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topic 536

Purification process for chromic acid anodizing


We are a state agency which assists Massachusetts businesses with technical problems. We are currently working with a company which does chromium anodizing and they are interested in an electrodialytic process to remove impurities from the chromic acid solution. I know that there are systems out there (Ionsep manufactures an electrodialytic unit) but I was wondering if anyone has had any success with these systems. Any information would be appreciated. Thanks.

Sean McGuigan
MA OTA - Massachusetts

There were, over the years, a number of suppliers of chromium purification systems of this sort. One was the "ChromeNapper" ; I don't know if they're still around or not. I believe that Cosmos Minerals of Camarillo, CA also offered a purification system. I'm confident that a literature search will give you the names of places where such systems were installed. But you might want to determine whether the simple and inexpensive porous pot system might work.

Ted Mooney, Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey


We installed an Ionsep regen system several years ago on our chrome anodize system. I think it removes impurities AND oxidizes trivalent chrome back to hexavalent chrome. Since installation, we only have to partially drain the tank maybe once a year if the acid/free acid balance gets off. Major maintenance still requires a total dump. It works well as long as they don't install it with the anode and cathode rod reversed.

Scott Fetter


The absolute cheapest system out there is from Clarence Peggar of Hard Chrome Consultants in Cleveland. His unit works well. Looks tinker toy, but is a fraction of what the big boys charge. Has three sizes. Removes copper and trivalent. Do not know what it does to the other trace metals in the alloy. Follow the instructions and do not get in a rush.

James Watts
- Navarre, Florida


Have you any info on chrome-napper or cat-napper, who manufactures them and their address.

Best Regards

Roger Biddlecombe

ChromeNapper was a product of Innova Technology Inc., Clearwater, FL. I haven't heard of the units in a few years, so either the product line is dead or they are pleasantly quiet people. I would suggest starting with a search for "Innova Technology" and Clearwater. Also contact Cosmos Minerals in Camarillo, CA; they also had a chrome purification system along the same general lines as the Chrome-Napper. Ion Exchange is a different technology, but Eco-Tec offers chrome purification systems based on that technology.

Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

May 6, 2008

I have seen an electrolytic purification system in action in Ohio. It was designed and manufactured by Reasco in Arvada, Colorado with the name CrPur. It works very well with Cation contaminants and oxidation of Hex-3+. The best feature is there is no waste stream, it produces a metallic sludge that concentrates metal wastes.

Michael Pace

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