Adsorption of Noble Gases on H-Mordenite

Abstract

Release of nuclear off-gas that contains various radioactive components to the environment could jeopardize public health and safety. Therefore a screening test was carried out to find suitable adsorbents for the removal of the radioactive noble gases from the reprocessing off-gas. The adsorption capacities of various adsorbents for Kr and Xe were investigated. Carbon based adsorbents such as Ambersorb 572, Merck, Ryujou-Shirasagi G2x4/6-3 and Molsievon X2M4/6 were found to have large adsorption capacities. The H-mordenite, a non-carbon based adsorbent prepared from natural mordenite by ion exchange with a HCl solution, demonstrated a large adsorption capacity for Kr almost comparable to that of activated charcoal. Since non-carbon based adsorbents have a very important feature, that is they are not susceptible to fire hazards, the adsorption equilibria of Kr and Xe on the H-mordenite adsorbent were more thoroughly studied. The adsorption experiments on the H-mordenite were conducted in the temperature range of 77 K to 353 K using a packed bed column. The adsorption isotherms obtained for the H-mordenite were successfully correlated with the vacancy solution model over wide partial pressure and temperature ranges.

Fy-12 Inl Kr Capture Activities Supporting the Off-Gas Sigma Team

“…As expected, the Xe capacities at 191 K were over an order of magnitude higher than capacities measured at ambient temperature. 5 As was found with the ambient temperatures, the addition of air did not have a significant impact on Xe capacities at 191 K. However, the addition of air did decrease the Kr capacity by an order of magnitude. Also, when comparing the Kr capacity for the Kr/He gas composition to the Kr/Xe/He gas composition, a Kr capacity decrease of about 30% was measured when Xe is present.…”

Selective Recovery of Radioactive Carbon Dioxide Released from Nuclear Off-gas by Adsorption

“…However, in the nuclear off-gas, other radioactive gases such as Kr and Xe are also coexistent, and thus the adsorption characteristics of these gases need to be considered as well. A pervious study suggests that the natural mordenite adsorbent has larger adsorption capacity for Kr and Xe (1) . The MS5A adsorbent also has moderate adsorption capacity for Kr and Xe (2,3) .…”

Radioactive Iodine and Krypton Control for Nuclear Fuel Reprocessing Facilities

“…Recent investigations into alternative materials, such as inorganic synthetic titanosilicates and MOFs for physisorption, have resulted in a broadened field of new materials for the capture of Kr [52][53][54][55][56][57]. Test results for hydrogen mordenite and silver mordenite have shown good capacities and selectivities for Kr and Xe, indicating that they may be suitable substitutes for activated charcoal thereby eliminating the fire hazard [53,58,59]. Although Xe consists of stable isotopes after about 1 y of UNF aging (about 10 half-lives) and, thus, would not contribute to the regulated radionuclide release, it is present in process offgas streams at about 10 times the Kr concentrations.…”