Date: Tue, 4 Sep 2007 09:49:03 -0400
Reply-To: al.muehlhausen**At_Symbol_Here**CIBAVISION.COM
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: al.muehlhausen**At_Symbol_Here**CIBAVISION.COM
Subject: 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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