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  for Metal Finishing since 1989
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Re-using used etch solutions for plating

We use ammonium persulphate and sulfuric acid bath to etch/mill copper. After the bath is saturated(used) can we use this for a plating bath? We currently dispose of it, but would like to get another use of it, or sell it.

Josh Sonju
- Kalispell, MT

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Why don't you recycle the bath and just remove the copper from it? Unless you kill the persulphate completely - and adjust the copper concentration - and add chloride and remove some of the free acidity - and remove the trace contaminants from the bath, such as chromium and other ions, I do not think that you would be pleased with your plating results, nor would it be a "saleable process solution".

You can easily remove most of the copper from the bath - and if you generate enough of it, there is technology that can restore the persulphate back to the process conditions continuously and remove the copper as a resaleble by-product.

Tom Baker
wastewater treatment specialist - Warminster, Pennsylvania