The number of studies on the capture of radioactive iodine compounds by porous sorbents has regained major importance in the last few years. In fact, nuclear energy is facing major issues related to operational safety and the treatment and safe disposal of generated radioactive waste. In particular during nuclear accidents, such as that in 2011 at Fukushima, gaseous radionuclides have been released in the off-gas stream. Among these, radionuclides that are highly volatile and harmful to health such as long-lived ¹²⁹I, short-lived ¹³¹I and organic compounds such as methyl iodide (CH₃I) have been released. Immediate and effective means of capturing and storing these radionuclides are needed. In the present review, we focus on porous sorbents for the capture and storage of radioactive iodine compounds. Concerns with, and limitations of, the existing sorbents with respect to operating conditions and their capacities for iodine capture are discussed and compared.

High pressure water and electrolyte solutions intrusion–extrusion experiments in pure-silica *BEA-type zeolite (zeosil β) were performed in order to study the performances of these systems in energy absorption and storage. The “zeosil β–water” system displays a bumper behavior with an intrusion pressure of 53 MPa and an absorbed energy of 8.3 J g⁻¹. For the “zeosil β–LiCl aqueous solutions” systems the intrusion pressure increases with the LiCl concentration to 95, 111 and 115 MPa for 10, 15 and 20 M solution, respectively. However, for concentrations above 10 M, a transformation of the system behavior from bumper to shock-absorber is observed. The zeolite samples were characterized by several structural and physicochemical methods (XRD, TGA, solid-state NMR, N₂ physisorption, ICP-OES) before and after intrusion–extrusion experiments in order to understand the influence of the LiCl concentration on the intrusion–extrusion behavior. It is shown that the intrusion of water and LiCl solutions with low concentration leads to the formation of Si-(OSi)₃OH groups, whereas no defects are observed under intrusion of concentrated LiCl solutions. A possible mechanism of LiCl solution intrusion based on separate intrusion of H₂O molecules and Li(H₂O)_x ⁺ ions is proposed.

Experimental water intrusion–extrusion isotherms were performed at room temperature on two pure silica MTT- and STF-type hydrophobic zeolites (zeosils) with 1D channel and cage pore systems, respectively by applying or releasing a high hydraulic pressure. These zeosils were obtained by hydrothermal synthesis in fluoride medium and characterized by structural and physicochemical methods before and after water intrusion. The system “MTT-type zeosil–water” displays a spring behavior with an intrusion pressure of 176 MPa and a stored energy of 5.3 J g⁻¹. No influence of water intrusion on the structure of MTT-type zeosil was found. The “STF-type zeosil–water” system shows a combination of shock-absorber and bumper behavior in the first cycle with an intrusion pressure of 51 MPa. Nevertheless in the following cycles the system demonstrates a spring behavior with an intrusion pressure of 38 MPa. Such behavior can be explained by the formation of silanol groups under intrusion in some pores confirmed by NMR spectroscopy and TG data.

An overview of all the studies on high-pressure intrusion—extrusion of LiCl aqueous solutions in hydrophobic pure silica zeolites (zeosils) for absorption and storage of mechanical energy is presented. Operational principles of heterogeneous lyophobic systems and their possible applications in the domains of mechanical energy storage, absorption, and generation are described. The intrusion of LiCl aqueous solutions instead of water allows to considerably increase energetic performance of zeosil-based systems by a strong rise of intrusion pressure. The intrusion pressure increases with the salt concentration and depends considerably on zeosil framework. In the case of channel-type zeosils, it rises with the decrease of pore opening diameter, whereas for cage-type ones, no clear trend is observed. A relative increase of intrusion pressure in comparison with water is particularly strong for the zeosils with narrow pore openings. The use of highly concentrated LiCl aqueous solutions instead of water can lead to a change of system behavior. This effect seems to be related to a lower formation of silanol defects under intrusion of solvated ions and a weaker interaction of the ions with silanol groups of zeosil framework. The influence of zeosil nanostructure on LiCl aqueous solutions intrusion–extrusion is also discussed.

The high pressure intrusion–extrusion process of different electrolyte aqueous solutions (NaCl and CaCl₂, 2 M and 3 M) in a hydrophobic pure-silica LTA zeolite was investigated for energetic purposes by means of in situ X-ray powder diffraction, porosimeter tests, thermogravimetric analysis and NMR spectroscopy. The intrusion pressure of the saline solutions was proved to be higher than that of pure water, with the highest value measured for CaCl₂, thus increasing the energetic performance of the system. The intrusion of NaCl solutions was irreversible (bumper behavior), whereas that of CaCl₂ solutions is partially reversible (shock absorber behavior). The structural investigation allowed interpreting these results on the basis of the different intrusion mechanisms, in turn induced by the different nature of the cations present in the electrolyte solutions. When Si-LTA is intruded by NaCl solution, firstly H₂O molecules penetrate the pores, leading to higher silanol defect formation followed by the solvated ions. With CaCl₂, instead, due to a higher solvation enthalpy of Ca²⁺, a higher pressure is required for intrusion, and both H₂O and ions penetrate at the same pressure. The structural refinements demonstrate (i) a different arrangement of the extraframework species in the two systems, (ii) the intrusion of the salt solutions occurs through strong desolvation of the ions and (iii) the salt/H₂O ratios of the intruded species are higher than those of the starting electrolyte solutions.