Radioactive Cs Research Articles

Spatial distribution of 137Cs; 40K, 226Ra, 232Th in soils of Monchegorsk city (Murmansk region)

The purpose of the study was to establish the patterns of spatial distribution of radioactivity of technogenic 137Cs and natural radionuclides 232Th, 226Ra, 40K in urban soils of Monchegorsk. Location and time of the study. Soil samples, were collected in summer 2018 in the Monchegorsk city, Murmansk region, Russia. To study the specific activity of radiocesium and natural radionuclides, soil samples were taken from topsoil (0-5 cm) at 82 sites, including 68 sites within the city territory (urban soils) and 14 sites beyond the city limits in the subtorch areas strongly affected by the Severonickel factory. Similar studies of urban soils in Monchegorsk had not been carried out previously. Methods. During expeditionary work and laboratory research, soil, radiological, and mathematical and statistical methods were used. When carrying out gamma spectrometric measurements, radionuclides 137Cs, 226Ra, 232Th and 40K were determined on a low-background semiconductor gamma spectrometer ORTEC (USA) based on a high-purity coaxial germanium detector GEM10P4–70 (HPGe) with a SBS-75 pulse signal processor and Gamma-software. The resolution of the gamma spectrometer along the 1.33 MeV line (60Co) was 1.75 keV, and the relative efficiency was 15%. Calibration and quality control of gamma spectrometric measurements was carried out using volumetric activity measurements with 1-L Marinelli vessels of different densities (RITVERZ, Russia-Germany). Main results. The values of specific activity of radionuclides in soil samples were as following: in the technogenic 137Cs up to 31.3 Bq/kg and in the subtorch soils up to 63.4 Bq/kg. Specific activity of natural radionuclides in urban soils reached to 14.2 Bq/kg for 226Ra, whereas in the subtorch soils it reached 21.6 Bq/kg. The specific activity of 232Th in urban soils reached 18.3 Bq/kg, with 17 Bq/kg registered for the subtorch soils. As for 40K, its specific activity reached 498 Bq/kg in the urban soils and 317 Bq/kg. Conclusion. The gamma survey of the Monchegorsk territory did not reveal any anomaly in radiation. The dose rate of gamma radiation in the city does not exceed 0.074 μSv/hour, which is less than the values elsewhere in Russia, ranging from 0.04 to 0.20 μSv/hour. The obtained data about specific activity of technogenic 137Cs and natural radionuclides 232Th, 226Ra, 40K in the Monchegorsk soils are typical for the Murmansk region.

Chemical Species Change of Radionuclides by Microorganisms: Effects of Exudated Siderophores

Microbial exudates including siderophore, which changes chemical species of actinides and lanthanides. We have investigated effects of desferrioxamine B (DFOB; one of the siderophores) and siderophore-like organic molecules (SLOM) on the adsorption of lanthanides by microbial cells, aluminium oxide (Al2O3), and manganese (Mn) oxides. When DFOB was present, the distribution coefficients of cerium (Ce) were measured to be lower than those of neighboring elements of lanthanum (La) and praseodymium (Pr) (Negative anomaly of Ce adsorption). Even though initial oxidation state of Ce in the solution was III, that was changed to IV after the addition of DFOB, indicating that Ce(III) was oxidized by forming complex with DFOB. When lanthanides were adsorbed by biogenic Mn(IV) oxides, negative anomaly of Ce adsorption was observed in the sorption in alkaline solution. Ce(III) was oxidized to forme the complexes of Ce(IV) with SLOM in the solution. These results show that siderophore possesses high performance of oxidation of Ce(III) to Ce(IV) during association, affectiong the adsorption behavior of Ce. After Fukushima accident, radioactive Cs accumulation by Eleutherococcus sciadophylloides (Koshiabura) caused by the dissolution of Fe from soil around the roots, that was dominated by siderophore releasing microorganisms (SB). These SBs may enhance dissolution of iron (Fe) and uranium (U) phases in the nuclear fuel debris formed in the nuclear reactors in Fukushima Daiichi nuclear power plant. Thus, in the interaction between microorganisms and radionuclides, SLOMs discharged by microorganisms are deeply involved in the chemical state change of radionuclides.

A Prussian blue analog-based copper-aluminum layered double hydroxide for cesium removal from water: fabrication, density functional theory-based molecular modeling, and the adsorption mechanism.

A new type of adsorbent, a Prussian blue analog-based copper-aluminum layered double hydroxide (PBA@CuAl-LDH), was successfully synthesized using a one-step method for the removal of radioactive Cs+ from wastewater. The adsorption performance, characteristics and the underlying adsorption mechanism of PBA@CuAl-LDH were systematically examined. The results showed that PBA@CuAl-LDH exhibited excellent adsorption performance, with a maximum adsorption capacity of 109.2 mg g-1. Over 85% of PBA@CuAl-LDH can be recycled, and the material exhibited only a 6.6% loss in adsorption performance. The adsorption process was well-fitted using the pseudo-second-order kinetic model and the Freundlich isotherm model, revealing the surface heterogeneity of the composite adsorbent. A molecular model of PBA@CuAl-LDH was constructed by combining density functional theory and multiple instrumental characterization techniques. Our results indicate that PBA crystals can be generated between layers and on the surface. Ion exchange was revealed as the main adsorption mechanism of Cs+ by PBA@CuAl-LDH. Specifically, the interstitial spaces of the PBA crystals generated between the layers and on the surface played an important role in ion exchange. These findings provide concrete theoretical support for radioactive pollution control and have significant value in directing the fabrication of cesium removal materials and their future engineering application.

Gamma radiation shielding properties of unsaturated polyester /Bi2O3 composites: An experimental, theoretical and simulation approach

Conventional gamma radiation shielding materials, such as lead and lead-based composites are heavy and hazardous to human health and the environment. This particular aspect has prompted research into alternative shielding materials. The key objective of this work is to investigate Bismuth Oxide and unsaturated polyester resin (UPR)-based polymer composite material as a radiation shielding. The investigation used a gamma spectrometer consisting of an HPGe detector and the radioactive point sources 60Co, 133Ba, and 137Cs that have energies ranging from 81 keV to 1332 keV for experimentally evaluating mass attenuation coefficient (MAC). Subsequently, the experimental results for MAC were compared with the corresponding values obtained from WinXCOM and Geant4 simulation. Our findings indicated that the mass attenuation coefficient values of experimentally investigated composites align well with the theoretical and simulated values. In addition, we examined the half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), and radiation protection efficiency (RPE) parameters. From the study, it can be inferred that lead (Pb) can be replaced by UPR+50 wt% Bi2O3 composite for low-energy gamma-ray shielding applications.

Relationship between stable cesium concentration and body size of Japanese flounder Paralichthys olivaceus and the effect of a size-dependent shift in diet.

To understand the relationship between the radioactive cesium (Cs) concentration in muscle of Japanese flounder Paralichthys olivaceus and the species' biological characteristics (size, sex, and age) under conditions of ecological equilibrium (i.e., distributed among ecosystem components over sufficient time, and with nearly constant ratios of Cs concentration in organisms to the concentration in water) as existed before the accident at the Fukushima Dai-ichi Nuclear Power Station (FDNPS), Japan, in 2011, we examined stable Cs, as it is thought to exist in equilibrium in the environment and behave similarly to radioactive Cs in aquatic animals. The concentration of stable Cs in 241 P. olivaceus (range 216-782 mm total length [TL]) collected in Sendai Bay, approximately 90 km north of the FDNPS, in June-July 2015 was expressed as an exponential function with size as an independent variable; the results show the concentration of stable Cs doubled with an increase in TL of 442 mm. Next, to evaluate the cause of the size-dependent change in stable Cs concentration, we examined 909 individuals (200-770 mm TL) collected in September 2013-July 2015 to determine their feeding habit based on size. Analysis of the frequency of occurrence of prey organisms in stomach contents showed that sand lance Ammodytes japonicus (55-180 mm standard length [SL]) was the most consistently consumed across size classes. Analysis on a wet-mass basis showed that A. japonicus and anchovy Engraulis japonicus (65-130 mm SL) were the main food of P. olivaceus sized 200-599 mm TL, whereas chub mackerel Scomber japonicus (120-230 mm SL) and two species of flatfishes (180-205 mm SL) were abundant in the diet of P. olivaceus sized ≥600 mm TL. All these prey items were presumed to have similar concentrations of stable Cs. Based on the above, the effect of diet on the relationship between stable Cs in muscle and fish size was considered negligible. That the diet of P. olivaceus largely did not change with size was also confirmed by C and N stable isotope ratios in P. olivaceus and their prey species. Therefore, the Cs-size relationship is probably determined by changes in the balance between the rate of Cs intake from food and seawater and the excretion rate during growth, both of which change as functions of body mass. Values of stable Cs concentrations among environmental components and animals appear to be a valid indicator for understanding the radioactive Cs distribution in the marine environment and aquatic animals under the equilibrium state, as existed before the 2011 nuclear accident.

Adsorption/Desorption Performances of Simulated Radioactive Nuclide Cs+ on the Zeolite-Rich Geopolymer from the Hydrothermal Synthesis of Fly Ash

The operation of nuclear power plants generates a large amount of low- and intermediate-level radioactive waste liquid. Zeolite-rich geopolymers, which are synthesized under hydrothermal conditions from industrial waste fly ash, can effectively immobilize radioactive nuclides. In this study, the synthesis law of zeolite-rich geopolymers and the adsorption/desorption performances of radioactive nuclide Cs+ were researched using XRD, SEM and ICP. The results show that the increase in curing temperatures and NaOH concentrations leads to the transformation of Y-type zeolite to chabazite and cancrinite at low NaNO3 concentrations. However, at high NaNO3 concentrations, NaOH above 2 M has no obvious effect on the phase transformation of the main zeolite of chabazite and cancrinite. In the adsorption and desorption experiment of Cs+ on the chabazite/garronite-rich geopolymer, it was found that the adsorption of Cs+ in the low initial concentration range is more suitable for the Freundlich equation, while the Langmuir equation fits in the adsorption process at the high initial concentration range. Moreover, the desorption kinetics of Cs+ are in good agreement with the pseudo-second-order rate equation. Thus, the adsorption of Cs+ on chabazite/garronite-rich geopolymers is controlled by both physical and chemical reactions, while desorption is a chemical process.

Characteristics of Cs pollucite synthesized at various Cs loadings for immobilization of radioactive Cs

Radioactive Cs is an important fission product known for the generation of a large amount of heat. Several ceramic matrices have been proposed to effectively immobilize radioactive Cs. Among them, pollucite stands out owing to its exceptional thermal and structural durability, low solubility in water, and high Cs retention. This investigation focused on the preparation and assessment of an appropriate precursor for a waste form tailored to the disposal of Cs-loaded silica–alumina (SA) filters. We synthesized simulated Cs-loaded SA filters and transformed them via calcination into a Cs pollucite (CsAlSi2O6) phase. To investigate the influence of Cs loading, five samples with different ratios of the Cs precursor and matrix were synthesized and subsequently subjected to characterization and chemical durability assessment. Depending on the Cs content, the calcination process led to a phase transformation, resulting in the formation of CsAlSiO4 and/or Cs pollucite (CsAlSi2O6). Following calcination, the degree of crystallinity of the samples increased, and in certain instances, their surfaces were covered with agglomerated particles. Building upon prior research, chemical equations elucidating the phase transformation of both the matrix material and Cs pollucite (CsAlSi2O6) were formulated. The chemical durability of the samples was evaluated via the product consistency test-A method. The lowest Cs leaching rate was 3.86 × 10−4 g/m2·day for the sample comprising a Cs2O/matrix ratio of 0.2 and calcined at 1200°C. The high leaching rates observed in certain P-1200 samples can be attributed to the presence of CsAlSiO4. The leaching behavior of Al resembled that of Cs. The leaching rate of Si remained consistent across the samples heat treated at 1200°C (P-1200), and it was lower than those of samples calcined at 1000°C (P-1000). P-1200 is expected to be a suitable precursor of the waste form tailored to Cs immobilization.

Comparison of 210Pb Age Models of Peat Cores Derived from the Arkhangelsk Region

Dating young peatlands using the 210Pb dating procedure is a challenging task. The traditional 210Pb age models assume an exponential decline in radioactivity in line with depth in the peat profile. Lead exhibits considerable migratory capacity in Arctic peatlands; hence, to perform precise peat dating, existing models should be enhanced to remove the effects of migration. Independent isotope chronometers, such as 137Cs, can verify this. The Monte Carlo method and IP-CRS were utilised, together with several CA, CF/CS, PF, and CF models, to analyse the peat core samples acquired in the Arkhangelsk region. Data analysis revealed that the height partitioning of 137Cs and 210Pb is associated with physical characteristics, like the peat ash and the bulk density of the bog. Comparison between the natural activity of 210Pb in the peat and the radioactivity of 137Cs measured at depths of 19–21 cm in relation to the global fallout in 1963 indicated that the CF/CS, CF, and IP-CRS models (1965, 1962 and 1964, respectively) gave the closest age to the reference point given. IP-CRS was found to be the preferred model of these three options, as it gave a rather closer correlation with the 137Cs activity specific to the reference layer, allowing the error. The core dating of 210Pb showed an age of 1963 for a depth of 17–19 cm, which was in agreement with the reference horizon 137Cs and ash content, thus validating the accuracy and sufficiency of the selected model turf profile chronology. The maximum content of man-made radioisotopes in the peatlands corresponded to the formulation of the Partial Test Ban Treaty of 1963. The rates of accumulation of peat and atmospheric flux of 210Pb are in good agreement with the values available for the bogs of Northern Europe and those previously estimated by the authors in the subarctic region of European Russia. Although the problems of the complex migration-related distribution of 210Pb in the peat layer were considered, the dating methods used were effective in our study and can be adapted in following studies to perform the age determination of different peat deposits.

Manganese silicate/MoS2 composite material with high adsorption capacity for the selectively removing Cs+ from aqueous solution over a wide pH

The wastewater generated by nuclear power plants contains a large number of radioactive substances, including 134Cs and 137Cs, which pose significant threats to human health and the environment. It is crucial to remove these radioactive substances from the nuclear waste. A significant challenge we encounter is the effective and selective extraction of cesium ions from wastewater. The wastewater is typically rich in competition ions and spans a wide pH range. In this report, we report a novel manganese silicate/MoS2 composite material with high adsorption capacity for selectively removing Cs+ from aqueous solutions with competition ions. Adsorption behaviors of cesium ions were investigated for composite ratio, adsorbent dosage, contact time, pH and competitive cations. Optimal conditions for the adsorption of cesium ions from aqueous solutions were achieved using a composite ratio of manganese silicate to MoS2 at 9:1, an adsorbent concentration of 1.0 g L−1, and a pH of 8 for a duration of 1 h. While the impact of K+ and Na+ is minimal at lower concentrations, it becomes more pronounced with increasing concentrations. The composite material demonstrates effective performance over the pH range of 2.0–12.0. Experimental data fitted with the pseudo-second-order kinetics and the Langmuir isotherm model suggests a single-layer chemical adsorption process, resulting in a remarkable adsorption capacity of 78.99 mg g−1. Microscopic analysis reveals the synergistic effect of manganese silicate and MoS2. The manganese silicate provides efficient active sites for selective Cs+ adsorption, while MoS2 allows the highly dispersed surface for manganese silicate. This work reveals new insights into the design and synthesis of high-performance Cs+ adsorption materials for application in the treatment of nuclear wastewater.

Compton Camera Arrangement With a Monolithic LaBr3(Ce) Scintillator and Pixelated GAGG Detector for Medical Imaging

The results presented in this manuscript are divided in two main parts. The aim of the presented work is to conduct feasibility tests on a Compton camera setup to be later scaled up and used for PET and triple coincidence γ-PET purposes. The first part is focused on laboratory characterization of a monolithic LaBr3(Ce) scintillator coupled to a 64-channel multi-anode photomultiplier (H8500C PMT from Hamamatsu) in combination with a well-established algorithm allowing to determine the interaction’s position resolution. The second part of the article is dedicated to the evaluation of a Compton camera detector arrangement in which the monolithic scintillator acts as an absorber, while a pixelated GAGG scintillator array, read out by a SiPM multi-pixel photon counter (MPPC), is used as a scatterer component. The accuracy achievable with this system for detecting γ rays from laboratory point sources is investigated. The Compton camera system has been tested with radioactive 137Cs and 60Co point sources. The signal readout and data acquisition system is based on individual spectroscopy electronics modules (NIM and VME), for the absorber and a customized electronics based on Anger logic for the GAGG scatter array. The raw data were analyzed to serve as input for the image reconstruction, performed using the MEGAlib toolkit software. With a spatial resolution of 1 mm for the scatterer and less than 3 mm for the absorber component, respectively, shifts of 2 mm of both radioactive sources (137Cs and 60Co) could be resolved with the whole Compton camera system.

Spongy porous CuFe Prussian blue deposited MXene nanosheets for quick removal of cesium ions from wastewater and seawater

The radioactive 137Cs is hazardous to human health and the environment once it is released into the environment due to its high radioactivity and solubility. Here, CuFe Prussian blue deposited MXene nanosheets (CuFe/MXene) was successfully prepared and used to capture Cs(I) ions from wastewater and seawater. Among them, spongy porous CuFe/MXene-2 can, not only facilitate the diffusion and adsorption of Cs(I) ions, but also avoid the stacking and agglomeration of CuFe, thus improving the effective utilization rate of CuFe. Consequently, CuFe/MXene-2 can remove up to 88.2% of Cs(I) ions within 3 min and reach the adsorption equilibrium of Cs(I) ions within 20 min with the maximum adsorption capacity (qmax) of 326.8 mg/g. Additionally, the removal rate of Cs(I) by CuFe/MXene-2 can reach up to 90% even in 0.5 M HNO3 solution and Cs(I) spiked seawater containing various competitive cations. More importantly, CuFe/MXene-2 can efficiently and selectively adsorb Cs(I) ions with excellent reusability.

Comprehensive study of the radiation shielding feature of polyester polymers impregnated with iron filings

Abstract Radiation and nuclear technologies have side effects in addition to their important applications, so appropriate shields must be used to protect users and the public from high doses as a result of exposure to this radiation. In this work, the attenuation coefficients for polyester composites doped with waste iron filings (IFs) were studied. Six samples of different IF concentrations were manufactured, namely, Poly, Poly-IF20, Poly-IF30, Poly-IF40, Poly-IF50, and Poly-IF60 (where Poly-IF60 represents 40% polyester and 60% IF). We measured the attenuation factors using high purity germanium (HPGe)-detector along with three radioactive sources 241Am (emitting energy of 0.06 MeV), 137Cs (emitting energy of 0.662 MeV), and Co-60 (emitting energy of 1.173 and 1.333 MeV). We compared the linear attenuation coefficient (LAC) obtained by theoretical (i.e., XCOM software) and experimental (i.e., HPGe-detector) approaches for the prepared polyester composites at various photon energies (0.060, 0.662, 1.173, and 1.333 MeV). The greatest difference between the LAC values of the samples occurs at 0.060 MeV, where the Poly-IF60 sample has a much greater LAC than the other shields, followed by the Poly-IF50 sample, Poly-IF40 sample, and so on until the pure polyester shield. Specifically, their values are equal to 0.245, 0.622, 0.873, 1.187, 1.591, and 2.129 cm−1 for Poly, Poly-IF20, Poly-IF30, Poly-IF40, Poly-IF50, and Poly-IF60, respectively. We calculated the transmission factor (TF) and the radiation shielding efficiency (RSE), and found that the TF for Poly-IF30 is equal to 28.82%, 77.94%, 82.75%, and 83.75% at 0.060, 0.662, 1.173, and 1.333, respectively, while its RSE is equal to 82.57%, 24.00%, 18.80%, and 17.72%, respectively. The fast neutron removal cross-section (FNRC) of the polyester samples was calculated and the values increase when more Ifs are added to the samples. More specifically, the FNRC values are equal to 0.095, 0.100, 0.103, 0.107, 0.110, and 0.113 cm−1 for Poly, Poly-IF20, Poly-IF30, Poly-IF40, Poly-IF50, and Poly-IF60, respectively.

Stable and Radioactive Cesium in Natural Environment

Cesium is the heaviest stable alkali metal (with only one stable isotope – 133Cs) and it occurs mainly as a potassium-substituting cation. It is an important trace element in rocks typical for the Earth crust, and its content in biomass is also relatively high compared to those abiogenic elements which are little soluble. Low-cost analytical methods like X-Ray Fluorescence are inadequate to quantify cesium in typical natural samples, so that the usage of ICP-MS (Inductively-Coupled-Plasma Mass Spectrometry) or INAA (Instrumental Neutron Activation Analysis) is necessary. Nevertheless, investigation of the pollution with the radioactive isotope 137Cs, which is an important fission product and can be measured with gamma-ray spectrometry, also contributed to the knowledge of biogeochemistry of cesium. It has been shown that Cs is usually strongly retained in humus (thank to clay minerals), or is cycling intensely within the soil-biomass system, being only slowly removed (at least, this is valid for ecosystems in temperate climate). The results of extensive biomonitoring in Czech coniferous forests (with prevailing spruce) also show that Cs is concentrated in humus (relatively to all other alkali elements) by natural processes.

Significantly enhanced alkaline stability and cyanide suppression of Prussian blue analogues using montmorillonite for high-performance cesium removal

Radiocesium (Cs+) treatment is getting more attention as Japan plans to dump wastewater from Fukushima nuclear meltdown into the Pacific Ocean. Prussian blue is a star material and medicine for intracellular and extracellular therapy of Cs+. However, it and its analogues are essentially unstable in alkali-solution and seawater due to break down easily into the hazardous cyanide substance. In this study, copper ferrocyanide/magnetic montmorillonite composites (KCuFC/M−MT) were prepared using an in-situ synthetic method. This method can inhibit the decomposition of Prussian blue analogues (PBAs) and the production of toxic cyanide. The 5KCuFC/M−MT composites exhibit excellent Cs+ adsorption properties (204.48 mg/g), good material chemical stable over a wide pH region (2 ≤ pH ≤ 12), safe amount of cyanide release (<0.2 mg/L, EPA, USA), and low-toxic to human hepatocytes (HepG2 cells), which are promising for the application in radioactive wastewater treatment. The adsorption mechanism and stabilization mechanism were systematically studied. This study provides a reference for the control radioactive Cs+ hazards by using clay material stabilized ferrocyanide material and provides a new direction for the research of cesium-control materials. This research solves the problem of basic instability of PBAs and expands new application fields for PBAs, especially decorporation agent for internal contamination by radiocesium.

Study on (n, α) reactions for the production of 51Cr, 89Sr, 99Tc, 131I, 133Xe, 137Cs and 153Sm radioisotopes used in nuclear medicine

Nuclear medicine seems to be a decent choice of medicine in the recent decade. The radioactive isotopes 51Cr, 89Sr, 99Tc, 131I, 133Xe, 137Cs and 153Sm are extremely essential in nuclear medicine. The excitation functions of the 54Fe (n, α) 51Cr, 92Zr (n, α) 89Sr, 102Rh (n, α) 99Tc, 134Cs (n, α) 131I, 136Ba (n, α) 133Xe, 140La (n, α) 137Cs and 156Gd (n, α) 153Sm reactions were calculated in this study using the EMPIRE 3.2.3 and TALYS 1.95 nuclear codes. Additionally, the cross sections at 14–15 MeV were calculated using empirical formulae and the experimental data. The computer codes were compared to the experimental data and Empirical formulas as well as the evaluated data (TENDL 2021, JENDL 3.3, JENDL 5, JEFF 3.3, EAF 2010, CENDL 3.1, CENDL 3.2, ROSFOND 2010, FENDL 3.2 b, and BROND 3.1).

Open-framework hybrid zinc/tin selenide as an ultrafast adsorbent for Cs+, Ba2+, Co2+, and Ni2+

Efficient adsorption of radioactive 137Cs+ and 60Co2+ and their decay products 137Ba2+ and 60Ni2+ bears significance for hazard elimination in case of nuclear emergency, which relies on the adsorption rate enhancement that takes advantages of compositional and structural optimization. Herein, we report a zinc-doped selenidostannate constructed from T2-supertetrahedral clusters, namely K3.4(CH3NH3)0.45(NH4)0.15Zn2Sn3Se10·3.4 H2O (ZnSnSe‐1K). The soft Se and micro-porosity synergistically endow this material with a binding affinity to Cs+, Ba2+, Co2+, and Ni2+ ions and ultrafast kinetics with R > 97.6% in 2–60 min. In particular, ZnSnSe‐1K can remove 99.34% of Cs+ in 2 min (KdCs > 1.5 × 105 mL g−1), contributing to a record rate constant k2 of 9.240 g mg−1 min−1 that surpasses all metal chalcogenide adsorbents. ZnSnSe‐1K exhibits good acid/base tolerance (pH = 0–12), and the adsorption capacities at neutral are 253.61 ± 9.15, 108.94 ± 25.32, 45.76 ± 14.19 and 38.49 ± 2.99 mg g−1 for Cs+, Ba2+, Co2+, and Ni2+, respectively. The adsorption performances resist well co-existing cations and anions, and the removal rates can keep above or close to 90% even in sea water. ZnSnSe‐1K is employed in continuous column and membrane filtration, both of which shows excellent elimination efficiency (R > 99%) for mixed Cs+, Ba2+, Co2+, and Ni2+. Especially, the membrane with an ultrathin (70 µm) ZnSnSe‐1K layer can remove 97–100% Cs+ in suction filtration with a short contact time of 0.33 s. Combined with the simple synthesis, facile elution and great irradiation resistance, ZnSnSe‐1K emerges as a selenide adsorbent candidate for use in environmental remediation especially that involving nuclear waste disposal.

In situ growth of metal hexacyanoferrate crystals on alginate beads for effective removal of radioactive cesium (137Cs) from seawater

Metal hexacyanoferrates (Me-HCFs) are highly effective materials for removing radioactive Cs (137Cs) in seawater. For their practical application, granulation of Me-HCFs is necessary. However, conventional granulation techniques using a polymer as a binding material adversely affect the adsorption performance of Me-HCFs by blocking their adsorption sites. In the present work, to minimize the interference of the binding material, Me-HCF crystals were synthesized on an alginate bead surface in situ for the treatment of 137Cs+-contaminated seawater. Three different Me-HCFs immobilized on alginate beads (Fe-HCF, Cu-HCF, and Co-HCF) were prepared via a simple and rapid method involving a reaction between ionophorically crosslinked alginate beads (Fe3+, Cu2+, and Co2+ ions) and HCF solution. Among them, Fe-HCF crystals were successfully grown on the alginate bead surface; the other crystals were hardly synthesized despite a longer reaction time. The Fe-HCF crystals composed 15.0 % (w/w) of the beads and were located on the surface of the beads rather than being embedded in the alginate matrix. Because the Fe-HCF crystals were located at the surface of the alginate beads, Cs+ adsorption onto the Fe-HCF crystals showed fast reaction kinetics (achieving equilibrium in ∼ 3 h) and a high Cs+ adsorption capacity (∼33.5 mg/g). Also, a feasibility test was carried out for the removal of radioactive 137Cs+ in real seawater medium. Finally, a continuous Cs+ removal test was conducted in a packed column of the Fe-HCF beads. It was able to treat 65 bed volume of 50 mg/L of Cs+ solution with a flow rate of 1 mL/min.

Magnetic flocculants and selective adsorbents for the decontamination of radioactive and acidic soil-washing effluent

We demonstrate that radioactive 137Cs-suspended soil and 137Cs+ ions in the effluent can be sequentially removed, enabling the effluent to be reused or released. Specially synthesized coagulant-flocculants and adsorbents were used to remove Cs-suspended soils and Cs+ ions under strongly acidic conditions. Polyethyleneimine coated magnetic nanoparticles (PEI-MNPs) was found to be the best coagulant-flocculants for removing Cs-suspended soil among various coagulant-flocculants, including inorganic, organic, and organic-inorganic ones. To optimize the separation conditions, such as the dosage and composition of the coagulant-flocculants and adsorbents, a nickel potassium hexacyanoferrate -embedded polyacrylonitrile (NiFC/PAN)-3.5, defined as a NiFC/PAN weight ratio of 3.5, was used to successfully remove Cs+ ions in nonradioactive and radioactive tests, meeting the release criterion of 50 Bq L−1 (South Korea). In the first step, the radioactivity of the effluent was reduced from 380 to 300 Bq L−1 by separating 137Cs-suspended soils with PEI-MNP coagulant-flocculants. In the next step, 137Cs ions were substantially removed using NiFC/PAN, resulting in a decrease of the radioactivity from 300 to 20 Bq L−1, which meets the release criterion. These results suggest that the proposed process is a potentially useful and effective method for treating radioactive effluent after soil washing.

Cesium ion removal from low-level radioactive wastewater utilizing synthesized cobalt hexacyanoferrate-sand composite

Abstract Here, a novel method of synthesis of a sand-based adsorbent for radioactive Cs+ ion removal is reported. Natural sand has been modified with cobalt hexacyanoferrate (CoHCF) using a simple and effective approach. The detailed physical–chemical characterization of the synthesized adsorbent is carried out using XRD, XPS, UV-visible, FT-IR, ICP-AES and Raman spectroscopy. Cs+ ion batch adsorption studies were conducted radio-analytically, and the sorbent’s adsorption capability was observed to be ∼5 mg g−1. The batch studies revealed that Cs+ ion was selectively adsorbed throughout a broad pH range of 1–10. The rate-controlling steps in the adsorption process, according to kinetic studies, are film diffusion and intraparticular diffusion and the adsorption process follows a second-order kinetics.

High-efficiently and rapidly capturing cesium from water with Prussian blue@expanded graphite as adsorbent

The removal of radioactive 137Cs from nuclear wastewater is still needed to mitigate their high radiological toxicity to living creatures. However, the industrial application of adsorbents is still challenging owing to the complex and costly preparation and slow adsorption rate for Cs wastewater with low concentration. Herein, cost-effective and fast removal of Cs+ is achieved by vermiform expanded graphite (EG) immobilized with potassium copper hexacyanoferrate (KCuHCF) via the in-situ synthesis method. We revealed that the nano-scale KCuHCF granules are dispersed homogeneously on the EG interlayers. With this design, it achieves an excellent Cs removal capacity of 16.24 mg/g within 30 min in ultralow Cs concentration and shows high selectivity among various competing ions. We systematically studied the associated adsorption mechanism by XPS and ICP, which revealed that ion exchange between the lattice K and Cs played critical roles. Our work paves the way for the design of economical adsorbents for radioactive Cs remediation.