Evaluating the Physisorption and Chemisorption of Iodine on Bismuth-Functionalized Carbon Foams

Bismuth-containing carbon materials have been shown to be highly promising sorbents for the capture of radioiodine. However, there is still a need to understand the effects of carbon and bismuth on the iodine sorption mechanism. In this study, we show the difference in the physical and chemical sorption of iodine under different bismuth loading conditions. Highly porous and nonfriable conductive carbon foams were prepared, and bismuth was electrodeposited to provide strong iodine binding sites. For pure carbon foams, equal ratios of physisorbed and chemisorbed iodine- carbon phases were detected before desorption. As the concentration of bismuth increased, the chemisorption between bismuth and iodine dominated the total capture mechanism, and physisorption was almost completely eliminated. Additionally, chemisorption of iodine depended upon the size and specific surface area of the bismuth clusters present within the framework of the foam.