Scrap Science - 2018-11-04
Electrochemically splitting magnesium sulfate into sulfuric acid and magnesium hydroxide using an electrolytic diaphragm cell. This is similar to a previous video I made where I made sulfuric acid from copper sulfate, though using a sulfate salt where the cation has a higher reduction potential than hydrogen makes the process a bit more difficult. Based on the fact that epsom salt is around $10/kg for me (AUD), theoretically the H2SO4 generated by this method would cost about $22.50/litre (if it were concentrated to 98%), much cheaper than most sulfuric acid sources. Link to the sulfuric acid from coppper sulfate video: https://www.youtube.com/watch?v=ZRYtAquxffE Link to the video of my method of making gelatin salt bridges: https://www.youtube.com/watch?v=-ObVHRa9WBc Link to the video where I made the power supply: https://www.youtube.com/watch?v=ygvbdwl-0bM Link to the video making the carbon electrodes: https://www.youtube.com/watch?v=KKCksH5m7s4 Link to the video about the DIY vacuum filter: https://www.youtube.com/watch?v=D4sqNA4s1cs
The water leaves the clay pot over time due to osmosis. You have a concentrated salt solution outside the pot and water will diffuse from a low concentration solution into the higher concentration solution over time.
Does the electrical charge contribute?
Man, i can't even remember how hard i looked for a way to make electrolylis processesses like this one viable, and the membrane part aways failed miserably, or wasn't ideal on my attempts... A flower pot as a diaphragm? That's straight up genius! I hope you get the appreciation you deserve, keep up with your quality content!
Great video! Something that's ACTUALLY done by a home experimenter! There's too many "safety" guys in the world and this is very refreshing!
?
@Yasyas Marangoz Duh?
@Donald Hoot What are "safety guys"?
i completely agree
Great video mate!
I have one question though: How do I concentrate this sulphuric acid? Can I just boil the water out of it?
Yep, boiling the water out will do the trick. It will be quite tricky to make >90% concentrated stuff, as you'd need temperatures of around 300C, but it should work to make 50% or higher. Be wary though, boiling acid is not something to treat lightly, make sure you use proper high quality glassware.
Boiling acid is definitely an outdoor pastime unless you have a commercial fume hood. The fumes produced can be corrosive in your lungs.
nice. give me some time to REALLY thank you...in the name of all the movements of 2000 and again :O)
magnesium sulfate is probably better than using calcium sulfate
I made a similar video using calcium sulfate and sodium hydroxide/sodium sulfate on the cathode side and had issues with the reaction being uneven and slow.
The reason why this process isnt done often in industry would be because of cost, maintenance and low efficiency.
but in a home experiment scale its really convinient if you cant get your hands on sulfuric acid.
However one thing to note is that as the concentration of your acid goes up it will eventually require more current flowing through the cell to keep the 2 products from reacting via the porous pot.
This can be solved by using a membrane but well you know those aint cheap and membrane fouling can occur due to the precipitation of magnesium hydroixide.
The best way is to run it for a certain time and concentrate the acid to precipitate any remaining salts in the anode compartment and feed it back for another run.
using alkaline sulfates are much more efficient than alkali sulfates because you do not get the formation of partially neutralized salts which can ruin efficiency.
NaHSO4 is a pain!!!
This is about as far as I went with that project but more cane be done such as the best time to swap the anolyte
Hi . Someone out there who knows how to make Sodium Chlorite NaClO2 effectively. THANKS.
I really love the video like this, when you can make much great esperiment with nothing of difficult to found
For a source of Carbon rods, they can easily be obtained by opening up Zinc Chloride Batteries. You can get a pack of them from the dollar store. They have chunky long rods, meaning they are fairly durable. Look up on YouTube a video of the disassembly, NileRed has a good video.
Avoid lead anodes because they will contaminate your sulphuric acid making it toxic, limiting what you can use it for and making disposing of it an environmental problem.
Pencil lead. Crack the pencil open with a knife.
Bailey Moody pencil "lead" hasn't been made from Pb metal in my lifetime - it is actually graphite in a clay binder. It will work for the reaction, but you would want a lot of them to increase the surface area and speed up the production.
@Kevin Bauer if you did not understand what i meant when i said "pencil lead" then i feel sorry for you
I just got some Epsom salt to revive my battery bank and I didn't knew what to do with it. Now I know! Thanks a lot! Exactly what I was looking for! Like number 300.
This is the kind of content we all need
For cleaning Mg(OH)2 just submerge the electrode in vinegar and it will dissolve.
Thanks for your comment.
I guess it will neutralize the alkalinity.
I had considered washing with acetone or burning / heating with connection to battery terminals and even boiling in hot water.
Will give it a try.
Just wondering: Can a dishwashing sponge act as a membrane for most of electrolysis processes?
It can definitely be used as a membrane, as anything porous will do the job. I’m not sure how well they would hold up to sulfuric acid though, if that’s what you’re planning on using it for.
What concentration did you get in the video do you think?
I forgot to mention in my comment below that my total volume of acid yield after filtering was around 200mL.
do u have a video of making the magnetic stirrer
I am very glad that this video is available and not censored/buried. Thank you for showing this process in a way that is accessible to us DIY science experimentors. Kudos to you! i will gladly be sharing your channel with others i know, that share the same interests.
You need more subs
You are great !
Is there a way to optimize this setup for magnesium hydroxide creation in higher quantities?
The easiest way of making magnesium hydroxide is to just mix a solution of magnesium sulfate with a solution of sodium hydroxide, as it'll precipitate the insoluble magnesium hydroxide which can be filtered out.
If you specifically want to use this type of setup however, the best way to go about it is to use pretty much the exact same method, but add the initial magnesium sulfate to the anode chamber rather than the cathode chamber. This will make sure that the magnesium hydroxide you generate (in the cathode chamber) is relatively pure.
yes... been looking for something like this.... however, wished you could show the one with gypsum
Great video,thanks for the help
Hydrogen peroxide will oxidize and remove the the unfiltered carbon sludge.
I actually don't know why you should do this - except for exploring the science behind. Sulfuric acid in comparable quality as you make it here is dirt cheap.
You could be electrolyzing the water away. We know.some.of it is going to make the magnesium hydroxide (MgOH) and some to make the sulphuric acid (H2SO4), but it shouldn't react that quickly.
Water will electrolyze at around 2 volts, and you are usimg high amperage 15v power.
Or you could be pumping water with the voltage difference and a membrane in the middle, or it could be osmosis.
Not sure which it is. Could be all three.
I did a quick search of the comments and didn't se "osmosis", so I'm chiming in: There may be considerable osmotic pressure pushing the water from the anolyte to the catholyte... You could check this theory by seeing if the total volume of the water is remaining roughly constant (minus the H2 and O2 generated) that would imply that the water is migrating from one side of the clay pot to the other, not vanishing or becoming something else.
Or just let both solutions sit for a while without electrolysis.
I wonder if its osmosis that made water lower
how did you seal the bottom of the clay pot? The ones that I've found have a tiny hole in bottom from the manufacturer.
Just plugging the bottom with some silicone sealant seems to work well.
Nice video :) Since it sounds like you're based in Australia, here is a breakdown that shows why using Ammonium Sulfate could be much cheaper:
Target
---------
Name: Sulfate
Formula: SO4
Molar mass: 96 g / mol
Manutec Epson Salt (Bunnings)
------------------------------------------------
Contents: Magnesium Sulfate Heptahydrate
Formula: MgSO4.7H20
Molar mass: 246 g / mol
% mass of SO4: 39%
Mass of SO4 / kg: 390 g
Cost of Manutec Epson Salt: $6.48 / kg
Cost of SO4: $6.48 / 390 g or 1.66c / g
Richgro Sulfate of Ammonia (Bunnings)
------------------------------------------------------------
Contents: Ammonium Sulfate
Formula: (NH4)2SO4
Molar mass: 132 g / mol
% mass of SO4: 73% (neglecting 1% impurities according to the MSDS)
Mass of SO4 / kg: 730 g
Cost of Richgro Sulfate of Ammonia: $10.58 / 5 kg or $2.12 / kg
Cost of SO4: $2.12 / 730 g or 0.290c / g
Cost Comparison
---------------------------
Manutec Epson Salt : Richgro Ammonium Sulfate = 1.66: 0.290 = 5.72
Savings over 10 bags of Manutec Epson Salt: $64.80 vs $11.32
Using Manutec Epson Salt costs 5.72 times as much as using Richgro Ammonium Sulfate when using these products as a source of sulfate ions. The mass of Manutec Epson Salt is overloaded due to the heptahydrate and the relatively high atomic mass of magnesium.
The reaction is a another thing to consider as there are a few things to take care of, but that's something that could be explored another time. This was more of a look at the cost of things and was a fun little exercise for me to tackle as I've spent the past 5 weeks rehashing high school chemistry from over 26 years ago. Since I'm only a chemy-baby, there could be some errors, but I think it checks out OK.
I hope this saves you some money since anyone who's into recycling is doing this beautiful planet and our future generations a huge favor.
As a matter of fact, I've also got a video about doing just that:
https://youtu.be/b2wTha6Z-fA
Ammonium sulfate is certainly a cheaper option when it comes to making H2SO4, and I think it might even give higher yields for the same current
Salt gradient difference
I'll use it when the mutans are invaded the world.
Wait, Epsom salts cost you 10$AUD/kg?
That's very expensive. I can get myself an 11kg bag for 4,70$CA/kg.
Also, what kind of separator do you think I should be using?
I currently have polyethylene separators from a lithium ion cell I salvaged a while back.
@Scrap Science So, I've managed to make 56% sulfuric acid via the constant current method, but it got so slow after 48% concentration.
So yeah, it's successful for making very large, and inexpensive batches of dilute sulfuric acid.
Would you like for me to ship you 2 sheets of the stuff? 10$ including shipping.
Great stuff, a 56% concentration is pretty useful. I think we might just hold off on shipping for while though, and I'll see if I can find an online seller and buy a bunch of them.
Hope your copper/nickel electroplating goes well
@Scrap Science Here's the link to the company from which I got it from:
https://www.alibaba.com/product-detail/AGM-battery-separator-combined-with-fiberglass_60763518908.html
I'm also planning to get 50-100 myself, since they work so well as acid filters(except for nitric acid), and filters in general, and galvanic cells in general.
It's kind of expensive to buy only in packs of 10. But more? It becomes a nice bargain.
@Scrap Science Thanks a lot.
You can also make sodium hydroxyde this way too, which is very nice.
But you need a different type of filter again.
@Scrap Science Also, RTV silicone works way better than hot glue.
.....I get my sulphuric acid by recharging dead sulphated lead acid batteries carefully at very high pulsing voltage and low current level governed by capacitor. Trouble is that the batteries often come good again not always good enough to start a car but okay to add to the solar storage. But if they ain't good enough then I'm happy with the acid for purpose of making copper sulphate with from copper scraps semi submersed in acid and put bucket with lid on top but slightly open away for one year for the copper sulphate to form slowly and collect the crystals after a year or more.
Could you use 2 jars and a salt Bridge of tissue paper/cotton in tube?
You certainly could. Keep in mind though that the resistance of the cell will be much higher, so the current you’ll be able to put through it will be lower, and the whole process will take a lot longer.
I posted this comment on another video - but here goes. The most likely cause of the migration of water is osmosis. Water molecules move from high concentration of water (the clay pot) to lower concentration - the salt solution. Confirmed by increase of volume in the cathode chamber as the magnesium sulphate solution is diluted. The large difference in volume of the two chambers means the volume increase of the magnesium solution is less obvious in this video.
@Duki Kuki exactly, but the original comment said otherwise
elyes grati per Wikipedia, "Osmosis is the spontaneous net movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides." It is about movement from the "pure" water in the pot to the concentrated MgSO4 solution in the outer chamber, and is independent of the electrolysis.
@elyes grati Please read my original contribution slowly and carefully! "Water molecules move from high concentration of water (the clay pot) to lower concentration - the salt solution."
@Dale Smith and that's wrong, water moves from low concentration to high concentration, not the opposite
@elyes grati I was writing about the water. What you mean is that water moves from low SALT concentration to high SALT. Water is the solute, magnesium salt is the solute (the minor component in a solution, dissolved in the solvent.) Osmosis is the movement of water through a semi-permeable membrane from a region of high concentration to a region of low concentration, tending to equalise the concentrations of the water. Osmosis is passive transport, meaning it does not require energy to be applied.
I think the water was pulled out of the pot through osmotic pressure because there was a higher concentration of salt on the outside
He deserve 1 million subcribers.Good luck buddy :)
Hi Mate, just found your channel. Its awesome. Explanation drawings are really good, and i like the fact you just use stuff from around the house. Love the stir bar 🤣🤣🤣 Can Magnesium metal be made from Epsom salts ? 🤔 And can Nitrates be made at home ? Just starting out with this interest as you may realise... Thanks.
Thanks very much.
As for your questions, I've tried many methods of making nitrates, but none have really worked very well so far, I'll make a video if I find a good one.
Making magnesium metal is something I've always wanted to try, electrolysis of molten magnesium chloride seems to be the most common method. I'll definitely get around to it one day.
@Scrap Science Thanks for replying... I live in Aussie also, such a pain getting anything here, i was going to order online, but wasnt sure if i would have success, by the way im trying to suck out nitric acid from miracle grow as i have no nitrates. My main objective is to deplate silver and make silver crystals and do stuff to gold when i eventually find some. Just made the sluice now putting the forge together.
Scrap Science I tried to use molten salt electrolysis to extract sodium when I was a kid, but could not get my mother's pan up to 800C on the kitchen stove. Step 2 would have been finding suitable electrodes, and Step 3 would have been not breathing chlorine gas. I think you might be able to do it with an Na/MgCl thermite reaction under Argon, but that kind of craziness seems suited for another channel.
8:41 As you said the Ph is 1 or lower then why don’t you stop the electrolysis
Just because the pH is 1 or lower doesn't actually indicate a particularly high concentration of acid. Despite being the end of the standard pH scale, a pH of 1 is only created by a 0.1M solution of H2SO4, meaning that there is a great deal more concentrating that can be done even past this point, even if it isn't indicated by pH measurement.
with 12V and 2 Amps is the time taken the same as your (salt bridge - Clay pot) (6 hrs)
Would stainless steel work in place of clay pot?
No, the separator between the two half-cells needs to be a non-conductive, porous diaphragm in order to block the passage of electrons, and allow the passage of ions. A porous clay pot, a fine fibreglass net, or even a piece of fabric (provided it'll withstand H2SO4) can be used as a separator, but any metal will split the construction into two separate electrolytic cells without the ability to make any acid.
I just performed this experiment and so far it's been successful, generating sulfuric acid without too much contamination unlike with a lot of other methods. However, in the cathode chamber, there's a stinky yellow precipitate forming along with white Mg(OH)2 forming. If anybody know what that is, I'd love to know!
Possibly elemental sulfur, although I've never heard of a sulphate electrolysis being able to reduce to the sulphate to sulfur - the electropotentials are just way too high and the water reduces instead...Maybe you have an unusual catalyst in there that's doing something? Or some other contaminant, possibly from the pot itself?
to get 24 supply you shoud use the blue wire as negative and the yellow wire as poseitive in the atx with out another 12 v supply
I gave this a go the last few days. I dissolved some 10 large spoons of copper sulfate in about 600ml of warm water. It was quite a vivid blue. I used a plastic container. I could not find a unglazed clay pot so I got a glazed ceramic 20cm diameter pink pot from Bunnings (only type they had with no hole). On two opposite sides I sand papered off the glazing both inside and outside. I put the pot in the plastic container with the copper sulfate and added about 2cm of demineralized water. It was more or less the same level inside the pot as in the plastic container. For the cathode I used copper pipe and for the anode 4 graphite rods tied together.
Initially I supplied 30V and the current went from 10mA steadily up at a decent rate. I then set the power supply current limit to 1 amp and let it ran for 1 amp for 5 hours or so. There was bubbling from the anode and a bit of copper around the cathode. I then increased the current to 2 amp and it ran for another 10 hour or so. I had to add water to the pot from time to time, and the pot liquid got warm. After the 10 hours at 2 amps (maybe it was longer as this happened over a few days) the copper sulphate was quite clear with only a hint of blue. There was lots of metallic copper visible and I also saw the outside of the pot was generating small bubbles, which did not happen early on. I then decided to stop.
After I filtered off the carbon particles from the solution in the pot I was surprised to see it was pale green. Where could this have come from? Contaminents or from the ceramic pot coloring?
The 'acid' from the pot reacts energetically with sodium carbonate. The leftover copper sulfate solution also had a reaction for sodium carbonate showing it became acidic but must less energetic than the acid.
I weighed the acid and a 100mL was 121gram. As far as I can gather this means my acid is at 30% concentration which is better than I thought I would reach.
Any comments will be appreciated.
Seeing as your starting material was copper sulfate, there's actually a much simpler and less complex way to turn it into sulfuric acid. For CuSO4 specifically, you can actually complete the synthesis without a membrane (or clay pot). Just electrolysing a solution of copper sulfate with a carbon anode and copper cathode works in a very similar way. Just keep electrolysing until the solution is clear (you may need to filter the carbon particles to check this) and you'll have converted almost 100% of the CuSO4 to H2SO4.
As for the green colouring, it could be one of three things. Contaminants from the pot I'd see as the most likely cause. Though it could be contaminants from the graphite electrodes you use or even the colour of the microscopic graphite particles coming off the electrodes. I don't think it'd be the contaminants of the copper sulfate (provided you got it from bunnings) as I've used the same stuff and had no problems with purity.
The fact that your cathode chamber was acidic too is also to be expected, as the clay pots aren't perfect at holding the solutions apart, and some acid may have leaked out.
A concentration of 30% is quite an achievement for this method, I wouldn't have expected that kind of efficiency, well done!
Can We Use Similar Method To Preduce H2co3 ??? By Na2co3 ?
While it would work theoretically, H2CO3 is an unstable compound which quickly splits into CO2 gas and H2O. So no, it won't end up working to any reasonable extent.
Scrap Science Thanks
just to clarify, did you omly put water in the anode chamber?
Yep, only thing in the anode chamber is water
You said that a titanium anode would work?
I'm afraid not, the titanium I referred to was actually a 'platinum on titanium' anode, which is pretty much just titanium coated in a thin layer of platinum. A titanium anode won't work by itself because it will quickly passivate to form a layer of titanium dioxide on the surface, stopping current flow.
The only anodes which I know to work for this process are:
- Platinum (or, as said above, platinum on titanium)
- Lead (which I would seriously avoid due to the toxicity)
- Carbon/Graphite (which I would recommend because it is cheap and easy to use)
(It's possible that gold would work too, but I don't imagine many people have a gold electrode)
@Scrap Science thanks!
@Scrap Science your videos are awesome btw. Having literally just discovered them, know they are appreciated by a true chemist who is so used to doing things in a clean lab. Seeing this stuff is so cool! Keep it up :)
Couldn’t you keep the carbon slough and just run a shielded contact wire to it, kinda like a mercury bed? I’d imagine there’d be enormous surface area.
This would work, but there are a couple of reasons which stop it from working very well.
First, the carbon particles don't make very good electrical contact, especially when gas bubbles are constantly generated between them, so the resistance of this kind of setup would be very high, limiting reaction rate.
Second, any wire you use to connect it up will inevitably corrode (even if it is shielded, you still need an exposed surface for electrical contact).
The best way I see of doing this is to just insert a graphite rod into the powder, but either way, the rate of the reaction seems to be influenced much more by the resistance of the diaphragm rather than electrode surface area
Would potassium sulfate be an acceptable substitute for epsom salt?
I am using a fertilizer which is filled with a ton of nitrogen compounds and a very small amount of potassium/ammonium sulfate.Will the contamination of all the nitrogen be a detriment to sulfuric acid production
I’m afraid your sulfuric acid will be heavily contaminated if you use an impure salt. This method actually just generates an acid which corresponds to the anion of the salt you have.
So if your fertiliser is mostly nitrates, this will end up generating mostly nitric acid rather than sulfuric.
On that note, be wary if your fertiliser contains chlorides, which won’t form hydrochloric acid like expected, but will instead make chlorine gas, which isn’t nice to handle.
@Scrap Science I am doing this all outside and everything is well ventilated and I am probably making nitric acid so I have stopped the operation till I get some better quality salts. Also, do you know if sulfuric acid etches steel?
I don’t really know if it’d etch steel, it probably would. Might be worth heating up the acid a bit first because I’d imagine the reaction at room temperature would be quite slow.
@Scrap ScienceOk thank you for the information
Would titanium as anode work here?
Not without a coating of platinum metal. Under these conditions, pure titanium metal will passivate and possibly break down when used as the anode.
The only materials which can work as an anode here are graphite, platinum (or platinum plated electrodes), or lead dioxide (which can only be used if the magnesium sulfate reactant is lab grade).
@Scrap Science Thanks for rely. Well that's a shame, titanium anodes are so cheap. Is there a way to make cheep platinum coated anodes? Would gold coated anode work? Maybe that's another future project for you :)
My H2SO4 is not reacting with Al but the Ph is 1 . Is my sulfuric acid waste ?
Don't expect a reaction if you're using aluminium foil, the oxide layer and plastics contained in the foil make it pretty resistant to sulfuric acid, even my 2M H2SO4 didn't do anything to it. Maybe try reacting it with zinc or some other metal to test it
But my NaOH reacted with Al to form NaAlO2
The foil will react with NaOH easily, but not with acids
oh,will H2SO4 react with iron nails
Probably not I’m afraid, the reaction with iron is pretty slow
Noq - 2019-11-09
This is the kind of content that YouTube needs more of. Informative, to the point, accurate. I've always thought sulfuric acid could be synthesized by the electrolysis of magnesium sulphate but I could never get it to work. Using a clay pot as an ion channel is damned genius. Thank you for taking the time to make this.
Tomas Blanco - 2020-07-19
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