Kinetics of the aging process
Figure 3 shows the effects of dry air and humid air on the performance
of Ag0Z at 150 oC for up to 6
months. Especially, the aged Ag0Z in dry air and humid
air (d.p. -15 oC) showed a significant decrease of
iodine loading capacities. For instance, the aged Ag0Z
in dry air and humid air for 1 month had a capacity loss for iodine by
34.7% and 49.4%, respectively. To obtain insight of the kinetics of
aging on Ag0Z, aging experiments under different
conditions including time (1 day to 1 month), temperatures (100oC to 200 oC), and water vapor
concentrations (d.p. -40 oC to +15oC) were performed.
Iodine loading data of each aged Ag0Z sample was
obtained and compared with the data of deactivation from the chemical
analyses because the iodine capacity loss should be consistent with the
amount of Ag which was oxidized. Figure 7 shows the kinetic data of
iodine loading capacities on the Ag0Z aged in
different gas streams including dry air and humid air (d.p. -40oC, -15 oC, and +15oC) at different temperatures (100oC, 150 oC, and 200oC) for from 1 day to 1 month. The kinetic data shown
in Figure 7 indicated that iodine loading capacities on the aged
Ag0Z decreased with increasing aging temperatures and
time when exposed to off-gas streams, which mean that dry air and humid
air have a negative impact on the iodine loading capacity of
Ag0Z. For example, iodine loading capacities on
Ag0Z aged in dry air (Figure (A)) decreased by 15.5%,
34.8%, and 36.4% at 100 oC, 150oC, and 200 oC after 1 month,
respectively. Iodine loading capacities on Ag0Z aged
in humid air (d.p. -15 oC, Figure (B)) decreased by
42.4%, 44.8%, and 58.2% at 100 oC, 150oC, and 200 oC after 3 days,
respectively. Figure (C) indicates the effect of water vapor
concentration on iodine loading capacity of Ag0Z;
iodine loading capacities were decreased by 34.8% (d.p. -40oC), 44.8% (d.p. -15 oC), and
56.3% (d.p. +15 oC) at 150 oC after
3 days. Results in Figure 7 (B) and (C) show that the effect of humid
air increases with increasing temperatures and water vapor
concentrations. The aging processes for short periods of time are
sensitive to time, so some aging experiments were repeated to make sure
of reliabilities of the results, and marked with standard error bars in
Figure 7.