Capture of harmful radioactive contaminants from off-gas stream using porous solid sorbents for clean environment – A review

Abstract

Nuclear energy production is growing rapidly worldwide to satisfy increasing energy demands. Reprocessing of used nuclear fuel (UNF) is expected to play an important role for sustainable development of nuclear energy by increasing the energy extracted from the fuel and reducing the generation of the high level waste (HLW). However, during the reprocessing of Used Nuclear Fuel (UNF) gaseous radioactive nuclides including iodine, krypton, xenon, carbon, and tritium are released into the atmosphere through off-gas streams.The volatile iodine ( 129 I), and krypton ( 85 Kr) gases have long lived-isotopes; which have adverse effects on the environment as well as human health. Consequently, the capture of these two target radionuclides (species) is essential for the enhanced growth of nuclear energy. In this review we discuss several techniques for capture of volatile contaminants iodine, krypton, and xenon, focusing upon adsorption using solid sorbents, which has shown promising results for more than 70 years. Commonly used and recently developed sorbents are summarized in this article along with a short review of the results. Metal-organicframeworks (MOFs), gaining favor in recent years as sorbents for the capture of off-gas contaminants are also discussed. Finally, some considerations of future trends and prospects for investigations of the capture of volatile radionuclides are presented.

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

“…The main components of such gaseous waste streams include the ssion products technetium ( 99 Tc), cesium ( 137 Cs) and strontium ( 90 Sr), as well as actinides, lanthanides and various volatile radionuclides ( 129 I, 131 I, 3 H, 14 C, 85 Kr, etc.). [5][6][7][8] Particular attention should be paid to iodine compounds, which are particularly abundant. 129 I is a highly volatile long-lived isotope with a half-life (t 1/2 ) of $1.57 Â 10 7 years, which needs to be captured and reliably stored during its long decay.…”

“…for a better understanding of iodine capture and its performance. [74][75][76][77][78][79][80][81] In addition, new porous sorbents have been added to the list of potential sorbents for iodine trapping, including titanosilicates, 82,83 mesoporous silicas, 6,81,[84][85][86] silverimpregnated silica and alumina (Ag/SiO 2 and Ag/Al 2 O 3 , respectively), 19,35,52,61,65,70,[87][88][89][90][91][92][93][94][95][96][97] silver-functionalized aerogels, chalcogels, 7,98-108 macroreticular ion exchange resins, 16,39,41,42,[44][45][46]50,53,55 metal-and covalent-organic frameworks (MOFs and COFs, respectively) 6,14, and porous organic polymers (POPs). [133][134][135]…”

Efficient Capture and Reversible Storage of Radioactive Iodine by Porous Graphene with High Uptake

“…Adsorption method was regarded as an effective and promising one among those traditional methods for iodine capture ,. Up to now, varieties absorbents such as activated carbon, porous organic polymers,, zeolites and Ag‐based materials,, were adopted for the enrichment of radioactive iodine.…”

Extra Unsaturated Metal Centers of Zirconium‐Based MOFs: a Facile Approach towards Increasing CO2 Uptake Capacity at Low Pressure

“…Particularly in frontline processes, carbon capture involving selective gas concentration plays a dominant role in CCSU. Vigorous exploration has been encouraged in the search for favorable material(s) for carbon capture …”