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

“…To increase the iodine adsorption capacities of activated carbons, these materials are impregnated with TEDA with a concentration of usually between 0 and 10 wt%. 6,17,27,57,148,151,156,157 However, a decrease in the accessibility of the surface and pores was observed by Chinn et al 158 and González-García et al 147,157 when the TEDA concentration was increased, which can be explained by the formation of TEDA clusters that blocked the entrances of pores. However, despite this phenomenon, it has been recognized that the presence of TEDA in activated carbons increases their iodine capture capacity (especially for CH 3 I).…”

“…For this reason, it is necessary to increase the affinity of activated carbons for iodine species, which can be achieved by functionalizing or impregnating the material with organic and/or inorganic compounds. The commonest compounds used for the treatment and capture of iodine compounds are triethylenediamine (TEDA) 6,18,43,69,73,[147][148][149][150][151][152][153][154][155] and potassium iodide (KI). 18,22,23,43,47,58,149 Recent studies from 2010 to 2017 on the subject have essentially focused on the utilization of activated carbon impregnated with TEDA for the capture of radioactive iodine.…”

“…159 During a severe nuclear accident, in a case in which the cooling system would stop running, the process and/or system would eventually be subject to an increase in temperature. Therefore, it is essential to study the adsorption capacities of activated carbon impregnated with TEDA at high temperatures, taking into consideration the fact that TEDA has a melting point of 158 C and an autoignition temperature of around 330 C. However, it was observed several times, notably in the study by Park et al 73 on activated carbon and in the study by Ampelogova et al 148 on carbon bres, that even at temperatures that are close to its boiling point TEDA maintains an acceptable capacity for the adsorption of methyl iodide thanks to chemisorption-type interactions (reaction of CH 3 I and TEDA to form a quaternary ammonium salt), in contrast to non-impregnated activated carbon, of which the adsorption capacity is controlled by physisorption-type interactions, although it was shown that the adsorption capacity of activated carbon impregnated with TEDA is reduced by a factor of 4 between 30 and 150 C. The contribution of TEDA to the adsorption (chemisorption) of CH 3 I was determined to be 25.4% at 70 C by the authors, whereas this contribution increases to 73.3% at 150 C. These observations conrm that TEDA plays an important role in the capture of methyl iodide at high temperatures in an irreversible way (chemisorption interactions) and can be used up to a temperature of 150 C (below the melting point of TEDA) in nuclear plants. It still needs to be conrmed that the autoignition temperature of TEDA and the thermal effect of its decomposition in the conditions of a real nuclear accident will not be detrimental to the capture performance of these materials.…”

“…Activated carbons are generally impregnated with 0 to 10 wt% KI. 18,20,[24][25][26][27]43,51,148,149,155 Various studies, especially during the 1980s and 1990s, were carried out to determine the performance of the capture of iodine species on activated carbon impregnated with KI (ESI, Table 2 †). Upon an examination of the work by Chien et al, 149 it is clearly observed that potassium iodide signicantly increases the performance of activated carbon in the capture of radioactive iodine species.…”

“…Firstly, it is generally accepted in the scientic community that the aging of activated carbons is perfectly capable of altering their adsorption performance. [25][26][27]148 Deuber 26 studied the performance of activated carbons impregnated with TEDA and/or KI over a time period of 0 to 12 months at 30 C and 130 C with a relative humidity of 95% and 2%, respectively, for various bed lengths. It is clear from the penetration proles that were obtained that the iodine adsorption performance was affected over time.…”