Effects of Zeolitic Parameters and Irradiation on the Retention Properties of Silver Zeolites Exposed to Molecular Iodine

Azambre, B.; Chebbi, Mouheb; Leroy, Olivia; Cantrel, Laurent

doi:10.1021/acs.iecr.7b03579

Cited by 42 publications

(33 citation statements)

References 22 publications

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“…DR-UV-Vis spectroscopy was used in order to provide complementary information on the electronic state of silver species incorporated within the investigated supports prior to calcination. According to the literature studies by us and others [ 14 , 15 , 16 , 17 , 30 , 33 , 34 , 35 ], the absorptions relevant to Ag + cations in different environments are usually found in the range 200–240 nm, whereas the plasmon resonance of silver nanoparticles is responsible of broad absorption bands in the visible region. Other signals are more difficult to assign, but it is generally admitted that charged and metallic clusters (Ag n δ+ and Ag ° m ) yield absorptions at 240–280 nm and 280–350 nm, respectively [ 14 , 15 , 16 , 17 , 30 , 33 , 34 , 35 ].…”

Section: Resultsmentioning

confidence: 99%

“…[ 9 , 10 ]. Indeed, we and others have tested a large panel of silver zeolite configurations (nature of cation, Si/Al ratio, zeolitic structure) by experimental and computational means in order to gain insights about the most prominent parameters affecting the retention of volatile iodine [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. Some silver zeolites are now still currently investigated at industrial scale in France for their future incorporation in Filtered Containment Venting Systems (FCVS).…”

Section: Introductionmentioning

confidence: 99%

“…Although many studies are available in the open and industrial literature about the performances of silver-based sorbents for the capture of iodine, the lack of adequate characterization data represents a strong limitation towards the understanding of the parameters governing the adsorption of I 2 or CH 3 I from a material viewpoint. Only recently, the relationships existing between the adsorption performances and the main physicochemical characteristics of the materials were identified for silver zeolites [ 14 , 15 , 16 ]. In that respect, we found that the silver oxidation state (Ag° or Ag + ) as well as its content and dispersion in the pore system of the host support are the most important parameters governing the adsorption performances for I 2 or CH 3 I [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

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

2021

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In this study, the performances of silver-impregnated adsorbents prepared from different host supports (SBA-15, alumina, ceria, and faujasite Y zeolite) and calcined or not at 500 °C (1 h) were compared for the capture of I2 and CH3I. By keeping the silver content rather similar (about 15–17 wt %) among the sorbents, it was possible to assess the effect of silver dispersion and speciation on the adsorption capacities measured for both adsorbates. In a first part, several characterization techniques (XRD, DRS-UV-Vis, TEM, etc.) were used to probe the state of silver in the calcined and non-calcined materials. It was found that the characteristics of silver species are strongly influenced by the thermal treatment, the presence or absence of exchange sites, and the stability of the supports. Silver agglomeration was enhanced after calcination at 500 °C especially for supports bearing no exchange sites (SBA-15) or no ordered pores (alumina and ceria). Then, the adsorption performances of the studied silver sorbents were discussed in relation with their physicochemical characteristics. After-test characterizations were useful to assess the proportion of silver species that have reacted with CH3I and I2 to yield AgI precipitates. Depending on the adsorbate, different trends were obtained. I2 adsorption/reaction with silver sites was found to be quantitative (I/Ag ≈1), whatever the silver speciation and dispersion on the support. By contrast, a high proportion of cationic silver species was found essential to increase CH3I adsorption (I/Ag about 0.6–0.7 against 0.2–0.3 for Ag agglomerated species).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2021

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“…Since the Fukushima disaster in 2011, many efforts were devoted to revisit the behavior of zeolitic sorbents because they were identified to present potentially satisfying performances even under severe accidental conditions [12][13][14][15]. Nevertheless, and before their potential application in FCVS-equipped nuclear power plants, several important issues remained to be solved about the effect of zeolitic parameters on their adsorption behavior, especially under extrapolated accident conditions (ionizing and oxidative conditions, presence of inhibitors (H 2 O, CO x , NO x , H 2 , chlorine compounds…), working temperature 25-250°C [16]…).…”

Section: Introductionmentioning

confidence: 99%

Effects of the cation and Si/Al ratio on CH3I adsorption by faujasite zeolites

Azambre

Chebbi

Hijazi

2020

Chemical Engineering Journal

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In this study, we aimed to investigate the effects of some specific zeolitic parameters on the retention properties of metal-exchanged faujasites (X and Y) for methyl iodide. In the first part, the nature of exchangeable cation (H + , Na + , Cu + /Cu 2+ , Ag + , Pb 2+) is discussed. In order to link the materials properties with the adsorption behaviour, the state and location of the exchanged transition metals after calcination at 500°C were first investigated using N 2 sorptiometry at 77K, DRS-UV-Vis spectroscopy, XRD and FTIR of adsorbed CO and NO. Adsorption capacities at breakthrough and saturation were obtained from CH 3 I breakthrough curves obtained at 100°C, this temperature being relevant to severe nuclear accident conditions. From the I/M ratio computed at saturation of the adsorbents by CH 3 I vapors, it was found that the efficiency of iodine trapping follows the order Cu + /Cu 2+ > Ag + >> Pb 2+ > Na + > H +. This efficiency roughly followed the trend of the different cations to form stable MI x precipitates from CH 3 I. Nevertheless, for nuclear application, it was found that Ag/FAU are preferred over Cu/FAU, due to the propension of the latter to oxidize CH 3 I to I 2 , which slips out of the sorbent bed at 100°C. The effect of the preparation method (ion-exchange vs impregnation) is then discussed for Ag/Y zeolites having different Si/Al ratio (2.5 and 40) but similar silver content (23 wt%). It is found that the silver oxidation state and silver dispersion have important effects on CH 3 I adsorption/desorption.

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“…It is worth noting that 808-PVDF0.7 shows the highest iodine adsorption capacity among the MOFs beads and other pellets, including commercial zeolite Ag/13X comm . 33 We also test the adsorption performance under an 18% RH at 80 C. As shown in Fig. 4(b), the three 808-PVDFx beads have a lower weight gain, exhibiting the similar patterns as their powder counterparts, due to the hydrophilic Zr nodes in the MOFs.…”

Section: Characterization Of Mof-808 Beadsmentioning

confidence: 97%