Airborne elemental iodine loading capacities of metal zeolites and a method for recycling silver zeolite

Evaluation of Getter Metals in Na–Al–Si–O Aerogels and Xerogels for the Capture of Iodine Gas

“…However, some sorbents have different binding mechanisms from physisorption to molecular sieving (e.g., graphene, MOFs). Several studies have focused on assessing metal-exchanged zeolites including the metals Cd, Cu, Hg, Mn, Pb, Pd, and Tl. − The approach of using a porous scaffold provides a means of allowing a gaseous stream containing I 2(g) to flow through the sorbent and have a higher probability of getter–I 2(g) interactions. Thus, the higher the specific surface area (SSA) present within the sorbent, the greater the opportunity for these interactions. …”

Structure–Activity Relationships between the State of Silver on Different Supports and Their I2 and CH3I Adsorption Properties

“…One efficient technological approach to overcome such releases is to trap the released iodine forms onto a sorbent. Owing to the possibility of forming thermally stable and insoluble AgI precipitates, silver-loaded materials were identified as efficient candidates for the trapping of methyl iodide, molecular iodine, and iodide ions at an industrial scale [ 5 , 6 , 7 , 8 ]. The most studied silver-based adsorbents for the capture of volatile iodine are silver zeolites and silver supported on various forms of silica.…”

Evaluation of Silver Zeolites Sorbents Toward Their Ability to Promote Stable CH3I Storage as AgI Precipitates

“…Existing FCVS technologies, which could be classified as “dry” and “wet”, are known to be efficient for aerosol retention, but much less for volatile iodine (I 2 and organic iodides). − Among “dry” systems, sorbents based on molecular sieves and activated carbons present a great interest because of their extended trapping surfaces . In that respect, inorganic sorbents such as silver zeolites were identified from pioneering works in the 1970s for their ability to promote stable iodine trapping by formation of AgI precipitates. − Moreover, silver zeolites are expected to be robust and to withstand elevated temperatures, humidity, irradiation, and oxidizing conditions. Under SA conditions, the efficiency of iodine trapping may be impacted by the nature of the sorbent itself, but also by temperature, bed dimensioning/flowing conditions, irradiation, as well as potential inhibitors such as steam and other gases. ,, Usually, retention performances are determined by a Decontamination Factor (DF), which represents the ratio of iodine concentrations measured at the inlet and outlet of a sorbent bed.…”

“…DF measurements are useful to compare the filtration efficiency of several sorbents for a given set of operating conditions (provided the sensitivity of the detection technique is sufficiently high) but fail in providing crucial information on the trapping stability or on trapping mechanisms. Although many zeolite structural types exist, most of investigations have been limited to Ag/X and Ag°/MOR zeolites. ,, These sorbents showed good filtration behavior under normal operating conditions (with DF about 10 3 –10 4 − ), but numerous uncertainties remain under SA conditions, especially regarding the stability of iodine trapping. Hence, a remaining gap for the application of silver zeolites in nuclear power plants is the lack of information available on the impact of zeolite structure and silver content on retention properties.…”