PNNL

Abstract

As the U.S. Department of Energy Hanford Site in Washington State is in the process of commissioning the Waste Treatment and Immobilization Plant to process a portion of the 54 million gallons of radioactive and chemical waste from Cold War weapon production. Technologies for the capture of volatile species of concern are still being assessed, and new methods and materials are developed as operational and flowsheet mission risks are identified. One such area still being assessed is the abatement efficacy of the Carbon Adsorber units to retain gaseous mercury and 129I released during processing. It is challenging to predict the mercury chemistry due to the variability of the feed, and different methods/materials are required for the capture of gaseous Hg0 and HgII compounds. In this study, the feasibility of using developmental carbon foam (CF) sorbents for the capture of iodine and mercury were assessed using static and dynamic flow testing, and compared against a commercially available sorbent, BATII-37. Results showed that CF functionalized with bismuth particles chemisorbed iodine and had similar mercury capture performance to BATII-37 in dynamic flow tests. Challenges with obtaining accurate concentrations of mercury and iodine – in simple and complex gas streams – are discussed to provide information