Adsorption of gaseous radioactive iodine by Ag/13X zeolite at high temperatures

Abstract

Ag/13X adsorbents were synthesized, characterized and tested for decontamination of gaseous effluents from 131 I 2 at high temperatures. X-ray diffraction patterns showed that the Ag/13X samples maintained a stable structure after calcined at 650°C for 2 h. The decontamination factors achieved with 15 % Ag/13X and 20 % Ag/13X adsorbents for 131 I 2 were nearly close to 10 3 at 650°C. In addition, 15 % Ag/13X had a stable performance for removal of 131 I 2 at 550 and 650°C, even after calcined at 550 and 650°C for over 10 h, which might be suitable for future potential use during nuclear reactor operation or in the case of nuclear accidents.

Porous sorbents for the capture of radioactive iodine compounds: a review

“…Later, numerous studies were carried out on this topic, especially during the 1970s and 1980s 21,29,34,38,40,47,52,180 and then between 2000 and 2017. 5,8,71,[74][75][76][77][78][79][80][169][170][171][173][174][175][176][177][184][185][186][187][188] These studies focused on the determination of the inuence of various parameters such as the temperature ( C), silver content (wt%), Si/Al ratio, supercial velocity, and pretreatment of the material on the adsorption capacities of silver-exchanged zeolites (ESI, Table 3 †). Other works focused on issues such as aging of the material under different atmospheres (NO x , humidity).…”

“…This ratio was optimal (>99%) for the zeolite with 10 wt% Ag, whereas it was only 85% and 68% for the zeolites with 20 wt% and 30 wt% Ag, respectively, at temperatures between 150 and 200 C. Because silver is expensive, there is interest in the incorporation of an optimal silver content with the highest efficiency. More recently, Cheng et al 188 studied the adsorption of I 2 on a silver-exchanged FAU-type zeolite (AgX) at temperatures between 250 and 650 C. They observed a decontamination factor (DF) in the range of >10 3 for a silver content of greater than 15 wt%, in contrast to 10 1.5 to 10 3 for a silver content of less than 15 wt%. However, only slight differences in the decontamination factor were observed between exchanged zeolites with 15 wt% Ag and 20 wt% Ag, which seems to be in agreement with the study by Choi et al, 71 which implies that there was no real increase in the adsorption capacity at a high silver content.…”

“…Studies for a long time mainly focused on zeolites of the FAU and MOR structural types. 5,8,29,31,34,38,40,47,52,71,[169][170][171]173,175,177,178,182,184,185,187,188 The interest in these two types of zeolites can be explained by their large pore openings, which allow easier diffusion of iodine (I 2 , CH 3 I) and non-iodine (NO x , CO x , H 2 O, etc.) compounds inside the zeolites.…”

Performance of CuII‐, PbII‐, and HgII‐Exchanged Mordenite in the Adsorption of I2, ICH3, H2O, CO, ClCH3, and Cl2: A Density Functional Study

“…Therefore, filtering devices must be improved to efficiently and selectively trap iodine products from this gaseous mixture. One of the most interesting technologies to address this issue is based on inorganic sorbents such as zeolites . These materials have found widespread applications in adsorption and catalytic processes due to their unique properties: ability to exchange ions, high specific surface area, and relatively low cost.…”

Optimization of sulfur adsorption over Ag-zeolite nanoadsorbent by experimental design method

“…1. XRD patterns show several index peaks at 2.18°, 2.79°, 2.89°, 3.33°, 3.79°,7.55°, 8.94°, 14.16°and 38.10°, 44.30°, 64.50°, 78.30°Å (Cheng et al 2015;Wajima and Ikegami 2009;Zhang et al 2013). The same parameters in XRD patterns and Table 3 exhibited similarities between AgX-zeolite and synthesized X-zeolite structure without any change in crystals after metal impregnation and heat process in a furnace.…”