Separation Of Cesium Research Articles

Modification of the Process of Cesium Separation from the Product of the High-Temperature Treatment of Spent Fuel with Molybdenum Trioxide

Modification of the Process of Cesium Separation from the Product of the High-Temperature Treatment of Spent Fuel with Molybdenum Trioxide

Rapid and efficient separation of radioactive cesium ion/other radioactive ions by reduced graphene oxide membrane

Separation of cesium ions from other radioactive ions is of great significance for recycling and utilization of radioactive sources, facilitating the management of highly radioactive liquid waste (HLW), as well as for environmental protection. We achieved a highly selective and efficient separation of binary mixtures of 137Cs/60Co, Cs+/Co2+, Cs+/Ni2+, and Cs+/Zn2+ using amino-hydrothermal reduced graphene oxide membranes. The separation factor for non-radioactive binary mixtures is up to 4290, with a water permeance of 50.8 L m−2 h−1 bar−1. The separation factor for radioactive 137Cs/60Co is 623, which is somewhat underestimated due to the detection limit of the high-purity germanium spectrometer. The rGO membranes has the high water permeance of 72.4 L m−2 h−1 bar−1, with a thickness of ∼300 nm. The rGO membrane achieved effective separation of cesium and cobalt ions over a wide range of cesium-to-cobalt ion concentration ratios, with the best results achieved at a concentration ratio of 100:1 for cesium and cobalt. In addition, the rGO membranes showed outstanding stability. The superior performance is attributed to the amino hydrothermal treatment, which reduced oxygen functional groups and directly inserted nitrogen atoms into the GO lattice, ultimately forming stable narrow nanochannels conducive to the size-sieving effect. The findings show that the rGO membranes have excellent separation performance due to their size-sieving effect, and this work has great potential for rapid and efficient treatment of radioactive liquid waste.

Screening diluents to optimize cesium contaminant separation using t-BAMBP extractant

The widespread use of nuclear energy has raised concerns about nuclear safety and radioactive waste management, particularly due to the release of radioactive cesium. This study investigates the use of t-BAMBP (4-tert-butyl-2-(α-methylbenzyl) phenol) for the extraction and separation of cesium from simulate high concentration cesium containing wastewater, focusing on the selection of suitable diluents to enhance the efficiency of the process. We performed a systematic study using density functional theory (DFT) calculations to evaluate the intrinsic properties and interactions of various common diluents with t-BAMBP. The diluents studied include aromatic hydrocarbons (benzene, toluene, xylene), alkanes (cyclohexane, hexane, heptane), and alcohols (hexanol, octanol). Our computational results revealed that cyclohexane is the most suitable diluent due to its moderate solvation-free energy, high nonpolarity, and optimal balance between solubility and reactivity. Experimental validation confirmed the computational findings. The cyclohexane-diluted t-BAMBP system achieved the highest cesium extraction efficiency of over 94 %, with a separation factor (βCs/K) of 767.67. Cyclohexane demonstrated the lowest toxicity and cost among the diluents evaluated, making it a safer and more economical choice for practical applications. The results of this study provide a comprehensive theoretical and experimental basis for the selection of diluents in the t-BAMBP extraction system, offering insights for the sustainable utilization of cesium resources and effective management of radioactive waste.

A reductive strategy with ultrahigh selectivity for sequential recovery of uranium from radioactive wastewater

Uranium is valuable metal, and it is of great significance to develop a simultaneous separation process of uranium and cesium from radioactive wastewater. Herein, a process was designed to separate sequentially uranium and cesium from wastewater. By comparing the limiting ability of OH− and CO32− to Co2+, Cd2+, and Sr2+ ions, it was found that CO32− could effectively limit the above ions to the solid phase. The result of X-ray photoelectron spectroscopy (XPS) and species analysis revealed that the restriction was achieved through complexation. Through this property, more than 99.9 % of cobalt and cadmium were limited in the solid phase, and U-Cs co-separation was realized. Furthermore, the results of cyclic voltammetry and XPS indicated that U(VI) could be reduced in the liquid phase, but Cs(I) could not, which was the basis for uranium and cesium separation. And more than 99.5 % of uranium was separated from cesium by the electrochemical separation process. Simultaneously, effective separation of uranium and cesium under different pHs has been achieved via selective uranium leaching using carbonate. The co-separation combined with electrochemical separation realized the recovery of pure uranium products, indicating a large potential for realizing uranium resources in wastewater.

Magnetic Prussian blue nanoshells are controllable anchored on the surface of molybdenum disulfide nanosheets for efficient separation of radioactive cesium from water

The rapid development of nuclear energy in China has led to increased attention to the treatment of radioactive wastewaters. Herein, a novel magnetic adsorbent, magnetic Prussian blue‑molybdenum disulfide (PB/Fe3O4/MoS2) nanocomposite, was prepared by a simple in-situ fixation of ferric oxide nanoparticles (Fe3O4 NPs) and Prussian Blue (PB) shell layers on the surface of molybdenum disulfide (MoS2) nanosheets carrier. The prepared PB/Fe3O4/MoS2 nanocomposites adsorbent displayed excellent fast magnetic separation and adsorption capacity of Cs+ (Qm = 80.51 mg/g) from water. The adsorption behavior of Cs+ by PB/Fe3O4/MoS2 conformed to Langmuir isothermal and second-order kinetic model, which belonged to chemical adsorption and endothermic reaction. The equilibrium adsorption capacity of PB/Fe3O4/MoS2 to Cs+ has reached 90 % in less than 110 min. Moreover, the adsorption properties of PB/Fe3O4/MoS2 remained good in the pH range of 2–7. Based on this, PB/Fe3O4/MoS2 complex was a fast and high selectivity adsorption material for Cs+, which was expected to be used in the practical treatment of cesium-containing radioactive wastewater.

Separation of fission products from high-level waste salt systems by partial crystallization: CsCl-NaCl-LiCl-KCl study

Pyroprocessing refers to a series of high-temperature molten-salt processes used to manage and recycle nuclear materials to reduce the waste volume and hazardous environmental impact of the final waste products. Fission products with high halide affinity, including cesium (Cs-137) with a half-life of 30 years, are dissolved into a molten-salt bath. The separation and recovery of cesium can benefit waste-stream minimization because Cs-137—a strong gamma-ray emitter—is a potential source of environmental contamination. This work proposes the recovery of Cs+ from a chloride-salt matrix using a thermally controlled solid-liquid separation. Thermodynamic calculations for the CsCl-NaCl-LiCl-KCl system were performed to predict the partitioning of Cs+ into liquid and solid phases as functions of salt composition and temperature. The selected composition simulated the formulation of high-level salt waste from used fuel treatment. These calculations showed that once the solidus temperature was reached, Cs+ partitions to the liquid phase. According to the thermodynamic calculations, a thermally controlled liquid-solid separation holds the potential to recover up to 92.8 % of the initial cesium chloride. The phase transition temperatures of the sample, including the solidus and liquidus temperatures, were determined using differential scanning calorimetry. The phase composition of the system was studied at various temperatures using high-temperature X-ray diffraction. A laboratory-scale crystallization apparatus was used to melt the sample partially, allowing the collection of the liquid fraction for elemental analysis. All results demonstrated that Cs+ in this system concentrates in the liquid phase and confirmed the viability of recovering CsCl through thermally controlled solid-liquid separation.

A novel adsorbent potassium magnesium ferrocyanide for selective separation and extraction of rubidium and cesium from ultra-high salt solutions

The unique properties of rubidium and cesium make them occupy a place in high-tech applications. In this paper, a novel adsorbent (potassium magnesium ferrocyanide—KMgFC) was synthesized and used to recover rubidium and cesium from ultra-high salt solutions. The composition of the material phase was determined to be K2.01[Mg0.97Fe(CN)6]‧xH2O by characterization and analysis of KMgFC. The effects of various factors on the extraction rates of Rb+ and Cs+ were investigated, and the results exhibited that the extraction rates of Rb+ and Cs+ could reach 90.7 % and 97.9 % at a reaction pH of 8.1, a temperature of 80 °C, an adsorbent dosage of 3 times the theoretical dosage, and an equilibrium time of 40 min. The equilibrium adsorption capacities of KMgFC for Rb+ and Cs+ were 158.91 mg/g and 8.11 mg/g, respectively. Furthermore, the mechanism analysis displayed that the structure of KMgFC changed slightly during the adsorption process, and the ion exchange process between Rb+ or Cs+ and K+ occurred to achieve the capture of Rb+ or Cs+. Based on the strong affinity for Rb+ and Cs+, KMgFC is expected to be a viable adsorbent to be applied for the selective recovery of rubidium and cesium.

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.

Non-swelling oxidized graphene ribbon membrane for the effective separation of cesium and strontium from radioactive liquid waste

The interlayer swelling effect of graphene oxide (GO) membranes seriously hinders their applications in the precise nanofiltration, especially sieving cesium and strontium from radioactive liquid waste. Herein, a non-swelling membrane was successfully prepared via vacuum-filtering oxidized graphene ribbons (OGR), one kind of GO analogs. The unchanged interlayer spacing in OGR membrane (OGRM) were proved to originate from the unique two-section structure of OGR building blocks. Specifically, the low-defect aromatic plane in the central axis region of OGR resulted in the strong π‒π interaction, which prevented the further intercalation of water molecules at the nanoribbon edges and locked the whole lamellar architecture, hence inhibiting the peripheral expansion of OGR. By virtue of fixed nanochannels of OGRM, an ideal separation of Cs+ and Sr2+ was realized in the multicomponent acidic waste (pH ∼2.3), and the separation factors relative to UO22+ were fCs/UO2 = 6319 and fSr/UO2 = 2705, respectively. Meanwhile, OGRM showed a fast water flux of 12.10 L m−2 h−1, 15% higher than that of graphene oxide membrane (GOM). In addition to the special interlayer nanochannels, an in-depth investigation revealed that oxygenated groups also played an important role in the ion selectivity of OGRM. This preparation strategy of the non-swelling membrane is crucial to overcome the inherent paradox between the optimal selectivity and low flux, and our findings are very useful to remediate radioactive pollution and ensure water security.

Lipophilic Guanidine with Enhanced Stability for Use in Cesium Separation from Legacy High-Level Nuclear Waste

Guanidine functional groups are found in a variety of biologically active molecules and specialized molecules used in industrial applications but often suffer from instability because of their tendency to hydrolyze. Here, guanidines with differently structured alkyl groups were synthesized and their stabilities tested to determine if there is a relationship between the locus of branching in the alkyl groups attached to a guanidine and its hydrolytic stability under the hypothesis that increased steric hindrance to hydrolytic attack will increase stability. The guanidines examined in this work are pertinent to the next-generation caustic-side solvent extraction (NG-CSSX) process, which was developed for the removal of radioactive cesium from highly radioactive and complex alkaline solutions. In the NG-CSSX process, a lipophilic alkylguanidine solvent component is highly important to maintain the effectiveness of the Cs+ stripping of the loaded organic solvent putatively by sequestering extractable anions. Currently used for this purpose, N,N′,N″-tri(3,7-dimethyloctyl)guanidine (TiDG) succumbs to slow hydrolysis under process conditions. Guided by quantum chemical calculations, two new guanidines with large, sterically bulky alkyl substituents have been designed, synthesized, and tested. More sterically hindering alkyl groups were found to increase the stability of guanidines, particularly for the guanidine with branching closest to the guanidine N atom: N,N′-dicyclohexyl-N″-(10-nonadecyl)guanidine (DCNDG). DCNDG was found to have a stability toward hydrolysis 8 to 44 times greater than that of TiDG under different simulated NG-CSSX process conditions, making it one of the most hydrolysis-resistant guanidine molecules reported to date.

Separation of Cesium and Rubidium from Solution with High Concentrations of Potassium and Sodium

Solvent extraction with 4-tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP) is an effective method for the separation and purification of rubidium and cesium. A solution containing a high K+ concentration (exceeding 80 g/L), which was ultra-salty, with about 200 g/L alkali metal ions, was used to extract Rb+ and Cs+. The effects of the process parameters on the separation of cesium and rubidium were systematically studied. The optimum conditions were as follows: NaOH concentration of 0.5 mol/L, t-BAMBP concentration of 1 mol/L (in sulfonated kerosene), organic/aqueous volume ratio (O/A ratio) of 3:1, and contact time of 1 min. The extraction rates of cesium and rubidium were 99.81 and 98.09%, respectively, and 19.31% of potassium was co-extracted in the organic phase after five-stage countercurrent extraction. About 99.32% of K+ in the organic phase could be removed after five-stage countercurrent scrubbing with deionized water at an O/A ratio of 2:1 for 2 min. When 0.5 mol/L hydrochloric acid solution was used as detergent, almost all of the cesium and rubidium (>99%) could be recovered by two-stage countercurrent stripping at an O/A ratio of 3:1 for 2 min. A solid compound was found and collected from the organic phase during multi-stage solvent extraction. Its composition and structure were determined by XRD, infrared Fourier-transform, and ICP-MS.

Design and Synthesis of Covalently Tethered "IsoG-Star" as Recyclable Host for Selective Cesium Separation.

The isoguanosine self-assembled pentamer (isoG-star) has exhibited remarkable selectivity for Cs+ binding over competing alkali and alkali earth metal cation, rendering it a promising extractor for radioactive waste 137Cs separation. However, to make isoG-star a pracrtical material for Cs+ isolation, the development of recyclable isoG-star material is required. In this study, a systematic screening of functional isoG derivatives was performed. By employing well-defined complex formation and post-assembly modification, a covalently tethered isoG5-star was prepared through olefin metathesis, utilizing a designed isoG monomer. The application of this newly developed covalently linked isoG-star enabled selective Cs+ extraction, followed by controled solvent-induced H-bond dessociation. This resulted in the creation of a recyclable Cs+ extractor, demonstrating excellent cation selectivity and good reusability (over seven cycles) the first time. Consequently, this new supramolecular macrocycle offers a practical new platform for the treatment of radiocesium (134Cs and 137Cs) in an environmentally friendly and highly effective manner.

A highly efficient metal ferrocyanide adsorbent based on zinc phytate for cesium removal

Human health and sustainable development of nuclear energy pose new challenges for cesium removal. Herein, exploiting a novel metal ferrocyanides (MFCs) adsorbent is highly desirable for efficiently eliminate Cs+ from contaminated water. Based on zinc phytate (Zn-PA), the newly synthesized hybrid material of ZnFC-PA exhibits top-class adsorption capacity (qm = 559.76 mg/g) and excellent stability in a wide range of pH. The rapid adsorption kinetics and superior selectivity in the existence of numerous competing ions confirm the outstanding performance for cesium separation. Furthermore, the adsorption performance is roughly static after several cycles, and the distribution coefficient Kd still remains at a high level (3.3 × 104 mL/g) even in practical geothermal water. The excellent adsorption performance and reusability make it a promising Cs+ adsorbent to remediate the environment.

Separation and Removal of Radionuclide Cesium from Water by Biodegradable Magnetic Prussian Blue Nanospheres

As the main component of radioactive wastewater, the cesium ion has seriously endangered the environment and human health. Prussian blue nanoparticles (PB NPs) are used as adsorbents for the purification of cesium-containing wastewater because of their ability to selectively adsorb cesium ions. In this work, novel magnetic Prussian blue nanospheres (MPBNs) were developed from polylactic acid nanospheres as a carrier, loaded with Fe3O4 nanoparticles (Fe3O4 NPs) inside and PB NPs outside for the removal of cesium ions with the help of magnetic separation. Meanwhile, the effects on the adsorption efficiency of MPBNs, such as pH, time, temperature and initial concentration of cesium ion solution, were studied. The adsorption isotherms, kinetic models and adsorption thermodynamics were investigated to research the absorption mechanism. The results showed that MPBNs were spherical with a rough surface, and their particle size, iron content and saturation magnetization were 268.2 ± 1.4 nm, 40.01% and 41.71 emu/g, which can be recovered by magnetic separation. At 293 K, MPBNs could reduce the cesium ion solution from 40 mg/L to 4.8 mg/L, and its cesium ion removal rate and adsorption capacity were 82.46% and 16.49 mg/g, respectively. The optimum pH of MPBNs for cesium ion adsorption was 5~9, the adsorption equilibrium time was 60 min, and the maximum adsorption capacity was 17.03 mg/g. In addition, MPBNs were separated rapidly by an external magnetic field, and the adsorption process was an endothermic reaction. The adsorption isotherm and kinetics of MPBNs were in accordance with the Freundlich model and quasi-second-order fitting model, respectively, and the adsorption process of MPBNs was controlled by the diffusion step in particles. Notably, these MPBNs could be effectively separated from water by a magnetic field, facilitating engineering applications in cesium-containing wastewater.

Encapsulation of ammonium molybdophosphate for removal of selected radionuclides from multicomponent solution in a fixed-bed column

ABSTRACT Encapsulation of the fine powder of ammonium molybdophosphate (AMP) was carried out to produce AMP-Ca-alginate composite beads for removal of Cs+, U6+, Co2+ and Sr2+ ions from multicomponent media using a fixed-bed column. The results denote that the initial concentration (50, 100 and 200 mg/L from each ion), bed length (3, 6 and 8 cm) and flow rates (0.5, 1.5 and 2 mL/min) affect the sorption operation. The column performance was 40, 37.5, 32.34 and 31.7% for Cs+, U6+, Co2+ and Sr2+, respectively. Thomas and Yoon-Nelson models were utilised to forecast the breakthrough curves for adsorption. The two models are found as well-fitted models for investigated ions adsorption system except for the adsorption of Cs+ is more fitted for the Thomas model at a high flow rate. Marquardt’s percent standard deviation error function was used and confirmed these results. Good separation of strontium and caesium with a purity of 100% from this multi-component solution is accomplished by elution using 4 M of NaNO3 and HNO3 solution. The desorption percent of the loaded ions was 98, 91, 76 and 37.5% for Cs+, Sr2+, U6+ and Co2+, respectively. Overall, AMP-Ca-alginate composite beads are an environmentally friendly potential sorbent for hazardous ions from multicomponent media.

Highly-Efficient adsorptive separation of Cs+ from aqueous solutions by porous polyimide membrane containing Dibenzo-18-Crown-6

To develop recyclable adsorptive materials for high-efficient separation of cesium (Cs+) from aqueous salt lake brine is of great significance. Herein, a novel polyimide (PI-18C6) with high molecular weight (Mn = 93 kDa) and high thermal stability (Td > 380 °C) was synthesized by the condensation and polymerization of di(aminobenzo)-18-crown-6 (DAB18C6) and 4,4′- (hexafluoro-isopropylidene) diphthalic anhydride. Simultaneously, porous membranes for Cs+ selective adsorption were prepared by non-solvent induced phase separation (NIPs) method. Results suggested that the adsorption of Cs+ on PI-18C6 membrane is the monolayer chemical adsorption as confirmed by fitting its adsorption data using pseudo-second-order adsorption model and Langmuir isotherm model, respectively. PI-18C6 membranes displayed a high adsorption capacity up to 54.08 mg g−1 combined with a higher selectivity of coexisting ions such as K+, Na+, Mg2+ and Rb+. Theoretical calculation results showed that the PI-18C6 has a higher adsorption energy for Cs+ (-395.72 kJ mol−1) than K+ and Rb+. The significant higher adsorption energy at the crown-ether sites is largely attributed to the fact that the cavity diameter cavity of DB18C6 (2.6–3.2 Å) is a closer to Cs+ (3.34 Å). The membrane also exhibited excellent repeatability. In summary, our study paves a facile way to develop functional membrane materials for the selective adsorption separation of Cs+ from aqueous solution.

Selective adsorption of Ba2+ using chemically modified alginate beads with enhanced Ba2+ affinity and its application to 131Cs production

The 131Cs radioisotope with a short half-life time and high average radiation energy can treat the cancer effectively in prostate brachytherapy. The typical 131Cs production processes have a separation step of the cesium from 131Ba to obtain a high specific radioactivity. Herein, we suggested a novel 131Cs separation method based on the Ba2+ adsorption of alginate beads. It is necessary to reduce the affinity of alginate beads to cesium ions for a high production yield. The carboxyl group of the alginate beads was replaced by a sulfonate group to reduce the cesium affinity while reinforcing their affinity to barium ions. The modified beads exhibited superior Ba2+ adsorption performances to native beads. In the fixed-bed column tests, the saturation time and adsorption capacity could be estimated with the Yoon-Nelson model in various injection flow rates and initial concentrations. In terms of the Cs elution, the modified alginate showed better performance (i.e., an elution over 88%) than the native alginate (i.e., an elution below 10%), indicating that the functional group modification was effective in reducing the affinity to cesium ions. Therefore, the separation of cesium from the barium using the modified alginate is expected to be an additional option to produce 131Cs.

Selective extraction of cesium from high concentration rubidium chloride leach liquor of lepidolite

A special extractant, 4-tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP), was applied in cesium separation and purification from high concentration of rubidium chloride leach liquor. Effects of various parameters, such as feed liquid alkalinity, reagent concentration, contact time, and phase ratio, on extraction, scrubbing and stripping were systematic studied. The results demonstrated that the extraction rate of cesium reached 99.18% after five-stage countercurrent extraction, with the optimal extraction conditions that a feed liquid initial alkalinity of 10 g/L, t-BAMBP concentration of 1 mol/L, contact time of 1 min, and phase ratio (O/A) of 1:4. In addition, the loaded organic phase coextracted impurity elements (15.78% Rb, 0.5% K) was scrubbed with 0.1 mol/L HCl. After four-stage countercurrent scrubbing, the scrubbing rates of rubidium and potassium were 99.83% and 100% respectively, as well as 5.73% of cesium was lost. Almost all cesium (99%) was stripped with 0.05 mol/L HCl by two-stage countercurrent stripping after the organic phase was scrubbed. The slope method calculated the composition of the extraction complex as CsOR ∙ 2ROH(o), and the cation exchange reaction was proven to be the extraction mechanism.

Selective recovery and efficient separation of lithium, rubidium, and cesium from lepidolite ores

Sulfation and decomposition were proposed to selectively recover lithium, rubidium, and cesium from lepidolite ore. The purpose was to solve the problems of high acid consumption and the difficulty of separating lithium and aluminum in the sulfuric acid method. First, the theoretical feasibility of the process was verified by thermodynamic calculations. The optimal parameters were determined according to the theoretical and experimental results. The extraction rates of lithium, rubidium, and cesium were 90.5%, 91.2%, and 89.4%, respectively, whereas those of aluminum and iron were only 0.08% and 0.02%, respectively. The selective extraction of lithium, rubidium, and cesium was realized, and 90.4% of sulfuric acid could be recycled during the process. Subsequently, the mechanism was discussed by XRD and SEM-EDS analysis. The first-step roasting was the sulfation process of lepidolite, and the second-step roasting was the decomposition process of partial sulfates. The separation of alkali elements and impurity elements could be realized by simple deionized water leaching. The production of Li2CO3 and single-alkali sulfates (K2SO4, Rb2SO4, and Cs2SO4) were obtained through the efficient separation methods of carbonization precipitation and solvent extraction. This process achieved the selective recovery and efficient separation of lithium, rubidium, and cesium from lepidolite ores. At the same time, the recycling of sulfuric acid was realized; it greatly reduced the amount of reagents, such as acid and alkali. It is an efficient, clean, and sustainable process for the utilization of lepidolite ores.

Review and assessment on the separation of cesium and strontium from the aqueous stream

Review and assessment on the separation of cesium and strontium from the aqueous stream