Metal finishing Q&As since 1989

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Reducing foam from acid/base reaction in Equalization tank

We have a lot of parts that get either Sulfuric Acid Anodization or Boric Sulfuric Acid Anodization. Before the parts are anodized though, they are cleaned in an Alkaline cleaner and etched with an Alkaline etch. Our Rinse tanks, the two Alkaline tanks, and the two Acid Anodization tanks all drain into the same Equalization tank. We are having an issue with foam building up in the EQ tank, which I suspect is from the mixing of the alkaline Cleaner/Etch and Acid Anodization mixture. Is there any way to reduce the foam buildup from this reaction?

Christopher Merritt
Plating Shop Chemist - Eastman, Georgia, USA
July 12, 2011

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Hi, Christopher.

If the wastewater will not be reused, a little bit of silicone defoamer goes a long way.

Regards,

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

Thanks for the response, do you have any suggestions on a good Silicone defoamer?

Christopher Merritt
- Eastman, Georgia, USA
July 18, 2011

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Hi, Christopher.

Your local supplier who sells you your other wastewater treatment chemicals will have silicone defoamer. I'll mention Dow, not in preference to other possible brands, but because if you google for "Dow silicone defoamer" you will find many good technical articles. Good luck.

Regards,

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