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Subject: Activated charcoal

Activated charcoal

From: Christoph Waller <cwaller>
Date: Wednesday, July 15, 1998
Helen Coxon <helenc [at] rom__on__ca> writes

>Has anyone any information on activated charcoal treated with iodine
>to make it a sorbent specific for sulphur compounds?
>Secondly, is anyone currently regenerating activated charcoal?

The impregnation of activated carbon with 2% potassium iodide (KI)
significantly accelerates removal of H2S from the air. In this
context, the impregnation with potassium iodide is preferable to
impregnation with Fe2O3 because KI also inhibits the resulting
elementary sulphur to react through to H2SO4. (information taken
from: Henning, K.D.: Impraegnierte Aktivkohlen im Umweltschutz,
Carbotech-Aktivkohlen GmbH, Franz-Fischer-Weg 61 D- 45307 Essen).
Impregnated activated carbons normally can not be regenerated
(without re-impregnation).

KI-impregnated activated carbon might be interesting to use in air
filters, although in this context other sorbents like 'Purafil
Select' might prove completely satisfactory as well. Some producers
of activated carbons say that under normal atmospheric conditions
like in showcases without ventilation there would be no advantage to
use impregnated types - while other producers recommend them even
for this purpose. If anybody knows about experimental evidence in
this matter please let me know.

In passive mode applications like in showcases without ventilation
the surface of the sorbent bed might be an important factor to
consider as well (see p. 138 Grosjean, Daniel et al.: Removal of air
pollutant mixtures from museum display cases Studies in Conservation
36, Nr.3, 1991, pl 129-142). Regarding the removal of H2S from
showcases (passive mode), pure or impregnated activated carbons
should be compared to other specialised sorbents such as Zinc Oxide
catalysts (like G-72 D / S'dchemie), modified Zinc oxide (like
Miracle Sac/ICEL), Pacific Silver Cloth (Springs Ind.), or others
(Feroxyhyte, Copper-Zinc-Cutters...). If anybody knows about a
scientific comparison of such sorbents regarding their passive-mode
efficiency for H2S please let me know.

Christoph Waller
Climate for Art and Showcases
Im Bueckle 4
D-79288 Gottenheim
+49 7665 94 03 90
Fax: +49 7665 94 03 91

                  Conservation DistList Instance 12:11
                   Distributed: Friday, July 17, 1998
                       Message Id: cdl-12-11-001
Received on Wednesday, 15 July, 1998

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