Rachel
Your question is a bit confusing. The surfaces you describe are non-porous and will not allow ions to penetrate. Aqueous F- sources of concern HF, NH4F2-, CF3COOH, etc, are completely miscible and soluble in water. As such, standard equipment washing methods, such as soaking in Alconox and thorough rinsing with tap water followed by DI will remove all F-. The proposed Ca binding step will create an insoluble CaF2, which will cling to surfaces by adsorption forces and will be more difficult to remove.
Can you provide a rationale for wanting to do the Ca step? I do not see the chemistry and am curious.
Thx
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From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Layman, Rachel
Sent: Tuesday, August 14, 2018 12:06 PM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: [DCHAS-L] Clarification: [DCHAS-L] HF working surface decontamination solution - recommended concentration or alternate?
Hello, thank you for replies so far. However, I am not interested in skin or other personal exposure or medical responses. We have those in place and they include calcium gluconate and other emergency practices.
We are solely interested in identifying the best work practice to recommend to lab personnel to clean tongs, utensils or other working surfaces before storing these reusable items after their use with HF. Our initial understanding was that a calcium hydroxide solution would be satisfactory; however, we realized providing the concentration would be more useful to lab personnel. We have not yet been able to locate such information.
Thank you for any input in advance.
Rachel
I am puzzled. My understanding is that HF, and other ionizable/ionized forms of fluoride, if exposed to the skin should be treated with calcium gluconate. ("Calgonate" is a preparation of calcium gluconate.) However, these treatments would neither be effective nor necessary if the fluorine-containing compound is covalently-bound F. Thus, I don't know what a "fluorinated acid spill" might be or whether calcium carbonate (which is not calcium gluconate/"Calgonate") would be effective. (An example of a fluorinated acid might be TFA, trifluoroacetic acid; these F atoms are not ionizable.)
When once researching medical events about fluoride exposures I came across anecdotes of medical ER folks using calcium gluconate on an exposure that was clearly a covalently-bonded fluorine compound. (I can't find this now.) The treatment was ineffective, as expected. But, the patient was not suffering from "fluoride exposure", either.)
I would welcome other insights that clarify my understanding.
Dave
David C. Finster
Professor, Department of Chemistry
Wittenberg University
937-327-6441
https://www.wittenberg.edu/academics/chemistry/facultystaff/finster2.html
From: ACS Division of Chemical Health and Safety [mailto:DCHAS-L**At_Symbol_Here**PRINCETON.EDU] On Behalf Of Sara J
Sent: Tuesday, August 14, 2018 11:32 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] HF working surface decontamination solution - recommended concentration or alternate?
Calgonate also has a lot of info. on HF safety and has spill kits and gels available. At my company we keep calcium carbonate on hand for any fluorinated acid spills, but we do not handle HF.
Sara Johnson, Ph.D.
Inorganic Chemist
The Shepherd Chemical Company
Norwood, OH 45212
sjohnson**At_Symbol_Here**shepchem.com
Cell: (810)730-8963
Office: (513) 731-1110
On Tue, Aug 14, 2018 at 11:21 AM, Paul Weller <wellerp**At_Symbol_Here**elon.edu> wrote:
Honeywell has a neutralization guide
https://www.honeywell-hfacid.com/literature/
Paul Weller
Paul Weller
Senior Science Laboratory Manager-Chemistry
Elon University
2625 Campus Box
Elon, NC 27244
Phone 336.278.6225
Location MCMI 302
wellerp**At_Symbol_Here**elon.edu
Hello,
Does anyone know what percent solution of calcium hydroxide would be appropriate for decontamination of working surfaces where HF has been used, or small spill of HF known?
Or is there a better solution anyone can recommend?
Thanks,
Rachel
Rachel M. Layman, MS, CHMM, CHO
University Chemical Hygiene Officer
Environmental Health and Safety
Virginia Tech
575 Beamer Way
(540) 231-3427
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