Porous microsphere of magnesium oxide as an effective sorbent for removal of volatile iodine from off-gas stream

Hydrophobic nanosheet silicalite-1 zeolite for iodine and methyl iodide capture

Effective capture of radioactive iodine from nuclear fuel reprocessing is of great importance for public safety as well as the secure utility of nuclear energy. In this work, a hydrophobic nanosheet silicalite-1 (NSL-1) zeolite with an adjustable size was developed for efficient iodine (I2) and methyl iodide (CH3I) adsorption. The optimized all-silica zeolite NSL-1 exhibits an excellent I2 uptake capacity of 553 mg/g within 45 min and a CH3I uptake capacity of 262 mg/g within 1 h. Benefiting from the reduced thickness and enhanced porosity, microporous NSL-1 possesses enhanced iodine adsorption capacity and fast adsorption kinetics, which is a considerable high value among inorganic materials. Unexpectedly, the remarkable characters of high hydrophobicity, acid-resistance and anti-oxidation endow it a higher iodine uptake capacity than traditional aluminosilicate zeolites. More importantly, the high uptake selectivity toward I2 possessed by NSL-1 owing to its hydrophobic skeleton under simulated dynamic conditions. The low cost, facile and scalable synthesis of NSL-1 further highlights great prospects for applications in the nuclear industry. This work provides useful insights for designing efficient adsorbents for iodine capture.

Efficient capture of radioactive iodine by ZIF-8 derived porous carbon

Due to the rapid diffusion of radioactive iodine, the demand for safe and efficient capture and storage of radioactive iodine is increasing worldwide. The use of porous carbon materials to capture iodine has aroused great interest. This work prepared porous carbon materials derived from polymetallic oxides of the zeolitic imidazolate framework (ZIF) by pyrolysis at 1000 °C. The carbon materials (CZIF-1000) have a high specific surface area of about 1110 m2/g and a total pore volume of 0.92 cm3/g. Adsorption studies have shown that the CZIF-1000 had significant adsorption performance for iodine, and the adsorption capacity can reach 790.8 mg/g at 8h. The potential mechanism of adsorption is that the carbonization causes the charge-transfer interaction and pore size distribution. Compared with the conventional adsorbents, the adsorbents showed faster kinetics and high extraction capacity for iodine. This experiment provides an effective method for designing a highly efficient adsorbent for iodine and broadens the ideas for developing new iodine extraction adsorbents.

Porous ZIF-8@polyacrylonitrile composite beads for iodine capture

The safe and effective capture and storage of iodine from nuclear waste is of great significance in industry. This article reports the preparation of a series of millimeter-sized ZIF-8@polyacrylonitrile composite beads with high specific surface area and porosity by the phase inversion method for iodine capture. The composite beads showed a higher capture capacity (4150 mg g⁻¹) under excess iodine vapor. The amount of iodine adsorbed in the organic solution is also as high as 643 mg g⁻¹, and the adsorption conforms to the Freundlich isotherm and the pseudo-second-order kinetic model. Moreover, composite beads also exhibit higher thermal stability (310 °C). Therefore, ZIF-8@polyacrylonitrile composite beads show great potential as a material for capturing and temporarily storing radioactive iodine.

This article reports the preparation of a series of millimeter-sized ZIF-8@polyacrylonitrile composite beads with high specific surface area and porosity by the phase inversion method for iodine capture.

Nanocage-Based InIII{TbIII}2-Organic Framework Featuring Lotus-Shaped Channels for Highly Efficient CO2 Fixation and I2 Capture

The exquisite combination of independent 3p [In(CO₂)₄] units and 4f [Tb₂(CO₂)₈] clusters in the presence of the designed hexatopic 2,4,6-tri(2,4-dicarboxyphenyl)pyridine ligand engenders one peculiar nanocaged In(III){Tb(III)}₂-organic framework: ({(Me₂NH₂)[InTb₂(HTDP)₂]·3DMF·3H₂O}_n, designated as NUC-5), which features dual types of lotus-shaped channels along the [100] and [110] axes with related node windows of 5.3 × 6.8 and 12.1 × 9.2 Ų, respectively. To the best of our knowledge, except several coexisted 3p-4f In/Ln clusters of {In₃Ln}- and {In₃Ln₂}-based metal-organic frameworks (MOFs), NUC-5 is one novel type of In/Ln heterometallic framework. In addition, its topology was an unprecedented 3D TAYZIC net with a Schläfli symbol of {4.⁴6²}{4.⁵6⁵}₂{4.⁶6.⁸8}. Moreover, activated NUC-5 is proved to be one efficient adsorbent for CO₂ and one recycled cycloaddition catalyst for the transformation of epoxides into related carbonates with high yields under mild conditions. Furthermore, the excellent reversible sorption performance for I₂ in the volatilization phase or in cyclohexane solution with a maximum adsorption capacity of 609.1 mg/g (3.75 iodine molecules per unit cell) makes NUC-5 a promising adsorbent for radioactive products of ¹²⁹I and ¹³¹I in the field of nuclear industry. This study provides one synthetic strategy that the original nature of MOFs could be enhanced by introducing some specific function-prompted inorganic subunits with the aid of predesigned supporting ligands.

Porous MOF-808@PVDF beads for removal of iodine from gas streams

The removal of radioiodine from the exhaust gas streams produced in spent fuel reprocessing plants is of paramount importance for the nuclear fuel cycle's security. Here, millimeter-sized poly(vinylidene fluoride) (PVDF) composites containing zirconium-based metal–organic frameworks, MOF-808, were synthesized by a facile phase inversion method to adsorb the volatile iodine. MOF-808@PVDF composites have inherited the crystallinity and pore accessibility of MOF-808, as well as its outstanding iodine capture performance. The MOF-808@PVDF composite beads containing 70 wt% MOFs, exhibited ultrahigh iodine adsorption capacity, 1.42 g g⁻¹ at 80 °C, much higher than other millimeter-sized adsorbents reported in the literature. Raman mapping suggests that the negative iodine ions were formed at the early stage of iodine adsorption, while the close-packed iodine molecules were subsequently trapped in the frames. Using dynamic adsorption, the influences of iodine concentration, operating temperature and humidity were analyzed to evaluate its application potential in industrial conditions. The iodine adsorption capacity could reach 1.36 g g⁻¹ at 80 °C, 100 °C and 120 °C in flow gas. And the elevated temperature (120 °C) is beneficial to accelerating the mass transfer of iodine vapor, as well as slightly inhibiting the competitive adsorption of water molecules under humidity. Besides, only one-third of the loaded iodine was released in nitrogen purging after saturated adsorption. The remaining majority was trapped firmly by the beads due to their strong interactions with the frameworks. This work highlights the millimeter-sized MOF-808@polymer composite beads with ultrahigh iodine adsorption capacity, providing experimental references for their application in radioiodine removal from hot and moist streams.

Porous millimeter-sized MOF-808@PVDF composite beads with ultrahigh iodine adsorption capacity for capture of radioiodine from gas streams.

Millimeter-sized Bi2S3@polyacrylonitrile hybrid beads for highly efficient iodine capture

Chemisorption of iodine by forming BiI₃was the main capturing mechanism of Bi₂S₃@PAN for iodine.

Controllable Synthesis of Porous Cu-BTC@polymer Composite Beads for Iodine Capture

The efficient and safe capture of radioactive iodine (¹²⁹I or ¹³¹I) is of great significance in nuclear waste disposal. Here, we report millimeter-scale poly(ether sulfone) composite beads loaded with porous Cu-BTC [Cu₃(BTC)₂, BTC = 1,3,5-benzenetricarboxylate] (Cu-BTC@PES), prepared by a phase inversion method for the removal of volatile iodine. Three kinds of Cu-BTC@PES composite beads were obtained with different Cu-BTC contents of 48.6, 60.2, and 71.9%, respectively. While maintaining crystallinity, the composite beads exhibited higher I₂ vapor adsorption capacity (639 mg/g) in the form of iodine molecules. The iodine absorption up to 260 mg/g and the adsorption was followed Langmuir isotherm and pseudo-second-order kinetic model. Furthermore, the composite beads can still absorb more than 85% of iodine after 3 cycles of regeneration with excellent recyclability. The resulting Cu-BTC@PES composite beads show great potential for the sustainable removal of radioactive iodine.

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

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.

In the capture of radioactive iodine compounds by porous sorbents, concerns with, and limitations of, the existing sorbents with respect to operating conditions and their capacities for iodine capture are discussed and compared.

Hierarchically structured magnesium based oxides: synthesis strategies and applications in organic pollutant remediation

In this highlight, we review the design and formation of MgO based hierarchical structures and cover some selected examples on their applications in adsorption of organic contaminants.