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Plating metals out of sea water

Hi, my name is John. I am interested in an alloy that has the elements of the same percentage as that of sea water. My first thoughts were to use deposition to build this alloy like a coral reef. We have a home on the ocean so the solution would be endless time is really not a factor. I would like to have some sort of solar energy source for power and just let it cook. So my question is without digging out my chemistry books looking for Faraday's Law, will this even work and if so would I use a battery or a solar cell be enough (35 watts) to grow something in my lifetime?

John Pellerito
product designer - Gainesville, Florida, USA
August 20, 2011

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Hi, John.

If you kept the voltage low enough, below the deposition potential of hydrogen, you might be able to plate something out with the patience of years on your side. However, you likely won't be able to plate an alloy. The law to look up for that one is the Nernst Equation. Good luck, maybe you'll recover gold. See letter 20612.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 21, 2011

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Electrolysis of sea water (sodium chloride solution) produces sodium hydroxide and chlorine. This is the well known industrial Solvey process. If the two products are not separated, they react to form sodium hypochlorite - household bleach.

Geoff Smith
Hampshire, England
August 29, 2011

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I found on the internet that the concentration of gold in seawater ranges from 5 to 50 parts per trillion (ppt) and the average is 13 ppt. I did this hurriedly but, if my math is right, using a gold spot of $1800/tr.oz. and the avg. conc. of 13 ppt., you would have to process about 357,000 gallons of seawater to get a penny's worth of gold.

Good luck!

Chris Owen
- Nevada, Missouri, USA
August 30, 2011