Marshall, Everybody,
The business of different approaches to silver, CS, dust, whatever,
continues to be important for treatment of the ceramic water purifiers,
here in South Asia. Now we've got three or four wholly different forms
of silver as alternatives for treatment. Following is an Indian
reference to the use of silver chloride, and I'm hoping friends on the
list will help me (and my artist's brain) to understand the chemistry.
I've got the basics but have yet to grasp the nuance.
The reference is to work of the authors, S. R. Deb and R. V. Lele, from
the bulletin of an Indian, technical ceramic institute.**
".....The activated form of silver deposited on to quartz-sand bed
filter is known as Katadyn........... Reduction of an ammoniacal
solution of silver nitrate to metallic silver by addition of
acetaldehyde is a well known standard organic reaction." Also, "The
baked ceramic filter candle was soaked in an ammoniacal solution of a
silver salt....."
The authors go on to describe how it is necessary to fire to 600oC,
keeping the kiln atmosphere in reduction so as to insure the silver
remains metalic and bonded to the ceramic. The difference between our
own prior silver nitrate work, here in Nepal, and that of the authors is
that we here did not reduce the silver salts prior to firing. My
speculation is that there is an economy at work here, maximizing silver
to bond and minimizing wast and a lot of expense.
We are taking it as fortuitous that this document is present, and the
research work has already been done and become accepted. Now it is our
intention to do our best in replicating this AgNO3 process, in hopes
this alternative may prove to be of interest. My question now is, what
would the best reducing agent be, for the AgNO3? What the heck is
acetaldehyde, and if this is something uncommon would there then be some
appropriate substitute? I really believe that silver ceramic filters
will take off, all over, if the silver alternatives become understood.
Thanks and cheers,
Reid
** Sited reference, S. R. Deb and R. V. Lele, "A Note on the
Manufacture of Self-Sterilizing Water Filter," Central Glass & Ceramic
Research Institute Bulletin, Calcutta, India. Volume 19, 1972.
Marshall wrote:
I would think nebulizing with CS would be better. The finest silver dust
I have found is available from companies that supply pigments for
paints. But I would not do this.
Marshall
Shirley Reed wrote:
List, anyone know where I can buy silver dust? I have looked in
several places and the smallest particle offered is silve filings. tia
pj ps I have a brother with emphysema and I have read things that
make me feel that inhalation of silver dust might be very advantageous
for him. At this stage he doesn't have a lot to lose even if it
backfires somewhat. Anyway, he can decide for himself. But he does
need some info and some silver dust maybe. haahDo you Yahoo!?
--
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