Cesium Uptake Research Articles

Economically friendly and facilely synthesized layered metal sulfide for efficient removal of aqueous cesium

Cost-effective and efficient capture of Cs+ ions from radioactive wastewater is crucial for the sake of environmental protection and human health but full of challenges. In this paper, we present the suitability of a layered metal sulfide, namely Na2Sn3S7 (NaTS), for the remediation of cesium by ion exchange, with the merits of facile preparation, cheap composition, high efficiency and good selectivity. The cesium adsorption behaviors including kinetic time, saturation capacity, pH values, interfering ions, dose and recyclability were explored in detail. The experimental results show that it has a fast cesium uptake kinetics (ca. 60 min), with a maximum adsorption capacity of 140.32 mg/g and a wide pH resistance of 2.2–12.6. Also, it exhibits the strong affinity for low-level Cs+ ion even in the presence of excessive Na+/Ca2+ ions, actual water environment and the dose-related researches, with the highest distribution coefficient Kd value reaching 9.61 × 103 mL/g. More importantly, the cesium adsorption performances in the recycling study and the flow membrane-like filtration application are still impressive. These advantages demonstrated by NaTS render it very promising for the inexpensive and effective incarceration of aqueous cesium.

Engineered species-selective ion-exchange in tuneable dual-phase zeolite composites.

Controllable sorption selectivity in zeolites is crucial for their application in catalysis, gas separation and ion-exchange. Whilst existing approaches to achieving sorption selectivity with natural zeolites typically rely on screening for specific geological deposits, here we develop partial interzeolite transformation as a straightforward and highly tuneable method to achieve sorption selectivity via forming dual-phase composites with simultaneous control of both phase-ratio and morphology. The dual-cation (strontium and caesium) exchange properties of a series of granular mordenite/zeolite P composites formed from a parent natural mordenite material are demonstrated in complex, industrially relevant multi-ion environments pertinent to nuclear waste management. The relative uptake of caesium and strontium is controlled via the extent of transformation: composites exhibit significantly increased ion-exchange affinity for strontium compared to both the parent mordenite and physical mixtures of mordenite/zeolite P phases with similar phase ratios. The composite with a 40 : 60 mordenite : zeolite P ratio composite achieves higher uptake rates than the natural clinoptilolite material currently used to decontaminate nuclear waste streams at the Sellafield site, UK. In situ X-ray image-guided diffraction experiments during caesium exchange demonstrate that the mordenite core retains rapid caesium uptake likely responsible for the unique ion-exchange chemistry achievable through the partial inter-zeolite transformation. These results offer a straightforward and controllable route to optimised zeolite functionality and a strategy to engineer composites from low-grade natural sources at low cost and with formulation advantages for industrial deployment.

Rapid and Selective Uptake of Radioactive Cesium from Water by a Microporous Zeolitic-like Sulfide.

The fast and efficient removal of 137Cs+ ions from water is of great significance for the further treatment and disposal of highly active nuclear waste. Hitherto, although many layered metal sulfides have been proven to be very effective in capturing aqueous cesium, three-dimensional (3D) microporous examples have rarely been explored, especially compounds that are systematically used to study cesium ion exchange behaviors. In this paper, we present detailed Cs+ ion exchange properties of a 3D, microporous, zeolitic-like sulfide, namely K@GaSnS-1, in different conditions. Isotherm studies indicate that K@GaSnS-1 has a high cesium saturation capacity of 249.3 mg/g. In addition, it exhibits rapid sorption kinetics, with an equilibrium time of only 2 min. Further studies show that K@GaSnS-1 also displays a strong preference and good selectivity for cesium, with the highest distribution coefficient Kd value up to 3.53 × 104 mL/g. Also noteworthy is that the excellent cesium ion exchange properties are well-maintained despite acidic, basic, and competitive multiple-component environments. More importantly, the Cs+-exchanged products can be easily eluted and regenerated by a low-cost and eco-friendly method. These merits demonstrated by K@GaSnS-1 render it very promising in the effective and efficient separation of radioactive cesium from nuclear waste.

Potassium applications reduced cesium uptake and altered strontium translocation in soybean plants

ABSTRACT After the Tokyo Electric Power Company’s Fukushima Dai-ichi Nuclear Power Plant accident in 2011, radioactive cesium (RCs) was released in greater concentrations than radioactive strontium (RSr) in the surrounding environment. Most of the countermeasures were developed to mitigate the RCs transfer from the soil to plants. However, to avoid what has happened after the Chernobyl and Mayak accidents, preventing the transfer of RSr from soil to plants should be a priority. Although the application of potassium (K) fertilizers is the most effective method for preventing agricultural crops from absorbing RCs in contaminated fields, this implementation increases the cost and labor requirements. Considering the preparedness for nuclear accidents, it remains unclear how this countermeasure will be affected if RCs and RSr are released simultaneously. We aimed to explore the effect of K applications on cesium (Cs) and strontium (Sr) uptake and their interaction with and correlation to other elements in the soybean plants and soil. The field experiments were conducted in Fukushima Prefecture, Japan, using different K applications (i.e., no, normal, and high K applications). The dry weight and mineral concentrations of K, Cs, Sr, calcium (Ca), magnesium (Mg), and nitrogen (N) concentration in plants and exchangeable K (ExK), exchangeable Cs (ExCs), exchangeable Sr (ExSr), exchangeable Ca (ExCa), exchangeable Mg (ExMg), NH4+ (ammonium), and NO3- (nitrate) concentrations in the soils were evaluated. This study revealed that K application reduced Cs, Ca, and Mg uptake but did not affect the ExSr, ExCa, and ExMg concentrations in the soil and did not change the uptake of Sr. On the other hand, K concentration of the plant especially at later growth stage, which indicates re-translocation of Sr was negatively regulated by K concentration.

Eco-friendly polyvinyl alcohol/beeswax blend prepared using gamma irradiation for adsorption of cesium ions from an aqueous solution

ABSTRACT The release of cesium ions in the environment is considered to be a dangerous pollutant. The present work deals with the gamma irradiation synthesis of novel adsorbent sustainable hydrogel from polyvinyl alcohol (PVA)/beeswax (BW) and its investigation for the uptake of cesium (I) from aqueous solutions. The characterization of synthesized PVA/BW hydrogel was provided by FTIR, SEM, XRD and gel content in addition to the water absorbency. The obtained results indicated that the prepared composite provides advantages over conventional preparation techniques. The batch technique experiments were occurred to investigate the adsorption kinetics, capacity, and optimum conditions for the uptake of cesium (I) by PVA/BW. The obtained data show that the maximum adsorption capacity of PVA/BW for cesium ion was estimated and it was provided at a contact time of 1.0 hr, pH = 3, and adsorbed dose of 0.10 g. The calculated thermodynamic parameters show that the adsorption of cesium ions by PVA/BW was an endothermic and spontaneous process.

Poly-condensation of N-(2-acetamido)-2-aminoethanesulfonic acid with formaldehyde for the synthesis of a highly efficient sorbent for Cs(I)

A new sorbent (ACES-F micro-particles) is readily synthesized by the one-pot reaction of N-(2-acetamido)-2-aminoethanesulfonic acid with formaldehyde (poly-condensation reaction). The mesoporous sorbent is characterized by BET analysis (SBET: ≈6 m2 g−1), SEM-EDX (N: ≈7–8 % and S: 5 %), FTIR spectroscopy (identification of amine, sulfonic groups and their interactions with metal ions), TGA, elemental analysis, and titration (pHPZC: ≈5.7). The study of pH effect on Cs(I) shows an optimum close to 8 (with intermediary optimum at pH 4, associated with different reactive groups). The micron-size sorbent shows fast sorption (equilibrium in 60 min) and the pseudo-first order rate equation fits the kinetic profile. The sorption isotherm reaches up to 1.99 mmol Cs g−1; the Langmuir equation models isotherm profiles. The sorption decreases with increasing temperature; sorption is exothermic. Cesium uptake is affected by the presence of NaCl; however, even in large excess of salt (i.e., 4 M) sorption remains relatively high (loss <60 %). Selectivity is confirmed by the remarkable preference of the sorbent for Cs against alkali and other competitor metal ions, especially at pHeq ≈7. Metal desorption is highly effective using 0.3 M HNO3 solutions: complete desorption occurs in 30 min. The sorbent can be recycled for at least five cycles (losses <3 %). The interest of ACES-F for cesium recovery from seawater is confirmed by the study of Cs(I) sorption (and other major elements) from Vietnam and Egypt samples. The safety of the sorbent for aqueous bodies is evaluated by the cytotoxicity of the sorbent (limited against normal cells but highly reactive for cancerous cells); while the sorbent shows interesting antimicrobial properties for Gram+, Gram- and pathogenic yeast.

Rice OsHAK5 is a major potassium transporter that functions in potassium uptake with high specificity but contributes less to cesium uptake.

Cesium (Cs) in the environment is primarily absorbed by a potassium (K) transporter. OsHAK5 is a KT/HAK/KUP family K-transporter showing a high affinity for K. We created cultured rice cells whose OsHAK5 was knocked down by RNAi (named KD). In the medium containing 1.0 m m and less K, the growth of KD was significantly suppressed, suggesting that OsHAK5 greatly contributed to K absorption under limited K conditions. Although Cs suppressed the growth of KD and WT, stronger inhibition was observed on KD. Both KD and WT accumulated similar amounts of Cs when they were cultured in a medium containing Cs, whereas lower amounts of K were detected in KD. These results suggest that OsHAK5 was less involved in the absorption of Cs, although it was essential to K absorption under limited K conditions. In contrast, this means that another transporter may contribute to cesium uptake in rice.

Reversible electro-mediated cesium ion removal using a zeolitic imidazolate framework derived zinc hexacyanoferrate composite

Cesium (137Cs) is one of the representative radionuclides which must be eliminated from nuclear waste. Here, we designed a zinc hexacyanoferrate (ZnHCF) composite using ZIF-8 derived carbon (ZDC) and utilized it as an electrode to selectively remove cesium ions. Specifically, we focused on how the ZIF-8 pyrolysis temperature affected the composite formation and non-radioactive cesium removal performance. With an optimized temperature of 700 °C, a highly conductive and uniform composite with well-distributed ZnHCF was produced, and it exhibited a large cesium uptake capacity (204.9 mg g−1). The composite electrode also retained high selectivity in Na-rich environments (molar Na/Cs = 1330, Kd (mL g−1) = 1.04 × 105), K-rich environments (molar K/Cs = 133, Kd (mL g−1) = 7.20 × 104), and groundwater conditions (95 % removal, C0 = 0.007 mM Cs+). Moreover, the reversible uptake and release of cesium over 5 cycles were feasible in our system without any chemical additives, which can be reached 100 % regeneration at the fourth cycle. Using in-depth characterizations including XRD and XPS, we investigated the faradaic behavior, phase transition, and structural stability of the ZnHCF-ZDC composite over 5 cycles. This study formed a composite electrosorbent with a ZIF-derived carbon support and applied it to cesium removal for the first time. This electro-mediated cesium removal process is expected to serve as a green technology for the future nuclear industry and environmental remediation.

Bioremediation potential of hexavalent chromium-resistant Arthrobacter globiformis 151B: study of the uptake of cesium and other alkali ions.

Cesium (Cs+) enters environments largely because of global release into the environment from weapons testing and accidents such as Fukushima Daiichi and Chernobyl nuclear waste. Even at low concentrations, Cs+ is highly toxic to ecological receptors because of its physicochemical similarity to macronutrient potassium (K+). We investigated the uptake and accumulation of Cs+ by Arthrobacter globiformis strain 151B in reference to three similar alkali metal cations rubidium (Rb+), sodium (Na+), and potassium (K+). The impact of hexavalent chromium (Cr+6) as a co-contaminant was also evaluated. A. globiformis 151B accumulated Cs+ and Cr6+ in a time-dependent fashion. In contrast, the uptake and accumulation of Rb+ did not exhibit any trends. An exposure to Cs+, Rb+, and Cr+6 triggered a drastic increase in K+ and Na+ uptake by the bacterial cells. That was followed by the efflux of K+ and Na+, suggesting a Cs+ "substitution." Two-dimensional gel-electrophoresis of bacterial cell proteomes with the following mass-spectrometry of differentially expressed bands revealed that incubation of bacterial cells with Cs+ induced changes in the expression of proteins involved in the maintenance of cellular homeostasis and reactive oxygen species removal. The ability of A. globiformis 151B to mediate the uptake and accumulation of cesium and hexavalent chromium suggests that it possesses wide-range bioremediation potential.

Strontium/strontium‐90 removal from c helate‐bearing Hanford tank waste using crystalline silicotitanate

A study was conducted to evaluate if crystalline silicotitanate (CST) could be used to remove 90Sr from highly chelated tank waste in support of tank waste immobilization. CST was shown to remove cesium from a high-complexant tank waste, AN-102 diluted to 5.7 M sodium ions (Na+), comparing well with an existing adsorption isotherm generated with a simplified simulant without chelates. Strontium, barium, and lead were also shown to partially exchange onto the CST, despite their expected chelation and without impacting cesium uptake. The moles of lead loaded onto CST were essentially equivalent to that of cesium. Increasing CST mass resulted in increasing strontium (barium and lead) uptake. Calcium was shown to not exchange, demonstrating strong calcium chelation, not amenable to exchange onto CST.

Bioaccumulation of 137Cs and 60Co in freshwater plants

Contamination of the aquatic environment by the heavy metals and radionuclides has become a serious concern in the world. In our study, gamma-spectrometry of freshwater plants Bacopa monnieri and Egeria densa growing in cultivation media spiked with 137CsCl and 60CoCl2 was used for quantitative determination of bioaccumulation kinetic and distribution Cs+ and Co2+ ions in plant tissues. We found, that bioaccumulation of Cs and Co by fully immersed B. monnieri in Hoagland media (HM) was dependent on ion concentration in medium. Approx. 5-times lower Cs uptake 2.9 nmol/g (d.w.) was obtained in plants cultivated in 20% HM than from deionized water. The maximal Co uptake was 4-times higher than cesium uptake at the same conditions. Both Cs and Co were localized mainly in roots. The highest immobilization from roots to shoots was found in the case of Co uptake from deionized water with concentration ratio [Co]leaves : [Co]stem : [Co]root = 1.00 : 5.33 : 56.8. Cesium uptake by submerged plant E. densa was also strongly dependent on nutrients concentration in medium. However, in the case of cobalt uptake this dependence was less pronounced. Nutrients concentration also had a significant influence on distribution of Cs between stems and leaves of E. densa. Cesium was localized in leaves, however with increasing of nutrients concentration in cultivation media Cs was localized for account of stem. On the other hand, cobalt was immobilized mainly in leaves in whole range of nutrients concentration. Obtained data can serve as a models for understanding of phytoaccumulation of radionuclides from open water ponds and water channels in the vicinity of nuclear power plants and monovalent and bivalent metals from industrial sources of contamination.

Copper hexacyanoferrate/carbon nanostructure hybrids: electrochemically switched ion-exchange electrodes for the sustainable removal of cesium from water

Herein, we report the design and fabrication of carbon supported copper hexacyanoferrate (CuHCF) based nanohybrids as potential electrode materials for electroadsorptive removal of Cs+ from aqueous solution. Specifically, we present a hydrothermal approach for the synthesis of cubic shaped CuHCF decorated carbon nanostructures (CuHCF/CNS) viz. multi-walled carbon nanotubes (CuHCF/f-CNT), graphene oxide (CuHCF/GO) and graphitic carbon nitride (CuHCF/g-C3N4). The crafted CuHCF/CNS materials exhibit an excellent ability for electroadsorptive removal of Cs+ from its aqueous solutions, due to enhanced charge transport and high surface area offered by the CNS support to the selectively ion specific CuHCF functional units in the CuHCF/CNS hybrid. Among the CuHCF/CNS hybrids crafted for the present work, the cesium uptake capacity of CuHCF/f-CNT hybrid is highest, almost 2–3-fold higher than that reported for the various state-of-art materials. The impact of electrolyte concentration, Cs+ ion concentration, and the regeneration and selectivity for Cs+ ions over K+ over the CuHCF/CNS hybrids is also presented. We opine that the results presented herein clearly reveal the fundamental requirements and the potential advantages of combining electro-adsorption and ion exchange strategy for selective and efficient removal of 137Cs+ from radioactive liquid wastes.

Uptake of cesium by the hydroxysulfate green rust-modified composite aluminosilicate materials, mathematical modeling, and mechanisms

The ecological hazards caused by the radioactive cesium (Cs) contaminants are long-standing and field-wide. In this study, the green rust (GR) was chemically formed and loaded onto the composite aluminosilicate materials (CAM) to enhance the adsorption capacities, environmental adaptability, and recyclability of CAM materials (GR-CAM) for Cs+ removal. The maximum monolayer adsorption capacities (mg/g) of GR-CAM for Cs+ adsorptions at pH of 2, 7, and 12 were 67.11, 104.93, and 129.03, respectively. The suitability of the pseudo-first-order kinetic model and Langmuir model for predicting Cs+ removal efficiencies and describing the isothermal fittings were observable and provable. Cs+ ions rebalanced the structural charge of GR-CAM by replacing some monovalent or divalent cations in mineral structures. The chemical loading of GR diversified the micromorphologies of CAM in different pH environments during the heterogeneous adsorption. The modification of GR strengthened the role of ion exchange in increasing the adsorption of Cs+ into GR-CAM. The excellent immobilization of Cs+ ions in GR-CAM in an alkaline environment was attributed to the formation of composite geopolymers. The different pH environments induced different adsorption mechanisms of GR-CAM towards Cs+ ions due to the sandwich structure of GR-CAM such as ion exchange, inner transferring, chemisorption, and co-precipitation.

Impact of soil moisture on cesium uptake by plants: Model assessment

Computational models of radioisotopes soil-to-plant transfer are an essential component of decision support systems for nuclear emergency and assessment impact of nuclear accidents on human beings and the environment. The soil water regime impact on cations behavior in the «soil-plant » system. Therefore, relationships between radioisotopes accumulation by plants and soil moisture should be included in the computational models. A kinetic model for simulation of Cs+ root uptake under alteration of soil moisture content in soil is presented in this paper. The model simulates Cs+ and K+ diffusion from bulk soil into rhizosphere under alteration of water content. The model results show a drop of Cs+ and K+ concentration in the rhizosphere with decreasing soil moisture. The magnitude of enhanced root uptake of Cs+ with soil moisture alteration depends on the exchangeable potassium content and soil texture. The Cs+ root uptake rate has a maximum at 60%–80% of field capacity under sufficient and high exchange potassium content. A similar dependence should also be seen for the RCs soil-to-plant transfer factor. The results indicate the importance of soil water content for modification of the RCs accumulation by plants and the necessity to include this factor into an appropriate semi-mechanistic model.

The quest for selective Cs+ transport in plants

The quest for selective Cs+ transport in plants

ATP binding cassette proteins ABCG37 and ABCG33 function as potassium-independent cesium uptake carriers in Arabidopsis roots

Radiocesium accumulated in the soil by nuclear accidents is a major environmental concern. The transport process of cesium (Cs+) is tightly linked to the indispensable plant nutrient potassium (K+) as they both belong to the group I alkali metals with similar chemical properties. Most of the transporters that had been characterized to date as Cs+ transporters are directly or indirectly linked to K+. Using a combinatorial approach of physiology, genetics, cell biology, and root uptake assay, here we identified two ATP-binding cassette (ABC) proteins, ABCG37 and ABCG33, as facilitators of Cs+ influx. A gain-of-function mutant of ABCG37 (abcg37-1) showed increased sensitivity to Cs+-induced root growth inhibition, while the double knockout mutant of ABCG33 and ABCG37 (abcg33-1abcg37-2) showed resistance, whereas the single loss-of-function mutants of ABCG33 and ABCG37 did not show any alteration in Cs+ response. In planta short-term radioactive Cs+-uptake assay along with growth and uptake assays in a heterologous system confirmed ABCG33 and ABCG37 as Cs+-uptake carriers. Potassium response and content were unaffected in the double-mutant background and yeast cells lacking potassium-uptake carriers transformed with ABCG33 and ABCG37 failed to grow in the absence of K+, confirming that Cs+ uptake by ABCG33 and ABCG37 is independent of K+. Collectively, this work identified two ABC proteins as new Cs+-influx carriers that act redundantly and independent of the K+-uptake pathway.

A Batch Experiment of Cesium Uptake Using Illitic Clays with Different Degrees of Crystallinity

Radiocesium released by the severe nuclear accident and nuclear weapon test is a hazardous material. Illitic clays play a key role in the spatial distribution of radiocesium in groundwater environments due to selective uptake sites at the illite mineral, such as frayed edge sites. However, the cesium uptake capabilities of illitic clays are diverse, which could be associated with the illite crystallinity. This study was performed to determine the cesium uptake of illitic clays and evaluate the crystallinity effects on cesium uptake using statistical approaches. A total of 10 illitic clays showed various crystallinity, which was parameterized by the full width at half maximum (FWHM) at 10 Å XRD peak ranging from 0.15 to 0.64. The uptake behavior of illitic clays was well fitted with the Freundlich model (i.e., r2 &gt; 0.946). The uptake efficiency of illitic clays increased with the decrease in dissolved cesium concentrations. The cesium uptake was significantly correlated with the FWHM and cation exchange capacity, suggesting that the uptake becomes higher with decreasing crystallinity through expansion of the edge site and/or formation of ion-exchangeable sites.

Effects of Biochars Produced from Coconut Shell and Sewage Sludge on Reducing the Uptake of Cesium by Plant from Contaminated Soil

Immobilization using biochar is a cost-effective and environmentally friendly remediation method to inhibit the transfer of soil contaminants to the food chain. This study evaluated the effects of coconut shell–derived biochar (CSB) and sewage sludge–derived biochar (SSB) on reducing the accumulation of cesium (Cs) by plant from contaminated soil. Pot experiment was conducted by cultivating Napier grass on the soil added with different Cs concentrations (0, 25, and 50 mg kg−1) and biochar ratios (0: control, 5% and 10%). It was observed that both biochars significantly restricted the transfer of Cs to the root, leaf sheath, and leaf blade of Napier grass (p < 0.01). The possible mechanisms of Cs immobilization by biochar could be the sorption of Cs on the surface of biochar as well as the restriction of the uptake of Cs by plant due to the increased K concentration of biochar-amended soil. CSB application was more effective than SSB on reducing the transfer of Cs to plant. Compared to control, the CSB application reduced the concentration of Cs in the plant by 80.2–98.2%. Moreover, obtained results in terms of pH, organic matter content, cation exchange capacity, specific surface area, and K concentration of biochar-amended soil highlighted the remarkable efficiency of CSB to adsorb Cs and restrict Cs transfer to plant providing the key evidences for Cs immobilization. Considering these results, CSB could be a potential amendment for the immobilization of Cs-contaminated soil.

More Efficient Prussian Blue Nanoparticles for an Improved Caesium Decontamination from Aqueous Solutions and Biological Fluids.

Any release of radioactive cesium-137, due to unintentional accidents in nuclear plants, represents a dangerous threat for human health and the environment. Prussian blue has been widely studied and used as an antidote for humans exposed to acute internal contamination by Cs-137, due to its ability to act as a selective adsorption agent and to its negligible toxicity. In the present work, the synthesis protocol has been revisited avoiding the use of organic solvents to obtain Prussian blue nanoparticles with morphological and textural properties, which positively influence its Cs+ binding capacity compared to a commercially available Prussian blue sample. The reduction of the particle size and the increase in the specific surface area and pore volume values compared to the commercial Prussian blue reference led to a more rapid uptake of caesium in simulated enteric fluid solution (+35% after 1 h of contact). Then, after 24 h of contact, both solids were able to remove >98% of the initial Cs+ content. The Prussian blue nanoparticles showed a weak inhibition of the bacterial luminescence in the aqueous phase and no chronic detrimental toxic effects.

Dynamics of Radio-Cesium in the Soils and Plants: Newly Elucidated Mechanism of the Cesium Uptake into Rice Plants

Dynamics of Radio-Cesium in the Soils and Plants: Newly Elucidated Mechanism of the Cesium Uptake into Rice Plants