Examining Practical Application Feasibility of Bismuth-Embedded SBA-15 for Gaseous Iodine Adsorption

Abstract

The purpose of this study is to examine the feasibility of using bismuth-embedded SBA-15 (Bi-SBA-15) as gaseous iodine filtration material for applications at higher temperatures, such as environmental release severe accident mitigation, while reducing the cost of production and maintaining its iodine adsorption capacity. It was shown that Bi-SBA-15 can be produced in a much more economically feasible way by (1) increasing the amount of the chemical reagents for SBA-15 synthesis, (2) decreasing the amount of other chemicals required to facilitate the chemical reactions, and (3) reducing the synthesis time, all while maintaining the iodine adsorption capability. Through both closed and open iodine adsorption experiments, it was shown that Bi-SBA-15 has a much higher adsorption capacity than silver-exchanged zeolites at 423°K (150°C) but decreases sharply as the temperature increases, resulting in about half of the iodine adsorption capacity of AgX at 523 K (250°C). Assuming that the commercialized cost of Bi-SBA-15 could be less than half of silver-exchanged zeolites, Bi-SBA-15 may be able to replace silver-exchanged zeolites at higher-temperature applications but only if the temperature of the gaseous iodine is less than 423 K (150°C) or if there is a presystem such as a pool scrubber to reduce the temperature of the gaseous iodine reaching the iodine filtration system. If Bi-SBA-15 can be produced much less expensively at a small fraction of cost compared with silver-exchanged zeolites, it may even be used at a temperature up to 523 K (250°C) with high enough iodine capture efficiency by simply increasing the mass of Bi-SBA-15 to more than double the mass of the required silver-exchanged zeolites.