Date: Tue, 4 Sep 2007 13:32:28 EDT
Reply-To: DanielD734**At_Symbol_Here**AOL.COM
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: DanielD734**At_Symbol_Here**AOL.COM
Subject: Re: nitric acid mixture with aqueous IPA
Comments: To: chemsafety**At_Symbol_Here**VERIZON.NET
I remember an incident way back in graduate school:
Another graduate student mixed nitric acid and ethanol ( I cannot remember  
the details of how he mixed them or why). After a few seconds the mixture shot  
out of the flask and covered the interior of his hood with orange fuming 
liquid.  He had a real mess to clean-up, but at least no one was hurt.
Mixing nitric acid with alcohol can create a potential disaster. I would  
strongly recommend against it.

In a message dated 9/4/2007 11:46:25 A.M. Central Daylight Time,  
chemsafety**At_Symbol_Here**VERIZON.NET writes:


Your concern is well-placed.  In many instances, the  procedure you describe 
would not cause any dire consequences. BUT!   There is always the exception 
(Murphy's Law) operating in the  background.  As you know, conc HNO3 is a 
pretty d____ good oxidizer  and it WILL oxidize any poor,unfortunate reducing 
agent in an eager, not  to say voracious, manner.  When, one day, somebody 
uses the procedure  described, the reducing agent will acquiesce a bit too 
readily and the  resulting exotherm could very well be catastrophic.

Jay A.  Young

----- Original Message -----  
Sent: Tuesday, September 04, 2007 9:49  AM
Subject: [DCHAS-L] nitric acid mixture with aqueous IPA

Has  anyone heard of the practice of mixing concentrated nitric acid (70%)
waste  contaminated by small amounts of organic polymer with aqueous
isopropyl  alcohol as a means to "passivate" the waste so it can be safely
mixed with  aqueous mildly acidic waste streams? One of my scientists
recently  described this "passivation" practice as routine during his
experience, but  I am sceptical about mixing the oxidizer with a flammable
organic, even if  the IPA is in aqueous solution. The procedure does not
seem prudent to me,  even under controlled conditions, and I have
recommended against  implementation. Here is the written procedure he

"The  procedure for passivation of HNO3 is as follows. 600 ? 800 mL of  50%
(weight) isopropanol in water is prepared in a 1-L beaker. The 50 ? 60  mL
of depleted HNO3 is added slowly to avoid any sudden temperature  rise.
This addition is accompanied by an evolution of gas, and the contents  of
the beaker change color from a deep orange to a lemon yellow.  Upon
completion of the addition, the beaker is stirred or swirled gently  to
degas, then capped with a watch glass and allowed to stand and  complete
passivating and degassing overnight (at least 12 hours). In the  morning,
the mixture is again stirred to remove any traces of gas, and then  is
commingled with the normal laboratory waste stream."

What are  your thoughts regarding the safety of the proposed procedure,
and do you  have recommendations for the best nitric acid waste  handling

Kind regards,

Al Muehlhausen
CIBA  Vision Corporation
Chemist/Certified Industrial Hygienist
Health,  Safety, and Environmental Officer JCE/JCA/BTI
Office 678-415-4217
Cell  678-644-7026

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