indigofuzzy
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Production of Copper Sulfate by Electrolysis
I was wondering if anyone else might have some experience with this. I've read some other threads about electrolysis of MgS04 to produce sulfuric
acid, but wondered if by using a copper anode and a (relatively) inert cathode (aluminum, stainless steel, carbon, etc) - would it be possible to
produce copper sulfate of sufficient purity to 1: grow pretty blue crystals, and 2: electroplate copper onto things.
I have an experimental setup (I'll post pictures if you want) - There are two clear plastic "jars" both initailly filled with a nearly staurated
solution of MgSO4, with an anode made of various sizes of copper wire balled up together in one "jar" and a cathode made of rolled up aluminum foil in
the other. I have a peice of PVC tubing acting as an ion bridge between the two jars. The good news is that the solution in the anode jar started
turning blue within a day or two, and after two weeks of continuous running, the anode solution has turned a deeper shade of blue, while the cathode
has accumulated a whole lot of of amorphous white crusty gunk. (Which from previous posts, i am lead to believe is Mg(OH)2)
The downside seems to be that when i draw off some of the blue sloution and try to crystallize it, the resultant crystals are clear, or very pale blue
at best, not the deep rich blue of pure CuSO4•5H2O that I would have hoped for.
Any advice?
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chromium
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Do not use ion bridge this just cuts current and is not needed for making CuSO4. Aluminium cathode seems problematic too. Al is covered with oxide
layer and has high reistance in electrolytic cell.
Copper is better idea. Graphite lead or stainless steel may also work. You need some testing.
One should put quite high current through solution to get remarkable amounts of substances made by electrolysis. Electrolysis is generally very slow.
At least some ampers should flow through solution if you do not want to wait for weeks. Part of copper will surely plate on cathode or precipitate as
black powder (if current density is too high). Adding some inhibitors will probably prevent plating out or precipitating in some extent but i do not
know what substance are suitable.
You probably had just too few CuSO4 made. Try with much higher currents and maybe with larger electrodes.
When all think alike, then no one is thinking. - Walter Lippmann
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not_important
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It takes a lot of electricty to affect a molar amount of something. If I'm remembering correctly, you'll need about 65 amp-hours to dissolve or plate
out a mole of copper going to/from the +2 state. So first off you may not have dissolved that much copper, or removed that much magnesium, the
solution is still mostly magnesium sulfate. If you can measure the current flow you can get a rough idea of how much copper should have dissolved.
(see Coulomb - very roughly 0,00001 moles of electrons = one Amp-second)
The second thing is that copper ions are going to diffuse on over into the cathode jar and plate out there. Any such plating may be buried under the
Mg(OH)2.
So what you are crystallizing is a mixture of copper and magnesium sulfates, with the Mg being the majority cation.
The idea is not a bad one, those darn practical aspects get in the way.
Copper sulfate is fairly easy to come by, often found in hardware stores as "root killer" (read the label). That might be the simplest way to obtain
it.
Other DIY routes include heating copper, in small pieces - fine wire, filings, with ammonium sulfate - just enough to keep melt it. This works best in
an open dish, so air can get at it. However you'll need an excess of ammonium sulfate, so you most likely will end up with a mixed sulfate. If you
heat the copper in air to oxidise it, then heat an excess of the oxide with ammonium sulfate until no more ammonia goes off, cool, dissolve, and
filter, that might be better.
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indigofuzzy
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Well, I disassembled my original copper sulfate experiment, and tried putting the copper anode and a new copper cathode into the solution that
remained clear.
WOW, lotsa bubbles! I got a little worried about how much H2 this may be producing, and figure that I should be trying to capture it somehow to either
vent outdoors, or build myself a mini-hindenberg 
ANyway, the solution began to take on a blueish tint after about 2 minutes.
BTW, it may be worth noting that my power supply is a 6VDC 2.1A "wall wart" transformer. Would that supply enough current?
My inexpensive VOM reads 6.9VDC across the cell, and 1.25A of current.
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Waffles
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I looked at his crystals. They certainly have some amount of copper sulfate in them, as they are noticeably blue, but they are very irregular- not at
all characteristic of pure copper sulfate crystals, as was said, mostly likely because they are significantly magnesium sulfate. I like the pale blue
tint though  .
\"…\'tis man\'s perdition to be safe, when for the truth he ought to die.\"
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indigofuzzy
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Having read another post on here about electrolysis of MgSO4, I'm beginning to think I had the right idea about the salt bridge. I should mention I've
tried this expreiment before without the slt bridge, i still got a *light* blue solution, but alot of blue-green precipitate (which according to the
other thread is probably Cu(OH)2. 
hmmmmm.... I think I'll set the ion bridge back up and keep electrolizing. Maybe the solution will continue to get bluer...
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12AX7
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Yeah, electrolysis of most any alkaline salt without a diaphragm will let the respective acidic and basic anode and cathode solutions mix,
neutralizing the pH and precipitating things.
Note also that, to dissolve copper, you need to release hydrogen, and Mg(OH)2 must be displaced (precipitated).
Tim
[Edited on 10-2-2006 by 12AX7]
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indigofuzzy
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After 4 months of fractional crystallization, I've gotten my original copper and magnesium sulfate solution down to half its original volume, and have
a pile of various sizes of magnesium sulfate crystals in a plastic box. It appears that not_important was right, and it would take a lot more
electricity to get any significant amount of magnesium out of the solution.
Considering how little copper had actually been pushed into the solution, I'm quite impressed at how intense the blue color of copper ions is.
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indigofuzzy
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This past week, I tried the Copper Sulfate experiment again, this time with success. I have about 1.5L of deep blue CuSO4 solution, and am working on
another 1.5L as I write this.
My setup right now, is a clear plastic container with a coil of heavy copper wire in the bottom, nested inside this container is an inverted 2L "soda
bottle" with filter paper secured over the mouth. The bottom of the bottle was removed for easy removal of the cathode which after a few hours becomes
heavily coated with a crust of Mg(OH)2. At present, I'm using a steel rod for the cathode, with good results.
My power supply is a 12V 1.5A "wall wart", with an automotive headlamp in series with the cell to limit current (just in case...).
Anyway aside from bragging about my success  I wanted to ask if anyone knows of
a good way to assay the solution for residual magnesium ions. I'm pretty confident that my solution is not pure copper sulfate, that's just what my
intuition tells me... So, if anyone has a good way to test that...
[Edited on 8.6.2007 by indigofuzzy]
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Eclectic
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Magnesium Ammonium Phosphate has very low solubility. You may be able to use that.
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16MillionEyes
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It's impressive that someone else already thought out of this way. I had planned it for days already but the lack of a good power supply (I haven't
found a good adapter to "hire" for business) and lack of decent copper supply had kept me from doing it.
I'm glad that someone else already tried it and that it works. As amazing as it might sound I don't live near a wal-mart (there are none around the
city as far as I'm aware) and the power adapters laying around aren't exactly mine so my experiment has to be delayed again.
Just as an alternative to electolysis a really easy way to do copper sulfate is by reacting copper oxide with sulfuric acid. It works wonders and it's
relatively pure (depending on your source for copper oxide). Unfortunately I don't have sulfuric acid.
[Edited on 20-8-2007 by __________]
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not_important
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Secondhand stores may have wallbugs for not much money, some of these are fairly low voltage at decent current.
There are mpre places to buy things than at WalMart. Hardware stores as well as garden shops and plant nurseries are likely to be useful. Hardware
stores should supply you with hydrochloric and/or sulfuric acids and maybe copper sulfate, garden supplies usually include ammonium sulfate, potassium
salts, aluminum sulfate, and others.
Aluminium sulfate might be better than magnesium sulfate. It certainly would make it easier to tell how much of it was in the copper sulfate, adding
strong ammonia solution to some will at first form the hydroxides, then dissolve the copper leaving the aluminium hydroxide behind.
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indigofuzzy
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Lol. I suppose me calling my adaptor a "Wal-wart" got people confused, thinking I got it form Wal*Mart....
I actually picked it up at Radio Shack.
BTW, the ammonia solution seems to work separating copper hydroxide from magnesium hydroxide as well - also leaving behind Mg(OH)2
For the record: I'm about to start a new batch tonight, my best friend just "donated" a kilogram and a half of MgSO4•7H2O to my cause
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not_important
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underscores referred to WalMart, and not owning the power adapters. People in the US seem to have been brainwashed into thinking Walmart is the only
supplier of stuff, overlooking many alternatives.
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chloric1
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| Quote: | Originally posted by not_important
underscores referred to WalMart, and not owning the power adapters. People in the US seem to have been brainwashed into thinking Walmart is the only
supplier of stuff, overlooking many alternatives. |
Yes you do make a valid point. I try to use the alternatives when I can. I am all about supporting the local economy. But you must admit sometimes
the prices can be much lower at Wal-mart and it can save you from driving all over creation looking for something. Then again the independent shops
can have better variety because they speciallize.
Fellow molecular manipulator
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dedalus
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To address the original question: I would use a diaphagm cell, with a block of Cu as the anode, 10 - 20% H2SO4 + 100 - 200 ppm Cl ion as the
electrolyte, and something Pt clad, or anything else with a nice low overvoltage for H2 evolution as the cathode. Run plenty of juice through, as
others have commented, and you'll get yer CuSO4 5H2O crystals.
Not sure if they do business via mail order, but there's a place in Berkeley, CA called Al Lasher's Electronics that has lots of neat stuff. They sell
nichrome wire and ribbon in a variety of sizes, I used to build all kinds or lab heaters with it.
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16MillionEyes
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| Quote: |
underscores referred to WalMart, and not owning the power adapters. People in the US seem to have been brainwashed into thinking Walmart is the only
supplier of stuff, overlooking many alternatives. |
I made the comment about not having any walmarts around to simply point out I don't have such a cheap source of things but by no means that I'm
limited by this otherwise invading company. I make use of small business to the full of their extend and my pocket (which is the real limiting factor
in my previous comment) so I really consider your comment unfounded and mostly insulting.
I'm not sure where you're from but if you've ever been to small rural or suburban town in the U.S you'll know that Wal-mart is basically the only
choice (unless you wish to drive 1hr away or more for the same product) for an easily convenient accessible place. I'm not saying that I love Wal-mart
or that I support their reign of super-control but for many cases the place Wal-mart becomes more of a 'must' than a 'taste'. Think about it, can you
truly fight capitalism's strength-jaw to a closed mouth?
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indigofuzzy
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Well, I gave this a third try now that I'm in a new house, this time using copper pipe scraps as my anode, and a thick strip of steel for a cathode. I
ran the cell (a one gallon jug with the same inverted mountain-dew-bottle-and-filter-paper setup) until the anode solution stopped changing color. I
now have four liters of the deepest blue copper sulfate solution I've yet been able to create. I'll try crystallizing it soon and post pictures if I
get anything noteworthy. That is, if I can resist converting the bulk of it to carbonate and painting with it 
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