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How to remove nitrates from silver cyanide plating bath

Q. Hello ,
I think nitrogen in our silver cyanide bath is a problem. I want to remove nitrogen compound as NO3 out of the bath . How I do that?

Any help please. Thank you very much. : )

Tawan
lab s. - bangkok, Thailand
2004

A. The plating manuals I have read claim that nitrates up to 100 g/liter are not usually detrimental to silver plating. Therefore, one of the alternative methods I use for carbonate removal has been the use of Barium Nitrate to drop out Barium Carbonate, leaving Potassium Nitrate in solution. I have used Nitrate (sparingly) in bright silver (Cookson Silverex II) for several years to no ill effect. I mostly use Barium Hydroxide to drop carbonate but if the pH goes over 13.2 I also use BaN03.

Ron Graf
- Claymont, DE, USA
May 26, 2009