Radioactive Iodine Waste Research Articles

Room temperature synthesis of piperazine-based nitrogen-rich porous organic polymers for efficient iodine adsorption

The proper management of radioactive iodine waste generated from nuclear energy has become one of the challenges in the sustainable development of nuclear power. With the continuous development of POPs materials, their high-efficiency iodine adsorption performance has been demonstrated to be related to the material's structural units and porous structure. In light of this, three two-dimensional porous organic polymers were synthesized using environmentally friendly non-metallic catalyzed coupling reactions. Their excellent chemical stability and nitrogen-rich porous structure endowed them with the ability to exhibit outstanding capture performance and recyclability in various media. Its iodine adsorption performance reached 3.81 g/g, 3.55 g/g and 3.19 g/g respectively. The research results provide a potential pathway for the design and synthesis of organic porous polymers with good chemical stability and iodine adsorption performance, showcasing the significant potential of POP-PDTE, POP-PDTK, and POP-PDTB in capturing radioactive pollutants.

Linkage Design in Two-Dimensional Covalent Organic Frameworks for High Iodine Uptake.

Radioactive iodine waste in the nuclear field is harmful to the environment and human health. Covalent organic frameworks (COFs) are a novel kind of porous organic material with a well-fine and unformal structure, which is an excellent candidate as a solid adsorbent for iodine adsorption. Herein, a linkage design is proposed for effective iodine adsorption. Imine-linkage COF (I-COF) and hydrazone-linked COF (H-COF) are constructed under solvothermal conditions. The Brunauer-Emmett-Teller surface area of H-COF is as high as 1747 m2 g-1 . Furthermore, the H-COF shows high porosity, stability, and rich atoms in the linkage. As a result, the work outperforms most of the previous reports in iodine capture with a high capture value at 5.72gg-1 .

The effects of dry grinding and wet grinding on synthesizing iodosodalite

How to dispose of radioactive iodine waste in a green and safe way has become a hot spot for research institutions around the world. In this study, we mainly compare the effects of wet grinding - hydrolysis transformation - sintering (wet grinding) and dry grinding - cold pressing - sintering (dry grinding) on the synthesis of iodosodalite. The analysis results show that the particle size of 4A zeolite treated by wet grinding for 2.5 ​h is approximately 5.5 ​μm. The results of in situ XRD, infrared spectroscopy, and in situ Raman show that the effect of wet grinding and refining treatment is more obvious for iodosodalite synthesis at 900 ​°C. TEM-EDS shows that the morphology of iodosodalite prepared by the wet method is more intact. Based on the above results, it is demonstrated that the wet milling treatment method is more favorable for the synthesis of iodosodalite.

Immobilization of iodine waste via moderate temperature sintering of (Ag)iodosodalite

The treatment of radioactive iodine waste is significant for the further expansion of the nuclear industry. In this study, AgI and zeolite-4A were used to synthesize iodosodalite. AgI in its molten state can not react with zeolite 4A to synthesis iodosodalite, ion exchange is used to exchange Ag+ for Na+ in zeolite 4A and transform zeolite 4A into AgAlSiO4. AgI can enter the lattice of zeolite through the action of Ag+, and then synthesize (Ag)iodosodalite. The phase composition, morphology and the main elements valence state of the sintered matrix were investigated. The results indicate that AgI and zeolite 4A successfully synthesize (Ag)iodosodalite after ion exchange, the moderate temperature sintering method can be employed for iodine waste immobilization.

Immobilization of iodine waste via the gas-pressure sintering of glass-bonded iodosodalite ceramic

The treatment of radioactive iodine waste is significant for the development of the nuclear industry. In this study, gas-pressure sintering was initially used to immobilize simulated iodine waste. The sintered matrix consisted of iodosodalite and amorphous phases, which was verified by morphological analyses. Transmission electron microscopy results revealed the morphology of iodosodalite and the distribution of related elements. Furthermore, the main form of iodine was proven to be iodide through valance-state results, which is consistent with the observation of iodosodalite phase. Based on the product consistency test standard leaching experiment, the concentration of iodine decreased rapidly in the first 14 days and then stabilized on the order of magnitude 10-4 g m-2 d-1, indicating the considerable leaching resistance of the sintered matrix. This work proposes the disposal of iodine waste by obtaining iodosodalite via gas-pressure sintering technology.

Sintering Bi2O3–B2O3–ZnO ternary low temperature glass by hydration device to solidify iodine containing silver-coated silica gel

Abstract A new glass solidification process aims at radioactive iodine waste was explored in order to reduce the possible harm to environment. Samples with different iodine content in silver-coated silica gel were pretreated by hydration device at 300 °C and then sintered at relatively low temperatures (500, 550 and 600 °C). XRD results show that AgI is mainly chemically fixed in the glass network with some AgI particles being physically wrapped by the glass. Moreover, as the sintering temperature reached to 550 °C, B element crystallized. SEM-EDS results show that Ag and I elements are enriched, while the other elements are evenly distributed. AFM results showed that the sample surface becomes rougher as the iodine content increases in the silver coated silica gel. The FT-IR results show that the structure of the sintered sample is mainly composed of [BiO3], [BiO6] and [BO3]. This study provides a new sintering method by hydration device for the treatment of radioactive iodine waste.

Bi2O3 doped B2O3-ZnO glass powder for immobilization of radioactive iodine waste at low temperature

In order to research the effect of Bi2O3 doped B2O3-ZnO matrix in immobilizing iodine waste, different Bi2O3 contents were doped into B2O3-ZnO glass to immobilize iodine loaded silver-coated silica-gel (AgIs). Bi2O3 content doped B2O3-ZnO (99:1) as raw materials held the good physical and chemical property (Vickers hardness 3.07 GPa), so, the pure glass matrix was manufactured at 550 °C. SEM-EDS results gave that element I distributed homogeneously in the samples with 5 wt% AgIs at 450 °C. Meanwhile, the glass powder immobilized AgIs samples gave the glass–ceramic phases according to the XRD results, and the hightest density and Vickers hardness were 1.78 g/cm3 and 0.30 GPa, respectively. The leaking rate of iodine was 1.89–3.40 × 10−5 g∙m−2∙d−1 for 7 days, which was low and supports the stability of the immobilized AgIs with glass materials. This work highlights the well immobilized effect of Bi2O3 doped B2O3-ZnO glass as raw material to immobilize iodine waste at low temperature.

Defect Engineering of Nanoscale Hf-Based Metal-Organic Frameworks for Highly Efficient Iodine Capture.

With the rapid development of the nuclear industry, how to deal with radioactive iodine waste in a timely and effective manner has become an important issue to be solved urgently. Herein, the defect-engineering strategy has been applied to develop a metal-organic framework (MOF)-based solid adsorbent by using the classical UiO-type Hf-UiO-66 as an example. After simple acid treatment, the produced defect-containing Hf-UiO-66 (DHUN) not only retains its topological structure, high crystallization, and regular shape but also shows a great increase in the Brunauer-Emmett-Teller value and pore size in comparison with the original Hf-UiO (HUN). These formed defects within DHUN have been demonstrated to be important for the great enhancement of the iodine capture and following application in computed tomography imaging in vitro. This present work gives a new insight into the control and formation of defect sites, and this simple and efficient defect-engineering strategy also shows great promise for the development of novel solid adsorbents and other functional MOF materials.

Application of silica gel to immobilise iodine waste by low-temperature sintering

ABSTRACT The disposal of radioactive iodine waste is a top priority for the nuclear industry. This work mainly studies the replacement of crystalline material (SiO2) in silicate-based material with amorphous material (silica gel) to immobilise iodine waste at low-sintering temperatures. The results show that under low-temperature sintering conditions, B2O3–Bi2O3–ZnO–silica gel is more suitable than B2O3–Bi2O3–ZnO–SiO2 for immobilising iodine waste because the former one has a higher amorphous index and density than the latter. This novel insight can improve the disposal of radioactive waste at low-sintering temperatures.

Role of amorphous silica gel in B2O3-Bi2O3-ZnO-SiO2 to immobilize iodine waste

The treatment of radioactive iodine waste is particularly difficult because of its volatilization issues. In this study, amorphous silica gel was used to gradually replace crystalline SiO2 in B2O3-Bi2O3-ZnO-SiO2 based materials aimed to investigate the effects on iodine waste immobilization. Samples with different silica gel replacements (0, 20, 40, 60, 80, and 100%) were characterized by XRD, FT-IR, and SEM-EDS. The results showed that silica gel had a benefit in the immobilization of iodine waste at low-sintering temperatures (500, 550, and 600 °C). At 550 °C, AgI was immobilized in the pure glassy matrix and elements (Ag and I) distributed uniformly on the matrix surface. FT-IR analysis presented the tetrahedral SiO4 units in the sintered samples that were mainly in the form of sheets. Our work revealed the potential application of silica gel in the field of iodine waste immobilization.

B2O3–Bi2O3–ZnO based materials for low-sintering temperature immobilization of iodine adsorbed waste

The treatment of radioactive iodine waste is a difficulty in the field of nuclear waste disposal. In this work, the B2O3–Bi2O3–ZnO based materials with 50 ​mol% of B2O3 is chosen to immobilize silver-coated silica gel with different iodine loadings at 500, 550, and 600 ​°C. The results show that the highest amorphous fraction is gotten as 0.88 for the sample with 20 ​wt% of iodine in silver-coated silica gel sintered at 600 ​°C. In addition, both of the amorphous fraction and density increase with increasing temperature. The SEM-EDS result indicates that part of iodine is fixed into the glassy phase and other AgI grains are physically wrapped by the vitrified bulk. Our findings demonstrate the feasibility of B2O3–Bi2O3–ZnO based materials for the immobilization of silver-coated silica gel with different iodine loadings.

Cross-linked chitosan microspheres entrapping silver chloride via the improved emulsion technology for iodide ion adsorption

Radioactive iodine waste from nuclear plant became the severe environmental problem and led to the public health concern. The cross-linked chitosan adsorbed iodide anions through the electrical attraction, yet performing limited-efficiently. Targeting as the better adsorption, the modified chitosan sorbent as AgCl@CM (silver chloride entrapped in the cross-linked chitosan microspheres) for iodine adsorption was proposed and implemented by chemisorption from AgCl and physisorption from chitosan via the improved emulsion method (emulsions mixing-collision and polymerization). With the broad application from pH 2 to pH 10, the spherical AgCl@CM (from 0.20 g silver nitrate) performed the I127 anions (instead of radioactive iodine) adsorption efficiency of higher than 90 % in 20 min, with the maximum adsorption capacity of 1.5267 mmol/g, well-fitting with the pseudo-first-order model and Sips isothermal model. AgCl@CM also performed I127 adsorption with the significant selectivity relative to Cl−. The micro-spherical AgCl@CM sorbents were therefore prospective-effectively for iodine waste water treatment.

Silver Nanomaterial-Immobilized Desalination Systems for Efficient Removal of Radioactive Iodine Species in Water.

Increasing concerns regarding the adverse effects of radioactive iodine waste have inspired the development of a highly efficient and sustainable desalination process for the treatment of radioactive iodine-contaminated water. Because of the high affinity of silver towards iodine species, silver nanoparticles immobilized on a cellulose acetate membrane (Ag-CAM) and biogenic silver nanoparticles containing the radiation-resistant bacterium Deinococcus radiodurans (Ag-DR) were developed and investigated for desalination performance in removing radioactive iodines from water. A simple filtration of radioactive iodine using Ag-CAM under continuous in-flow conditions (approximately 1.5 mL/s) provided an excellent removal efficiency (>99%) as well as iodide anion-selectivity. In the bioremediation study, the radioactive iodine was rapidly captured by Ag-DR in the presence of high concentration of competing anions in a short time. The results from both procedures can be visualized by using single-photon emission computed tomography (SPECT) scanning. This work presents a promising desalination method for the removal of radioactive iodine and a practical application model for remediating radioelement-contaminated waters.

Investigation of ionic liquids for efficient removal and reliable storage of radioactive iodine: a halogen-bonding case

A series of ionic liquids (ILs) were investigated for removal and storage of radioactive iodine (I2) waste released by nuclear power plants. The I2 removal efficiency of ILs was dependent upon the anion species while cation species seemed to have little influence. Particularly, the I2 removal efficiency of [Bmim][Br] was higher than 96% in 5 hours. The nitrogen gas sweeping tests showed that [Bmim][Br] holds I2 tightly, and the leak of I2 from it was negligible under daily life conditions. Spectroscopy studies indicated that high removal efficiencies and storage reliability of ILs were attributed to halogen bonding (XB).

Iodine Transmutation through Laser Compton Scattering Gamma Rays

Research on laser Compton scattering gamma-ray-based nuclear transmutation has been carried out to identify a method of reducing the hazards of long-lifetime radioactivity of nuclear waste. To study the photonuclear reaction experimentally, a laser Compton scattering gamma-ray facility was built on a storage ring at NewSUBARU and ~17MeV gamma-ray photons were produced. An investigation on the reaction rate of radioactive iodine waste was carried out. Based on the characteristics of laser Compton scattering gamma rays, a cylindrical target was adopted for the irradiation experiment. The radioactivity of the irradiated target was measured and the transmutation reaction rate was deduced. Experimental results were close to simulation findings.

Aqueous Dissolution of Silver Iodide and Associated Iodine Release under Reducing Conditions with FeCl2 Solution

An empirical and analytical study was performed on the aqueous dissolution of silver iodide (AgI) to release iodine under reducing conditions with Fe2+ in order to understand the fundamental chemical and/or physical behavior of potential radioactive iodine waste forms under geological disposal conditions. Aqueous dissolution tests of AgI powder in FeCl2 solutions (10−6 M to 10−3 M) were performed in a glove box purged with a gas mixture (Ar + 5% H2). The test results showed that AgI dissolves to release iodine at extremely slow rates, being controlled by a diffusion process in any FeCl2 solution. The comparison with thermodynamic calculations based on redox equilibria suggested that the AgI dissolution proceeds by redox reaction between Ag+ and Fe2+; however, it was far from the thermodynamic equilibrium. These results suggested that the form of AgI itself has a potential to immobilize iodine for a long time even under the disposal conditions. Solid-phase analysis for the reacted AgI by using SEM/EDS showed a certain amount of silver (maybe metallic silver) precipitated at the surface. On the basis of these results and discussion, a potential mechanism for the actual AgI dissolution was proposed as follows. The AgI dissolution proceeds by redox reaction between Ag+ and Fe2+ to release I−, which results in the precipitation of metallic silver as a reduction product of Ag+ at the AgI surface to form a thin layer covering the AgI surface. The silver layer evolves to be protective against the transport of reactant species, by which the further dissolution to reach the equilibrium is suppressed. Consequently, the dissolution proceeds at extremely slow rates, being controlled by a diffusion process.

Aqueous Dissolution of Silver Iodide and Associated Iodine Release under Reducing Conditions with FeCl2 Solution

An empirical and analytical study was performed on the aqueous dissolution of silver iodide (AgI) to release iodine under reducing conditions with Fe2+ in order to understand the fundamental chemical and/or physical behavior of potential radioactive iodine waste forms under geological disposal conditions. Aqueous dissolution tests of AgI powder in FeCl2 solutions (10−6 M to 10−3 M) were performed in a glove box purged with a gas mixture (Ar + 5% H2). The test results showed that AgI dissolves to release iodine at extremely slow rates, being controlled by a diffusion process in any FeCl2 solution. The comparison with thermodynamic calculations based on redox equilibria suggested that the AgI dissolution proceeds by redox reaction between Ag+ and Fe2+; however, it was far from the thermodynamic equilibrium. These results suggested that the form of AgI itself has a potential to immobilize iodine for a long time even under the disposal conditions. Solid-phase analysis for the reacted AgI by using SEM/EDS showed a certain amount of silver (maybe metallic silver) precipitated at the surface. On the basis of these results and discussion, a potential mechanism for the actual AgI dissolution was proposed as follows. The AgI dissolution proceeds by redox reaction between Ag+ and Fe2+ to release I−, which results in the precipitation of metallic silver as a reduction product of Ag+ at the AgI surface to form a thin layer covering the AgI surface. The silver layer evolves to be protective against the transport of reactant species, by which the further dissolution to reach the equilibrium is suppressed. Consequently, the dissolution proceeds at extremely slow rates, being controlled by a diffusion process.

Radioactive iodine waste treatment using electrodialysis with an anion exchange paper membrane

In order to simply and safely treat radioactive iodine waste, a study of the removal of iodide ion from radioactive waste using electrodialysis with an anion exchange paper membrane, in which trimethylhydroxylpropylammonium groups were homogeneously dispersed with high density. In Na 125I and Na 36Cl concentration-cell system, electric ion and water conductances, phenomenological coefficients, have been experimentally determined on basis of nonequilibrium thermodynamics. Prepared paper membrane had higher permselectivity of 125I ion than 36Cl ions by approximately 21%. On the other hand, water flux that was accompanied by an ionic transference in prepared paper membrane was greatly larger than that in typical synthesized membrane. It is suggested that a depression of water mobility is important to practice an ideal radioactive iodide waste electrodialysis system with a novel anion exchange paper membrane.

Method to Reduce the Volatility of Radioactive Iodine Waste

Method to Reduce the Volatility of Radioactive Iodine Waste