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Regeneration of Chromic Acid Activating Solutions

IP.com Disclosure Number: IPCOM000085193D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Macur, GJ: AUTHOR

Abstract

It is highly desirable to be able to regenerate chromo-sulfuric acid activating solutions to avoid the necessity of having to treat old spent solutions for disposal, since the waste treatment process is costly and the resultant loss of CrO(3) and H(2)SO(4) is even more costly.

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Regeneration of Chromic Acid Activating Solutions

It is highly desirable to be able to regenerate chromo-sulfuric acid activating solutions to avoid the necessity of having to treat old spent solutions for disposal, since the waste treatment process is costly and the resultant loss of CrO(3) and H(2)SO(4) is even more costly.

The regeneration of CrO(3)/H(2)SO(4) activator solutions can be accomplished by ozone-air or ozone-oxygen gas regeneration using a silver catalyst. An example of the process used is as follows:

One thousand milliliters of spent activator solution was analyzed prior to treatment and found to contain approximately 62 gm/1 of CrO(3) approximately 9 gm/1 of Cr III, and approximately 5O% sulfuric acid by weight. If all the Cr III is converted by regeneration to CrO(3), the solution would contain approximately 80 gm/1 of CrO(3) and the sulfuric acid concentration would increase slightly. The silver catalyst is provided by dissolving approximately 1 gm of silver nitrate (AgNO(3)) and a minimum amount of water, which is added to an activator before commencing the ozone regeneration process.

During the ozone regeneration, the solution was maintained at about 160 degrees F and a mixture of ozone and oxygen is bubbled into the solution by a dispersion tube of coarse porosity. The gas mixture used was about 4 wt.%O(3) when the flow rate was 30 standard liters per hour at 7.5 P.S.I.G.

In slightly more than 50 hours, 80 gm/1 of CrO(3) was found in the ana...