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Titanium Etching, Nitric Acid Reclaimation

We use Nitric acid to etch various Titanium alloys. After a couple of months the tank has to be drained and refilled with fresh acid at significant cost and environmental impact. This is not because the acid is no longer present (pH is still within range) but because there is so much titanium in solution that the etching reaction is inhibited. Is there some way to remove the Ti and reclaim the acid?

Karl D'Ambrosio
- Kent, Washington, USA
2000

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There is about a 100% probability that you have a nitric-Hydrofluoric mixed acid which is extremely aggressive on most materials making it difficult to recover. There are ways to recover it, but the question is "is it worth it"?

Check out a listing in the metal finishing guidebook or similar reference for companies that sell that type of equipment.

James Watts
- Navarre, Florida
2000

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This acid can be reclaimed using several technologies. Depending on volumes, recovery can be very expensive, or it can be moderate. We manufacture an acid recovery system that uses acid retardation technology. It can capture up to 80-85% of the remaining free acid in the solution and recycle it back to your process. You will end up with a solution that has 15%-20% of the acid to treat with 90%+ of the metal in it. Depending on your loading profile, this system can be available for a remarkably small capital investment.

Tom Baker
wastewater treatment specialist - Warminster, Pennsylvania
2000

At what point does the titanium content begin to inhibit the reaction?

John S. Mars
- Wichita
2003