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.

Natural gas is one of the critical fossil fuel sources in the world to fulfill current energy demand in the global market. Methane is the primary component in natural gas and its concentration is dependent on the source; a variety of impurities, such as nitrogen, carbon dioxide, oxygen, helium, hydrogen sulfide, water, and heavier hydrocarbons can be present, which reduces the overall fuel quality. Purification of natural gas is important in order to meet the U.S. pipeline and minimum heating value specifications. The separation of nitrogen from methane is challenging because of their similar molecular size (i.e., the two gases differ in kinetic diameter by only 0.16 Å). This Review discusses different methods for separating nitrogen from methane. Of these methods, pressure swing adsorption is one of the most effective techniques for separating nitrogen from natural gas using porous adsorbents, and encouraging results have been demonstrated in the past few decades. Many types of porous adsorbents are discussed here, including carbon molecular sieves, activated carbons, zeolites, titanosilicates, and metal−organic frameworks. Future trends and materials are discussed to put into perspective the new opportunities in this research area.

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