From: "CHANDRA, Tilak" <tchandra**At_Symbol_Here**FPM.WISC.EDU>
Subject: Re: [DCHAS-L] help w/ mystery scale on exterior of copper pipes
Date: November 5, 2012 1:13:41 PM EST
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Ammonia or amines may increase copper's susceptibility to being oxidized by air-oxygen. The blue coloring of the copper compound may be a clue. Amines are good ligands for copper compounds and could be lowering the oxidation potential. Hydroxide and cyanide ions do this and I suspect that amine or ammonia will as well. Also, there is some vapor pressure of hydrated sodium hydroxide from concentrated solutions (try making up an 8 molar solution outside of a hood!) of it and this may be in the air at low level. Phosphoric and sulfuric acids: not so much at all. Hydrogen chloride vapor is another possibility as chloride is a good ligand for copper ion (iron(III) chloride has been used to etch copper in making circuit boards) that can be formed from oxidation by the hydrogen ion.
Tilak Chandra, Ph.D.
Chemical Safety Specialist
EH&S; Chemical Safety
30 East Campus Mall
Madison, WI 53715
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of scrooks**At_Symbol_Here**PPEPPRO.COM
Sent: Monday, November 05, 2012 11:02 AM
Subject: [DCHAS-L] help w/ mystery scale on exterior of copper pipes
Room contains a medium size waste water pretreatment system where you have typical H2SO4, H3PO4 and NaOH for pH adjust. No excessive mists or vapors from these sources are apparent. The room itself is approx. 30'x30'x20' and also contains an industrial sized autoclave/steam sterilizer which is opened after runs and vents essentially to the room. Plants and soil are a portion of matl being autoclaved as well as (I'm afraid) everything up to the kitchen sink. No reported exposure symptoms from anything (yet) while working in room. Copper pipe was new and developed scale rather suddenly but within the first 6 mos of operation in this new AgriBioPharma facility. Fresh copper pipe pieces have subsequently been hung to determine if this is on-going. The blue color had me thinking an H2SO4 reaction w/ Cu but since Cu has a lesser tendency to give up electron than H, Cu wouldn't reduce H+ ion given by what I suspect at best would be a very dil. H2SO4 in air (if any.) Any chance of Cu(II) Oxide being formed on exterior of pipe from anything in room atmosphere and then making reaction with H2SO4 more likely with extremely low atmospheric vapor conc? Any help is appreciated. Thanks,Steve Crooks
I was recently asked to look at a dark blue scale appearing on the exterior of some copper piping and determine possible causes and if any human health risk is likely. I am asking here primarily for anyone who's possibly seen this blue scale appear in similar installation. I don't want to take anyone's time going deep as this is a paid consulting task and I do have access to other resources (and this one appears complicated.) This group has seen and experienced so much collectively though that I couldn't pass it up as a great sounding board. Then again, most on this list are being rewarded in some manner through the advice, ideas and answers obtained through the group so my shame isn't too unbearable.
Steve Crooks, MS, CIH, CSP President & Sr. Consultant People, Property & Environmental Protection, Inc.
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