Removal Of Radioactive Iodine Research Articles

A Sponge‐Like 3D‐PPy Monolithic Material for Reversible Adsorption of Radioactive Iodine

3D polypyrrole (3D‐PPy) monolith is prepared by a simple chemical oxidation of pyrrole monomer using FeCl3 as an oxidant. The as‐prepared PPy monolith exhibits an abundant porosity and with a mesopore size of about 9.1 nm in diameter. Taking advantage of its mesoprous feature as well as the unique chemical composition, the 3D‐PPy is employed as the porous medium for adsorption and removal of radioactive iodine from environment. A high iodine adsorption capacity of 1.6 g g−1 for 3D‐PPy is obtained which is competing with that of those reported porous organic polymers. Besides, the adsorption kinetics and adsorption thermodynamic experiments show that the adsorption is dominated by the pseudosecond‐order kinetics and Langmuir models. Considering its simple and low cost‐effective preparing method, unique monolithic porous as well as π–π conjugated chemical structure, the resulted 3D‐PPy may be found useful applications for removal of radioactive iodine to address environmental issues.

Novel N-rich porous organic polymers with extremely high uptake for capture and reversible storage of volatile iodine

The imino group-contained porous organic polytriphenylamine, which originated from diphenylamine and 1,3,5-tris(4-bromophenyl)benzene, was designedly synthesized though Buchwald-Hartwig coupling reaction. The basic properties including morphologies, structure and thermal stability of the resulting POPs were investigated by scanning electron microscope(SEM), thermo gravimeter analysis (TGA), 13C CP/MAS solid state NMR and Fourier transform infrared spectroscope (FTIR). The pore size distribution of POPs present uniform mesoporous of sizes less than 50nm. Scanning electron microscope images show that the resulting POPs formed as an aggregation composed of nanospheres. The POPs were employed as a physicochemical stable porous medium for removal of radioactive iodine and an iodine uptake of up to 382wt% was obtained. To our knowledge, this is one of the highest adsorption value reported to date. Based on these findings, the resulting POPs shows great potential in the removal of radioactive iodine at different states, through a green, environmentally friendly, and sustainable way.

Efficient and selective removal of radioactive iodine anions using engineered nanocomposite membranes

A hybrid membrane consisting of gold nanoparticles immobilized on cellulose acetate has been developed for the selective removal of radioactive iodine from various aqueous media.

Gold-Nanoparticle-Immobilized Desalting Columns for Highly Efficient and Specific Removal of Radioactive Iodine in Aqueous Media.

There has been worldwide attention on the efficient removal of radioactive iodine, because it is commonly released in nuclear plant accidents. Increasing concerns on environmental problems due to the radioactive iodine are leading us to develop stable and sustainable technology for remediation of radioelement contaminants. In this work, we report a highly efficient chromatographic method for specific and rapid capture of radioactive iodine. The gold nanoparticles immobilized dextran gel columns showed excellent removal capabilities of radioactive iodine in various conditions. These results suggested that our platform technology can be a promising method for the desalination of radioactive iodines in water.

Shape‐Controlled Preparation of Basic Bismuth Nitrate Crystals with High Iodide‐Removal Capacities

AbstractBismuth compounds have generated much interest as agents for the removal of radioactive iodine. In this work, we present the shape‐controlled preparation of basic bismuth nitrate crystals (BBN) in the form of Reuleaux triangles, hexagons, and deformed hexagon disks. Shape control was achieved through modulation of the effect of the shape‐directing agent 2,3‐bis(2‐pyridyl)pyrazine (dpp). The crystals were shown to be capable of iodide removal through reaction with I− to form BiOI. Depending on the degree of saturation, the resultant solids can exhibit colors ranging from yellow (unsaturated) to orange (saturated). Sedimentation of the products facilitates its removal after use. While the removal capacities did not depend on the crystal morphology, the Reuleaux triangle disks exhibited faster reaction rates than the other two shapes. With improved removal capacities of up to 3.6 mmol g−1, fast removal kinetics, good selectivity, and capture irreversibility, the BBN crystals show good potential as agents for radioactive iodine removal.

Simultaneous removal of various iodine species in aqueous solutions of high salt concentrations using novel functional adsorbents

Novel tannic acid-type resin combined with benzimidazole-type anion-exchange resins embedded in high-porous silica beads, named improved tannic acid (ITA)-type resin was synthesized successfully and the adsorption behavior of iodine and iodide species on the synthesized resin have been studied in several types of seawater at a temperature range of 278–318 K, compared with those of some typical resins. We have confirmed that ITA can strongly adsorb iodine and iodide species. From these results, we have proposed that the synthesized ITA is suitable for selective removal of radioactive iodine and iodide species in contaminated seawater containing radioactive nuclides.

Capture and reversible storage of volatile iodine by porous carbon with high capacity

The capture of iodine using porous materials has attracted considerable interest. In this work, porous carbon with a special surface area of 1973 m2 g−1 was prepared by simple activation method. As an adsorbent, the adsorption capacity of the resulting porous carbon could reach up to 376 wt% for iodine vapor and 460 mg g−1 for iodine uptake in cyclohexane, which both are among the highest values reported up to now. Taking advantages of its high special surface area, easy preparation, low cost, as well as good regeneration, the resulting porous carbon shows great potential in the removal of radioactive iodine at different states.

Removal of radioactive iodine and cesium in water purification

Radioactive iodine, one of the radionuclides released in the nuclear power plant accident on 11 March 2011, was detected in purified water at water purification plants (WPPs). However, information about removal of radioactive materials in actual water purification process was limited. Therefore, we investigated the removal of radioactive materials (iodine and cesium) immediately after the detection. It is found that non-radioactive iodine in water could be removed by the combined use of pre-chlorination and powdered activated carbon (PAC) treatment. The same result was also obtained in terms of radioactive iodine. Removal of non-radioactive iodine in WPPs was also investigated. Approximately, 60% of iodine was removed by combination of pre-chlorination (0.5–1.0 mg/L) and PAC (15–30 mg/L) in coagulation and sedimentation processes. In water purification process, cesium was mostly removed by coagulation and sedimentation; hence, radioactive cesium was not detected in purified water. It was confirmed that a thorough turbidity control is essential for the prevention of radioactive cesium contamination of purified water. Meanwhile, radioactive iodine in purified water has not been detected since 5 April 2011 and radioactive cesium since 22 March 2011, when the measurement was commenced. Moreover, dehydrated sludge including radioactive cesium has been treated in accordance with Japanese laws and regulations.

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).

The dynamic process of radioactive iodine removal by ionic liquid 1-butyl-3-methyl-imidazolium acetate: discriminating and quantifying halogen bonds versus induced force

The halogen bonds vs. induced force of the dynamic process of iodine removal by ionic liquid is discriminated and quantified.

Removal of radioactive iodine and cesium species from rainwater by a pot-type water purifier, and chemical and physical analysis of radioactive components in rainwater

Removal of radioactive iodine and cesium species from rainwater by a pot-type water purifier, and chemical and physical analysis of radioactive components in rainwater

Midterm Report on Removal of Radioactive Iodine and Cesium from Rainwater Contaminated by Fukushima Daiichi Nuclear Accident

Midterm Report on Removal of Radioactive Iodine and Cesium from Rainwater Contaminated by Fukushima Daiichi Nuclear Accident

Removal of radioactive iodine from water using Ag2O grafted titanate nanolamina as efficient adsorbent

Emergency treatment of radioactive material leakage and safety disposal of nuclear waste is a constant concern all along with the development of radioactive materials applications. To provide a solution, titanate with large surface area (143m2g−1) and a lamina morphology (the thickness of the lamina is in range of tens of nanometers) was prepared from inorganic titanium compounds by hydrothermal reactions at 433K. Ag2O nanocrystals (5–30nm) were deposited onto the titanate lamina. The surface of the titanate lamina has crystallographic similarity to that of Ag2O nanocrystals. Hence, the deposited Ag2O nanocrystals and titanate substrate join together at these surfaces, forming a well-matched phase coherent interface between them. Such coherence between the two phases reduces the overall energy by minimizing surface energy and anchors the Ag2O nanocrystals firmly on the external surface of the titanate structure. The composite thus obtained was applied as efficient adsorbent to remove radioactive iodine from water (one gram adsorbent can capture up to 3.4mmol of I− anions). The composite adsorbent can be recovered easily for safe disposal. The structure changes of the titanate lamina and the composite adsorbent were monitored by various techniques. The isotherm and kinetics of iodine adsorption, competitive adsorption and column adsorption using the adsorbent were studied to assess its iodine removal abilities. The adsorbent exhibited a capacity as high as 3.4mmol of iodine per gram of adsorbent in 1h. Therefore, Ag2O deposited titanate lamina is an effective adsorbent for removing radioactive iodine from water.

Removal of radioactive iodine and cesium in water purification processes after an explosion at a nuclear power plant due to the Great East Japan Earthquake

The presence of radionuclides at five water purification plants was investigated after an explosion at a nuclear power plant hit by the Great East Japan Earthquake on 11 March 2011. Radioactive iodine (131I) and cesium (134Cs and 137Cs) were detected in raw water in Fukushima and neighboring prefectures. 131I was not removed by coagulation–flocculation–sedimentation. 131I was removed by granular activated carbon (GAC) and powdered activated carbon (PAC) at a level of about 30%–40%, although 131I was not removed in some cases. This was also confirmed by laboratory-scale experiments using PAC. The removal percentages of 131I in river and pond waters by 25 mg dry/L of PAC increased from 36% to 59% and from 41% to 48%, respectively, with chlorine dosing before PAC. 134Cs and 137Cs were effectively removed by coagulation at both a water purification plant and in laboratory-scale experiments when turbidity was relatively high. In contrast, 134Cs and 137Cs in pond water with low turbidity were not removed by coagulation. This was because 134Cs and 137Cs in river water were present mainly in particulate form, while in pond water they were present mainly as cesium ions (134Cs+ and 137Cs+). However, the removal of 134Cs and 137Cs in pond water by coagulation increased markedly when 134Cs and 137Cs were mixed with sediment 24 h before coagulation.

Evaluation of the sorbent layer thickness in iodine filters

A method for evaluating the serviceability of an iodine filter is proposed. For the projected apparatus, the minimum volume and height of the sorbent layer is calculated using the sorption power index and the contact time between the gas flow and the sorbent layer. For the iodine filters in use at nuclear power plants, to attain the required efficiency of removal of radioactive iodine from gas flows it is recommended that the sorbent be based on the total volume and operating conditions of the apparatus.

Intracrystalline Oxidation of Thiosulfate-Intercalated Layered Double Hydroxides

Thiosulfate-intercalated zinc-aluminum LDH was prepared by anion exchange reaction. The interlayer thiosulfate ions of this LDH could be quantitatively oxidized to tetrathionate ions using iodine and sulfate ions using H2O2. Both of these intracrystalline reactions are topotactic in nature. The reaction of the LDH with molecular iodine makes it a potential material for the removal of radioactive iodine from effluents.

Prediction of a Breakthrough Curve of Iodine on a Reduced Silver-Loaded Adsorbent Bed

An adsorption process of iodine using Ag0-loaded adsorbents was studied for the removal of radioactive iodine in the process off-gas from a spent nuclear fuel reprocessing plant. A mathematical model to predict a breakthrough curve of I2 on the adsorbent bed was proposed. This model consists of the mass balance equation of I2 in the adsorbent bed, the mass transfer equation of I2 through the boundary layer surrounding the adsorbent particle, the intraparticle diffusion equation of I2, and the kinetic equation for the gas-solid reaction between I2 and loaded Ag0. Two unknown parameters in the model, the intraparticle diffusivity De and the apparent rate constant for the gas-solid reaction kr were determined simultaneously from the adsorption data measured by a thermogravimetric analyzer. The breakthrough curves predicted by the model using these parameters were in good agreement with the experimental ones. The rate-controlling step was evaluated by the effectiveness factor calculated from the kr value and the concentration gradient of I2 in the adsorbent particles, which was estimated by the model. From these results, the adsorbent structure required to improve the process performance is discussed. The proposed model is available as a calculation tool to support the design of the adsorption process.

亜硝酸によるヨウ素酸イオンの還元反応速度

As a part of the fundamental research work for radioactive iodine removal in the reprocessing of spent fuel from a nuclear reactor, the reduction reaction of iodate ion by nitrous acid was experimentally examined in an aqueous acidic solution with a spectrophotometer. The overall reaction is as follows: 2IO3-+5HNO2+2H+→I2+5HNO3+H2O. In this reaction, there exists an induction period when production of iodine is very slow. The reaction is accelerated by the produced iodine, and finally the whole iodate ion is converted into iodine, though the rate is fairly small. The overall auto-catalytic production rate of iodine was formulated and the temperature dependency of the reaction rate constant was determined. The resulting activation energy was 61.6kJ·mol-1.

Interaction of radioactive iodine gaseous species with nuclear-grade activated carbons

Carbons from different sources and impregnations were systematically exposed to unfiltered outdoor air and all degraded with respect to radioactive methyl iodide trapping efficiency. The same carbons, exposed to air flows of known contaminant species and concentrations under controlled laboratory conditions, behaved similarly. Local meteorological conditions of high humidity combined with atmospheric pollutants in the test vicinity contributed jointly to the degradation. When service activated carbons were exposed to radiation levels of 10 7–10 9 rads, the iodine isotope exchange capacity was regenerated. The efficiency for iodine isotope exchange was vastly improved, but the removal of methyl iodide-127 was only slightly improved or not at all. It was possible to regenerate the iodine isotope-exchange efficiency by reaction with airborne chemical reducing agents such as hydrazine with little or no improvement in methyl iodine-127 retention. The removal of radioactive iodine by impregnated activated carbons depends on three distinguishable reactions: 1. (1) adsorption on the carbon networks of the activated carbons, 2. (2) iodine isotope exchange with impregnated iodine-127 3. (3) chemical combination with impregnated tertiary amines when present. After the carbon is placed in service, the three mechanisms of iodine removal are degraded by the contaminants of the air at different rates; the adsorption process degrades faster than the other two.

Removal of radioactive iodine from waste by using ion exchange resin column (author's transl)

Removal of radioactive iodine from waste by using ion exchange resin column (author's transl)