Aging effects of off-gas streams on the aged
Ag0Z
The data of iodine adsorption on the aged adsorbents are placed in
Figure 3 which show iodine loading capacity on the
Ag0Z aged in dry air (d.p. < -70oC) and humid air (d.p. -15 oC) at
150 oC for up to 6 months (1 week ~ 6
months). Iodine loading capacity of the Ag0Z decreases
after being aged in dry air and humid air. The aged
Ag0Z samples in dry air for 1 week indicates that
iodine loading capacity decreases to 10.5 wt.% from 12.3 wt.% (unaged
Ag0Z), and further decreases to 8.0 wt.% after being
aged for 1 month. Iodine loading capacity of Ag0Z aged
in dry air for 1, 2, and 4 months shows similar drops which indicate no
further degradation occurs during aging process over 1 month. A modest
drop is observed after being aged for 6 months, but it could merely be
owing to an experimental deviation caused by material nonuniformity. For
the humid air aged Ag0Z, iodine loading capacity
decreases to roughly 6 wt.% which is dropping more rapidly than dry
air. No further significant drops are observed after 1 month. Compared
to the dry air aged Ag0Z, these results suggest that
the degradation rate increases as water is included in the air stream.
The decrease of maximum iodine loading capacity on both dry air aged and
humid air aged Ag0Z as a function of aging time are
consistent with previous studies5, 6 which show that
dry air stream leads to a roughly 40% iodine capacity loss over 6
months and humid air stream leads to a roughly 50% iodine capacity loss
over 6 months. However, the results of the aged Ag0Z
in humid air show less iodine capacity loss than previous
studies5, 6. It is because a higher dew point of humid
air (+15 oC) was used in previous studies than a dew
point of humid air (d.p. -15 oC) used in this study.
It is appropriate to expect that the lower concentration of water vapor
used in this study would result in a less deactivation which is
consistent with the following discussion on Figure 7. To summarize, in
terms of iodine adsorption capacity loss on both dry air and humid air
aged Ag0Z, the aging effect of the humid air (d.p. -15oC) is higher than that of dry air.