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Subject: Zeolite

Zeolite

From: Karin von Lerber <karin.vonlerber>
Date: Friday, January 11, 2002
After having received some fire damaged textiles for treatment, I
have searched the Internet for the possibilities of removing odor
and found the posting by Jane C. Hammond in Cons DistList Instance
14:61, May 10th 2001, who recommends using Zeolite Paper
(Conservation Resources) for wrapping objects to remove the odor.
Trying to find information about Zeolite in general, I found a
technical bulletin "Zeolite--a versatile air pollutant adsorber" by
the United States Environmental Protection Agency, dated July 1998
<URL:http://www.epa.gov/ttn/catc/dir1/fzeolite.pdf>, in which I
found the following sentence:

   "Zeolite can be a solid acid catalyst. It can function as a
    strong acid (though it remains solid) when the hydration has
    substituted a hydrogen for the additional valence electron, or
    isoelectronic exchange with the aluminum occurs."

Now, what does this mean? As I understand, there are many different
synthetically produced Zeolites. For paper, a hydrophobic zeolite is
normally used (although--as Conservation Resources has no
information available on the net, I do not know the specifics of
their paper as yet). Hydrophobic Zeolites seem to be produced by
enhancing the amount of Si in relation to Al. Can I therefore
conclude, that, if the paper really is coated with hydrophobic
Zeolite, hydration will not be a problem and, because of the reduced
(or even eliminated?) amount of Al isoelectronic exchange should not
be a problem either? Can someone who has more chemical knowledge
than I do please comment on this?

Have there been more recent tests with Zeolite coated cardboards or
papers ("MicroChamber", "ArtCare")? I am aware of the article
"Zeolite Molecular Traps and Their use in Preventative Conservation
by Siegfried Rempel in WAAC Newsletter vol 18, No 1 January 1996
<URL:http://palimpsest.stanford.edu/waac/wn/wn18/wn18-1/wn18-106.html>.

In case of a whole collection and archives being affected by smoke
during fire, has somebody used Zeolite in its granular form instead
of wrapping each object? Is this effective at all? Do I need air
circulating in order for granular Zeolite to work, or can I simply
inclose a bag with a bunch of objects and wrap them airtight (i.e.
no circulation). How do I realize if the capacity of adsorption is
reached?

As far as I understood from what I read about Zeolite, it can be
"reactivated" by heating, (thus releasing the trapped gases?). But,
will I then change its own structure and create a potentially more
harmful substance (see my concern above about the solid acid
catalyst)?

As becomes evident, I do not yet feel, I understand enough about
zeolite to immediately use it. Any help / information is most
welcome.

Karin von Lerber
Prevart GmbH
Konzepte fur die Kulturgutererhaltung
Oberseenerstrasse 93
CH-8405 Winterthur
+41 52 233 12 54
Fax: +41 52 233 12 57


                                  ***
                  Conservation DistList Instance 15:49
                Distributed: Saturday, January 12, 2002
                       Message Id: cdl-15-49-012
                                  ***
Received on Friday, 11 January, 2002

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