Iodine Retention Research Articles

Construction of heterogeneous MOF-on-MOF for highly efficient gaseous iodine sequestration under static conditions

Considering the unexpected nuclear power waste emission and potential nuclear leakage, the exploration of robust materials for the effective capture and storage of radioactive iodine is of great importance but still remains a challenge. In this work, we report the rational synthesis of functionalized NH2-UiO-66-on-ZIF-67 architecture to enhance the static adsorption and retention of volatile iodine. Such MOF-on-MOF heterostructures was fabricated through seeding ZIF-67 core on the surface of NH2-UiO-66 satellite via a facile polyvinylpyrrolidone (PVP) regulated internal extended growth strategies. NH2-UiO-66-on-ZIF-67 exhibited unique core-satellite structure, which significantly promotes the binding interactions with iodine through synergizing of the N-rich imidazole moieties and surface functionalized amino groups within the porosity channels. As a result, the as fabricated NH2-UiO-66-on-ZIF-67 achieves enhanced mass diffusion and high capture capacity of 3600 mg/g for iodine vapor under static sorption conditions. Moreover, water vapor in humid conditions (relative humidity of 18 %) has almost no effect on the static iodine adsorption performance of the material. This study sheds light on a reliable MOF-on-MOF hybrid strategy for effective radioiodine treatment to ensure the safety nuclear waste management.

Tunable sulfur vacancies in amorphous-crystalline AC-Bi2S3-x@C derived from CAU-17 for efficient capture of radioiodine: Comparison of sulfur vacancies in amorphous and crystalline structures

Solid-phase adsorption has been recognized as an effective method for the control of volatile radioactive iodine in spent fuel reprocessing plant off-gases. However, it is still a challenge to develop efficient and stable iodine capture adsorbents. In this work, sulfur-vacancy-rich amorphous-crystalline AC-Bi2S3-x@C was prepared by solvothermal vulcanization using CAU-17 as a precursor. Based on the synergistic effect of the amorphous structure and sulfur vacancy defects, AC-Bi2S3-x@C exhibited fast adsorption equilibrium time (15 min), distinguished iodine adsorption capacity (1763.9 mg g−1), high percentage of chemical adsorption (93.4 %) as well as favorable thermal and irradiation stability. Adsorption experiments and theoretical calculations verified that the amorphous structure not only enhance the charge transfer between sulfur vacancy defects and iodine molecules, but also offers rapid diffusion channels for iodine molecules to the interior of the adsorbent and sufficient internal binding sites to promote iodine molecule adsorption in its interior. The used adsorbent showed high iodine retention (92.3 %) and excellent chemical durability (normalized iodine leaching rate of 4.63 × 10-5 g m−2 d-1) in glass solidification. In general, this work presented a new concept in the design and synthesis of efficient radioactive iodine capture materials.

Photochemical synthesis of hierarchical adsorbents for gaseous iodine capture and storage

Developing rapid, cleaner synthesis strategies for adsorbent preparation through preparative chemistry, and elucidating pore and metal adsorption mechanisms, represent essential goals in achieving highly efficient capture and storage of radioactive iodine in the nuclear industry. This work utilizes solvent-free photopolymerization and one-step photoreduction methods to synthesize hierarchical zeolite Silicaite-1 (denoted as MS-1) and copper-modified zeolite Cu@MS-1, respectively. Focusing on the effects of metal species and pore structure on adsorption performance and mechanisms, their application to radioactive iodine sequestration from spent fuel is evaluated. The findings show adsorption of gaseous iodine by hierarchical zeolite MS-1 is predominantly physical. At 75 °C, it rapidly reaches high equilibrium adsorption capacity (524 mg/g) within 40 min, with faster iodine uptake kinetics than fully microporous zeolites and higher capacity than fully mesoporous silica. Introduction of metallic copper contributes additional chemical adsorption, efficaciously enhancing the MS-1 affinity for gaseous iodine. Cu@MS-1 achieves considerable equilibrium adsorption capacity (520 mg/g) in only 30 min, and improved radioactive iodine retention. The photochemical synthesis approach generates no liquid waste and forms the zeolite framework in 10 min. The obtained hierarchical zeolites MS-1 and Cu@MS-1 have high gaseous iodine capture and storage abilities, opening a new route for rapid and cleaner synthesis of highly efficient radioactive iodine adsorbents.

Synthesizing covalent organic frameworks for unprecedented iodine capture performance

Nuclear energy continues to be an important supplier of electricity, but it has problems with waste management and the possibility to leak radioactive material. Iodine, a potentially harmful byproduct of uranium fission, is hazardous to both the environment and human health. Therefore, developing safe, effective, and affordable storage facilities for iodine waste is crucial. Owing to their well-controlled pore structure and substantial certain surface area, covalent organic frameworks (COFs) show promise for the adsorption of radioactive iodine. The newly developed COFs (SJ-COF, YA-COF, and AA-COF) shown amazing properties, including strong thermal and chemical stability, which made them ideal for efficient iodine capture. Notably, the ultrahigh iodine capture capacities of these COFs—8.52 g g−1, 8.12 g g−1 and 7.01 g g−1—were significantly greater than most previously reported materials. And The % removal efficiency for SJ-COF, YA-COF and AA-COF from I2/cyclohexane solutions were 87.9 %, 88.6% and 82.6 % respectively. It is noteworthy that the three COFs have high selectivity, reusability, and iodine retention abilities, maintaining iodine even after five recyclings. Based on the outcomes of the experiments, the adsorption processes of the three COFs were examined, and it was discovered that iodine was bound through physical-chemical adsorption. The findings of our work provide a ground-breaking standard for the removal of nuclear waste and demonstrate the enormous potential of COFs as adaptable porous structures that may be specifically designed to address major environmental concerns.

131I dose coefficients for a reference population using age-specific models

Age-specific dose coefficients are required to assess internal exposure to the general public. This study utilizes reference age-specific biokinetic models of iodine to estimate the total number of nuclear disintegrations ã(r S,τ) occurring in source regions (r S) during the commitment time (τ). Age-specific S values are estimated for 35 target regions due to 131I present in 22 r S using data from 10 paediatric reference computational phantoms (representing five ages for both sexes) published recently by the International Commission of Radiation Protection (ICRP). Monte Carlo transport simulations are performed in FLUKA code. The estimated ã(r S,τ) and S values are then used to compute the committed tissue equivalent dose HT(τ) for 27 radiosensitive tissues and dose coefficients e(τ) for all five ages due to inhalation and ingestion of 131I. The derived ã(r S,τ) values in the thyroid source are observed to increase with age due to the increased retention of iodine in the thyroid. S values are found to decrease with age, mainly due to an increase in target masses. Generally, HT(τ) values are observed to decrease with age, indicating the predominant behaviour of S values over ã(r S,τ). On average, ingestion dose coefficients are 63% higher than for inhalation in all ages. The maximum contribution to dose coefficients is from the thyroid, accounting for 96% in the case of newborns and 98%–99% for all other ages. Furthermore, the estimated e(τ) values for the reference population are observed to be lower than previously published reference values from the ICRP. The estimated S, HT(τ) and e(τ) values can be used to improve estimations of internal doses to organs/whole body for members of the public in cases of 131I exposure. The estimated dose coefficients can also be interpolated for other ages to accurately evaluate the doses received by the general public during 131I therapy or during a radiological emergency.

A technological approach based on engineered nanoclay composites for cesium and iodine retention.

The development of effective and environmentally friendly methods for separating hazardous radionuclides from waste poses a significant technological challenge. 137Cs and 131I are among the most important radionuclides discharged into the environment by nuclear power plants. One of the best ways to eliminate them involves adsorption on clay minerals. In this regard, studies have demonstrated that organofunctionalized clay minerals are effective adsorbents. Thus, this study investigates the capability of organofunctionalized synthetic design clay minerals to jointly eliminate cesium and iodine. The adsorbents studied are a range of organofunctionalized clay minerals with alkylammonium cations of different alkyl chain lengths (2, 3 and 18) and some physical mixtures of raw clay minerals and octadecylammonium compounds. Organofunctionalized synthetic swelling highly charged micas are effective adsorbents for the simultaneous adsorption of cesium and iodine. In addition, the optimal system is a mixture of Na-M4 with octadecylammonium (50% w/w).

Iodine avidity in papillary and poorly differentiated thyroid cancer is predicted by immunohistochemical and molecular work-up.

Successful radioiodine treatment of differentiated thyroid cancer requires iodine avidity: that is, the concentration and retention of iodine in cancer tissue. Several parameters have previously been linked with lower iodine avidity. However, a comprehensive analysis of which factors best predict iodine avidity status, and the magnitude of their impact, is lacking. Quantitative measurements of iodine avidity in surgical specimens (primary tumour and lymph node metastases) of 28 patients were compared to immunohistochemical expression of the thyroid-stimulating hormone receptor, thyroid peroxidase (TPO), pendrin, sodium-iodide symporter (NIS) and mutational status of BRAF and the TERT promoter. Regression analysis was used to identify independent predictors of poor iodine avidity. Mutations in BRAF and the TERT promoter were significantly associated with lower iodine avidity for lymph node metastases (18-fold and 10-fold, respectively). Membranous NIS localisation was found only in two cases but was significantly associated with high iodine avidity. TPO expression was significantly correlated with iodine avidity (r = 0.44). The multivariable modelling showed that tumour tissue localisation (primary tumour or lymph node metastasis), histological subtype, TPO and NIS expression and TERT promoter mutation were each independent predictors of iodine avidity that could explain 68% of the observed variation of iodine avidity. A model based on histological subtype, TPO and NIS expression and TERT promoter mutation, all evaluated on initial surgical material, can predict iodine avidity in thyroid cancer tissue ahead of treatment. This could inform early adaptation with respect to expected treatment effect.

Influence of throat and diverging section on the performance of venturi scrubber by using computational fluid dynamics

Filtered Containment Venting System (FCVS) is a safety system of nuclear power plants whose primary objectives are control of over-pressurization and prevention of release of radioactivity in severe accidents. In a severe accident scenario, when pressure of containment exceeds a set limit, this system gets activated and part of containment steam/gases mixture is transferred to FCVS where removal of hazardous radioactive gases like iodine takes place via scrubbers and then cleaner air is vented out. Iodine removal is necessary because if discharged into environment, it can cause serious health concerns including thyroid cancer. Venturi scrubbers are a key component in FCVS for retention of iodine. Research on various parameters of venturi scrubbers is necessary in order to attain maximum removal efficiency. This research was carried out to investigate the effect of geometric parameters of venturi scrubber on iodine removal using Computational Fluid Dynamics. Parameters such as number of orifices, diameter and length of diverging section and length and diameter of throat section were studied. Influence of variation in above-mentioned geometric parameters on different operational parameters like pressure, volume fraction phase-1, velocity, mass transfer rate and iodine mass fraction was investigated. Order of effect of geometric parameters on iodine removal from lower to higher comes out to be diverging diameter, diverging length, throat length, number of orifices, and throat diameter. 5–68% increase in mass transfer rate was observed from variation in parameters. This research would be very helpful for researchers and designers in parametric optimization and design of an efficient venturi scrubber.

An iodine balance study in Chinese school-age children.

Few iodine balance studies have been conducted in school-age children. This study aimed to conduct an iodine balance study in school-aged children. We measured daily iodine intake, excretion, and retention for three consecutive days without any dietary interventions in school-age children. Linear mixed-effects models were used to fit the relationship between total iodine intake (TII) and iodine retention (IR). 29 children aged 7-12 years (mean age 10.2 ± 1.4 years) with normal thyroid function and thyroid volume (Tvol) were recruited. The zero balance value (iodine intake = iodine excretion, iodine retention = 0 μg/d) shifted with iodine intake in an iodine sufficient population. The zero balance value for school-aged children with an iodine intake of 235 (133, 401) μg/d is 164 μg/d. Children aged 7-12 years with iodine intake >400 μg/d were almost in a positive iodine state. An iodine intake of 235 (133, 401) μg/d for children aged 7-10 years achieved a zero balance value of 164 μg/d. Long-term iodine intake of >400 μg/d is not recommended.

Capture of iodine gas by Bi-based composites derived from rice husk: Influence of the type of support on the iodine adsorption and retention

The development of Bi-based composites with low cost, high adsorption capacity and retention is highly desired for iodine gas capture. Herein, three novel Bi-based composites (Bi0-SiO2, Bi0-C/SiO2 and Bi0-C) were prepared by simple sintering process using rice husk as C and SiO2 sources and applied for iodine gas capture. The results demonstrated that the type of support strongly affected the iodine adsorption and retention. The Bi0-SiO2, Bi0-C/SiO2 and Bi0-C composites exhibited the iodine adsorption capacity of 812, 911 and 1334 mg/g, and the iodine retention ratio of 90.9, 86.9 and 65.4%. The Bi0-SiO2 showed the highest iodine retention because the SiO2 supports have no affinity for iodine and the adsorption mainly came from the chemical adsorption of Bi0 (2Bi + 3I2 = 2BiI3). While the Bi0-C exhibited the highest adsorption capacity due to the synergistic adsorption effect between C supports and Bi0 sites. Except for the chemical reaction, charge transfer between C and I (C-I) also contributed to the iodine adsorption. The results demonstrated that the new Bi-based composites would be promising iodine gas adsorbent and the new strategy could be extended to the development of other adsorbents.

Iodotyrosines Are Biomarkers for Preclinical Stages of Iodine-Deficient Hypothyroidism in Dehal1-Knockout Mice.

Background: Iodine is required for the synthesis of thyroid hormone (TH), but its natural availability is limited. Dehalogenase1 (Dehal1) recycles iodine from mono- and diiodotyrosines (MIT, DIT) to sustain TH synthesis when iodine supplies are scarce, but its role in the dynamics of storage and conservation of iodine is unknown. Methods: Dehal1-knockout (Dehal1KO) mice were generated by gene trapping. The timing of expression and distribution was investigated by X-Gal staining and immunofluorescence using recombinant Dehal1-beta-galactosidase protein produced in fetuses and adult mice. Adult Dehal1KO and wild-type (Wt) animals were fed normal and iodine-deficient diets for 1 month, and plasma, urine, and tissues were isolated for analyses. TH status was monitored, including thyroxine, triiodothyronine, MIT, DIT, and urinary iodine concentration (UIC) using a novel liquid chromatography with tandem mass spectrometry method and the Sandell-Kolthoff (S-K) technique throughout the experimental period. Results: Dehal1 is highly expressed in the thyroid and is also present in the kidneys, liver, and, unexpectedly, the choroid plexus. In vivo transcription of Dehal1 was induced by iodine deficiency only in the thyroid tissue. Under normal iodine intake, Dehal1KO mice were euthyroid, but they showed negative iodine balance due to a continuous loss of iodotyrosines in the urine. Counterintuitively, the UIC of Dehal1KO mice is twofold higher than that of Wt mice, indicating that S-K measures both inorganic and organic iodine. Under iodine restriction, Dehal1KO mice rapidly develop profound hypothyroidism, while Wt mice remain euthyroid, suggesting reduced retention of iodine in the thyroids of Dehal1KO mice. Urinary and plasma iodotyrosines were continually elevated throughout the life cycles of Dehal1KO mice, including the neonatal period, when pups were still euthyroid. Conclusions: Plasma and urine iodotyrosine elevation occurs in Dehal1-deficient mice throughout life. Therefore, measurement of iodotyrosines predicts an eventual iodine shortage and development of hypothyroidism in the preclinical phase. The prompt establishment of hypothyroidism upon the start of iodine restriction suggests that Dehal1KO mice have low iodine reserves in their thyroid glands, pointing to defective capacity for iodine storage.

Performance of bubble column for iodine removal in a lab scale setup of filtered containment venting system

Iodine is one of the most hazardous fission products that can get released into environment after a severe nuclear accident and can cause thyroid cancer. Removal of iodine is necessary to ensure safety of people and environment. Different experiments were performed in a lab scale setup of FCVS containing a bubble column. Purpose of this research was to understand the mechanism involved in wet scrubbing in order to improve the removal efficiency of iodine. Influence of many parameters such as gas flowrate, liquid level height, gas holdup, additives, bubble diameter etc. on retention of iodine was studied. Results showed major dependance of decontamination factor on gas flowrate and liquid level height. Bubble diameter was observed to be dependent on gas flowrate, viscosity of liquid and density of liquid and gas. Decrease in bubble diameter was observed with increase in superficial gas velocity which enhanced overall mass transfer and hence, removal efficiency was increased as well. Overall, greater than 99.9% removal efficiency was achieved.

P-Sulfonato-Calix[4]arene Micelles Stabilize a Povidone Iodine Solution: Supramolecular Interactions, Iodine Retention, and Bactericidal Activity.

Povidone iodine (PVPI) is an antiseptic widely used against a broad spectrum of pathogens. However, undesired side-effects are still associated with PVPI treatment due to the irritant effect of iodine. Reducing the concentration of a PVPI formulation could provide safer and more friendly formulations, for routine use and applications in very delicate organs such as the eye. However, managing the storage of a low-concentration solution of PVPI is challenging due to the high iodine volatility. In this study, we demonstrated that an amphiphilic p-sulfonato-calix[4]arene derivative forming micelles (SC4OC6) improves the stability of a 0.1% PVPI aqueous buffered solution. UV-vis and NMR spectra as well as dynamic and electrophoretic light scattering measurements showed that SC4OC6 establishes non-covalent supramolecular interactions with PVPI, resulting in the formation of nanoaggregates with a negatively charged surface. Isothermal titration calorimetry provided the aggregation parameters and evidenced that the formation of the supramolecular assembly is an enthalpically favored process. The interaction of SC4OC6 with PVPI enhances the iodine retention and stability of the solution without affecting the rapid and effective bactericidal activity of PVPI, as demonstrated by a time-killing assay with Staphylococcus epidermidis.

Iodine Intakes of 550 μg/day are Not Recommended during Pregnancy: A Balance Study

BackgroundAdequate iodine intake during pregnancy is critical for maintaining maternal and fetal thyroid function and development. There are only limited data from iodine-balance studies to inform iodine requirements during pregnancy. ObjectivesThis is an iodine-balance study conducted to explore the associations among iodine intake, excretion, and retention to provide information regarding iodine requirements during pregnancy. MethodsA 7-d iodine-balance experiment enrolled 93 healthy pregnant Chinese women from Hebei, Tanjin, and Shandong. Duplicates of all foods and beverages consumed were systematically collected and measured for iodine content. Iodine excretion was measured by collecting 24-h urine and feces samples. Simple linear regression models were used to assess relationships between total iodine intake and iodine retention, whereas mixed effect models were used to assess the relationship between daily iodine intake and iodine retention. ResultsThe mean ± SD age of participating pregnant women was 29 ± 2 y at a median 22 (IQR: 13–30) wk of gestation. The mean 7-d iodine retention was 43.0 ± 1060 μg/7 d. A negative iodine balance was present in 56% of women whereas 44% had a positive balance. Pregnant women with iodine intakes <150 μg/d were in negative balance whereas those with intakes >550 μg/d were in positive balance. The daily iodine intake at zero balance was 343 μg/d, which was higher in women from Shandong (492 μg/d) than in those from Hebei and Tianjin (202 μg/d). ConclusionsIodine intake at zero balance determined in pregnant women with adequate iodine nutrition is 202 μg/d, and the calculated recommended nutrient intake (RNI) is 280 μg/d. Iodine intakes of <150 μg/d and >550 μg/d are not recommended during pregnancy.This trial was registered at clinicaltrials.gov as NCT03710148.

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.

Sawdust Amendment in Agricultural and Pasture Soils Can Reduce Iodine Losses

Iodine loss is common in the soil of hilly regions due to higher precipitation rates and steeper slopes. Iodine deficiency in soil reduces iodine’s bioavailability to fruits and vegetables and consequently may contribute to health complications. However, the iodine retention of soils after the addition of selected organic and inorganic amendments has not been studied. Therefore, a study was carried out to investigate iodine loss during surface runoff. For this purpose, a soil amendment (namely, sawdust, charcoal, wood ash, lime or gypsum) was applied separately to pasture and agricultural soils under natural rainfall conditions. The soil was fertigated with iodine in the form of potassium iodide (KI) at the rate of 200 ppm. Surface runoff was related to soil properties. Results showed that iodine content in surface runoff was linearly related with soil pH (R2 = 0.89, p &lt; 0.05) and inversely related with soil organic carbon (R2 = −0.76, p &lt; 0.05). Soils amended with sawdust had significantly reduced iodine content in runoff. A higher amount of iodine was lost via surface runoff from soil after inorganic amendment. Soil amendments were varied for iodine retention in soil in the order of sawdust &gt; charcoal &gt; wood ash &gt; lime &gt; gypsum. The study results indicated that organic amendments, especially sawdust, improved soil properties and increased the iodine retention capacity of soils.

Triple fortification of salt with iron, iodine and zinc oxide using extrusion

Diets poor in essential vitamins and minerals, also known as micronutrients, are widespread worldwide. Food fortification is considered to be the most cost-effective approach to addressing micronutrient deficiencies in regions consuming poor diets. We have developed a cost‐effective technology to simultaneously deliver zinc, iron, and iodine through salt as a strategy to combat iron and zinc deficiencies. Two different approaches for adding zinc to the double fortified salt were investigated: spraying in solution, or incorporation into a solid premix. Zinc sulfate or zinc chloride was added to the iodate spray solution or zinc oxide was added into the iron premix used for making Double Fortified Salt. Of these two approaches, incorporating zinc into iron premix was superior, based on the stability of fortificants. For incorporating zinc into the iron premix, zinc oxide was either included in the extruded premix core or used as part of the color masking system with titanium dioxide (TiO2). The latter approach proved to be preferable as it resulted in higher iodine retention after one year of storage. This technology is a cost-effective public health measure for improving the health of populations with diets deficient in these critical micronutrients.

A model to determine at-home restrictions for cats after treatment of hyperthyroidism with radioiodine.

Felinehyperthyroidism is the most common endocrine disease of older cats and radioiodine is considered to be the gold standard treatment. Isolation periods following treatment vary depending on both individual treatment facilities and the relevant legislation of the country; therefore, there is no recognised standardised protocol defining the length of isolation. This work describes how our institution validated that its owner restrictions met dose constraints by using a model of iodine retention to calculate the required duration and nature of owner restrictions. The retained radioactivity of cats at the point of discharge was used to simulate the radiation dose to owners in the 90 days following release. The model created was used to calculate the minimum duration of isolation for a range of administered activities and owner restrictions. Using the model, it was found that when injected with the maximum dose used, 222 MBq radioiodine, it was possible to release cats after 14 days of isolation and keep owner doses below 0.30 mSv (whole-body effective dose constraint for a single radiation source) with some restrictions. It was possible to release after 23 days with no restrictions. The present study provides clinicians with a consistent and verified method in which they can calculate the isolation periods for radioiodine-treated cats.

Stability of Iodine in Differently Iodised Salts

Iodine deficiency is a public health problem worldwide. Iodization of salt is a valuable technique to overcome iodine insufficiency. There are, however, problems in uniform iodization of salt. The study was conducted to investigate comparative stability and uniformity of mixing of iodine in iodized salt fortified with aqueous solution of KIO3 (powder grade salt) or the same compound added additionally in dry form (granular grade salt). The research study was conducted in the laboratory of Nutrition, Section of the Food science Division of Nuclear institute for Food and Agriculture (NIFA), Peshawar. Salt samples were prepared in a medium sized salt crushing facility at Lahore. These samples were transported in bulk packing to Nuclear Institute for Food and Agriculture (NIFA), Peshawar. Following 3 types of samples will be prepared; powder grade salt fortified with 50 ppm of iodine as KIO3 solution using drip system, granular grade salt iodized with the same system without additional KIO3 (this grade of iodized salt always lacks complete and homogeneous iodization and needs addition of more iodine to attain the 50 ppm level) and granular grade salt iodized with additional KIO3 to make up the total to 50 ppm. the salt samples were packed in high density polyethylene (HDPE) and low density polyethylene (LDPE) packing separately. Analysis was carried out at the initial stage (0day) and subsequently at monthly interval up to fourth month. By standard iodometric titration all collected salt samples were tested for their iodine levels. Data were statistically analyzed using Statistix version 8.0. ANOVA were worked out by completely randomized design with factorial arrangement. Means were separated using Tucky HSD test. The mean moisture contents of salt packed in LDPE and HDPE varied significantly (P &lt; 0.05), salt packed in LDPE showed higher average moisture contents than the salts packed in HDPE. Effect of iodization type was also significant (P&lt;0.05) on the moisture contents of the salts. Granular salt iodized with drip and additional dry KIO3 had the highest moisture contents followed by granular salt iodized with drip system and the lowest moisture content was exhibited by powdered salt iodized with drip system only. The mean moisture contents of salt during different storage intervals were significantly (P &lt; 0.05) different from each other, except during third and four month, With the salt showing higher average moisture contents during the last month and lowest in the first month. Effect of iodization type was also significant (P&lt;0.05) on the moisture contents of the salt. Granular salt iodized with drip and additional dry KIO3 had the highest moisture contents followed by granular salt iodized with drip system and the lowest moisture content was exhibited by powdered salt iodized with drip system only. The mean moisture contents of salt during different storage periods were significantly (P &lt; 0.05) different from each other, except during third and four month. The salt showed higher average moisture contents during the last month and lowest in the first month. Effect of packing material type was also significant (P&lt;0.05) on the moisture contents of the salt. The mean moisture contents of salt packed in LDPE and HDPE varied significantly (P &lt; 0.05).However, salt packed in LDPE showed higher average moisture contents than that of salts packed in HDPE. The powder salt retained iodine better than the other two salts types used. The iodine retention gradually decreased during storage periods. Among the packaging material used the salt in low density polyethylene showed higher moisture content. During storage intervals the average moisture content increased. The granular salt (grade II) showed maximum moisture content among the three salt types

Oxygen-rich microporous carbons with exceptionally high adsorption of iodine

The effective adsorption of radioactive iodine from nuclear waste using porous carbons remains significantly challenging, which currently appears to have an upper limit for their uptake capacity. Here, to overcome this upper limit, we explore the potential of oxygen-rich microporous carbons derived from cellulose diacetate via a general hydrothermal carbonization and KOH activation route. These activated carbons show exceptionally high adsorption of radioactive iodine due to the combined effect of their high surface area, large pore volume and intrinsic oxygen-rich nature. Our results indicate that these activated carbons have large surface areas of 1829–2997.7 m2 g−1, large pore volumes of 0.88–1.40 cm3 g−1 and high oxygen contents of 19.32–26.14%. They possess high iodine adsorption capacities of up to 6.44 g g−1 in dry conditions and 2.44 g g−1 even at high humidity (74.0 ± 0.9%). Further DFT calculations reveal that the oxygen-rich nature of activated carbon enhances its interaction with iodine molecules, resulting in a high pore accessibility. Also, the porous carbon shows good iodine retention and good reusability for practical applications. These results have fundamental implications for understanding the iodine uptake of oxygen-rich porous carbon and designing materials to handle radioactive iodine emission.