@@CatboyChemicalSociety Hi, I'm making the membrane from the video. I'm realy looking forward to the next one. Could you give an idea of how long it will take until it is published?
I'm trying to learn more about different kinds of membranes. What better way than to see one being constructed from scratch from (mostly) common materials. Thanks for sharing this! I'll be exploring your channel further as I want to learn how membranes might be used for electrodialysis, as in the fascinating of Matt Eisaman. Liked and subscribed.
electrodialysis membranes are usually a pair of cation and anion exchange membrane cells stacked together such that water is fed into neutral chambers with either membrane on both sides. The respective ions pass through the cation exchange membrane on one side and the anion exchange membrane on the other. The water that comes out from the outlet of that neutral chamber is said to be de ionized. The electrodes are located at the opposite ends of the cell.
Wonderful and useful technical information you have shared with detailed video. I respect your efforts taken to share with all. From Jawaharlal Bharat 🙏
@@jvon3885 Clay is a nonselective membrane; it's just lots of tiny holes that make it harder for everything to get through, so things that are forced through by the current (ions) end up going more than things that are just diffusing. What MB showed here is an actual legit semipermeable membrane, which at a molecular scale actually only lets certain chemical species through (positive ions in this case (and possibly water), not negative ions, or gases; though in the comments they also explain you can switch out the citric acid for aspartic acid to make one that passes negative ions) If all you need is a porous membrane (like clay) not a selective one, you can use clay but you can also use the first step without the PVA as they show in this video here :) th-cam.com/video/foQHygE2Mkw/w-d-xo.html
This looks very interesting thanks! Strangely I cannot find any other videos on the subject of DIY ion exchange membranes. I'm not knowledgeable enough to understand why your process works. I think some explanations would encourage this experiment to be replicated. DIY nafion would be awesome for many hobbyists.
Really interesting video. I'm wanting to make a Proton Exchange Membrane for a Direct Ethanol Fuel Cell. I was wondering if you have tried these membranes in that type of cell or if some modification to the recipe is needed.
pva chains contain alcohol groups and when you have a carboxylic acid under anhydrous conditions it will esterify and remove a water molecule. this occurs during the oven baking part of the proceedure. since citric acid is a tricarboxylic acid, it will react to crosslink the chain and will have 1 free carboxylate group which can bind to cations in the electrolyte. When a voltage is present across the cell, the ions migrate to the cathode chamber from the anode chamber.
what is that kind of ovens ??? the first time I see this ..... and how and from where you learned the whole process of making (ion exchange membrane) ???
@@CatboyChemicalSociety I appreciate your comments. I was wondering, since these bipolar membranes are typically not permeable, how about putting anionic resin on one side and cationic resin on the other side of a pvc membrane? (ie from water treatment resins)
This is really cool - thanks for sharing this! Following up on an earlier comment, is there any technical papers or something that I could read to explain how this coating method using PVA and citric acid creates these cation-exchange membranes (as opposed to anionic ones... or why PVA and citric acid?)? Just wondering how it compares to the commerical nafion 117 and n324. Would there be any way to further optimize what you have done for membranes in a chlor-alkali cell? Perhaps just use teflon-fiberglass cloth, PVA/citric coat, bake, and do that a few times, but not so many times that you increase the resistance of the membrane to electric current?
anionic exchange membranes need a different thing than citric acid which is aspartic acid and subsequent treatment with methyl iodide converts the amines into quaternary ammonium compounds. These membranes are quite conductive and if you want to look for technical papers on threm just look up PVA and citric acid crosslinking and you will find many such papers talking about the mechanism and the crosslinked structure that forms as a result of baking the mixture. It was from one of these papers that got me the ratio of 4:1 10% PVA solution with citric acid. Most clear PVA glues are 10% PVA solutions with some other additives. Nafion is of course the king of membranes but its price makes it unreasonable for prototyping and small scale experiments. You can also use Sulfosuccinic acid instead of citric to get the sulfonate groups instead which is also found in commercial nafion membranes. Sulfosuccinic acid is made by sulfonation of maleic or fumaric acid. and there are papers talking about membranes made from PVA and sulfosuccinic acid aswell.
Thanks for such a fantastic video detailing the process, and thanks for still being so active in the replies. I'm looking to build a rudimentary PEM fuel cell and it requires Nafion for the PEM. Obviously, as you've mentioned, it's very expensive and not so easy to get hold of so I am looking to follow your video and make my own. I read in the descriptino that I can skip the PVC cement and dechlorinating step if I'm making a PEM for a fuel cell. Is that correct? What kind of cleaning cloths did you use, does it matter? And I saw someone mentioned using fibreglass cloth instead, is that viable and do I need a specific type? I'm sorry for all the questions, thanks again for your help!
Thanks for posting this video. I made a membrane using these instructions and used a standard procedure to measure the permselectivity using NaCl 0.1M | NaCl 0.5M. The permselectivity values I got were never greater than 0.5. I believe this had to do with citric acid being poorly crosslinked without an acid catalyst present, which matches literature on crosslinking of PVA using citric acid. I obtained much better success using a 10% molar equivalent of sulfuric acid or phosphoric acid to the moles of PVA alcohol groups. Let me know if you get some data on the permselectivity of the membranes you have produced.
@@tmz9756 You can use aspartic or glutamic acids, however you will need to use a small amount of a strong acid during the esterification reaction to catalyze it, as I mentioned before. However a membrane like this will only be an anion exchange membrane under acidic pH, under basic pH it will loose this ability and become permeable to anions. To make it an anionic exchange membrane regardless of the pH, you will need to do an additional reaction to make the amine groups quaternary.
If I'd be using shampoo for the benzalkonium chloride then how much do I use? It's meant to be a catalyst... would 50 ml be enough? Does it go faster/better if I use more?
Look into algaecide products at your local garden supply store (to remove algae, moss, moulds and lichens from hard surfaces), they often consist of concentrated (up to 50%) aqueous benzalkonium chloride solutions with no other additives. Alternatively you'll also encounter 5-10% solutions of didecyldimethylammonium chloride sold as algaecide, or mixtures of the two.
Thank you for the informative video! I've been scrounging academia for information concerning the manufacturing methods IEMs. How typical would you say is this process compared to something you would see in industry? And a little deeper knowledge, if you have it; what are the main cost drivers for ion exchange membranes? based on this video, the manufacturing seems like a very long and involved process.
This is good only for mild conditions or prototype cells proof of concept. This membrane is made of crosslinked PVA and the linker also contains the ion exchange groups. Commercial membranes use a backbone polymer usually PTFE modified wity alcohol then you add a diglycydyl ether as a tail to these sites and finally an amine or sulfonate containing group is reacted to the other end of the diglycidyl ether. These are all perfluorinated in other sites. The main cost is that perfluorinated diglycidyl ethers probably aren't cheap
I've seen videos where they had made use of a ceramic pot inside a tupperware container. The ceramic doubled as a diaphragm and a separate container. What's your take on that?
🤩 This is a best solution for the CEM over the web! Thanx a lot for the job you did over it, to make it cost-appropriate! BTW, can I use a fiberglass fabric (ρ=30g/m2) or a Nylon-6 mesh (25 microns) as a polymer matrix? Or the cleaning cloth will be better? Best regards, Linda
Not sure you will get a comment from OP, however couple things to note here. For one it cannot really be considered a CEM as you don’t functionalize the membrane and/or PVA. Sure, there will be some tiny selectivity that arises from citric acid monoesters, but it’s mostly unselective as the citrate/citric acid just acts as crosslinker. Further, you can use fiberglass, but you should avoid nylon or any other material that can be hydrolyzed under your reaction conditions. Likewise avoid glass when working in caustic conditions
@@1495978707 In my opinion, not significantly, no. However you have ho consider that your overall selectivity also depends on the prevalent species in the electrolytes. Say you have a highly acidic/alkaline environment, then the charge transport will mainly be due to hydrated protons / OH-. Alternatively, functionalize the PVA, you can phosphorylate or sulfonate it. Ofc something exotic like adding fluorinated acids would be optimal due to increased acidity by the stabilization of the anion by -I effect of the fluorine to stabilize the anion, but that’s nothing you could or would want to do at home
@@GreenCaulerpa Thanks a lot for the answer! BTW Aktavesh answered me in the discord not in YT sadly XD Anyways yes the pure CA have a lower level of the selectivity. And I found some papers about the reducing the quantity of SSA by a adding a CA as addition to improve the overall quality and charge ability of the CEM. "Synthesis of cation exchange membranes for capacitive deionization based on crosslinked polyvinyl alcohol with citric acid" if you interested. But the SSA is a pretty expensive and i will try to synth it first for my experiments. And my CEM will be used in Hydrogen PEMFC so the env will not be so aggressive, exclude CO and Water.
@@MethelinaPills No problems. Yea, adding poly(styrene sulfonic acid) (if that is what you are referring to?) as ionomer would help. But to be honest, I wouldn’t bother with exotic ionomers if it’s just for a PEMFC. It may sound weird, but consider that: the overall performance of your PEMFC will depend on the overall contact area of the ionomer to the catalyst. Using a solid ionomer will pose the same challenge as solid state batteries do - the quality of the interface will be the current limiting factor. An alternative approach you can do however is to acid dope your polymer electrolyte so you essentially get a gel. This gel will have more favorable characteristics but will only be stable to around 50-60C (for polyvinyl alcohol). Using a corrosive electrolyte won’t really matter here as well as your main catalyst will be platinum or a mixed PGM (platinum group metal) catalyst. Also I would advice to maybe start with an anion exchange membrane fuel cell or alkaline fuel cell as you can use cheap catalysts like nitrogen doped carbon for oxygen reduction and nickel (urushibara or raney Ni, even a metal hydride from Ni-Mh batteries) as nickel boride as anode catalyst
If I want to electrolysis water in 3 conditions as bellow, can you say me if it is possible to use a type of membrane that prevents mixing of initial materials with each other: 1- cathod side H2SO4 and anode side NaOH 2-cathod side H2SO4 and anode side Na2SO4 and3- cathode side Na2SO4 and anode side NaOH , and which one is more practical? since I want to lower over potential of both cathode and anode by preparing better ion accessibility on each side. I am really thankful for your excellent video and more excellent answers via comments.
thanks for reply, no goal is to having H+ near cathode and OH- near anode to assist electrolysis, if possible please guide how it is possible, but if not perhaps at one side we can use a neutral salt, @@CatboyChemicalSociety
@@sinaTonewood Whichever membrane you use it will actually attempt to diffuse unless maybe you use a seperator instead of a membrane which is only porous to OH- and H+ but these are very exotic.
Really thanks, do you mean separators are more rare and expensive in comparison to this membrane? or there are some materials near us could be used as separator? @@CatboyChemicalSociety
While its more selective towards monovalent cations im not sure how efficient it would be for seperation of divalent ions as they will still somewhat pass thru albeit slower but you could give it a try
@@CatboyChemicalSociety Thank you very much friend, one last thing, do you recommend a chemistry book to learn more about the interaction that molecules have with others.
yes this is what that process uses. cation exchange resin with anodic chamber feed of NaCl. Be very careful of the chlorine released in that process it will surprise you.
@@CatboyChemicalSociety wow. Thanks for the information. I was intended to produce small lab scale NaOH production using your membrane. Do you have any suggestions for me to do it? I mean, is there something that I have to do to get efficient process?
@@andrianwijayono6658 make sure the membrane cell doesnt leak and repeat the coating process of PVA and citric and cooking 2 or 3 times over to increase selectivity.
Did you say bake the sheets? At what temp would that be? I'ld watched one of your vids about a year ago on making with pvc cement and citric acid. It looked like a easier and cheaper way, is this a upgrade or for another application? Also was wondering about voltage for gypsum or magnesiumsulfate (epsum salt) for sulfiric acid generation. My guess is somewere between 5 and 12 volts. I'm thinking of trying to plate some stainless steel or steel screen with platnum or gold as anodes and cathiods in platnum are so costly. Thank for your time and work on putting out these vids.
this membrane is more selective than the previous one. if you add too many layers of the PVA citric acid resin then you cannot feed in CaSO4 as it becomes selective to cations only. for CaSO4 or MgSO4 you only do like 1 coat of PVA-Citric resin. The voltage would be around 8 and as for the anode better to use Ti substrate as the passivation will help prevent total corrosion of the substrate and gold only works if you dont have chloride contamination. A good cheap anode for this application is lead sheets or PbO2 on graphite.
Hi! Many thanks for this amazing video! I am actually interested in fuel cells so I can use the PVA instead of PVC. I just did not understand what do you mean by citric? I assume you meant citric acid, right?
partially dechlorinated PVC is just as a failsafe for added chemical resistance should the crosslinked ion ester be hydrolyzed and also is primed to crosslink with PVA chains. yes citric acid is used as the crosslinking agent and the mix can be put directly onto fiberglass substrate.
@@CatboyChemicalSociety Thank you. For what I understand, for fuel cells we can directly use the PVA/citric acid on cloth and skip the PVC part, right? I love this idea of using a cloth as a membrane as it is elegant and cost-effective.
Could you add a carbon powder to the cloth before coating to make it more conductive? I have been experimenting with a substance known as GANS Plasma and I have some really promising data from such material. However there is very little information anywhere regarding this material because it's kinda new and many are claiming its not a beneficial substance. Hence why I began researching it. I've found that it has an amazing effect on vegetables. It's almost as if it puts off a radiant energy that the plants use to maintain their shelf life. Take for instance I had onions cut in the fridge and before I ever made a batch of GANS Plasma they would rot within a month. Now I've had onions begin to grow in my fridge after 5 months of sitting. I had a pumpkin that we got last year around October and it just now began to rot. I have had tomatoes that have not spoiled sitting in my window sill since last August. That is something I've never seen in my entire life. I would like to share my findings if you are interested. I could even send samples if you know how to test to see what's going on. I'm new to chemistry do I'm not well informed. But I see real promise.
hi iam barely knew chemistry, but from my understanding is that some very fine filter that will bypass ion so by put on PVC cement it will be more rigid and inert? then what about acrylic glue as PVC cement substitute? do you think it will work? i have some homemade acrylic glue on my workshop
The PVC increases chemical resistance only as a trade off for ion conductivity. The material is not a traditional filter and the crosslinked PVA ionomer blocks uncharged molecules and only allows for positively charged ions to pass through the plastic film while blocking water and bulk solution.
very interesting your answer, i found in my home cleaner that contain benzonium chloride 0.75% do you think it have sufficient concentration for doing process like yours?
@@dogodogo5891 yea you can basically use any cleaner with these ammonia based surfactants to dechlorinate PVC but remember you need 4 molar or higher NaOH so take into account the water.
Hi MB, I just found your very interesting work, it is so fantastic. I want to try it in my lab. in this video you made 1:4 citric acid : PVA, but in your comment you said 10% citric acid, which one do you think better? 1:4 or 10% citric acid? Thank you so much for your answer
1:4 citric to 10% PVA solution is nice and I said 10% PVA solution and that's whats in clear glues like the one in this video. Since some people start with PVA powder.
Hi MB, about the length of the oven process (150 C), is 45 mnuts is a must? Or it can be faster? I tried 45 mnts, the cloth getting burn, but it didn’t when I tried with 30 mnts, please advise..
Hi MB, thank you so much for your advice.. 1 more need your advice, the thin layer was appear, but when I washed it, those thin layer fell off. Please advise, am I rubbing the membrane too hard? Or I did it too long in water? Please advise.. and thank you again for your advice..
yes you can technically do this to seperate H2 and O2 via membrane flow cell and 2 holding tank to seperate both gasses and liquid phases of O2 and H2 respectively.
@@CatboyChemicalSociety Thank You for Your answer. Do You know which membrane I could make myself and it would poduce best result with KOH?. Trying to learn about all this stuff but it seems a bit comlicated. Thanks
@@andy86376 if you are using NaOH as electrolyte then use steel as an anode and cathode as its inert in those conditions assuming your NaOH is pure. If not use baking soda as it soon forms NaOH anyway and is usually pure.
Thank you very much indeed for the video. I was going to ask something, if you'd like. I am trying to prepare a membrane to obtain liquid caustic from salt water. Would this system be suitable for me or do I need to use different compounds? I would be incredibly grateful if you could reply. Thank you in advance, good work.
I would like to try and replicate this. Thank you for the video and for sharing so much information. Can you suggest any simple tests one could perform to verify if the membrane is working correctly?
@@ferriswhitehouse1476 compare conductivity with porous PVC substrate alone in a setup in brine or NaOH or Na2SO4. Set same distance and same voltage and measure and compare current. Be wary that temperature affects the ion mobility so be sure to do it in a temp controlled environment.
@@CatboyChemicalSociety Makes sense. Thanks again. How important is the concentration of the quaternary ammonium salt? I just picked up some cleaner with benzalkonium chloride but there is no information on concentration of course. I found an sds on a similar cleaner that show concentration was 0.1 - 1%. So I would need to use quite a lot of that right?
yes you can and also the PVC is just a layer to make it more chemically resistant because partially dechlorinated PVC is more resistant than just crosslinked PVA. The real ion exchange resin is the PVA crosslinked with citric acid which provides 1 free carboxylic acid which allows ions to be pulled through the polymer. Microwave is helpful in crosslinking but ive had it burn up sometimes which is why oven is still the best. I had more luck when using aspartic/glutamic acid HCl salt at pH 1 though as the crosslinker as the microwave really worked for this one. The only issue is HCl fumes released when preparing anion resins and the microwave didnt like that.
Depends as the mobility of the ions depends on their valency and ionic radius or is it to prevent further oxidation of iron during electrowinning by using an aem on the anode
just make sure the dechlorination solution is 4 molar NaOH as the one who did the prep in this video (not me) made a mistake in measurements. also if you want less permeability of the solution and more ion selectivity then you must paint and bake the PVA citric step 3-4 times and be sure to do washings inbetween.
Am I right in that the point of the washcloth is really to be a substrate for the ion-exchange membrane which is really comprised of PVA? If so, could one simply impregnate a fiberglass weave with PVA/citric directly?
Thanks for sharing this video Can these membranes be used for a small alkaline chlorine small workshop with a capacity of 500 kg of caustic soda per day? How many cells do you think is needed for a capacity of 500 kg caustic soda per day and in what dimensions? What is your idea about most cost-effective anodes and cathodes I can use? ( there are access to cheep power and NACL in our Region)
most membranes tolerate a max of 200ma/cm^2 you have to calculate the amount of amps required to produce the amount of product needed in the given amount of time. Then you would have to find the surface area of membranes required to run it at that current density and current required.
@@CatboyChemicalSociety Ok. Thanks for your reply Do you think these membranes are suitable for the production of caustic soda on a small industrial scale? What is your idea about most cost-effective anodes and cathodes I can use?
@@mohammadmoradimajd7256 for anodes in terms of long term costs saving you really should get DSA which is industry standard and get Ir-Ru type because its more efficient for chlorine evolution. The anodes sold also have similar current density rating to these membranes up to 250ma/cm^2. Membrane cells usually run lower current densities. Now in terms of current for 500kg of product per day we are talking a lot of amps here which ive calculated to be 1,338 AMPS assuming 100% efficiency given that its more like 89% it would then much more than this and depending on input voltage the watts of heat that must be dealt with will be high. DSA has a high initial cost the costs of the electrodes will be quite high due to the amount required here you will need 5,352cm^2 of surface area. I assume you plan to make 1 large membrane flow cell assembly with several compartments for this. The maximum concentration of NaOH produced via membrane in industry is 30% since efficiency and current draw drops off after that. if the budget concerns you then graphite runs at lower current densities and given resistances of membranes is also a reasonable choice. These membranes can survive sulfuric acid electrolyte and I have used them in a chloro alkali cell in labscale and they survive the conditions. For an industrial scale plant though it may not have the same results and nafion is probably the better option sinch buying it in bulk is cheaper anyway.
@@mohammadmoradimajd7256 the main issue why I recommend just getting commercial membranes is that the surface area you require for your flow cell will be large. I doubt a simple oven will be large enough for each membrane for each cell compartiment. but if you have a large enough oven or the equipment to make large industrial flow cell sized membranes then go for it and use this recipe. Cathodes used can be stainless steel as the alkaline conditions will protect them or nickel plated steel.
Thank you very much for sharing this video. I also had a question for you about this membrane. Can this type of membrane help us absorb heavy metals from water or effluents, and if so, thank you for your help. do
yes it can but not exactly this type but it is possible to synthesize PVA-Citrate resin then break it up to make filter media for an ion exchange bed which can be regenerated by passing HCl to leach the collected heavy metals.
You need both cation and anion membranes for that so you can also use aspartic acid for making the anion resin membranes and optionally treatment with a methylating agent like methyl iodide to convert the amines into quaternary amines
I followed the direction by getting a cloth then putting the PVA and citric acid combination on a cloth then baking it for a microbial fuel cell. But what happened is the holes in the cloth are still too big. The water passed right through it, so it doenst really act as a membrane. What should I do instead? What kind of cloth should I use? Do you have an amazon link?
No, those are completely different types of membranes. In order to dehumidify a room you can use several types of methods, among them chemical or physical. For chemical dehumidifying you would use a substance which binds water and does so strongly enough that it will only release the water when heated considerably, so it wouldn't release the absorbed water prematurely. Chemicals well suited for that are calcium chloride, various sulfates such as potassium, sodium or magnesium sulfate, silica gel, and sulfuric acid, all of them can absorb quite a bit of water and binds it quite strongly, sulfuric acid can bind by far the most water for a set volume of sulfuric acid compared to the other chemicals, but it has the huge downside that it would need to be quite concentrated in order to do a good job at absorbing water and concentrated sulfuric acid is a hazardous chemical. So using one of the salts such as calcium chloride or the mentioned sulfate salts would be your best bet as they are solids so easier to handle than sulfuric acid not to mention much safer. All you need to do is dry a couples hundred gram of one of the aforementioned salts in the oven to drive off any water it will likely already contain. In order to find out at what temperature you need to dry them, check Wikipedia, it will mention for most of the salts at what temperature it will become anhydrous '(meaning free of water). For example with magnesium sulfate Wikipedia says you need to dry it at 250C, and for calcium chloride Wikipedia says you need to dry it at 260C, concidering over don't go that high you could predry it to the monohydrate in the oven as it will be able to reach the required temperature for that, and then drive off the last molecule of water by putting the salt on a steel baking tray and heating the tray from underneath with a small handheld butane gas burner. For physical dehumidifying you need a kind of retrofitted airconditioner, except with the minor difference that unlike airco's it doesn't blow any air over it but just has a large aluminium or steel cooling plate which is cooled by the airconditioner to a fair bit below the temperature in your room and preferrably just a couple degrees above 0C. The large difference in temperature between the metal plate and your room will cause the moisture in the air to condense on the cold plate, and it will rapidly start to collect droplets of condensation which can then be collected in a container underneath it. The only action you periodically need to undertake is to empty the container full of condensate, but other than that it's very simple. However the big downside is that airconditioners use a huge amount of electricity, and the same goes for these dehumidifiers, which as I mentioned are basically just retrofitted airconditioners.
FOR pem membrane required for hydrogen production by electrolysis direct on clean cloth pva and citric acid is aplied no pvc and dechorination solution is required then baked the sheet
if I am using this for a fuel cell do I need to make any other changes other than skipping the PVC cement or would I be able to use it like a Nafion or Dupont PEM membrane? also would using the PVC glue anyway make the fuel cell better for my purpose?
The pvc glue is only for chloroalkali compatibility and yea pva citrate blend is a good alternative to nafion for the case of fuel cells. Just be sure to bake many layers to improve ion selectivity.
so if i understand your method correctly the electrolysis of sodium sulfate works because the sodium ion can pass pass through the membrane, same as the hydrogen ions, but the other ions are stuck, and in the calcium sulfate salt, thanks to insolubility of gypsum the sodium sulfate is always regenerated to give more sodium which then forms calcium hydroxide and more materials for the formation of sulfuric acid, correct? but if that is the case the limiting reagent becomes the sodium sulfate which is not as cheap as gypsum
Yes but then sodium hydroxide formed at the cathode reacts with calcium sulfate in an equilibrium reaction forming sodium sulfate. Then due to voltage gradient the sulfate ions pass through and in this process the anion membranes are better which I show in a seperate video. The limiting reagent is calcium sulfate and sodium sulfate is an intermediate and sodium ions are a catalyst.
Respect. I hope you will be interested in why I am watching this video of yours. I want to commend your work, if I understood these membranes can I in some way replace expensive nafion proton membranes? I make water electrolyzers, so I study various ionic membranes, what is the porosity of these membranes after this operation of putting pva glue and dechlorination, what is the porosity of water, and what types of ions does this membrane leak?
the PVA citrate membranes leak both protons and cations and block anions. ofc more layers of Citrate esterified PVA chains will increase resistance but make it more selective. These membranes however get hydrolzed in certain strongly acidic conditions or strongly basic conditions. The free carboxylic groups are what hold on to protons and other cations which allow them to flow through the membrane. These membranes overall arent going to outlast nafion for the long long run in certain corrosive conditions. But for some applications with milder conditions or for simple proof of concept testing where you only care to run it for a few hours then this will suffice.
@@CatboyChemicalSociety Hmmm, that now brings me a little bit of disappointment, I have created quite optimistic expectations. And I want you to advance in the prolanals of making membranes that can literally replace nafion membranes, and that can be made from affordable and economical materials on the market!
@@hydrogenh2energy964 well such a dream material would be nice but these membranes are mostly just for really short experiments or proofs of concepts where you are testing shit for awhile and dont wanna spend on nafion.
@@CatboyChemicalSociety Colleague, I would ask if you are able to do one test, with PVA membrane, it is in my interest to find out the time resistance of the membrane to the research concept, electrolysis of water, where the catholyte is 1 M citric acid, anolyte base, sodium hydroxide concentrations 1 M
Is there a source you can give on understanding membranes like this? I was chatting with ChatGPT and it said that PVA citric acid membrane isn’t used for electrolysis because it’s not really conductive, but that cellulose acetate and cation exchange resin are used at least for chloralkali. But it seems clear that it works here for you… so is it just that you’re showing an easy to make but low performance membrane or is ChatGPT wrong?
This is a cation exchange membrane and overall chat GPT was not really very good when it came to chemistry. This is a polycarboxylate cation exchange resin made by crosslinking PVA chains together with citric acid leaving 1 free carboxylic acid to exchange ions. There are a few papers on this topic but more on the info that chat GPT gave is that you cannot use cellulose acetate in chloro alkali proess it will quite literally get destroyed. They use polysulfonate cation exchange resin which is usually but not aways perfluorinated to increase chemical resistance. This membrane has a layer of PVC which is partially dechlorinated by the alkali treatment allowing it to bond to the actual ion exchange polymer blend o PVA+citric acid baked above. This partial PVC layer gives it some chemical resistance to use it in production of acids or chloro alkali process.
yes it will work for that pupose but a simple porous cloth will work too though that depends on the battery. Lithium ion batteries use very selective membranes.
@@CatboyChemicalSociety i want to supress self discharge in my cell by using a cation membrane seperator to prevent ion gradient diffusion. Do you think your selective Membrane will help?
the issue is that highly sulfonated membranes need to be crosslinked or else they will just dissolved. The way sulfonated PS membranes are produced is they sulfonate the monomers and use divinylbenzene as a crosslinker and this forms a crosslinked polymer.
very nice. , excellent.I want to use these membrances as AEM for electrolysis of water for G.H. Production. In addition, i want to use this manual process as the first step to commercially see if this first step is viable. then, reactor and choloromethylation and amination steps with reactors and fabricating the membranes. is it possible pl.
yes but you need to switch citric acid to aspartic acid hydrochloride or glutamic acid hydrochloride which then need to be further treated after baking step with a methylating agent such as methyl iodide to form the quaternary amine which will be the anion exchanging group.
@@baburamabadhran1437 well these PVA membranes are mostly for prototyping as they dont last as long as other types of more resistant ion exchange membranes. Most anion membranes are either functionalized perfluorinated compounds on fiberglass substrate or a duropolymer comprised of aminophenol and formaldehyde also baked on a substrate like fiberglass. There is one more involving amine functionalized styrene which is also allowed to polymerise onto some PVC. Commercialization of the process is something I could think of with some work like if I were to make a very basic scale up proceedure for a block diagram I would break it into these parts. 1. Large rolls of fiberglass substrate is prepered on a long conveyor. 2. prepolymer blend is coated on prepared substrate. 3. prepolymer is baked in a continuos feed oven or whatever other conditions are required (inert atmosphere) etc. 4. baked polymer would be washed to remove unreacted prepolymer using sprayers. 5. prepared ionomer is cut into shape. 6. further treatment if required (anion resin). steps 5 and 6 can be interchanged depending on convinience.
@@CatboyChemicalSociety I saw this sentences in google. But how the product of these reactions be??? "A homogeneous anion-exchange membrane can be obtained by introducing a quaternary amine group into polystyrene by a chloromethylation procedure followed by an amination with a tertiary amine" In addition we speak about Green Hydrogen bur Fibre glass reinforced is not recyclable and has poor Sustainability index.can there be an alternate for it pl.
@@baburamabadhran1437 thing with more recyclable membranes is that they do not lasts as long. I am sure there is an alternative but I am only telling you what is industry standard and it is your job to find the alternative. Also you have to decide whether you want longevity or recyclability and overall you must do the cost analysis and environmental impact analysis yourself. The reaction to make anion membranes is something you can understand by looking at the reaction mechanism as its really just methylation of an amine. If you actually want full assistance to your researchwork I can provide it but I am going to need some compensation if you really want me to hold your hand all the way.
I followed your directions and tried to make ur PEM for a microbial fuel cell. Since, u said that if we are making a fuel cell, we can skip the first two steps (applying PVC cement and the dechlorination solution), we directly applied the glue and citric acid to our cloth. But once we baked it, it got burnt and it doesn't have the shiny layer. It also stuck to the foil and was very hard to remove (broke some of the times) So I was wondering what went wrong? What type of cloth did you use and does it matter? We don't have a thermocouple probe so we didn't can't use that, so is there any problem with a burnt PEM? Does it impact the function? Also how do we know that we did this right and the PEM actually works before using it in the fuel cell?
Temp control wasn't adequate because these ovens tend to do something called 30 seconds on and some seconds off so the elements maybe at higher temp so preheat your oven. Also gas oven doesn't work
Removal from foil is easy just dissolve the foil in NaOH if its stuck which is why foil is used. If its medium brown its ok but black means too burnt. Fiberglass mesh substrate is best. Theres going to be a new membrane video involving fusing deionizer resin just tested it works well.
@@CatboyChemicalSociety Thanks for the response! I don't have an electric oven, is there any alternative? Also, I saw in some comments you said tissue paper, so should I use that or the fiberglass mesh? Would I repeat the steps multiple times? My membranes all turned brown so ig that's good. Also, would the holes in fiberglass mesh be completely fine?
@@srimayikukkadapu2425 yea multiple coats work but yea I suggest getting an electric oven even a small toaster because gas ovens rly don't work for this. Maybe you can also bake the membrane in a hotplate between foil
Thanks for the response! Thankfully, I was able to borrow someone's electric oven! Just to clarify, would tissue paper or fiberglass mesh be best to use? Would the holes in fiberglass mesh be completely fine? Also, I realized the citric acid I got wasn't pure, it has less than 2% silicon dioxide. Is that fine or does it need to be pure? I also estimated the measurements when mixing the PVA and citric acid together. Would that be too problematic? Do I need precise measurements?
Supposing I want to do this to fit into a tubular stainless steel container to replace asbestos in Nelson Chloro alkali cell, how do I do it? And secondly will it work efficiently?
First ensured to roll the cloth in a tube before coating it then this maybe possible to do. Cation exchange resin is always more efficient than porous barriers. If you add the PVA-Citrate layer above the PVC resin then it could be nice. We have one issue though and that is that it was rolled into a tube before curing which makes it very hard to cure it evenly in an oven. I would get some sort of forced convection cooker/kiln to cure the rolled up membrane. If the membrane can be made flat and segmented into 2 or 3 sections then this will be better than curing a rolled up membrane which will be challenging. If the membrane is just dechlorinated PVC then it will still perform well but only comparable if not worse than asbestos. If the membrane is only PVA-Citrate then it will perform the best but I have no idea about its longevity in strongly alkaline and strongly chlorinated solutions for long periods of time compared to the mixed layers where the PVC layer will naturally be ok in the anode chamber and the PVA layer will be fine in the cathode chamber.
Nafion membrane from China top quality cost 500$ m2, I know very well the factory. Also I will test PFSA resin that is the raw material to make Nafion membrane.
you would have to find a way to melt/fuse it and roll it into thin sheets or laminate some fiberglass sheets with it. I reckon under inert atmosphere knowing how fluorinated stuff behaves when heated in the presence of oxygen.
@@gilbertquarshie3932 its not since you really only need the ionomer for milder conditions. all you need to do is bake PVA and citric on a substrate like fiberglass or cloth.
@@CatboyChemicalSociety How do I apply multiple layers of the PVA-Citric acid blend? (Im asking cause I realized some people run into a problem where the membrane was porous) Do I apply the on the substrate, bake and repeat process or I apply on the substrate wait for sometime and apply again then bake the whole thing
Very interesting! Can I use this membrane to make KOH from KCL solution? Im having a hard time finding KOH in my country and it's quite expensive (60 dollars a kilo). It seems that is controlled by the federal police, Im not sure why, maybe people are making drugs or explosives with it, lol... I just need KOH for making liquid soap to be used as wetting agent for organic pesticide application, but at USD60.00 a kilo the whole endeavor becomes pointless. Which cathode and anode materials that are relatively cheap and easy to obtain can be used to make around 3kg of KOH? (that's the amount I need for a batch of 100L liquid soap/detergent using the korean JADAM natural farming) Sorry for the basic questions, Im just getting started on this. Looks like I still have a long way to go... Thank you!
@oddjobbob Thanks, I'll keep looking. The only thing I could find so far is 98 or 99% pure KOH used for hydrogen fuel cells. Quite expensive though... around USD 30/lb
@@CatboyChemicalSociety Thank you for your response. In your opinion or experience how much purity can one achieve making KOH with this method? I need 90% KOH for my purposes, do you think it's feasible using this method and materials?
@@virusmyth4930 30% KOH solution is usually what you can produce before the membranes get fked. seperation of that with KCl must be done. 90% KOH solution is not feasible with membranes as the current is gonna drop and the membranes will be damaged no matter how good they are. downstream steps are usually employed to seperate out chlorides with hydroxides which you must do.
Pvc cement is only for chloro alkali process compatibility and for other milder conditions or fuel cells then you don't need precoat and can use pva citric to form crosslinked cation membrane
got a link to the original research paper? also, how would i go about making a membrane that is meant for anion exchange as opposed to cation exchange?
change citric into glutamic/aspartic acid HCl salt. I have a video on that too. also just search this on google for the paper "ion exchange resin made from polyvinyl alcohol and citric acid" and you get a research article as your 1st result talking about this polymer. I simply put it on a substrate.
@@CatboyChemicalSociety thanks! i didnt think there was much of a chance that you would reply, but you also replied real quick! time to go down the google rabbit hole lol. also, do you think this type of membrane would be able to handle turning concentrated potassium nitrate into potassium hydroxide and nitric acid?
9:50 This is backwards I think. White school glue has polyvinyl acetate with polyvinyl alcohol colloid to protect it, which is why it’s not reactive. You want the clear because it is only polyvinyl acetate, and for the resin it is carboxyl groups you want, which the acetate provides, as well as the citric acid.
but polyvinyl alcohol is hydrophillic due to several OH groups and results in a clear solution with water while acetate groups make it less hydrophillic which is why white glue is white containing polyvinyl acetate colloid. esters are more hydrophobic than alcohols so I think you have it backwards as an example the molecule ethyl acetate is insoluble in water while ethyl alcohol is.
Good point… also thanks for being so interactive. What’s the use of the hydrophilicity though? It’s not water you’re trying to pass through the membrane, and I don’t think polyvinyl acetate is exactly hydrophobic. Thing is, PVA is used to refer to both acetate and alcohol which is really confusing. Am I wrong about the carboxyl groups being the means of cation transfer?
@@1495978707 once the esterification occurs then it becomes hydrophobic and does not let the solution pass ideally but it has one free carboxylic acid which allows for transfer of cations. the esterified bits cannot transfer ions because they no longer have that charge or a proton to exchange with a cation.
if its cleaning cloth yes and if its made of cotton its fine as long as its a sheet that is porous and can be coated in PVC glue. IF you mean cotton balls then it will have an issue of very low permeability when you apply PVC glue but it can be applied with PVA + Citric acid and baked as that layer is the better ion exchange layer and will have the ion exchange groups distributed throughout the polymer.
Why do you dechlorinate the PVC? What is the point of the PVC anyway if the goal is to have citric acid crosslink pva to have sites for ion transfer? What is the point of the quaternary ammonium salt?
the PVC increases chemical resistance and while you can simply use pure PVA. when you have partially dechlorinated PVC then you also get crosslinking of PVA chains to the PVC chains due to one of the products of dechlorination is alcohol group instead of chlorine the other is a double bond. The quaternary ammonium salt was from that 1 paper talking about aqueous dechlorination of PVC films at made by dissolving PVC in THF which basically is PVC glue and quaternary ammonium compounds act as a phase transfer catalyst allowing the strong NaOH to attack the PVC films. a purely PVA and Citric membrane actually is more conductive but against really strong solutions it is simply gonna dissolve while if you have a PVC film you can have resistance against hydrolysis of the crosslinked PVA in strong acid solutions.
My previous reply seems to have disappeared, or maybe it’s under review? I was just asking more questions. Anyhow, apparently ion exchange resins that use carboxylic acid groups are called “Weak Acid Cation Exchange Resins”. Is the citric acid just to help the PVA crosslink?
Oh I think maybe it’s because I included a doi link… Well since I can’t edit the comment to remove that, how is the PVC conductive at all to cations? Also, how does the PVC help resist hydrolysis, when it is behind the PVA, not covering it? Sorry about all the questions, but can you recommend a book that I could learn about this from?
@@1495978707 PVC is non conductive neither is PVA but partially dechlorinated PVA has some OH groups attached to it which allows for inter esterification between PVA and (dechlorinated) PVC chains creating a good chlorinated resin backbone which resists chemical attack while containing some ester linkages. I have the paper that describes the dechlorination process and it is titled. "Dehydrochlorination of Poly(viny1 Chloride) by Aqueous Sodium Hydroxide Solution under Two-Phase Conditions" by hideo KISE 1982 Join the Catboy Chemical Society discord for more interactive questions and answers link is in one of my community posts.
these are cation exchange membranes and if the process needs those types of membranes then it can be used. Anion exchange membranes can be made from substituting out citric acid for aspartic acid and optional post treatment with Methyl Iodide. They arent really nano/ultrafiltration membranes if that is what you are looking for.
thats not a good PbO2 anode as the anode produced is porous and unsuitable for perchlorates. the plating solution requires membrane electrolysis of either sodium nitrate or chlorate with lead electrodes to make lead nitrate/chlorate then using that on a titanium mesh with undercoat to make an electrode.
if consutructed right in ideal conditions or many layers of esterified PVA then it should only allow ions but if you add fewer layers then it will be a bit more porous to the solution.
Hi. Mysteriousbhoice I want to make a hydrogen separator electrolyzer using koh as a electrolyte. Can I use this membrane and second option a porous PVC membrane for this purpose.to achieve pure hydrogen and oxygen through electrolysis. How long these two membrane will work or degrade in koh solution? Kindly reply I want to build hydrogen generator
@@CatboyChemicalSociety is there any way so that these membrane can last for 3 to 4 years I want to run electrolyzer for a long time. What about with sulfuric acid as a electrolyte does membrane works long with this or not Need your suggestion plz
@@hamidamjad7521 the PVC membranes are more likely to last long but the PVA-Citrate ester ones are less likely but are more selective in the short term. The membranes shown in this vid is a mix of both types layered above eachother but overall in general PVC membranes last longer and can handle up to 30% wt alkali fairly well. If you just want porous membranes just do the PVC and dechlorination step and leave it at that but if you want selective ion exchange then add the layer of PVA Citrate ester ion exchange resin. I have not done any long long term testing of these membranes but I can say in sulfuric acid the PVC holds up very and its actually me using polystyrene as the frames that failed and not the membrane after using it for 5 months the membrane was still good albeit white due to magnesium fouling but that is solved with simple HCl soaking.
I checked it just now and the yield is 30% due to the other reaction producing CO2 instead. The catalyst is also 0.4M HClO4. yea u need Ir-Ta MMO electrodes or this wont fly.
Finally someone shows reasonable alternatives to buying Nafion or other proprietary membranes. Love it
really this video is appreciated since it is alternative to buying expensive Nafion
@@sinaTonewood wait till u see the total nafion replacement for harsh conditions up to 36% HCl membrane video coming up
@@sinaTonewood wait till u see the total nafion replacement for harsh conditions up to 36% HCl membrane video coming up
@@CatboyChemicalSociety Hi, I'm making the membrane from the video. I'm realy looking forward to the next one. Could you give an idea of how long it will take until it is published?
@@CatboyChemicalSocietyhi sir how r you kindly share material info and can we made this at home easily
Thanks for the video, very cool. If anyone wants to replicate this, make sure you buy PVC cement, not PVC-C cement. It doesnt dechlorinate properly.
I'm trying to learn more about different kinds of membranes. What better way than to see one being constructed from scratch from (mostly) common materials. Thanks for sharing this! I'll be exploring your channel further as I want to learn how membranes might be used for electrodialysis, as in the fascinating of Matt Eisaman. Liked and subscribed.
no problem
electrodialysis membranes are usually a pair of cation and anion exchange membrane cells stacked together such that water is fed into neutral chambers with either membrane on both sides.
The respective ions pass through the cation exchange membrane on one side and the anion exchange membrane on the other.
The water that comes out from the outlet of that neutral chamber is said to be de ionized.
The electrodes are located at the opposite ends of the cell.
Hi. @ML Franklin did try this method to make these membranes for electrodialysis water desalination? Regards
Thanks a lot for the video, it is nice to have people like you who share useful knowledge. Just what I've been looking for.
Respectfully, are you interested in self-building a fuel cell using more economical, cheaper PVA membrane technology compared to the Nafion N117?
@@hydrogenh2energy964 yes
@@hydrogenh2energy964 sure
@@hydrogenh2energy964hi sir how r you kindly share info how to make pva membrane cell
Wonderful and useful technical information you have shared with detailed video. I respect your efforts taken to share with all. From Jawaharlal Bharat 🙏
Thanks for sharing, your instructional video production skills are getting very good.
That’s useful! Thanks for sharing I’ll have to try this myself soon.
@@shlomibenyair3405 a clay pot would work too, but ceramic membranes have very high resistance
@@shlomibenyair3405 so you are saying that clay will work as a membrane? Any specific clay?
@@shlomibenyair3405 I've done a quick look but can mot find anything. Would you have any helpful info to share? Thanks in advance.
@@jvon3885 Clay is a nonselective membrane; it's just lots of tiny holes that make it harder for everything to get through, so things that are forced through by the current (ions) end up going more than things that are just diffusing. What MB showed here is an actual legit semipermeable membrane, which at a molecular scale actually only lets certain chemical species through (positive ions in this case (and possibly water), not negative ions, or gases; though in the comments they also explain you can switch out the citric acid for aspartic acid to make one that passes negative ions)
If all you need is a porous membrane (like clay) not a selective one, you can use clay but you can also use the first step without the PVA as they show in this video here :)
th-cam.com/video/foQHygE2Mkw/w-d-xo.html
Super cool! I should really get around to making some of these.
yea overall these membranes are cheap to prepare and have really good performance.
Bro you should make a part 2 video about nitrate using this method and urea,
This looks very interesting thanks!
Strangely I cannot find any other videos on the subject of DIY ion exchange membranes.
I'm not knowledgeable enough to understand why your process works. I think some explanations would encourage this experiment to be replicated.
DIY nafion would be awesome for many hobbyists.
DIY Nafion is not possible… it requires doing a lot of fluorine chemistry which is extremely dangerous. You will die.
Thanks for the video! Are these resistant to acids and bases
Really interesting video. I'm wanting to make a Proton Exchange Membrane for a Direct Ethanol Fuel Cell. I was wondering if you have tried these membranes in that type of cell or if some modification to the recipe is needed.
this is a proton exchange membrane.
Love the presentation. Can you provide some more information about what exactly is happening with the reactions you performed here?
pva chains contain alcohol groups and when you have a carboxylic acid under anhydrous conditions it will esterify and remove a water molecule.
this occurs during the oven baking part of the proceedure.
since citric acid is a tricarboxylic acid, it will react to crosslink the chain and will have 1 free carboxylate group which can bind to cations in the electrolyte.
When a voltage is present across the cell, the ions migrate to the cathode chamber from the anode chamber.
🙏👏
what is that kind of ovens ??? the first time I see this .....
and how and from where you learned the whole process of making (ion exchange membrane) ???
it would be great if you had time, to do a video on making cationic and anionic membranes using this principle. Thanks for sharing this with us!
this video is on cation membranes and I have a seperate video on anion membranes using the same process but swapping out citric for glutamic acid.
@@CatboyChemicalSociety I appreciate your comments. I was wondering, since these bipolar membranes are typically not permeable, how about putting anionic resin on one side and cationic resin on the other side of a pvc membrane? (ie from water treatment resins)
@@en2oh you would have to find a way to dissolve those or maybe grind them up into a powder and mix with PVC glue to make a paste.
@@en2oh bipolar membranes are permeable but they are not selective.
@@CatboyChemicalSociety some are, but not all.... I've been reviewing some of the literature for HAN production using bipolar membranes....
This is really cool - thanks for sharing this! Following up on an earlier comment, is there any technical papers or something that I could read to explain how this coating method using PVA and citric acid creates these cation-exchange membranes (as opposed to anionic ones... or why PVA and citric acid?)? Just wondering how it compares to the commerical nafion 117 and n324. Would there be any way to further optimize what you have done for membranes in a chlor-alkali cell? Perhaps just use teflon-fiberglass cloth, PVA/citric coat, bake, and do that a few times, but not so many times that you increase the resistance of the membrane to electric current?
anionic exchange membranes need a different thing than citric acid which is aspartic acid and subsequent treatment with methyl iodide converts the amines into quaternary ammonium compounds.
These membranes are quite conductive and if you want to look for technical papers on threm just look up PVA and citric acid crosslinking and you will find many such papers talking about the mechanism and the crosslinked structure that forms as a result of baking the mixture.
It was from one of these papers that got me the ratio of 4:1 10% PVA solution with citric acid. Most clear PVA glues are 10% PVA solutions with some other additives.
Nafion is of course the king of membranes but its price makes it unreasonable for prototyping and small scale experiments. You can also use Sulfosuccinic acid instead of citric to get the sulfonate groups instead which is also found in commercial nafion membranes.
Sulfosuccinic acid is made by sulfonation of maleic or fumaric acid. and there are papers talking about membranes made from PVA and sulfosuccinic acid aswell.
Can I use lemon juice instead of citric acid?
Thanks for such a fantastic video detailing the process, and thanks for still being so active in the replies. I'm looking to build a rudimentary PEM fuel cell and it requires Nafion for the PEM. Obviously, as you've mentioned, it's very expensive and not so easy to get hold of so I am looking to follow your video and make my own. I read in the descriptino that I can skip the PVC cement and dechlorinating step if I'm making a PEM for a fuel cell. Is that correct? What kind of cleaning cloths did you use, does it matter? And I saw someone mentioned using fibreglass cloth instead, is that viable and do I need a specific type? I'm sorry for all the questions, thanks again for your help!
Would a thinner fibreglass cloth be better?
@@CaptainOcboter yes fiberglass mesh can act as a substrate for the ionomer baked directly.
Thanks for posting this video. I made a membrane using these instructions and used a standard procedure to measure the permselectivity using NaCl 0.1M | NaCl 0.5M. The permselectivity values I got were never greater than 0.5. I believe this had to do with citric acid being poorly crosslinked without an acid catalyst present, which matches literature on crosslinking of PVA using citric acid. I obtained much better success using a 10% molar equivalent of sulfuric acid or phosphoric acid to the moles of PVA alcohol groups.
Let me know if you get some data on the permselectivity of the membranes you have produced.
The 10% molar equivalent of sulfuric acid is an alternative for what exactly in the membrane construction?
@@tmz9756 Not an alternative, just additional to the citric acid, to catalyze the esterification of citric acid with the PVA.
@@danielppps if I am preparing an (AEM) should I use aspartic acid or what exactly if you know
@@tmz9756 You can use aspartic or glutamic acids, however you will need to use a small amount of a strong acid during the esterification reaction to catalyze it, as I mentioned before. However a membrane like this will only be an anion exchange membrane under acidic pH, under basic pH it will loose this ability and become permeable to anions. To make it an anionic exchange membrane regardless of the pH, you will need to do an additional reaction to make the amine groups quaternary.
NEW MEMBRANE LORE JUST DROPPED GUYS
if you want lore I will drop a totally different video for that dont worry its coming.
@@CatboyChemicalSociety we are waiting for your next video on lore
And Also make a video for anion exchange membrane
If I'd be using shampoo for the benzalkonium chloride then how much do I use? It's meant to be a catalyst... would 50 ml be enough? Does it go faster/better if I use more?
Look into algaecide products at your local garden supply store (to remove algae, moss, moulds and lichens from hard surfaces), they often consist of concentrated (up to 50%) aqueous benzalkonium chloride solutions with no other additives. Alternatively you'll also encounter 5-10% solutions of didecyldimethylammonium chloride sold as algaecide, or mixtures of the two.
@@bromisovalum8417 cool thanks
There was some very good answers to my question. Awesome, would this be useful in a zinc bromide battery? That bromine is crazy corrosive.
Thank you for the informative video! I've been scrounging academia for information concerning the manufacturing methods IEMs. How typical would you say is this process compared to something you would see in industry? And a little deeper knowledge, if you have it; what are the main cost drivers for ion exchange membranes? based on this video, the manufacturing seems like a very long and involved process.
This is good only for mild conditions or prototype cells proof of concept. This membrane is made of crosslinked PVA and the linker also contains the ion exchange groups. Commercial membranes use a backbone polymer usually PTFE modified wity alcohol then you add a diglycydyl ether as a tail to these sites and finally an amine or sulfonate containing group is reacted to the other end of the diglycidyl ether. These are all perfluorinated in other sites. The main cost is that perfluorinated diglycidyl ethers probably aren't cheap
Thanks for showing this! Can this be used in a flow battery? If so what chemistries?
Electrospun PVDF-carbon membranes preparation for water filtration. Pls watch our video
th-cam.com/video/VoBOMrVbDyU/w-d-xo.html
Wow underated channel!! Love it
thank you so much for this video plsz what is the concentration of the pva i should use it to make PEM membrane
I've seen videos where they had made use of a ceramic pot inside a tupperware container. The ceramic doubled as a diaphragm and a separate container. What's your take on that?
It works but it has less ion selectivity
🤩 This is a best solution for the CEM over the web! Thanx a lot for the job you did over it, to make it cost-appropriate! BTW, can I use a fiberglass fabric (ρ=30g/m2) or a Nylon-6 mesh (25 microns) as a polymer matrix? Or the cleaning cloth will be better?
Best regards, Linda
Not sure you will get a comment from
OP, however couple things to note here. For one it cannot really be considered a CEM as you don’t functionalize the membrane and/or PVA. Sure, there will be some tiny selectivity that arises from citric acid monoesters, but it’s mostly unselective as the citrate/citric acid just acts as crosslinker. Further, you can use fiberglass, but you should avoid nylon or any other material that can be hydrolyzed under your reaction conditions. Likewise avoid glass when working in caustic conditions
@Andre Could you improve selectivity by having more citric acid in the mix?
@@1495978707 In my opinion, not significantly, no. However you have ho consider that your overall selectivity also depends on the prevalent species in the electrolytes. Say you have a highly acidic/alkaline environment, then the charge transport will mainly be due to hydrated protons / OH-.
Alternatively, functionalize the PVA, you can phosphorylate or sulfonate it. Ofc something exotic like adding fluorinated acids would be optimal due to increased acidity by the stabilization of the anion by -I effect of the fluorine to stabilize the anion, but that’s nothing you could or would want to do at home
@@GreenCaulerpa Thanks a lot for the answer! BTW Aktavesh answered me in the discord not in YT sadly XD Anyways yes the pure CA have a lower level of the selectivity. And I found some papers about the reducing the quantity of SSA by a adding a CA as addition to improve the overall quality and charge ability of the CEM. "Synthesis of cation exchange membranes for capacitive deionization based on crosslinked polyvinyl alcohol with citric acid" if you interested. But the SSA is a pretty expensive and i will try to synth it first for my experiments. And my CEM will be used in Hydrogen PEMFC so the env will not be so aggressive, exclude CO and Water.
@@MethelinaPills No problems. Yea, adding poly(styrene sulfonic acid) (if that is what you are referring to?) as ionomer would help. But to be honest, I wouldn’t bother with exotic ionomers if it’s just for a PEMFC. It may sound weird, but consider that: the overall performance of your PEMFC will depend on the overall contact area of the ionomer to the catalyst. Using a solid ionomer will pose the same challenge as solid state batteries do - the quality of the interface will be the current limiting factor. An alternative approach you can do however is to acid dope your polymer electrolyte so you essentially get a gel. This gel will have more favorable characteristics but will only be stable to around 50-60C (for polyvinyl alcohol). Using a corrosive electrolyte won’t really matter here as well as your main catalyst will be platinum or a mixed PGM (platinum group metal) catalyst.
Also I would advice to maybe start with an anion exchange membrane fuel cell or alkaline fuel cell as you can use cheap catalysts like nitrogen doped carbon for oxygen reduction and nickel (urushibara or raney Ni, even a metal hydride from Ni-Mh batteries) as nickel boride as anode catalyst
Will try for use as shock electrodialysis desalination
Give me an update if that process works or not
Can I use the ion exchange resin for a water filter? Or is it a different kind?
thank you so much for this video. i was wondering what is the difference between this and a PEM. (proton exchange membrane)
This is a PEM but if you swap out the citric for aspartic acid HCl you make an anion exchange resin instead.
Great presentation!
If I want to electrolysis water in 3 conditions as bellow, can you say me if it is possible to use a type of membrane that prevents mixing of initial materials with each other: 1- cathod side H2SO4 and anode side NaOH 2-cathod side H2SO4 and anode side Na2SO4 and3- cathode side Na2SO4 and anode side NaOH , and which one is more practical? since I want to lower over potential of both cathode and anode by preparing better ion accessibility on each side. I am really thankful for your excellent video and more excellent answers via comments.
if the goal is transfer of SO4 ions through the membrane then using a cation selective membrane would be best.
thanks for reply, no goal is to having H+ near cathode and OH- near anode to assist electrolysis, if possible please guide how it is possible, but if not perhaps at one side we can use a neutral salt, @@CatboyChemicalSociety
@@sinaTonewood Whichever membrane you use it will actually attempt to diffuse unless maybe you use a seperator instead of a membrane which is only porous to OH- and H+ but these are very exotic.
Really thanks, do you mean separators are more rare and expensive in comparison to this membrane? or there are some materials near us could be used as separator? @@CatboyChemicalSociety
I have a question. Could this membrane be able to purify the hardness of water, that is, calcium and magnesium?
While its more selective towards monovalent cations im not sure how efficient it would be for seperation of divalent ions as they will still somewhat pass thru albeit slower but you could give it a try
@@CatboyChemicalSociety Thank you very much friend, one last thing, do you recommend a chemistry book to learn more about the interaction that molecules have with others.
What is the cloth you're using made of?
Can I use this membrane to get sodium hydroxide from brine with the chlor-alkali process?
yes this is what that process uses. cation exchange resin with anodic chamber feed of NaCl.
Be very careful of the chlorine released in that process it will surprise you.
@@CatboyChemicalSociety wow. Thanks for the information. I was intended to produce small lab scale NaOH production using your membrane. Do you have any suggestions for me to do it?
I mean, is there something that I have to do to get efficient process?
@@andrianwijayono6658 make sure the membrane cell doesnt leak and repeat the coating process of PVA and citric and cooking 2 or 3 times over to increase selectivity.
Did you say bake the sheets? At what temp would that be? I'ld watched one of your vids about a year ago on making with pvc cement and citric acid. It looked like a easier and cheaper way, is this a upgrade or for another application? Also was wondering about voltage for gypsum or magnesiumsulfate (epsum salt) for sulfiric acid generation. My guess is somewere between 5 and 12 volts. I'm thinking of trying to plate some stainless steel or steel screen with platnum or gold as anodes and cathiods in platnum are so costly. Thank for your time and work on putting out these vids.
this membrane is more selective than the previous one. if you add too many layers of the PVA citric acid resin then you cannot feed in CaSO4 as it becomes selective to cations only.
for CaSO4 or MgSO4 you only do like 1 coat of PVA-Citric resin.
The voltage would be around 8 and as for the anode better to use Ti substrate as the passivation will help prevent total corrosion of the substrate and gold only works if you dont have chloride contamination.
A good cheap anode for this application is lead sheets or PbO2 on graphite.
Hi! Many thanks for this amazing video! I am actually interested in fuel cells so I can use the PVA instead of PVC. I just did not understand what do you mean by citric? I assume you meant citric acid, right?
partially dechlorinated PVC is just as a failsafe for added chemical resistance should the crosslinked ion ester be hydrolyzed and also is primed to crosslink with PVA chains.
yes citric acid is used as the crosslinking agent and the mix can be put directly onto fiberglass substrate.
@@CatboyChemicalSociety Thank you. For what I understand, for fuel cells we can directly use the PVA/citric acid on cloth and skip the PVC part, right? I love this idea of using a cloth as a membrane as it is elegant and cost-effective.
@@MrJcmcoelho yes for fuel cells direct PVA crosslinked with citric acid can work.
Could you add a carbon powder to the cloth before coating to make it more conductive? I have been experimenting with a substance known as GANS Plasma and I have some really promising data from such material. However there is very little information anywhere regarding this material because it's kinda new and many are claiming its not a beneficial substance. Hence why I began researching it. I've found that it has an amazing effect on vegetables. It's almost as if it puts off a radiant energy that the plants use to maintain their shelf life. Take for instance I had onions cut in the fridge and before I ever made a batch of GANS Plasma they would rot within a month. Now I've had onions begin to grow in my fridge after 5 months of sitting. I had a pumpkin that we got last year around October and it just now began to rot. I have had tomatoes that have not spoiled sitting in my window sill since last August. That is something I've never seen in my entire life. I would like to share my findings if you are interested. I could even send samples if you know how to test to see what's going on. I'm new to chemistry do I'm not well informed. But I see real promise.
is there anything i could use instead of pvc cement that is available for under 18s
hi iam barely knew chemistry, but from my understanding is that some very fine filter that will bypass ion so by put on PVC cement it will be more rigid and inert?
then what about acrylic glue as PVC cement substitute? do you think it will work? i have some homemade acrylic glue on my workshop
The PVC increases chemical resistance only as a trade off for ion conductivity.
The material is not a traditional filter and the crosslinked PVA ionomer blocks uncharged molecules and only allows for positively charged ions to pass through the plastic film while blocking water and bulk solution.
very interesting your answer, i found in my home cleaner that contain benzonium chloride 0.75% do you think it have sufficient concentration for doing process like yours?
@@dogodogo5891 yea you can basically use any cleaner with these ammonia based surfactants to dechlorinate PVC but remember you need 4 molar or higher NaOH so take into account the water.
does other acid such sulphuric acid etc.. produce same effect?
Hi MB, I just found your very interesting work, it is so fantastic. I want to try it in my lab.
in this video you made 1:4 citric acid : PVA, but in your comment you said 10% citric acid, which one do you think better? 1:4 or 10% citric acid?
Thank you so much for your answer
1:4 citric to 10% PVA solution is nice and I said 10% PVA solution and that's whats in clear glues like the one in this video. Since some people start with PVA powder.
Ah thank you so much MB.. will try it and comeback to you if there is something unique in my work..
Hi MB, about the length of the oven process (150 C), is 45 mnuts is a must? Or it can be faster? I tried 45 mnts, the cloth getting burn, but it didn’t when I tried with 30 mnts, please advise..
@@achfaridwadjdi9518 even 30 mins is fine and I recommend putting a thermocouple on your membrane while it bakes to know real temperature
Hi MB, thank you so much for your advice..
1 more need your advice, the thin layer was appear, but when I washed it, those thin layer fell off. Please advise, am I rubbing the membrane too hard? Or I did it too long in water?
Please advise.. and thank you again for your advice..
This is awesome. Subscribed!. Thanks for sharing this stuff. Can this be used for H2 separation from water using KOH or NaOH?. Thanks
yes you can technically do this to seperate H2 and O2 via membrane flow cell and 2 holding tank to seperate both gasses and liquid phases of O2 and H2 respectively.
@@CatboyChemicalSociety Thank You for Your answer. Do You know which membrane I could make myself and it would poduce best result with KOH?. Trying to learn about all this stuff but it seems a bit comlicated. Thanks
@@CatboyChemicalSociety I am going to use graphite as anode and cathode but not sure which membrane would be cheap , separate gases and be officent.
@@andy86376 if you are using NaOH as electrolyte then use steel as an anode and cathode as its inert in those conditions assuming your NaOH is pure.
If not use baking soda as it soon forms NaOH anyway and is usually pure.
@@andy86376 for H2 and O2 seperation u dont rly need a selective membrane just a fiberglass cloth seperator will do.
Thank you very much indeed for the video. I was going to ask something, if you'd like. I am trying to prepare a membrane to obtain liquid caustic from salt water. Would this system be suitable for me or do I need to use different compounds? I would be incredibly grateful if you could reply. Thank you in advance, good work.
This membrane as it's shown is for that kind of work
Thank you very much. I have one more question, will you work with chlorine dioxide? Thank you from now.@@CatboyChemicalSociety
@@fescamakina I will if I ever need to dissolve iridium into solution
I am waiting for your chlorine dioxide video with curiosity. success and respect.@@CatboyChemicalSociety
@@fescamakina need to make SnCl2 first because I plan to use it to dissolve rocks containing precious metals
I would like to try and replicate this. Thank you for the video and for sharing so much information. Can you suggest any simple tests one could perform to verify if the membrane is working correctly?
@@ferriswhitehouse1476 compare conductivity with porous PVC substrate alone in a setup in brine or NaOH or Na2SO4. Set same distance and same voltage and measure and compare current. Be wary that temperature affects the ion mobility so be sure to do it in a temp controlled environment.
@@CatboyChemicalSociety Much appreciated! 🙏 So you would be expecting relatively high current in a lower pH solution, if it is working correctly?
@@ferriswhitehouse1476 yea higher current initially and lower pH on anode chamber after some time compared to ordinary porous barrier.
@@CatboyChemicalSociety Makes sense. Thanks again. How important is the concentration of the quaternary ammonium salt? I just picked up some cleaner with benzalkonium chloride but there is no information on concentration of course. I found an sds on a similar cleaner that show concentration was 0.1 - 1%. So I would need to use quite a lot of that right?
@@ferriswhitehouse1476 yea it's annoying that most are low conc but where im at now I can get 50% or pure powder of quaternary amines
Thanks for recipe. Is Microwave useful for membrane preparation? and could i prepare PVC cement by disolving PVC in dichloroethane and acetone?
yes you can and also the PVC is just a layer to make it more chemically resistant because partially dechlorinated PVC is more resistant than just crosslinked PVA.
The real ion exchange resin is the PVA crosslinked with citric acid which provides 1 free carboxylic acid which allows ions to be pulled through the polymer.
Microwave is helpful in crosslinking but ive had it burn up sometimes which is why oven is still the best. I had more luck when using aspartic/glutamic acid HCl salt at pH 1 though as the crosslinker as the microwave really worked for this one. The only issue is HCl fumes released when preparing anion resins and the microwave didnt like that.
very good video. Could this membrane be useful for zinc electrolysis? the electrolyte contains zinc and iron ions
Depends as the mobility of the ions depends on their valency and ionic radius or is it to prevent further oxidation of iron during electrowinning by using an aem on the anode
thanks for pointing this video out to me, I think I might try this
just make sure the dechlorination solution is 4 molar NaOH as the one who did the prep in this video (not me) made a mistake in measurements.
also if you want less permeability of the solution and more ion selectivity then you must paint and bake the PVA citric step 3-4 times and be sure to do washings inbetween.
@@CatboyChemicalSociety here's how mine just came out. Think I may have messed up somewhere Not tested yet
th-cam.com/video/B1ufNDBMVS4/w-d-xo.html
Am I right in that the point of the washcloth is really to be a substrate for the ion-exchange membrane which is really comprised of PVA?
If so, could one simply impregnate a fiberglass weave with PVA/citric directly?
Yes you can add the resin to fiberglass directly and bake
Thanks for sharing this video
Can these membranes be used for a small alkaline chlorine small workshop with a capacity of 500 kg of caustic soda per day?
How many cells do you think is needed for a capacity of 500 kg caustic soda per day and in what dimensions?
What is your idea about most cost-effective anodes and cathodes I can use?
( there are access to cheep power and NACL in our Region)
most membranes tolerate a max of 200ma/cm^2 you have to calculate the amount of amps required to produce the amount of product needed in the given amount of time.
Then you would have to find the surface area of membranes required to run it at that current density and current required.
@@CatboyChemicalSociety Ok. Thanks for your reply
Do you think these membranes are suitable for the production of caustic soda on a small industrial scale?
What is your idea about most cost-effective anodes and cathodes I can use?
@@mohammadmoradimajd7256 for anodes in terms of long term costs saving you really should get DSA which is industry standard and get Ir-Ru type because its more efficient for chlorine evolution.
The anodes sold also have similar current density rating to these membranes up to 250ma/cm^2. Membrane cells usually run lower current densities.
Now in terms of current for 500kg of product per day we are talking a lot of amps here which ive calculated to be 1,338 AMPS assuming 100% efficiency given that its more like 89% it would then much more than this and depending on input voltage the watts of heat that must be dealt with will be high. DSA has a high initial cost the costs of the electrodes will be quite high due to the amount required here you will need 5,352cm^2 of surface area.
I assume you plan to make 1 large membrane flow cell assembly with several compartments for this.
The maximum concentration of NaOH produced via membrane in industry is 30% since efficiency and current draw drops off after that.
if the budget concerns you then graphite runs at lower current densities and given resistances of membranes is also a reasonable choice.
These membranes can survive sulfuric acid electrolyte and I have used them in a chloro alkali cell in labscale and they survive the conditions.
For an industrial scale plant though it may not have the same results and nafion is probably the better option sinch buying it in bulk is cheaper anyway.
@@mohammadmoradimajd7256 the main issue why I recommend just getting commercial membranes is that the surface area you require for your flow cell will be large.
I doubt a simple oven will be large enough for each membrane for each cell compartiment. but if you have a large enough oven or the equipment to make large industrial flow cell sized membranes then go for it and use this recipe.
Cathodes used can be stainless steel as the alkaline conditions will protect them or nickel plated steel.
@@CatboyChemicalSociety I will start my experiments according to your instructions and let you know the results. Thank you for your guidance.
Thank you very much for sharing this video. I also had a question for you about this membrane. Can this type of membrane help us absorb heavy metals from water or effluents, and if so, thank you for your help. do
yes it can but not exactly this type but it is possible to synthesize PVA-Citrate resin then break it up to make filter media for an ion exchange bed which can be regenerated by passing HCl to leach the collected heavy metals.
is this proton, cation or anion exchange membrane
Thank you very much. Does this works for Electrodialysis?
You need both cation and anion membranes for that so you can also use aspartic acid for making the anion resin membranes and optionally treatment with a methylating agent like methyl iodide to convert the amines into quaternary amines
I followed the direction by getting a cloth then putting the PVA and citric acid combination on a cloth then baking it for a microbial fuel cell. But what happened is the holes in the cloth are still too big. The water passed right through it, so it doenst really act as a membrane. What should I do instead? What kind of cloth should I use? Do you have an amazon link?
How many coats did you do because you can do multiple coats. I used microfiber cloth from cleaning section.
using this could you create membranes that water vapour can go through but air can not? how much would you need to dehumidify a typical room.
No, those are completely different types of membranes. In order to dehumidify a room you can use several types of methods, among them chemical or physical.
For chemical dehumidifying you would use a substance which binds water and does so strongly enough that it will only release the water when heated considerably, so it wouldn't release the absorbed water prematurely. Chemicals well suited for that are calcium chloride, various sulfates such as potassium, sodium or magnesium sulfate, silica gel, and sulfuric acid, all of them can absorb quite a bit of water and binds it quite strongly, sulfuric acid can bind by far the most water for a set volume of sulfuric acid compared to the other chemicals, but it has the huge downside that it would need to be quite concentrated in order to do a good job at absorbing water and concentrated sulfuric acid is a hazardous chemical. So using one of the salts such as calcium chloride or the mentioned sulfate salts would be your best bet as they are solids so easier to handle than sulfuric acid not to mention much safer. All you need to do is dry a couples hundred gram of one of the aforementioned salts in the oven to drive off any water it will likely already contain. In order to find out at what temperature you need to dry them, check Wikipedia, it will mention for most of the salts at what temperature it will become anhydrous '(meaning free of water). For example with magnesium sulfate Wikipedia says you need to dry it at 250C, and for calcium chloride Wikipedia says you need to dry it at 260C, concidering over don't go that high you could predry it to the monohydrate in the oven as it will be able to reach the required temperature for that, and then drive off the last molecule of water by putting the salt on a steel baking tray and heating the tray from underneath with a small handheld butane gas burner.
For physical dehumidifying you need a kind of retrofitted airconditioner, except with the minor difference that unlike airco's it doesn't blow any air over it but just has a large aluminium or steel cooling plate which is cooled by the airconditioner to a fair bit below the temperature in your room and preferrably just a couple degrees above 0C. The large difference in temperature between the metal plate and your room will cause the moisture in the air to condense on the cold plate, and it will rapidly start to collect droplets of condensation which can then be collected in a container underneath it. The only action you periodically need to undertake is to empty the container full of condensate, but other than that it's very simple. However the big downside is that airconditioners use a huge amount of electricity, and the same goes for these dehumidifiers, which as I mentioned are basically just retrofitted airconditioners.
Amazing video much appreciated
Do you have a video on a membrane specifically for a pem fuel cell, as simple as possible/few steps?
This one but skip pvc and directly apply pva and citric on substrate and bake then wash.
Reapply steps 2 more times and let itdry
FOR pem membrane required for hydrogen production by electrolysis direct on clean cloth pva and citric acid is aplied no pvc and dechorination solution is required then baked the sheet
Yea you can directly bake the ionomer mixture for use in milder conditions
thanx for reply
if I am using this for a fuel cell do I need to make any other changes other than skipping the PVC cement or would I be able to use it like a Nafion or Dupont PEM membrane? also would using the PVC glue anyway make the fuel cell better for my purpose?
The pvc glue is only for chloroalkali compatibility and yea pva citrate blend is a good alternative to nafion for the case of fuel cells. Just be sure to bake many layers to improve ion selectivity.
so if i understand your method correctly the electrolysis of sodium sulfate works because the sodium ion can pass pass through the membrane, same as the hydrogen ions, but the other ions are stuck, and in the calcium sulfate salt, thanks to insolubility of gypsum the sodium sulfate is always regenerated to give more sodium which then forms calcium hydroxide and more materials for the formation of sulfuric acid, correct? but if that is the case the limiting reagent becomes the sodium sulfate which is not as cheap as gypsum
Yes but then sodium hydroxide formed at the cathode reacts with calcium sulfate in an equilibrium reaction forming sodium sulfate. Then due to voltage gradient the sulfate ions pass through and in this process the anion membranes are better which I show in a seperate video. The limiting reagent is calcium sulfate and sodium sulfate is an intermediate and sodium ions are a catalyst.
Have you done Amy calibration measurents/calculations to find out the mass transfer resistance or permeability of the membrane?
someone with better equipment was supposed to help me with that but I guess he has yet to actually mount the membranes in a working cell or test cell.
Love to see some measurements. I can offer to compare with nefon 117, which i have already.
Respect. I hope you will be interested in why I am watching this video of yours. I want to commend your work, if I understood these membranes can I in some way replace expensive nafion proton membranes?
I make water electrolyzers, so I study various ionic membranes, what is the porosity of these membranes after this operation of putting pva glue and dechlorination, what is the porosity of water, and what types of ions does this membrane leak?
the PVA citrate membranes leak both protons and cations and block anions.
ofc more layers of Citrate esterified PVA chains will increase resistance but make it more selective.
These membranes however get hydrolzed in certain strongly acidic conditions or strongly basic conditions.
The free carboxylic groups are what hold on to protons and other cations which allow them to flow through the membrane.
These membranes overall arent going to outlast nafion for the long long run in certain corrosive conditions.
But for some applications with milder conditions or for simple proof of concept testing where you only care to run it for a few hours then this will suffice.
@@CatboyChemicalSociety Hmmm, that now brings me a little bit of disappointment, I have created quite optimistic expectations. And I want you to advance in the prolanals of making membranes that can literally replace nafion membranes, and that can be made from affordable and economical materials on the market!
@@hydrogenh2energy964 well such a dream material would be nice but these membranes are mostly just for really short experiments or proofs of concepts where you are testing shit for awhile and dont wanna spend on nafion.
@@CatboyChemicalSociety Colleague, I would ask if you are able to do one test, with PVA membrane, it is in my interest to find out the time resistance of the membrane to the research concept, electrolysis of water, where the catholyte is 1 M citric acid, anolyte base, sodium hydroxide concentrations 1 M
Can a Fuel Cell Fuel Cell be made with these PVA membranes ?
Do you need to let it air dry first?
Is there a source you can give on understanding membranes like this? I was chatting with ChatGPT and it said that PVA citric acid membrane isn’t used for electrolysis because it’s not really conductive, but that cellulose acetate and cation exchange resin are used at least for chloralkali. But it seems clear that it works here for you… so is it just that you’re showing an easy to make but low performance membrane or is ChatGPT wrong?
This is a cation exchange membrane and overall chat GPT was not really very good when it came to chemistry. This is a polycarboxylate cation exchange resin made by crosslinking PVA chains together with citric acid leaving 1 free carboxylic acid to exchange ions.
There are a few papers on this topic but more on the info that chat GPT gave is that you cannot use cellulose acetate in chloro alkali proess it will quite literally get destroyed.
They use polysulfonate cation exchange resin which is usually but not aways perfluorinated to increase chemical resistance.
This membrane has a layer of PVC which is partially dechlorinated by the alkali treatment allowing it to bond to the actual ion exchange polymer blend o PVA+citric acid baked above.
This partial PVC layer gives it some chemical resistance to use it in production of acids or chloro alkali process.
Will this membrane work when applied to a battery/galvanic cell? Great video by the way
yes it will work for that pupose but a simple porous cloth will work too though that depends on the battery.
Lithium ion batteries use very selective membranes.
@@CatboyChemicalSociety i want to supress self discharge in my cell by using a cation membrane seperator to prevent ion gradient diffusion. Do you think your selective Membrane will help?
@@comfortpooe7588 yea just add more layers of PVA and Citrate bake steps till you get the results you want.
@@CatboyChemicalSociety Thank you bro
have you given any thought to sulfonating porous membranes with chlorosulfuric acid?
the issue is that highly sulfonated membranes need to be crosslinked or else they will just dissolved. The way sulfonated PS membranes are produced is they sulfonate the monomers and use divinylbenzene as a crosslinker and this forms a crosslinked polymer.
that Christie solvent glue is made in Trinidad....where was this video filmed?
Somewhere in the Carribbean and it's done thanks to reform labs
can this membrane be used in Vanadium Redox Flow battery?
Anion resin needed just replace citric acid with glutamic or aspartic acid hydrochloride salt of either.
very nice. , excellent.I want to use these membrances as AEM for electrolysis of water for G.H. Production. In addition, i want to use this manual process as the first step to commercially see if this first step is viable. then, reactor and choloromethylation and amination steps with reactors and fabricating the membranes. is it possible pl.
yes but you need to switch citric acid to aspartic acid hydrochloride or glutamic acid hydrochloride which then need to be further treated after baking step with a methylating agent such as methyl iodide to form the quaternary amine which will be the anion exchanging group.
@@CatboyChemicalSociety thank you.can this be industrialized. Where can I get the block diagram for this process pl.
@@baburamabadhran1437 well these PVA membranes are mostly for prototyping as they dont last as long as other types of more resistant ion exchange membranes.
Most anion membranes are either functionalized perfluorinated compounds on fiberglass substrate or a duropolymer comprised of aminophenol and formaldehyde also baked on a substrate like fiberglass.
There is one more involving amine functionalized styrene which is also allowed to polymerise onto some PVC.
Commercialization of the process is something I could think of with some work like if I were to make a very basic scale up proceedure for a block diagram I would break it into these parts.
1. Large rolls of fiberglass substrate is prepered on a long conveyor.
2. prepolymer blend is coated on prepared substrate.
3. prepolymer is baked in a continuos feed oven or whatever other conditions are required (inert atmosphere) etc.
4. baked polymer would be washed to remove unreacted prepolymer using sprayers.
5. prepared ionomer is cut into shape.
6. further treatment if required (anion resin).
steps 5 and 6 can be interchanged depending on convinience.
@@CatboyChemicalSociety I saw this sentences in google. But how the product of these reactions be???
"A homogeneous anion-exchange membrane can be obtained by introducing a quaternary amine group into polystyrene by a chloromethylation procedure followed by an amination with a tertiary amine"
In addition we speak about Green Hydrogen bur Fibre glass reinforced is not recyclable and has poor Sustainability index.can there be an alternate for it pl.
@@baburamabadhran1437 thing with more recyclable membranes is that they do not lasts as long. I am sure there is an alternative but I am only telling you what is industry standard and it is your job to find the alternative.
Also you have to decide whether you want longevity or recyclability and overall you must do the cost analysis and environmental impact analysis yourself.
The reaction to make anion membranes is something you can understand by looking at the reaction mechanism as its really just methylation of an amine.
If you actually want full assistance to your researchwork I can provide it but I am going to need some compensation if you really want me to hold your hand all the way.
Brilliant idea
I followed your directions and tried to make ur PEM for a microbial fuel cell. Since, u said that if we are making a fuel cell, we can skip the first two steps (applying PVC cement and the dechlorination solution), we directly applied the glue and citric acid to our cloth. But once we baked it, it got burnt and it doesn't have the shiny layer. It also stuck to the foil and was very hard to remove (broke some of the times)
So I was wondering what went wrong? What type of cloth did you use and does it matter? We don't have a thermocouple probe so we didn't can't use that, so is there any problem with a burnt PEM? Does it impact the function? Also how do we know that we did this right and the PEM actually works before using it in the fuel cell?
Temp control wasn't adequate because these ovens tend to do something called 30 seconds on and some seconds off so the elements maybe at higher temp so preheat your oven. Also gas oven doesn't work
Removal from foil is easy just dissolve the foil in NaOH if its stuck which is why foil is used. If its medium brown its ok but black means too burnt. Fiberglass mesh substrate is best. Theres going to be a new membrane video involving fusing deionizer resin just tested it works well.
@@CatboyChemicalSociety Thanks for the response! I don't have an electric oven, is there any alternative? Also, I saw in some comments you said tissue paper, so should I use that or the fiberglass mesh? Would I repeat the steps multiple times? My membranes all turned brown so ig that's good. Also, would the holes in fiberglass mesh be completely fine?
@@srimayikukkadapu2425 yea multiple coats work but yea I suggest getting an electric oven even a small toaster because gas ovens rly don't work for this. Maybe you can also bake the membrane in a hotplate between foil
Thanks for the response! Thankfully, I was able to borrow someone's electric oven! Just to clarify, would tissue paper or fiberglass mesh be best to use? Would the holes in fiberglass mesh be completely fine? Also, I realized the citric acid I got wasn't pure, it has less than 2% silicon dioxide. Is that fine or does it need to be pure? I also estimated the measurements when mixing the PVA and citric acid together. Would that be too problematic? Do I need precise measurements?
If you had a large enough oven, you'd think it would be possible to make large sheets of this stuff, to then cut to size when needed?
yes
Can we use this membrane in microbial fuel cell (microbial electrolysis cell) as the replacement of nafion 117 proton exchange membrane?
Yes since it's mild conditions and also skip PVC part and directly bake PVA and citric on substrate
@@CatboyChemicalSociety Alright thank you 🌠
Supposing I want to do this to fit into a tubular stainless steel container to replace asbestos in Nelson Chloro alkali cell, how do I do it? And secondly will it work efficiently?
First ensured to roll the cloth in a tube before coating it then this maybe possible to do. Cation exchange resin is always more efficient than porous barriers. If you add the PVA-Citrate layer above the PVC resin then it could be nice. We have one issue though and that is that it was rolled into a tube before curing which makes it very hard to cure it evenly in an oven. I would get some sort of forced convection cooker/kiln to cure the rolled up membrane.
If the membrane can be made flat and segmented into 2 or 3 sections then this will be better than curing a rolled up membrane which will be challenging.
If the membrane is just dechlorinated PVC then it will still perform well but only comparable if not worse than asbestos.
If the membrane is only PVA-Citrate then it will perform the best but I have no idea about its longevity in strongly alkaline and strongly chlorinated solutions for long periods of time compared to the mixed layers where the PVC layer will naturally be ok in the anode chamber and the PVA layer will be fine in the cathode chamber.
Excellent thank you
What do you think of using a paper towel rather than a washing cloth as the substrate to first coat with PVC glue?
it can work too since the PVC does most of the job anyway holding up.
Nafion membrane from China top quality cost 500$ m2, I know very well the factory.
Also I will test PFSA resin that is the raw material to make Nafion membrane.
you would have to find a way to melt/fuse it and roll it into thin sheets or laminate some fiberglass sheets with it.
I reckon under inert atmosphere knowing how fluorinated stuff behaves when heated in the presence of oxygen.
Hello, I'm making a double chamber Microbial Electrolysis Cell. I want to know if i should skip the first two steps or i should do the whole thing
skip the PVC step
@@CatboyChemicalSociety Just to be clear, is the Dichlorination step necessary as well.
@@gilbertquarshie3932 its not since you really only need the ionomer for milder conditions.
all you need to do is bake PVA and citric on a substrate like fiberglass or cloth.
@@CatboyChemicalSociety Yes Please. Can Acetic Acid be used in place of citric acid. I want to create a cation exchange membrane?
@@CatboyChemicalSociety How do I apply multiple layers of the PVA-Citric acid blend? (Im asking cause I realized some people run into a problem where the membrane was porous)
Do I apply the on the substrate, bake and repeat process or I apply on the substrate wait for sometime and apply again then bake the whole thing
Very interesting!
Can I use this membrane to make KOH from KCL solution?
Im having a hard time finding KOH in my country and it's quite expensive (60 dollars a kilo).
It seems that is controlled by the federal police, Im not sure why, maybe people are making drugs or explosives with it, lol... I just need KOH for making liquid soap to be used as wetting agent for organic pesticide application, but at USD60.00 a kilo the whole endeavor becomes pointless.
Which cathode and anode materials that are relatively cheap and easy to obtain can be
used to make around 3kg of KOH? (that's the amount I need for a batch of 100L liquid soap/detergent using the korean JADAM natural farming)
Sorry for the basic questions, Im just getting started on this.
Looks like I still have a long way to go...
Thank you!
@oddjobbob
Thanks, I'll keep looking.
The only thing I could find so far is 98 or 99% pure KOH used for hydrogen fuel cells. Quite expensive though... around USD 30/lb
@@virusmyth4930 you can use this for making KOH but you have to seperate excess KCl from the cathode side.
@@CatboyChemicalSociety Thank you for your response. In your opinion or experience how much purity can one achieve making KOH with this method? I need 90% KOH for my purposes, do you think it's feasible using this method and materials?
@@virusmyth4930 30% KOH solution is usually what you can produce before the membranes get fked.
seperation of that with KCl must be done.
90% KOH solution is not feasible with membranes as the current is gonna drop and the membranes will be damaged no matter how good they are.
downstream steps are usually employed to seperate out chlorides with hydroxides which you must do.
@@CatboyChemicalSociety I meant 90% purity after evaporation, not solution. Thanks.
Is the pvc cement important? can you use pva for the whole cloth?
Pvc cement is only for chloro alkali process compatibility and for other milder conditions or fuel cells then you don't need precoat and can use pva citric to form crosslinked cation membrane
Are these cotton cloths or leather or synthetic?
they are made of cotton but some are other stuff
love this channel
Can I get only positive hydrogen ion from these membranes if I pass hydrogen through membrane filter? Or just the membrane by itself won't do it?
These are proton exchange membranes for H+ ions but if you want to diffuse H2 use an RO membrane they work for that
but yes they can selectively pass H+ ions through and infact polycarboxylate are more selective towards protons than polysulfonates.
This is fantastic as Nafion is still extremely cost prohibitive for hobbyists.
Yea it's still not as cheap as it should be
Can this membrane also be used for other solvents like alcohol, acetic acid and ethyl acetate?
the porous PVC layer will be fine for sure but for the PVA-Citrate ion exchange resin layer I am not sure. I have not tested that out.
got a link to the original research paper? also, how would i go about making a membrane that is meant for anion exchange as opposed to cation exchange?
change citric into glutamic/aspartic acid HCl salt. I have a video on that too. also just search this on google for the paper "ion exchange resin made from polyvinyl alcohol and citric acid" and you get a research article as your 1st result talking about this polymer. I simply put it on a substrate.
@@CatboyChemicalSociety thanks! i didnt think there was much of a chance that you would reply, but you also replied real quick! time to go down the google rabbit hole lol. also, do you think this type of membrane would be able to handle turning concentrated potassium nitrate into potassium hydroxide and nitric acid?
@@josephgauthier5018 nitric acid is finnicky because it oxidizes at the anode to nitrogen and reduces at the cathode to nitrite and ammonia.
@@CatboyChemicalSociety does that come down to electrode material selection?
@@josephgauthier5018 well the issue is also concentration not just electrode
Will using a pvc coated paper work for a bleach/ sodium hydroxide brine set up ?
it should work yes but I can imagine its a little fragile.
9:50 This is backwards I think. White school glue has polyvinyl acetate with polyvinyl alcohol colloid to protect it, which is why it’s not reactive. You want the clear because it is only polyvinyl acetate, and for the resin it is carboxyl groups you want, which the acetate provides, as well as the citric acid.
but polyvinyl alcohol is hydrophillic due to several OH groups and results in a clear solution with water while acetate groups make it less hydrophillic which is why white glue is white containing polyvinyl acetate colloid.
esters are more hydrophobic than alcohols so I think you have it backwards as an example the molecule ethyl acetate is insoluble in water while ethyl alcohol is.
Good point… also thanks for being so interactive. What’s the use of the hydrophilicity though? It’s not water you’re trying to pass through the membrane, and I don’t think polyvinyl acetate is exactly hydrophobic. Thing is, PVA is used to refer to both acetate and alcohol which is really confusing. Am I wrong about the carboxyl groups being the means of cation transfer?
@@1495978707 once the esterification occurs then it becomes hydrophobic and does not let the solution pass ideally but it has one free carboxylic acid which allows for transfer of cations.
the esterified bits cannot transfer ions because they no longer have that charge or a proton to exchange with a cation.
thank you
Can i know whether a normal pure cotton cloth will be enough?
if its cleaning cloth yes and if its made of cotton its fine as long as its a sheet that is porous and can be coated in PVC glue.
IF you mean cotton balls then it will have an issue of very low permeability when you apply PVC glue but it can be applied with PVA + Citric acid and baked as that layer is the better ion exchange layer and will have the ion exchange groups distributed throughout the polymer.
Why do you dechlorinate the PVC? What is the point of the PVC anyway if the goal is to have citric acid crosslink pva to have sites for ion transfer? What is the point of the quaternary ammonium salt?
the PVC increases chemical resistance and while you can simply use pure PVA. when you have partially dechlorinated PVC then you also get crosslinking of PVA chains to the PVC chains due to one of the products of dechlorination is alcohol group instead of chlorine the other is a double bond.
The quaternary ammonium salt was from that 1 paper talking about aqueous dechlorination of PVC films at made by dissolving PVC in THF which basically is PVC glue and quaternary ammonium compounds act as a phase transfer catalyst allowing the strong NaOH to attack the PVC films.
a purely PVA and Citric membrane actually is more conductive but against really strong solutions it is simply gonna dissolve while if you have a PVC film you can have resistance against hydrolysis of the crosslinked PVA in strong acid solutions.
My previous reply seems to have disappeared, or maybe it’s under review? I was just asking more questions. Anyhow, apparently ion exchange resins that use carboxylic acid groups are called “Weak Acid Cation Exchange Resins”. Is the citric acid just to help the PVA crosslink?
Oh I think maybe it’s because I included a doi link… Well since I can’t edit the comment to remove that, how is the PVC conductive at all to cations? Also, how does the PVC help resist hydrolysis, when it is behind the PVA, not covering it? Sorry about all the questions, but can you recommend a book that I could learn about this from?
@@1495978707 PVC is non conductive neither is PVA but partially dechlorinated PVA has some OH groups attached to it which allows for inter esterification between PVA and (dechlorinated) PVC chains creating a good chlorinated resin backbone which resists chemical attack while containing some ester linkages.
I have the paper that describes the dechlorination process and it is titled.
"Dehydrochlorination of Poly(viny1 Chloride) by
Aqueous Sodium Hydroxide Solution under Two-Phase
Conditions" by hideo KISE 1982
Join the Catboy Chemical Society discord for more interactive questions and answers link is in one of my community posts.
Can these membranes be used for microbial desalination cells please?
these are cation exchange membranes and if the process needs those types of membranes then it can be used.
Anion exchange membranes can be made from substituting out citric acid for aspartic acid and optional post treatment with Methyl Iodide.
They arent really nano/ultrafiltration membranes if that is what you are looking for.
Is this pvc cement like plumbers glue? can I use CPVC glue?
Another commenter said to use "PVC Cement" and PVC-C (which I assumed is CPVC)
th-cam.com/video/tiMt4tIced8/w-d-xo.html&lc=Ugxb72KxkJEmJH1plIV4AaABAg
Will u show pbo2 anode prepatation by electrolysis of pb in h2so4?
thats not a good PbO2 anode as the anode produced is porous and unsuitable for perchlorates.
the plating solution requires membrane electrolysis of either sodium nitrate or chlorate with lead electrodes to make lead nitrate/chlorate then using that on a titanium mesh with undercoat to make an electrode.
Most excellent!
Do ion exchange membrane is also different from fuel cell?
Fuel cells use membrane electrodes but overall they both use ion exchange resins
does this membrane allow fluid to pass through it or just ions
if consutructed right in ideal conditions or many layers of esterified PVA then it should only allow ions but if you add fewer layers then it will be a bit more porous to the solution.
hi , is that membrane same as the Anion exchange membrane ?
Cation exchange
Hi. Mysteriousbhoice
I want to make a hydrogen separator electrolyzer using koh as a electrolyte.
Can I use this membrane and second option a porous PVC membrane for this purpose.to achieve pure hydrogen and oxygen through electrolysis.
How long these two membrane will work or degrade in koh solution?
Kindly reply I want to build hydrogen generator
in KOH they last a long time basically months. It is only in NaCl and a few others like HClO4 that they degrade over time.
@@CatboyChemicalSociety is there any way so that these membrane can last for 3 to 4 years
I want to run electrolyzer for a long time.
What about with sulfuric acid as a electrolyte does membrane works long with this or not
Need your suggestion plz
@@hamidamjad7521 the PVC membranes are more likely to last long but the PVA-Citrate ester ones are less likely but are more selective in the short term.
The membranes shown in this vid is a mix of both types layered above eachother but overall in general PVC membranes last longer and can handle up to 30% wt alkali fairly well.
If you just want porous membranes just do the PVC and dechlorination step and leave it at that but if you want selective ion exchange then add the layer of PVA Citrate ester ion exchange resin.
I have not done any long long term testing of these membranes but I can say in sulfuric acid the PVC holds up very and its actually me using polystyrene as the frames that failed and not the membrane after using it for 5 months the membrane was still good albeit white due to magnesium fouling but that is solved with simple HCl soaking.
know anything about making formaldehyde from electrolysizing a methanol solution?
I checked it just now and the yield is 30% due to the other reaction producing CO2 instead. The catalyst is also 0.4M HClO4. yea u need Ir-Ta MMO electrodes or this wont fly.
Is it possible to generate chlorates using one of these membranes?
no this would actually produce chlorine and NaOH instead