Filtering Copper Sulfate - (May/23/2010 )

Hello Everyone

I am making copper sulfate using the electrolysis method; I have a copper anode and cathode connected to a variable power supply in a sulfuric acid and water bath.
When done the electrolysis process, I boil the blue solution to solidify the copper sulfate.
Then I run what’s left through a few coffee filters and I am left with a blue paste. Then left to dry and after a few days noting happen.
What I would like it a dry blue powder of dry crystals.
I must be doing something wrong.

Is there a better way of doing this ??

Thanks in advance
Big’s

You probably need to neutralize your acid prior to drying the solution. If you neutralize with NaOH, you'll end up with some sodium sulfate in your final product. If you neutralize with (for example) barium hydroxide, then the barium sulfate will precipitate, leaving the copper sulfate in solution. You can remove the copper sulfate solution, then dry and crystallize the result.

Biggermens on May 23 2010, 05:49 AM said:

Umm... buy it?

If purity is your concern. You can get some very pure chemicals from supplier of chemistry labs. Purity up to 99.999% can be purchased.

If you are looking for regular CuSO4 (purity of 99%), then you can get it cheap from suppliers of biological labs.

It is very likely your Copper sulfate paste is contaminated with "stuff" from coffee filters and excess sulphuric acid. You will have to remove the excess sulphuric acid, probably with a base. Although this will leave you with a salt mixture, which requires recrystalisation to separate out your copper sulphate.

As for the water problem, you could heat up your paste in an oven and drive the water out.

If you keep the temperature below 150C you will get hydrate copper sulphate
If you keep the the temperature between 150C and 560C, you should get anhydrous powder.
Above 560C and Copper sulphate decomposes to CuO.

Unless there is a particular reason you are doing this experiment, it would be easier to just buy the copper sulphate.

Copper Sulfate is very difficult to find were I am. I found a few places that sell it but they will not sell to me unless I have some kind of permit. And I found a few place in the us but they don’t want to ship to canada

Thanks Big's

Why electrolysis?
H2SO4 + H2O2 + Cu --> CuSO4 + 2H2O
use warm sulphuric acid (30%) and pure copper, perhaps some calculations are necessary to know the amount of copper and sulphuric acid you need...and using the hydrogen peroxide slow and with care.

If you filter your electrolysis product then wash it with ice-cold water and then let it dry. Perhaps it's necessary to recrystallise it (also a cleaning step).

I find that electrolyses is more efficient then the hydrogen peroxide method.
I will try to use water and let it dry out see what will happen

Thanks agine for all of your help
Big's

Biggermens on May 23 2010, 09:40 PM said:

BTW what do you meant with that after a few days nothing happened? If you dry it with heating up too strong you'll get a white powder finally, as the crystal water is gone...the blue crystals is CuSo4 * 5 H2O. Only slight heating up is allowed...