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Ask the Expert Question-and-Answer Archive (Wastewater Treatment)
by Mike McGinness, EcoShield Environmental Systems, Inc.
January, 2007Electrowinning dilute copper sulfate
Q. I have been having a problem with trying to plate out a 45 gallon tank of DI Water and copper sulfate. The % of copper sulfate in the tank is pretty low, hence trying to plate out the copper sulfate so I can discard the DI water Safely. There are no florides in the copper sulfate. I have tried usin a sheet of copper (-) and a sheet of stainless steel (+) to no great avail. My solution is turning a green tint wich is telling me that the stainless steel is desolving. I would like to try a platinumize titanium sheet as the (+) to see if this may help. Any help or ideas on this matter would greatly be appreciated.
A. Platinized titanium will help keep the nickel and iron from the stainless out of the solution.
Q. Thanks for the quick reply Mike. I am using a sheet of copper as the cathode (-) and the sheet of stainless as the anode (+). ( plating directly to the cathode ) It is in a plastic 45 gallon tank, (full). There really is not much copper sulfate in the tank. I tried just plating it out at 4 volts @ about 560 mA. As far as the concentration goes, on my first try I did plate out most of the copper sulfate to a point then it seems to start dissolving the stainless. I could tell this by inspecting the stainless, it did have pitting.
A. In that case a platinum coated titanium wire mesh would probalby do you quite nicely! You might want to monitor the pH and see how acidic it is getting as the copper is plated out. Might want to try and keep the pH above 5.5 to 6.0 with a trace of sodium sulphate added during the process.
Have you considered using a small Reverse osmosis water filter with it to further concentrate the copper, and possibly reuse the RO/DI water?
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