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Q&As since 1989


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Copper and Salt Water

Q. If I use copper anode and copper cathode and salt water, when I pass current through the solution will I end up with a copper salt solution that I can use to plate with? And is the solution I have safe to tip away or should I take it somewhere? And what solution would I end up with?

Baxters [last name deleted for privacy by Editor]
- UK
2003

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A. Assuming that the water conducted, you would merely pass a current through the water. Nothing would leave the cathode except electrons. Assuming you were using a copper sulphate [on eBay or Amazon]solution and a copper cathode, copper ions would pass through the solution and be deposited on the anode. Copper plating can be achieved in this manner. copper sulphate is highly poisonous... and it was once known by the name "Blue Vitriol". Interesting enough, the word "vitriolic" takes its name from it... as does "en vitro" (in glass) and vitreous humor (that clear jelly stuff within your eyeball). The crystal is a translucent blue in appearance and the dual connotation is one of transparency and of a bitter tasting poison. Obviously, it is unsafe and probably unlawful to dispose of such a solution in an improper manner. Clement Alberts - Santa Barbara, California 2003 A. An interesting concept. In theory, you will dissolve the copper anode to produce a solution of copper chloride. Once the copper in solution has reached a suitable concentration, you will start to deposit copper onto the cathode. So, hypothetically, you can do what you asked, but in practise it is not so easy. You really need to have a high concentration of metal in solution, otherwise other cathodic reactions will take place and dominate the overall process. Using a copper cathode is not a good idea as you will just be coating copper with more copper; if you want to try it, you will want to see your copper go down, so use a cathode of a different colour. Copper will also deposit itself onto lots of metals without passing an electric current - this is called immersion coating, and you may well experience this effect in your system if you have the correct metals, such as iron or nickel. The simplest way of copper plating is to use a mixture of copper sulphate and sulfuric acid. Trevor Crichton R&D practical scientist Chesham, Bucks, UK 2003

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Remove copper from contaminated salt water and aquarium rocks

December 1, 2015

Q. Hi all, my name's pete and I am a keen marine aquarumist. I have a problem that I hope you may be able to shed some light on.
I have a 55 gallon marine aquarium, unfortunately in my inexperience with marine life, but my career experience in boat building, I've used a brass water valve in my recent tank build. Unfortunately the copper in the brass has began to leach out and mildly poison my tank. I have made attempts with the use of activated carbon and commercially available filters that remove metal traces, now as much as these will clear the copper traces in the water common opinion is the amount of copper absorbed by any rocks and sand in the tank will leach out back into the water over time. I'd rather not clear up the water, and restock it only to have them die. Unfortunately the rocks are not cheap and I'm not in any position to be replacing them and starting again.

So my questions...

1. How much copper do you think could leach from brass in 12 weeks when subjected to a flow of salt water with a gravity of 0.025 and a temp of 23 °C?

Most importantly, question 2.

If I removed all life from the tank first, is there a means to use electrolysis to collect the copper from the water, rock and sand.
I have made to a 12-14v power pack but this is where I need some pointers please. I was thinking it may work similar to plating but obviously not with the same result, just to collect the copper.

I know its all a bit obscure from your norm but I hope you can give me a helpful answer!

Many thanks Pete

Peter Cruttenden
Aquarium keeper - Bournemouth, Dorest england