3.4 Iodine desorption experiments
To examine the reusable possibility of shaped silicalite-1, the iodine desorption experiments after iodine adsorption on shaped silicalite-1 were tested at 348 K,373 K and 398 K. The iodine desorption curves are shown in Figure 11. The EDS spectrum and XRD pattern on shaped silicalite-1 after iodine desorption are shown in Figure 12 and Figure 13 respectively. The results showed that the combination of adsorbent and iodine was reversible, and followed a physical combination. Moreover, the higher the temperature, the faster the desorption rate of iodine. Iodine adsorbed under the saturated vapor pressure of iodine at 348 K could be desorbed completely after 6 hours proved by EDS spectrum when the temperature increased at 398 K in Figure 12. Moreover, the structure of shaped silicalite-1 had no change after iodine desorption, manifesting the stability of adsorbent. It can be considered that the shaped silicalite-1 all-silica zeolite could be recycled repeatedly and continued to be used for iodine adsorption, providing the possibility for iodine removal industrial applications.
Figure 11 Iodine desorption curves for silicalite-1 at different temperatures
Figure 12 XRD patterns of silicalite-1