Adsorption Equilibrium and Modeling of Water Vapor on Reduced and Unreduced Silver-Exchanged Mordenite

Abstract

This work is related to the removal of tritiated water and radioactive iodine from off-gases released during spent nuclear fuel reprocessing. Specifically, it is focused on the adsorption equilibrium of water on reduced silver mordenite (Ag0Z), which is the state-of-art solid adsorbent for iodine retention in the off-gas treatment. As the off-gases contain different gas species, including iodine and water, Ag0Z would take up iodine and water simultaneously during the adsorption process. Therefore, understanding the adsorption of water on Ag0Z is important and necessary for studying the performance of Ag0Z in off-gas treatment processes. The isotherms of water (nonradioactive water) on Ag0Z were obtained at temperatures of 25, 40, 60, 100, 150, and 200 °C with a continuous-flow adsorption system. The data were analyzed using the Heterogeneous Langmuir and generalized statistical thermodynamic adsorption (GSTA) models, and thermodynamic parameters of the isotherms were obtained from both models. Both models were found capable of describing the isotherms. Isotherms of water on the unreduced silver mordenite (AgZ) were also obtained at 25, 40, and 60 °C and parametrized by the GSTA model. Through the comparison of the isotherms of Ag0Z and AgZ, it was found that Ag0Z had a higher water adsorption capacity than AgZ. The comparison of their thermodynamic parameters suggested that the interaction of water molecules with the H+ in Ag0Z was stronger than that with the Ag+ in AgZ.

Adsorption of Methyl Iodide on Reduced Silver-Functionalized Silica Aerogel: Kinetics and Modeling

“…The continuous flow adsorption system was used for iodine and water vapor adsorption on multiple materials previously by Nan et al 19,38,39 and Lin et al 40,41 and has been modified for performing the adsorption of CH 3 I on Ag 0 -Aerogel experiments. Figure 1 shows the schematic diagram of the modified adsorption system.…”

Ethylene and Water Co-Adsorption on Ag/SSZ-13 Zeolites: A Theoretical Study

“…Herein, inexpensive Ag was chosen to test its resistance to water adsorption, and also for its high release temperature for hydrocarbons (>200 °C), which would prove very useful for trapping of vehicle emissions. ,− The SSZ-13 zeolite was chosen in this work for its desirable properties such as hydrothermal stability and shape selectivity with regards to adsorbate shape, for automotive emissions control applications. While SSZ-13 is known to be hydrothermally stable, the zeolite can also exhibit shape selectivity for adsorption of small molecules such as ethylene and water due to its small pore size and pore windows. , This work focuses on the adsorption capacity of Ag/SSZ-13 for molecules present in the vehicle exhaust, one of the major considerations for evaluating a trapping material. , Studies have been conducted on the diffusion and adsorption of small molecules, such as methane, ethylene, and water onto zeolites. − , In the most recent of these studies, Jaramillo et al constructed a model using a force-field fit to experimental adsorption isotherms.…”

Adsorption of methyl iodide on reduced silver‐functionalized silica aerogel: Kinetics and modeling

“…The continuous flow adsorption system was used for iodine and water vapor adsorption on multiple materials previously by Nan et al 19,38,39 and Lin et al 40,41 and has been modified for performing the adsorption of CH 3 I on Ag 0 -Aerogel experiments. Figure 1 During the adsorption process, the temperature was controlled by the furnace controller and N 2 was used as the protective gas for the microbalance system.…”