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Next by Date: Subject: Re: [DCHAS-L] Perchloric acid-organic mixtures Date: Thu, 5 Jun 2014 12:46:22 -0400 Author: George C. Walton |
You want to get a copy of the book “Perchloric Acid and Perchlorates” by Alfred A Schilt. I obtained my copy from GFS Chemicals, Inc. Page 140 ff has a discussion of the issues related to electropolishing with many literature references.
In the absence of specific data, I urge you to have a DSC analysis of the specific mixtures to determine their stability. The thermal data will provide you with the boundaries for safe work.
nl
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From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Dan Kuespert
Sent: Thursday, June 05, 2014 7:21 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: [DCHAS-L] Perchloric acid-organic mixtures
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, et.al.) 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.
regards,
dan
=============================
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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