From: Dan Kuespert <dkuespert**At_Symbol_Here**JHU.EDU>
Subject: [DCHAS-L] Perchloric acid-organic mixtures
Date: Thu, 5 Jun 2014 14:20:36 +0000
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: D5F8F4B5-877F-4D3F-BB43-0D0482608320**At_Symbol_Here**

I was wondering if anyone knows of any actual data about the stability of various perchloric acid-organic solvent mixtures. The mixtures in question are relatively (<10-15%) dilute solutions of perchloric in ethanol, ethylene glycol, butyl Cellosolve, etc. used for electropolishing. I'm having trouble finding literature reports.. Of course, there's plenty of reports (Bretherick's, about hazards, but no actual information on how much is too much.

Normally, I would recoil from such mixtures, but perchloric-organic mixtures are pretty extensively used in the metallurgy literature. Just because something has been successfully used without incident, though, does not mean that it was used "safely." It may mean that the lab was lucky.

I've had some problems in the past with other witch's brews used for electropolishing, after which I determined that the literature-reported composition was beyond the actual stability limit for the particular (ethanol-nitric acid) system, so that's kind of sensitized me to this application.


Dr. Daniel R. Kuespert
Homewood Laboratory Safety Advocate
Krieger School of Arts & Sciences/Whiting School of Engineering
The Johns Hopkins University
103G Shaffer Hall
3400 North Charles St.
Baltimore, MD 21218
(410) 516-5525

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