to the better membrane process. So now almost all NaOH would work in our processes but, membrane grade is still much cheaper than mercury grade. It is possible that, at the time, some of the suppliers did not want to tell us membrane grade was so much better because they made a premium from “mercury grade” which may well have been made in a membrane cell. I was lucky to find a supplier that that had completely switched to membrane grade and was willing to sell at near diaphragm prices. It still took some months to run lab experiments with the membrane grade to demonstrate that it was suitable for all of our our processes. It was probably good for the supplier that provided the membrane grade since we bought the stuff in rail car quantities. Ah the life of an industrial chemist.
Interesting experiment! Your videos are always interesting to see, especially since some chemicals always seem like these mystical things that could only be produced in big and complex industrial processes. I wish you would get more views and subscribers, you deserve it.
nice work ! maybe also cover the kathode chamber with a funnel and tubing to then merge both tubings and trigger HCl formation with a spak every few seconds. Saves NaOH for Cl2 deactivation and you can make some HCl solution next to the NaOH solution :)
or trigger it with a UV Lamp/Laser
That's definitely a possible plan for the future, just need to reach the point where I'm comfortable working with such an explosive reaction.
I used Tyveck great non interactive permeable material and easy to find.
use some 2 part epoxy instead of the silicone sealant, its worked for me for i think about 30 hours now and its shown no signs of degradation. when i formed mine, i used parchment paper as a sort of mould, and the epoxy didnt stick to it at all.
You are right about the terracotta pot it's way better than the membrane I first tried.
Cellulose acetate PEMs are also a good idea, cigarettes filters, acetone and calcium carbonate
A really good diaphragm, mineral wool fire/sound reducer insulation packed tight in a open tube . It seals great and holds up very well. I just don't know if the mineral wool will react, it doesn't seem to be.
Bravo......love the pot.......coat the pot pva........ion transfer medium......cheers
Hi, i love watching your videos and I find them very useful. In this NaOH production experiment I noticed that just to produce 15g it took you two days, what advice would you give to someone who would want to produce that same 15g in just 12 hrs? Your answer will be highly appreciated
To do this, you'd just need to run four times as much current through your cell. The best way to do this may be to build a slightly bigger cell (with a bigger diaphragm and bigger electrodes), allowing you to run it at a higher current. You could even buy some nafion membrane (to replace the clay pot diaphragm) if you want to spend a little extra money, in order to allow for more current as well.
Perhaps a diamond core drill in a drill press without the pilot drill will be able to cut curved disks from any part of the clay pot. Also some garden suppliers will have clay saucers for the pots that are flat with no hole.
Also a local potter will probably make a suitable shape from suitable clay and fire it suitably in exchange for a bit of promotion.
15:50 This isn’t pressure applied directly, they just keep the liquid level higher in the anode side, which gives hydrostatic pressure. The way they deal with the salt is that NaCl has about the same solubility at 25C as 100C, but NaOH is much more soluble at 100C. So they boil it down until NaCl starts falling out, until it stops falling out, and then decant and finish the boiling to get the solid NaOH. Also NaOH is a few times more soluble than NaCl even at room temp.
Acrylic plastic is good with chlorine according to a chemical resistance chart I found online.
I confirmed this through practical experience.
how about cell membrane from a lead acid battery?
That'll definitely do a good job! The only reason I haven't given it a go is the fact that I've never found any cheap sellers online, and I'm very much not a fan of dismantling lead-acid batteries.
Can u explain more on this please
some one answered ur ? but dismantling a battery is no hard. Drain , flush and use bicarbonate of soda to neautrilize.
The fabric used as divider is a semipermeable film. Resist to acids and bases
If u have any solar panel (0.35 A,6v minimum requirement) use this
that can also reduce the price of manufacturing NaoH
Cool video yet again.
Do you think this works better than just using a clay pot in an open tank? Also I bought some small pots recently and I had to sand paper them to make them porous, they are probably frost proof and made to not absorb water at the surface, once rubbed down they worked fine.
This setup doesn't really work much better than using a clay pot in a tank. I simply find it more convenient to have the two chambers positioned this way when it comes to extracting the product or collecting gasses (and also for consistency when comparing different reaction conditions, seeing as it can be used as a standardised cell construction).
A lot of clay pots are glazed after firing, making them non-porous. Sanding them down to the porous section is a good idea if you can't find non-glazed ones.
@@ScrapScienceyou can make your own clay membrane from backyard dirt, turn it into clay, shape it, dry it air for a few days, bake it in oven for half an hour or so, then fire it in your aluminium melting furnace to red heat.
Great demo!
I wonder if hot glue would perform comparably to silicone as the adhesive.
Thanks!
I'd imagine hot glue would be slightly more resistant than silicone, but I've always had trouble getting a proper seal when using the stuff.
Do a web search of "Chemical comparability chart" for the material you are working with.
It turns out that acrylic is pretty good with chlorine.
Wow I learned so much :) Thank you!
I used a clay pot to generate sulfuric acid from NaHSO4 and while distilling it I started to see purple vapors, and after a few minutes fucking iodine crystals started growing in the condenser!?
I tested my initial electrolyte for iodine but there was none, I also did not use any in the past month so it had to have come from the clay pot which was brand new.
Well, then it seems you were visited by the iodine fairy! Most fortuitous!
That's certainly a weird thing to have happened. I've got no idea why a clay pot would have iodine/iodide content. Could possibly be something from your electrodes too, I've got no idea.
@@ScrapScience yeah me too, my electrodes where platinum and copper, so should come from there either...
i wanted to ask, can i use copper wire for both electrodes? will it affect the process negatively?
Copper is fine for the cathode, but does not work at all as the anode. You need an anode that can withstand the oxidation of chloride to chlorine. The only commonly available options are graphite, platinum, and mixed metal oxide electrodes (such as the one I use here).
Intrigues me that there is hydrogen and chlorine going to waste could these be flamed or catalysed into HCl??
Yep! They definitely could be. However, the reaction between hydrogen and chlorine tends to be extremely explosive, so I'm not yet anywhere near confident that I could do it safely with my setup.
Would be working for making clean of graphite kclo3 with carbon anode?! On both side the same kclo soultion.
No. The carbon anode will still degrade and fill your product with carbon dust. Additionally, the process will be far more expensive.
U could use cellophane membrane also.
I was wondering what other things you can put in your scrubber to get useful products, man was that a deep rabbit hole! So many things are only a few steps away from having Cl2 and something to react it it with.
Yeah! Chlorine gas really is an extremely useful chemical to have at your disposal, provided you know how to keep it away from people's lungs.
Hi sir could you please post a video on how to crystalize sodium hydroxide
Can you edit down some of the talking? I truly don't mean it in a rude way even though I might sound like it. I like your videos but it's hard to listen to that much dialogue
The copper will corrode over time, so if you are planning on running it for a long time you should use carbon or platinum on both sides.
Why would the copper corrode under cathodic conditions? I don't know of any mechanism by which that would occur in this setup.
I've had previous electrolytic cells running with a copper cathode in sodium hydroxide electrolyte for months on end and have never witnessed any corrosion.
@@ScrapScience I've never had a copper wire corrode on its own, I have only had it happen when using salty water, and making the mistake of using ac current. But you are right, cathodic conditions shouldn't corrode the copper.
@@ScrapScience for months u say, I need advice on how I can produce what u produced in months just in one week, that's my biggest challenge
Instead of the diaphragm method, you mentioned you could make a ion exchange membrane? How would you do this? Any videos or materials on this? Or where could you buy a nafion membrane? Anyways, thanks for the video - really cool that you could run this process without going industrial!
I haven't tried making an ion exchange mambrane yet, and I haven't yet found a good guide to doing it, but others seem to have had very good results with it. Some videos on the topic include:
ua-cam.com/video/vJfc6dxrllI/v-deo.html
ua-cam.com/video/BT3HjyziH_0/v-deo.html
(note, that second guide is for an anion exchange membrane, which isn't useful for this process).
Nafion is a little tricky to find, but there are a couple of websites which will sell to individuals:
www.fuelcellstore.com/membranes/nafion
www.aliexpress.com/w/wholesale-nafion.html
Seriously, I really need to see this video, it helps me so much,Can Nafion diaphragm electrolyze sodium chloride？
He belongs to the cation exchange membrane？
Nafion can be used as a membrane for this process, yes.
Is there a disadvatage to using graphide instead of mmo?
They will slowly disintegrate over time, so you’ll end up with carbon dust in your anode chamber. This isn’t a problem if sodium hydroxide is all you’re after (and if you don’t mind replacing the graphite electrodes every now and then).
What did you put in the middle of the pottery membrane
Silicone sealant, to plug the hole in the middle of the terracotta
good job , which kind of material we can use as membrane instead of nafion ? we can use sponge or filter paper ?
If you can't get nafion, a clay pot or some kind of porous ceramic are usually the best membrane options. You can use filter paper or even cotton if you must, but these will likely lower the purity of your final product since they tend to allow significant diffusion between the chambers.
How possible would it be to bubble air through it and make sodium bicarbonate generator?
That would definitely work to some degree, I'm not sure how well the reaction would go to completion though. You'd likely still have some hydroxide in there, but I'm not sure how much.
Is it necessary to close the sodium field
What are you referring to by the ‘sodium field’?
as for scrubbing the chlorine, wouldnt it even be easier to use the hydrogen from the naoh side of things to burn the chlorine into hydrochloric acid? I mean, best case you need the hcl anyways, so its a useful biproduct, worst case you can just neutralize it with naoh/nahco3(Ironic again, I know) or dilute it with a lot of water water and flush it?
If it were an easy thing to do, this would be a great use for the chlorine.
Sadly, the reaction between chlorine and hydrogen is extremely energetic (with enough explosive power to shatter test tubes with the combustion of only a few millilitres of gas). I'm afraid it's just not feasible to do safely without an extremely reliable setup.
@@ScrapScience hey and thanks for the reply. I have to be honest, the only time I have ever seen that reaction was in a I think 7th grade chemistry lesson in school(and that was like 25 years ago) with my teacher submerging a Bunsenbrenner with hydrogen into a large cylinder filled with chlorine, turning the flame white. I wasn't aware that it was that energetic, especially when working with the rather small volumes that the electrolysis process produces at once. Honest question as a follow up. Does your setup produce more than one Mol(6*10^23 or 22.4l) of gas per minute?
The setup shown in this video doesn't make anywhere near one mole of gas in a minute I'm afraid. Instead, it produces about 0.0006 mol per minute of each of the respective gasses, and that's being optimistic.
@@ScrapScience that's what I guessed - thank you for answering all my questions
what happens if you use a 12v 200Ah car battery for this experiment? Does it speed up the reaction process? Or what are the side effects or benefits of using 12v 200Ah batteries?
A 12 V battery will work fine for this experiment. The only drawback will be the fact that you won't have direct control over the current. To control the amperage, you'll probably need to adjust the depth of your electrodes every few hours in order to change the surface area in contact with the solution.
Hi, i love watching your videos and I find them very useful. In this NaOH production experiment I noticed that just to produce 15g it took you two days, what advice would you give to someone who would want to produce that same 15g in just 12 hrs? Your answer will be highly appreciated
A way to mitigate the destruction of the membrane, is to dilute the solution.
That's true, but diluting the solution also severely decreases the efficiency of the cell, so it's not really worth it given how slow the degradation is.
I have an idea to make in more efficient
You could use a joint to connect 3 pipes and then add two membranes and place brine in it. Can u tell if it will work and then only particular ions will be attracted
If I'm understanding you correctly, I don't think that setup will make the process more efficient.
Assuming you have three chambers, a cathode chamber, a centre chamber (for the brine solution), and an anode chamber, separated by diaphragms, you will still generate sodium hydroxide in the cathode chamber by the same sodium ion transfer process. Additionally, you'll drag the chloride ions into the anode chamber to form a very low concentration of hydrochloric and hypochlorous acid, along with the main product, chlorine gas.
In terms of the current efficiency, you might actually lose efficiency by allowing for hydrogen ion transport (seeing as you're generating a small amount of acid at the anode), as this additional process will diminish the current efficiency of the desired reaction.
The benefit for your method, however, is the fact that the brine solution will be contaminated with hypochlorite and chlorate to a much lesser extent, and the design might be more efficient at making chlorine gas too.
@@ScrapScience ok thanks
this is awesome thanks!~ im gonna make one. can this be made to make large qunatities of hcl at home. i ideally want to make 1 gallon of 12ish molar hcl per day. would mercury work for thi and make efficiency much better than flowerpot
As it turns out, hydrochloric acid can't be made directly by diaphragm electrolysis. It's destroyed by the action of oxidising chloride to chlorine on the anode.
If you're instead planning on making HCl by reacting the chlorine and hydrogen gas outputs together, that's definitely a viable (though very dangerous) way of doing it. Just keep the explosive nature of this reaction in mind if you're giving it a go.
Mercury will definitely work as the cell separator here. However, I've never given it a go, so I'm not sure if you'll get an efficiency increase. As far as I can tell, the overall energy efficiency might be a little lower than using a ceramic diaphragm, but the current efficiency should be higher.
Personally, I don't like the idea of working with mercury, especially as a sodium amalgam. If you've got the proper setup to deal with this safely however, feel free to give it a go.
Creative Video . I have some questions . If you work on a larger amount of the solution. About 400 kg of solution. What is the ratio of sodium chloride to water? Is it possible to use pure sea water after the concentration of sodium chloride in it? What is the best volt for quick work on this volume? Thank you
400 litres is a lot. This requires a pretty serious setup and if you're going this route, I'd recommend doing some proper reading on the topic (start here maybe: shorturl.at/rA378 ).
As for your questions:
- The sodium chloride should remain saturated on the anode side for best efficiency
- Seawater contains a significant quantity of cations that are not sodium. You might need to remove the magnesium and calcium before you use it directly, but it should work to some degree.
- The voltage should always be as low as possible for best efficiency, but you obviously need a high enough potential to draw your desired current. The voltage you actually need will depend on the shape and design of your cell.
@@ScrapScience Thank you very much for the quick reply. But I will do the experiment and study it first and then tell you the result. But what is the ratio of sodium chloride salt to distilled water? How much sodium hydroxide and chlorine is extracted from a ton of salt. I can succeed with your help. I tried to translate the file. I will try to translate it.
Does chlorine evaporate from the positive or negative electrode?
Chlorine is generated on the anode (the positive electrode in the case of electrolysis).
蜀牛烧杯好评👍👍
I want to see you produce sodium using only salt. Even using just salt to produce the electricity.
Hi! Harry, Can you make a video on electrolysis of molten NaOH to form Sodium. Its done at 330 C.
One day I'll definitely get around to it.
Currently, I don't have any way to heat a cell to the right temperature range reliably and stably, but eventually I'll build something and do some experiments in the electrolysis of molten salts.
@@ScrapScience Looking forward to it.
Any one ever tried a carbon fiber arrow?
I missed something what is MMO?
MMO is 'mixed metal oxide'. It's a titanium electrode coated in oxides of precious metals (usually ruthenium and iridium, and maybe some tantalum). Generally, it's the ideal anode for chlorine evolution and chloride electrolysis, and they're not too expensive or difficult to find online.
I talk about this more in the videos leading up to this one.
I reveled in making bricks from mudhole sediment and hay in the yard for fun...
👌👌👌👌👌
Why don't you use Clay tiles and a Masonry hole saw, wouldn't be it easier than smashing clay pots? If you really stuck with clay pots that you should consider to use the whole clay pot with the same diameter of the tube more surface area than a flat disk and less sealer work to do
I've tried this in the past, but clay tiles actually have a different degree of porosity when compared with garden pots. The pots are specifically designed to allow a small amount of air and water to pass through them, while tiles are designed to absorb as little water as possible.
Regardless, a higher surface area does seem like a good idea, thanks! I'll keep that in mind in the future.
What is MMO?
MMO is just a type of electrode that involves a titanium substrate, coated with a thin layer of various precious metal oxides (such as ruthenium, iridium, platinum, and even tantalum in some cases). It stands for 'mixed metal oxide'.
Ooooh I read ChlorKali, the thing Nazis used to make that gas...
Hydroxide for soap making and chloride for cleaning the patio the ducks 🦆 are pleased 🎉✨🧼🪣🧹✨ gracias