Development and evaluation of a silver mordenite composite sorbent for the partitioning of xenon from krypton in gas compositions

Abstract

A new engineered form composite sorbent for the selective separation of xenon from krypton in simulant composition off-gas streams resulting from the reprocessing of used nuclear fuel has been developed and evaluated. A sodium mordenite powder was incorporated into a macroporous polymer binder, formed into spherical beads and successfully converted to a 9 wt.% silver form composite sorbent. The final engineered form sorbent retained the characteristic surface area indicative of sodium mordenite powder. The sorbent was evaluated for xenon adsorption potential with capacities measured as high as 30 millimoles of xenon per kilogram of sorbent achieved at ambient temperature and 460 millimoles of xenon per kilogram sorbent at 220 K. Xenon/krypton selectivity was calculated to be 22.4 with a 1020 µL/L xenon, 150 µL/L krypton in a balance of air feed gas at 220 K. Adsorption/desorption thermal cycling effects were evaluated with results indicating sorbent performance was not significantly impacted while undergoing numerous adsorption/desorption thermal cycles.

Iodine Capture with Metal-Functionalized Polyacrylonitrile Composite Beads Containing Ag0, Bi0, Cu0, or Sn0 Particles

“…To further remove DMSO, the beads were placed in fresh DIW baths to help drive the diffusion process by maintaining the concentration gradient. It is likely that different polymers could be implemented in a similar technique, but PAN was selected based on success of implementing this same process to create other hybrid sorbents. ,− …”

“…X-ray absorption near-edge structure (XANES) analyses, including Bi L 3 and I L 3 edges, were also conducted on the Bi-containing materials. This work was based off our previous study evaluating pure metal wires without the porous polymer scaffold, and the 75 mass% loadings used were based off previous work on embedding active particle or powdered sorbents into PAN composites. ,− Due to kinetics limitations of iodine vapors reacting through thick (0.5 mm) wires from a separate study, small particles were selected instead for use in the current study as the active metal sites.…”

Role of Zeolite Structural Properties toward Iodine Capture: A Head-to-head Evaluation of Framework Type and Chemical Composition

“…These materials are connected through an open network of corner-shared tetrahedra (e.g., SiO 4 4– and AlO 4 5– ) with charge balancing provided to the negatively charged framework by cations (e.g., Na + and Ca 2+ ). Zeolites have a wide range of applications, including molecular sieving, water softening, catalysis, carbon capture, and separations. − Zeolites have also been used to remove a range of radioactive contaminants from aqueous or gaseous streams or for immobilizing nuclear wastes in waste forms. − …”

Densification and Immobilization of AgI-Containing Iodine Waste Forms Using Spark Plasma Sintering

“…The main diffraction peaks for the AgI-MOR samples were AgI phases, but some mordenite peaks were shown in the SPS pellets. For the mordenite phase, Na 5.5 (Al 6 Si 42 O 96 )(H 2 O) 19.44 (ICSD 98841) was used to fit the data, as there was no matching Ag-MOR phase; also, the existence of water in the structure at 700 °C is probably an incorrect assumption. For AgI-MOR-2, made at 700 °C for 30 min, the presence of SiO 2 was observed.…”

“…Based on this reaction of Ag with iodine, Ag-based sorbents have been in development for many years for the remediation of gaseous iodine. The majority of this work has included research on Ag-based zeolites including Ag-mordenite (Ag-MOR also called AgZ) − but other zeolites have been studied including Ag-faujasite (Ag-FAU, also called AgX or AgY), Ag-BEA, Ag-FER, Ag-MFI, and Ag-TON. − Additionally, studies on Ag-functionalized aerogels − and xerogels − have been done recently to compare these alternative and amorphous scaffolds to their crystalline zeolite counterparts. Recent studies on reactions between iodine and pure Ag metal have also been done, , and all of these studies confirm the high affinity of Ag for iodine in different forms from the nanometer-scale to the bulk scale.…”