Immobilization Of Iodine Research Articles

Construction of nitrogen-rich groups @ zirconium-based metal-organic frameworks for efficient iodine capture

Efficient capture of radioactive iodine serves as an inevitable demand for secure utilization of nuclear energy, environmental conservation, and human health. In this contribution, a series of iodine adsorbent materials Im@UiO-66 were fabricated by encapsulating imidazole (Im) molecules into the pore of a classical zirconium-based metal–organic frameworks UiO-66, employing a simple and feasible vapor-diffusion strategy. Compared with original UiO-66, the resulting composites achieved a significant enhancement in iodine capture performance. Particularly, Im@UiO-66-3 demonstrated outstanding iodine adsorption performance with capacities of 4.66 g g−1 for vapor and 915 mg g−1 for solution, which were 3.5 and 9.2 times of the original UiO-66, respectively. Moreover, the introduction of nitrogen through ligand encapsulation provided additional sites for iodine immobilization. The primary mechanism underlying this remarkable performance was identified as charge transfer between iodine and imidazole (Im) molecules. The research offers valuable insights for the design of high-efficiency iodine adsorbents.

Recent Advances in Metal-Organic Frameworks and Their Derivatives for Adsorption of Radioactive Iodine.

Radioactive iodine (131I) with a short half-life of ~8.02 days is one of the most commonly used nuclides in nuclear medicine. However, 131I easily poses a significant risk to human health and ecological environment. Therefore, there is an urgent need to develop a secure and efficient strategy to capture and store radioactive iodine. Metal-organic frameworks (MOFs) are a new generation of sorbents with outstanding physical and chemical properties, rendering them attractive candidates for the adsorption and immobilization of iodine. This review focuses on recent research advancements in mechanisms underlying iodine adsorption over MOFs and their derivatives, including van der Waals interactions, complexing interactions, and chemical precipitation. Furthermore, this review concludes by outlining the challenges and opportunities for the safe disposal of radioactive iodine from the perspective of the material design and system evaluation based on our knowledge. Thus, this paper aims to offer necessary information regarding the large-scale production of MOFs for iodine adsorption.

Hidden Role of Organic Matter in the Immobilization and Transformation of Iodine on Fe-OM Associations.

The biogeochemical processes of iodine are typically coupled with organic matter (OM) and the dynamic transformation of iron (Fe) minerals in aquifer systems, which are further regulated by the association of OM with Fe minerals. However, the roles of OM in the mobility of iodine on Fe-OM associations remain poorly understood. Based on batch adsorption experiments and subsequent solid-phase characterization, we delved into the immobilization and transformation of iodate and iodide on Fe-OM associations with different C/Fe ratios under anaerobic conditions. The results indicated that the Fe-OM associations with a higher C/Fe ratio (=1) exhibited greater capacity for immobilizing iodine (∼60-80% for iodate), which was attributed to the higher affinity of iodine to OM and the significantly decreased extent of Fe(II)-catalyzed transformation caused by associated OM. The organic compounds abundant in oxygen with high unsaturation were more preferentially associated with ferrihydrite than those with poor oxygen and low unsaturation; thus, the associated OM was capable of binding with 28.1-45.4% of reactive iodine. At comparable C/Fe ratios, the mobilization of iodine and aromatic organic compounds was more susceptible in the adsorption complexes compared to the coprecipitates. These new findings contribute to a deeper understanding of iodine cycling that is controlled by Fe-OM associations in anaerobic environments.

Copper tellurite glass for radioactive iodine immobilization

Radioactive iodine-129 can easily diffuse into the environment and possesses a half-life of 1.57 × 107 years. Therefore, durable and stable waste forms are required for the treatment I-129. In this study, CuI·Cu2O·TeO2 glasses were fabricated by incorporating CuI into a copper tellurite glass (0.3Cu2O·0.7TeO2) matrix at different concentrations ranging from 0 to 30 mol%. The X-ray diffraction analysis confirmed the amorphous phase of all prepared samples, and X-ray fluorescence analysis verified iodine volatilization during the melting process. With the addition of 30 mol% CuI, the maximum iodine loading was approximately 13.79 wt%. X-ray photoelectron spectroscopy and Raman spectroscopy were used to understand the structure of the CuI·Cu2O·TeO2 glass waste forms. As the CuI content increased in the glass matrix, there was an increase of +2-valent Cu and OBO. It was further confirmed that there were no significant changes in the structure of Te, which serves as the glass network former. Furthermore, all samples satisfied the US regulation of 2 g/m2 for the normalized release of all elements, as confirmed through the product consistency test. The proposed glass waste forms have cost advantages over previously developed silver-based glasses, making them a promising avenue for further research.

High-performance rechargeable aqueous zinc-iodine batteries via a dual strategy of microporous carbon nanotubes for cathodic iodine immobilization and modified separator

Compared with lithium-ion battery, aqueous rechargeable zinc-iodine is of interest due to their high safety and low cost. Unfortunately, the host material's low conductivity, small specific surface area, shuttling effect, and high soluble iodine species (I2, I-, and I3-) are inhibiting its wide development. In this work, a dual strategy of fixing iodine active material with nanotubular microporous carbon (MCN) and modified cotton fiber separator (MCN@CF) is employed to solve the above-mentioned problem. The Zinc-ion batteries (ZIBs) assembled with an MCN/I2 cathode and MCN@CF separator show up to 162 mA h g-1 of reversible initial capacity with 85 % capacity retention at 100 mA g-1 after 100 cycles. Moreover, besides featuring excellent long-term cyclability, MCN@CF battery delivers a Coulombic efficiency of 99 % over 2000 cycles with a current density of 1 A g-1. This study would lead to opening of a new paradigm for the development of highly reversible aqueous rechargeable ZIBs.

Core–shell Ag@polypyrrole for synchronous pre-enrichment and immobilization of iodine (I−, IO3−) from liquid radioactive wastes

A core–shell silver-encapsulated polypyrrole, Ag@PPy, was prepared via in situ synthesis for simultaneous efficient adsorption and immobilization of iodide and iodate.

Silver tungstate–tellurite glass for radioactive iodine immobilization

The use of 235U as a fuel in nuclear power plants results in the formation of various fission products. Among them, 129I exhibits a long half-life (t1/2 = 15.7 million years) and tends to easily volatilize, making its capture and treatment necessary. In this study, silver tungstate–tellurite glass (Ag2O·WO3·TeO2 with different mol% of AgI loading) was developed for radioactive iodine immobilization. The glass matrix was investigated by varying the fraction of Ag2O and/or WO3. AgI was added to each matrix, ranging from 0 to 40 mol% in increments of 10 mol%. The glass samples were prepared by the melt-quenching process at 850 °C for 90 min. X-ray fluorescence analysis indicated no significant loss of elements in the samples, whose amorphous phase was confirmed by X-ray diffraction analysis. The effects of increasing the amount of AgI on the glass matrix are discussed considering the results of X-ray photoelectron spectroscopy. The leaching properties of all samples were evaluated via the product consistency test-A. Finally, the normalized release of all elements satisfied the US regulation of 2 g/m2.

Pyrazole-directed functionalization of activated collagen fiber for highly specific capture of iodine vapor

The highly specific capture of radioactive iodine vapor generated during spent fuel reprocessing exerts a pivotal influence on ensuring the sustainable development of nuclear energy. In this study, we successfully prepared pyrazole-directed functionalized leather waste collagen fiber composite (Pyrazole@ACF) by immobilizing pyrazole ring through Schiff base reaction on the alkaline-activated collagen fiber (ACF) interface. The peak capacity for capturing iodine vapor by Pyrazole@ACF is shown to be 3.494 g/g, which is markedly higher compared to that of ACF (0.928 g/g). Pyrazole@ACF was characterized using FE-SEM, FT-IR, and XPS, revealing the release of numerous active functional groups from ACF that facilitated iodine-induced capture and pyrazole ring immobilization. Furthermore, the interaction mechanism between functional groups and iodine was further elucidated through Density Functional Theory (DFT) calculations. The iodine capture effect of Pyrazole@ACF is primarily ascribed to the existence of active functional groups (C = O, –OH, and –NH2) on ACF, as well as the charge transfer occurring between the grafted pyrazole moieties and iodine, ultimately leading to the generation of I3− polyiodide complexes and subsequent iodine capture. Consequently, Pyrazole@ACF exhibits a strong specific capture capability for iodine vapor, along with excellent thermal stability and iodine immobilization properties, meeting the application requirements under practical conditions.

2D Mesoporous Naphthalene‐Based Conductive Heteroarchitectures toward Long‐Life, High‐Capacity Zinc‐Iodine Batteries

AbstractNowadays, rechargeable aqueous zinc‐iodine batteries have attracted extensive attention due to their low cost, high safety, and high theoretical capacity. However, the poor electrical conductivity of iodine and the shuttling effect of soluble polyiodide ions impose an insurmountable constraint on their performance. Here, a facile soft‐hard‐templated co‐assembly strategy is proposed to fabricate naphthalene‐based heteroarchitectured conductive nanosheets with ordered mesopore arrays (≈10 nm), uniform thickness (24.5 nm), high specific surface area (221.5 m2 g−1), and good electronic conductivity (3.9 × 10−3 S cm−1). Density function theory calculation and systematic experimental results show that the complementary combination of the 2D polar semiconducting polymer chains and conductive carbon framework enables the highly efficient immobilization of iodine and then constrains their shuttling effect through strong physicochemical interactions. Accordingly, the resultant zinc‐iodine batteries deliver a high specific capacity of 271.4 mAh g−1, excellent rate capability, and impressive long‐term cycling stability (35 000 cycles at a high current density of 10 A g−1), superior to most of the previous reports. This study opens new venues for rationally constructing heteroarchitectured porous materials for energy storage applications.

Three-Dimensional-Network-Structured Bismuth-Based Silica Aerogel Fiber Felt for Highly Efficient Immobilization of Iodine.

The effective capture and deposition of radioactive iodine in the spent fuel reprocessing process is of great importance for nuclear safety and environmental protection. Three-dimensional (3D) fiber felt with structural diversity and tunability is applied as an efficient adsorbent with easy separation for iodine capture. Here, a bismuth-based silica aerogel fiber felt (Bi@SNF) was synthesized using a facile hydrothermal method. Abundant and homogeneous Bi nanoparticles greatly enhanced the adsorption and immobilization of iodine. Notably, Bi@SNF demonstrated a high capture capacity of 982.9 mg/g by forming stable BiI3 and Bi5O7I phases, which was about 14 times higher than that of the unloaded material. Fast uptake kinetics and excellent resistance to nitric acid and radiation were exhibited as a result of the 3D porous interconnected network and silica aerogel fiber substrate. Adjustable size and easy separation and recovery give the material potential as a radioactive iodine gas capture material.

Iodine Capture by Ag-Loaded Solid Sorbents Followed by Ag Recycling and Iodine Immobilization: An End-to-End Process

The article demonstrates the complete process of I2(g) capture using Ag-exchanged faujasite (AgX) and Ag-exchanged mordenite (AgZ) zeolite sorbents, the recovery of Ag for recyclability of iodine capture, and the immobilization of iodide (from the elution process) into an iodosodalite waste form, which is chemically and environmentally stable. The gaseous iodine, I2(g), was captured in the AgX via chemisorption by Ag and converted to AgI within the aluminosilicate zeolite frameworks. The elution reaction in Na2S resulted in the precipitation of Ag2S and dissolution of I– and Na+ into the aqueous solution, where powdered sorbent showed higher conversion efficiency than the granular form, which is attributed to Na2S-solution diffusion limitations in the granules. The Ag2S-containing aluminosilicate precipitates were filtered out of the solution, and the filtrate (aqueous solution) was used to synthesize iodosodalite to immobilize iodide. The iodine capture using the recovered Ag2S-containing sorbents shows equivalent iodine loadings to the AgX starting material of Qe = 0.355 g/g for powdered material and 0.255 g/g for granular material, demonstrating the potential recycling of Ag for iodine capture as Ag2S-based sorbents.

Recent advances in the removal of radioactive iodine by bismuth-based materials.

Nowadays, the demand for nuclear power is continue increasing due to its safety, cleanliness, and high economic benefits. Radioactive iodine from nuclear accidents and nuclear waste treatment processes poses a threat to humans and the environment. Therefore, the capture and storage of radioactive iodine are vital. Bismuth-based (Bi-based) materials have drawn much attention as low-toxicity and economical materials for removing and immobilizing iodine. Recent advances in adsorption and immobilization of vapor iodine by the Bi-based materials are discussed in this review, in addition with the removal of iodine from solution. It points out the neglected areas in this research topic and provides suggestions for further development and application of Bi-based materials in the removal of radioactive iodine.

High Retention Immobilization of Iodine in B-Bi-Zn Oxide Glass Using Bi2O3 as a Stabilizer under a N2 Atmosphere.

The immobilization of iodine waste suffers from serious iodine loss during heat treatment. Herein, we reported on the high iodine retention immobilization of simulated radioiodine-contaminated Bi0-SiO2 sorbent in B-Bi-Zn oxide glass using Bi2O3 as a stabilizer under a N2 atmosphere. The effects of the Bi2O3 content and sintering atmosphere on the iodine immobilization behaviors (iodine retention ratio, phase composition, microstructure, and chemical stability) were investigated. It was found that the decomposition of BiI3 was prevented by adding Bi2O3 and sintering in a N2 atmosphere. The iodine retention ratio in the obtained glass waste form was significantly enhanced with increasing Bi2O3 content and sintering in the N2 atmosphere due to the synergistic effect. The achieved record-high iodine retention (92.22 ± 2.6%) was much higher than that of conventional heat treatment route (18.01 ± 3.5%). The results demonstrated that iodine was effectively immobilized through the formation of stable BixOyI (Bi5O7I and BiOI). Furthermore, the obtained iodine waste form exhibited excellent compactness and chemical stability. Owing to its high iodine retention ratio, this route can be employed to effectively immobilize radioactive iodine.

Strategy to combine two functional components: Efficient nano material development for iodine immobilization

The development of effective radioactive iodine adsorption materials from nuclear waste remains a significant challenge due to the drawbacks of the previous technologies such as complex synthesis process, high cost, and low stability. In this work, a Metal Oxidation-Carbon (MOC) composite material was designed and synthesized to solve this problem. The structure, composition, and physicochemical properties of this MOC were characterized to reveal its mesoporous material properties. Experiment results showed that this MOC material contain great physical and chemical adsorption efficiency towards iodine vapor, the adsorption capacity could up to 2647.54 mg/g. And the average desorption rate of 86.57% (in absolute ethanol) further proved its advanced recyclability. Moreover, this mesoporous material has great prospects in industrialization due to its simple one-step synthesis method, well-defined adsorption mechanism, and competitive application property.

In situ modification of JUC-160-derived carbon with Cu/ZnO nanoparticles for efficient capture and reversible storage of radioiodine

Proliferation of nuclear technology has also resulted in radionuclide release into the environment. Key among them is radioiodine which threatens human health through thyroid cancer and endangers the environment. The efficient removal of iodine is important to curb these threats. Herein we report a facile in situ Cu-ZnO decorated JUC-160 derived carbon for efficient volatile iodine adsorption. The as-prepared Cu/ZnO@C displayed a high iodine adsorption capacity of 521 wt% and 1280.14 mg g−1 in vapor phase and in solution respectively. Furthermore, kinetics and isotherm studies showed a monolayer and chemisorption dominant adsorption process confirmed by pseudo-second-order and Langmuir models. Moreover, this high adsorption capacity and mechanism was attributable to electron-donor-acceptor interactions, charge transfer complexes and oxidation of Cu0 to Cu+. Additionally, the in situ doping of nitrogen via the ligands used resulted in added nitrogen sites for iodine immobilization. The as-fabricated material also exhibited exceptional recovery and reusability such that it is proposed as a promising volatile iodine adsorbent.

Preparation of silver vanadate glass containing PbO or TeO2 for radioactive iodine immobilization

In this study, iodine immobilization matrices were developed using PbO or TeO2 as additives in AgI–Ag2O–V2O5 glass systems. Excluding oxygen, iodine loading in the matrix was observed to be 32–36% by weight. The waste form was fabricated by melting at 800 °C for 1 h. The normalized release of elements in the waste form was below the order of 10−1 g/m2, thereby confirming the immobilization of iodine and satisfying the USA regulation (<2 g/m2). Iodine release was suppressed by the addition of PbO and TeO2; however, silver release was not as suppressed as effectively as iodine. This paper also discusses the structural factors affecting the chemical durability of the glass matrix.

Novel synthesis of NaY-NH4F-Bi2S3 composite for enhancing iodine capture

Effective capture of radioactive iodine in spent fuel reprocessing is an urgent problem to be solved. In this study, we reported a novel fluoride modified bismuth sulfide supported NaY zeolite material (NaY-NH4F-Bi2S3), prepared by hydrothermal method. The zeolite with a hydrophobic skeleton was obtained by etching with NH4F solution. The adsorption mechanism generally follows preferential iodine enrichment in NaY zeolite microporous channels and is subsequently immobilized by loaded bismuth sulfide sites on NaY zeolite. Under the combination of physical and chemosorption, the sorption capacity of NaY-NH4F-Bi2S3 reaches 491 mg/g, which is much higher than that of bare NaY zeolite. The excellent thermal stability and radiation stability greatly enhance its iodine capture performance under harsh conditions. The comprehensive characteristics of high cost-effectiveness, low toxicity, good radiation resistance, and good thermal stability make it have potential applications in the capture, immobilization and storage of radioactive gaseous iodine during spent fuel reprocessing.

Cs3Bi2I9-hydroxyapatite composite waste forms for cesium and iodine immobilization

Perovskite-based ceramic composites were developed as potential waste form materials for immobilizing cesium (Cs) and iodine (I) with high waste loadings and chemical durability. The perovskite Cs3Bi2I9 has high Cs (22 wt%) and I (58 wt%) content, and thus can be used as a potential host phase to immobilize these critical radionuclides. In this work, the perovskite Cs3Bi2I9 phase was synthesized by a cost effective solution-based approach, and was embedded into a highly durable hydroxyapatite matrix by spark plasma sintering to form dense ceramic composite waste forms. The chemical durabilities of the monolithic Cs3Bi2I9 and Cs3Bi2I9-hydroxyapatite composite pellets were investigated by static and semi-dynamic leaching tests, respectively. Cs and I are incongruently released from the matrix for both pure Cs3Bi2I9 and composite structures. The normalized Cs release rate is faster than that of I, which can be explained by the difference in the strengths between Cs−I and Bi−I bonds as well as the formation of insoluble micrometer-sized BiOI precipitates. The activation energies of elemental releases based on dissolution and diffusion-controlled mechanisms are determined with significantly higher energy barriers for dissolution from the composite versus that of the monolithic Cs3Bi2I9. The ceramic-based composite waste forms exhibit excellent chemical durabilities and waste loadings, commensurate with the state-of-the-art glass-bonded perovskite composites for I and Cs immobilization.

Incipient wetness impregnation to prepare bismuth-modified all-silica beta zeolite for efficient radioactive iodine capture

The economical and effective capture of radioactive iodine has always been an important field of research in the reprocessing of spent fuel. In this work, we successfully prepared a novel bismuth-modified all-silica beta zeolite material (Bi@Si-BEA) though a modified incipient wetness impregnation method. A series of iodine sorption and desorption experiments and characterization methods (PXRD, SEM, TEM, TG, XPS, FTIR, 29Si NMR, Raman, PDF, and DFT calculation) were performed to reveal the structural characteristics and the mechanism of iodine capture of Bi@Si-BEA. The results showed that the sorption mechanism generally involved the preferential enrichment of iodine molecules in the 12-ring channels of the Si-BEA, for which the adsorption energy was −0.23 ​eV. The enriched iodine molecules subsequently reacted with the active bismuth sites (Bi0 and β-Bi2O3) on the surface of Si-BEA to form bismuth iodine compounds (BiI3 and BiOI), thereby achieving immobilization of iodine through strong chemical interactions. Through a combination of physical and chemical effects, Bi@Si-BEA could reach a sorption capacity of 600 ​mg/g, of which the chemisorption accounts for approximately 350 ​mg/g, in approximately 2 ​h. In addition, we explored the effects of different loadings of bismuth and experimental temperatures on the iodine sorption performance and scaled up the preparation of Bi@Si-BEA.

Effects of additives on the thermal stability of silver tellurite glass system

129I is notable for its long half-life of 1.57 × 107 y and high mobility in the environment. It should be immobilized in a geological disposal environment through a stable waste form. In this study, additives including Al, Bi, Pb, V, Mo, and W were added to silver tellurite glass, and the thermal properties of this matrix for radioactive iodine immobilization were evaluated. The glasses were prepared by the melt-quenching method, including the melting of the glass precursor mixtures at 800 °C for 1 h. The loading of iodine in the matrix was approximately 11–15% by weight, excluding the oxygen element. Differential scanning calorimetry was performed to evaluate the thermal properties of the glass samples. The glass transition temperature (Tg), crystallization temperature (Tc), and glass stability were investigated. The addition of MoO3 or WO3 in the glass system increases Tg and Tc while maintaining the glass stability.