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topic 1310

"Porous pots" for chrome purification


Our client is using a "porous pot" for rinse water treatment. We need basic training in theory and operation. How do they work?

[name deleted due to age of inquiry]


Porous pots do exactly the same thing, and function in exactly the same way, as membranes. Now, if only I really understood how membranes work, I'd be getting somewheresmiley

I know you put an electrode in the pot, and it oxidizes trivalent chrome back to hex chrome, while simultaneously attracting the iron and other metallic contaminants. I understand that chromic acid remains an anion while the other metals are cations. But exactly why the membrane or pot is necessary for the electrode process is what I don't understand.

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


We had a chatroom discussion about this a while back, and it turns out that the AESF sponsored a research project on porous pots. Email them ( and ask for a copy of the report. The scientists spent some time in the report explaining the mechanism, and had data about the pore size and anode and cathode ratios that are important to the proper operation.

tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania


Check the December 1977 issue of "Plating and Surface Finishing" (AESF trade journal). You will find an excellent article about porous pots, how they work, and tips on usage.

Jeff W [last name deleted for privacy by Editor]

Ed. note: Thanks, Jeff!

(1999) -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

how the porous pot works? how to get rid of chromium trivalent?

daniel spatafora


I'd like to know how many porous pots I need --

I have a workshop for the plating of plastic, and I have a 100 gal. tank of chromium etch. Where I can buy the porous pots.

Mario E [last name deleted for privacy by Editor]
- Mexico

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