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Hydrofluoric Acid Solution Analysis

 

My company uses a 10% HF acid solution for several glass polishing and cleaning processes. I am searching for the best method to use to monitor the status of the acid solution. At one time we had a very routine schedule of use and replacement but now a higher demand has been placed on some of the cleaning processes. Therefore, I would like to be able to maximize our productivity while maintaining the integrity of the solution.

We have many analytical tools available but I would like to have some outside input before trying anything.

Would an ISE method be best? Should I try to monitor the silica content?

Aaron Joseph O'Connor
- Urbana, Illinois, USA

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Go with the ISE. Most of the folks I know with HF Nitric pickles use this method.

Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England
 

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Does the Ion Selective Electrode method correlate with etch rates of the solution? The glass dissolving into the solution may interfere with the etch, and the fluoride content may not be the best may to control the solution. How about titrating with caustic to get an acid content, and determining the weight loss of a piece of glass for estimating the etching capability?

  
Tom Pullizzi
Falls Township, Pennsylvania
 

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Tom,

I think you are right here. Lets go for the simple but right answer. Etch rate testing would be the best control as you are testing the function you wish to control. Also it is cheaper!

Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England

Finding concentration of Hydrofluoric acid and sulfuric acid from a mixture I have received a sample of an acid mixture, I would like know a method by which I could determine the approximate concentration of both hydrofluoric acid and sulfuric acid.

Reema G
Microbiologist - Mumbai, Maharashtra, India
2007