Where the
world gathers for metal finishing
Q&As since 1989


-----

Regenerating Phosphoric Acid

2001

Is there a method for the removal of iron from my phosphoric acid bath (so that I can keep using it)? I have heard that it is possible to use a cathode to precipitate out iron after it has been oxidized, but that a catalyst is necessary.

Any help is appreciated.

Thank you,

Vinnie Stocks
trophy plating company - Daytona, Florida

Vinnie,

You can also consider using ion-exchange anionic resins for acid retardation process. Such resins in the first passage keep acid and let metal go out; in the second passage, demi water displaces metal-free acid. In your case, in the first passage you have iron and a small percentage of phosphoric acid, in the second one phosphoric acid (virtually iron-free). This process works only if iron is more than few grams/litre.

Good luck

Francesco Cicchetti
- Sulmona, Italy
2001