Removal Of Radioactive Cesium Research Articles

Synthesis of copper hexacyanoferrate from copper oxide catalyzed by trimesic acid for removal of radioactive cesium

Synthesis of copper hexacyanoferrate from copper oxide catalyzed by trimesic acid for removal of radioactive cesium

A prototype system for the removal of 137Cs from liquid radioactive waste using reverse osmosis membrane

Cesium removal from aqueous solutions of radioactive waste streams is a challenge in the field of radioactive waste management; this is due to the small atomic radii of Cs+ metal ions and their high migration ability. So, the development of a withstand system for the removal of Cs+ is crucial. In the current study, the removal of radioactive cesium from aqueous solutions using an RO-TLC membrane was studied. Two modifications were conducted; the first is to enlarge the cesium metal ion radii by interacting with mono- and dibasic acids, namely, stearic acid, tartaric acid, citric acid, and EDTA, and the second is the modification of the RO membrane pore size via reaction with the same acids. The modification was confirmed using SEM, FTIR, and EDX analysis techniques. The Cs+ and K+ rejection capacities and water permeability across the membrane at 1.5 bars were evaluated. Along with using the above-mentioned acids, the Cs+ metal ion retention index (RCs) was also obtained. It was found that employing EDTA as a chelating agent in an amount of 1.5 g/L in conjunction with the variation of feed content since it provided the highest value of RCs ~ 98% when used. Moreover, the elution of Cs+ using water, EDTA, ammonia, and HCl is also investigated. The optimal value of the eluent concentration was (0.25 M) HCl. Finally, Langmuir and Freundlich isotherm models were applied for a better understanding of the sorption process. The results of the present work more closely match the Langmuir isotherm model to determine the dominance of the chemical sorption mechanism.

Magnetic hierarchical titanium ferrocyanide for the highly efficient and selective removal of radioactive cesium from water

Selective adsorption is the most suitable technique for eliminating trace amounts of 137Cs from various volumes of 137Cs-contaminated water, including seawater. Although various metal ferrocyanide (MFC)-functionalized magnetic adsorbents have been developed for the selective removal of 137Cs and magnetic recovery of adsorbents, their adsorption capacity for Cs remains low. Here, magnetic hierarchical titanium ferrocyanide (mh-TiFC) was synthesized for the first time for enhanced Cs adsorption. Hierarchical TiFC, comprising 2-dimensional TiFC flakes, was synthesized on SiO2-coated magnetic Fe3O4 particles using a sacrificial TiO2 shell as a source of Ti4+ via a reaction with ferrocyanide under acidic conditions. The resultant mh-TiFC exhibited the highest maximum adsorption capacity (434.8 mg g−1) and enhanced Cs selectivity with an excellent Kd value (6,850,000 mL g−1) compared to those of previously reported magnetic Cs adsorbents. This enhancement was attributed to the hierarchical structure, which reduced intracrystalline diffusion and increased the surface area available for direct Cs adsorption. Additionally, mh-TiFC (0.1 g L−1) demonstrated an excellent removal efficiency of 137Cs exceeding 99.85% for groundwater and seawater containing approximately 22 ppt 137Cs. Therefore, mh-TiFC offers promising applications for the treatment of 137Cs-contaminated water.

MXene/AgNW composite material for selective and efficient removal of radioactive cesium and iodine from water

Toxic fission products, such as cesium (137Cs) and iodine (129I) are of great concern because of their long half-lives and high solubility in water. The simultaneous removal of Cs and I using a single adsorbent is an area of increasing interest. In this study, MXene/silver nanowire (AgNW) composite was synthesized through physical mixing and employed for simultaneous removal of iodide (I−) and cesium (Cs+) ions from contaminated water. The MXene/AgNW composite demonstrated excellent adsorption capacities of 84.70 and 26.22 mg/g for I− and Cs+, respectively. The experimental data supported the hypothesis of multilayer adsorption of Cs+ owing to the inter-lamellar structures and the presence of heterogeneous adsorption sites in MXene. The interaction between I− and the AgNW involved chemisorption followed by monolayer adsorption. MXene/AgNW composite material exhibited promising results in the presence of competitive ions under extreme pH conditions. Thus, synthesized composite materials holds promising potential as an adsorbent for the remediation of radioactive liquid waste.

Preparation of nano-scale ferric hexacyanoferrate using coal ash by microwave-assisted hydrothermal process for cesium removal

The removal of radioactive cesium (Cs+) has received considerable attention owing to its chemotoxicity and radiotoxicity. This study presents a method for producing ferric hexacyanoferrate nanoparticles (Prussian blue, PB), using recycled magnetic coal ash (M-CA) as an effective and selective adsorbent for Cs+ removal. A microwave-assisted hydrothermal technique was employed to recover the Fe solution from M-CA and a simple sol–gel technique was used to synthesize PB nanoparticles. The PB nanoparticles exhibited cubic cluster structures with an average size of 20.67 nm. Their Cs+ adsorption capacity reached 213.061 mg/g, significantly surpassing the capacities of absorbents reported in previous studies. Cs+ was observed to be associated with localized adsorption sites on the PB surfaces, with minimal internal diffusion. In addition, the hydrated radius of Cs+ emerged as a critical factor influencing its adsorption onto PB surfaces, enabling the efficient removal of Cs+ even in the presence of competing ions. These findings offer valuable insights for the straightforward synthesis of highly efficient and selective adsorbents for radioactive substances, as well as the recovery of valuable materials from industrial solid waste.

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.

Fabrication of self-assembled Prussian blue graphene hydrogel for highly selective removal of radioactive cesium in water: Adsorption study

This paper reports a simple and cost-effective method for fabrication of a 3D porous and redox-active Prussian blue-graphene (PBG) hydrogel using ferrous ions to reduce graphene oxide sheets. The hydrogel was obtained via sonication for 5 min only at a low temperature of 40 °C without the need of purification or centrifugation. The hydrogel exhibited high selectivity for cesium ions due to the cubic framework of iron centers bound by cyanide bridges, which allows for intercalation of additional cations. The hydrogel's centered-cubic phase of Prussian blue was confirmed through XRD, and its existence was demonstrated through FTIR and XPS. The BET surface area measurements revealed that the composite's adsorptive surface area increased as compared to magnetic PBGO. Furthermore, the hydrogel's adsorption potential for cesium ions increased to 4.67 mmol/g (621.11 mg/g) compared to the previous work, fitting well with the Langmuir isotherm and the pseudo-second order kinetic model. Moreover the optimal values for temperature and pH for cesium ions removal were found to be 30 °C and neutral, respectively.

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.

Effective removal of non-radioactive and radioactive cesium from wastewater generated by washing treatment of contaminated steel ash

The co-precipitation process plays a key role in the decontamination of radionuclides from low and intermediate levels of liquid waste. For that reason, the removal of Cs ions from waste solution by the co-precipitation method was carried out. A simulated liquid waste (133Cs) was prepared from a 0.1 M CsCl solution, while wastewater generated by washing steel ash served as a representative of radioactive cesium solution (137Cs). By co-precipitation, potassium ferrocyanide was applied for the adsorption of Cs ions, while nickel nitrate and iron sulfate were selected for supporting the precipitation. The amount of residual Cs ions in the CsCl solution after precipitation and filtration was determined by ICP-OES, while the radioactivity of 137Cs was measured using a gamma-ray spectrometer. After cesium removal, the amount of cesium appearing in both XRD and SEM-EDS was analyzed. The removal efficiency of 133Cs was 60.21% and 51.86% for nickel nitrate and iron sulfate, respectively. For the ash-washing solution, the removal efficiency of 137Cs was revealed to be more than 99.91% by both chemical agents. This implied that the co-precipitation process is an excellent strategy for the effective removal of radioactive cesium in waste solution treatment.

Designer biochar with enhanced functionality for efficient removal of radioactive cesium and strontium from water

Radioactive elements released into the environment by accidental discharge constitute serious health hazards to humans and other organisms. In this study, three gasified biochars prepared from feedstock mixtures of wood, chicken manure, and food waste, and a KOH-activated biochar (40% food waste + 60% wood biochar (WFWK)) were used to remove cesium (Cs+) and strontium (Sr2+) ions from water. The physicochemical properties of the biochars before and after adsorbing Cs+ and Sr2+ were determined using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, extended X-Ray absorption fine structure (EXAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX). The WFWK exhibited the highest adsorption capacity for Cs+ (62.7 mg/g) and Sr2+ (43.0 mg/g) among the biochars tested herein. The removal of radioactive 137Cs and 90Sr exceeded 80% and 47%, respectively, in the presence of competing ions like Na+ and Ca2+. The functional groups present in biochar, including –OH, –NH2, and –COOH, facilitated the adsorption of Cs+ and Sr2+. The Cs K-edge EXAFS spectra revealed that a single coordination shell was assigned to the Cs–O bonding at 3.11 Å, corresponding to an outer-sphere complex formed between Cs and the biochar. The designer biochar WFWK may be used as an effective adsorbent to treat radioactive 137Cs- and 90Sr-contaminated water generated during the operation of nuclear power plants and/or unintentional release, owing to the enrichment effect of the functional groups in biochar via alkaline activation.

Preparation of a GO/PB-modified nanofiltration membrane for removal of radioactive cesium and strontium from water

In this study, a novel modified nanofiltration (NF) membrane was fabricated to treat radionuclide-contaminated water by incorporation of Prussian blue (PB), graphene oxide (GO) and polyethylene glycol (PEG) into polysulfone (PSf) substrate. In this work, PB provided a large number of adsorption sites for the membrane, GO improved the Donnan effect of the polyamide (PA) layer by enhancing the negative charge, and PEG promoted the uniform dispersion of PB through interparticle electrostatic interaction and steric hindrance while increasing the adsorption sites on the surface of channels in the substrate by adjusting the pore structure. A conceptual model for the role of substrate in interfacial polymerization was then proposed. The modified membrane achieved efficient rejection of cesium (Cs+, 99.5%) and strontium (Sr2+, 97.5%). Its Cs+ rejection rate still remained high (about 96%) even in the treatment of natural surface water containing various inorganic salts and organic matters. What’s more, the modified membrane exhibited excellent stability in both strong acid solutions and long-term operation. Then, potassium chloride (KCl) solution was applied to regenerate the modified membrane, which achieved high generation rate as compared to traditional acid regenerants. The excellent filtration performance inferred that the novel GO/PB-modified NF membrane holds great application potential for the application of simultaneous removal of radioactive Cs+ and Sr2+ from contaminated water.

Insights and Further Understanding of Radioactive Cesium Removal Using Zeolite, Prussian Blue and Graphene Oxide as Adsorbents

Abstract The efficient removal of radioactive cesium (137Cs) from contaminated water around nuclear plants and/or after nuclear accidents has become an emerging issue since the Fukushima Daiichi Nuclear Power Plant (Fukushima, Japan) disaster on March 11, 2011. Herein, we have demonstrated and compared the adsorption performances of both 137Cs and 133Cs using three potential adsorbents, zeolite (ZL), Prussian blue (PB) and graphene oxide (GO), in deionized water and simulated seawater. The adsorption efficiencies are determined in terms of the adsorbent amount, initial Cs concentration, and the effect of other competing ions in the system. In addition, the practical application of the materials was justified by evaluating the elution/retention of the adsorbed Cs with different volumes of solvent. Significantly, we illustrated a practical validation of a purification route for 137Cs-contaminated fly ash generated from nuclear power plant accidents, while PB can be a potential adsorbent for large-scale implementation.

Surface modification of polypropylene non-woven filter by O2 plasma/acrylic acid enhancing Prussian blue immobilization for aqueous cesium adsorption

Radioactive cesium is commonly emitted during nuclear accidents and Prussian blue (PB) is an effective adsorbent with superior selectivity toward cesium. This study describes the surface modification of a polypropylene non-woven filter (PP) as the supporting material for PB immobilization, which included O2 plasma treatment and acrylic acid (AA) modification. AA was successfully polymerized using O2 plasma to provide a reaction site for the polymerization. The carboxylic acid groups introduced by the polymerization of AA induced a higher amount of PB immobilization on the surface. The cesium adsorption performance of the prepared adsorbent filter was evaluated via adsorption kinetics and isotherm analyses. The maximum adsorption capacity was calculated as 51.9 mg/g according to the Langmuir isotherm. To confirm its long-term practical applicability, the adsorbent filter was incorporated into a flow-through water treatment system that was operated for three months. The tested five-layer filter achieved a 100% cesium removal efficiency (initial concentration 40 μg/L) during the first 12 days, after which a 50% removal efficiency was maintained for 24 days. Therefore, the surface modification methodology proposed herein provides a promising means to convert commercial filter materials into advanced water treatment filters for the removal of radioactive cesium from contaminated water.

Mechanochemically Synthesized Prussian Blue for Efficient Removal of Cesium Ions from Aqueous Solutions.

The adsorptive removal of radioactive cesium [Cs(I)] is important for ensuring a clean aquatic environment. In this work, the adsorption of Cs(I) was carried out using Prussian blue (PB) prepared by mechanochemical synthesis. X-ray diffraction, Fourier-transform infrared spectroscopy, and field-emission scanning electron microscopy results indicated that PB had been successfully synthesized by mechanochemical synthesis. Thermogravimetric analysis, contact angle analysis, inductively coupled plasma atomic emission spectrometry, elemental analysis, and electrophoretic light scattering spectrophotometry confirmed that several defects were formed, explaining the principal mechanism for the efficient adsorption over PB prepared by mechanochemical synthesis. The superior adsorption properties toward Cs(I) make PB prepared by mechanochemical synthesis an attractive candidate material for the efficient, economical, and eco-friendly processes for purifying radioactive wastewater.

Sorption characteristics of bismuth tungstate nanostructure for removal of some radionuclides from aqueous solutions

• Nano-rods-like shape bismuth tungstate was synthesized using sol–gel method. • The bismuth tungstate was used as an adsorbent to remove 134 Cs and 152+154 Eu radionuclides. • The kinetic adsorption studies have been discussed. • The thermodynamic parameters were investigated. Treatment and ensuring the safe elimination of radioactive wastes are significant challenges in nuclear facilities; achieving this target is essential with the increment in employing nuclear energy in several applications. Herein, nanostructured rods-like shape bismuth tungstate Bi 2 WO 6 was synthesized using the eco-friendly sol–gel method and characterized by different techniques. The ability of nanostructured bismuth tungstate for the removal of radioactive cesium and europium from the liquid phase was evaluated to protect the environment. X-ray diffraction and Fourier transform infrared spectrum confirmed the successful preparation of bismuth tungstate. Also, the transmission electron microscope exhibited that the Bi 2 WO 6 has a rods-like structure in the nano-range. Further, the adsorption processes were achieved, and many parameters as pH of the medium, contact time, initial metal ion concentration, and temperature were studied. Also, it is clear that the bismuth tungstate can be utilized for many cycles. Furthermore, kinetic adsorption studies have been discussed. Besides, the parameters of thermodynamic were investigated. The negative value of Gibbs free energy and the positive value of enthalpy unveiled that the sorption process possesses a spontaneous and endothermic nature.

Novel One-Pot Solvothermal Synthesis of High-Performance Copper Hexacyanoferrate for Cs+ Removal from Wastewater

Efficient removal of radioactive cesium from complex wastewater is a challenge. Unlike traditional precipitation and hydrothermal synthesis, a novel vast specific surface area adsorbent of copper hexacyanoferrates named EA-CuHCF was synthesized using a one-pot solvothermal method under the moderate ethanol media characterized by XRD, SEM, EDS, BET, and FTIR. It was found that the maximum adsorption capacity towards Cs+ was 452.5 mg/g, which is far higher than most of the reported Prussian blue analogues so far. Moreover, EA-CuHCF could effectively adsorb Cs+ at a wide pH range and low concentration of Cs+ in geothermal water within 30 minutes, and the removal rate of Cs+ was 92.1%. Finally, the separation factors between Cs+ and other competitive ions were higher than 553, and the distribution coefficient of Cs+ reached up to 2.343 × 104 mL/g. These properties suggest that EA-CuHCF synthesized by the solvothermal method has high capacity and selectivity and can be used as a candidate for Cs+ removal from wastewater.

Removal of radioactive cesium from liquid waste by zeolite


 
 
 
 A radioactive fluid waste polluted with cesium-137 from Al-Tuwaitha site -south of Baghdad-Iraq is used in this paper. Commercial zeolite is used as a sorbent material in the present work for the removal of radioactive cesium-137. The removal efficiency for radioactive liquid was 96.43 % with 2 h mixing time, 0.04 g sorbent mass and pH=6.8 and at room temperature. The Freundlich and Langmuir isotherm models were found to represent the experimental results well and these results are more consistent with Freundlich model than Langmuir model.
 
 
 

Simultaneous removal of radioactive cesium and strontium from seawater using a highly efficient Prussian blue-embedded alginate aerogel

Radioactive cesium (137Cs) and strontium (90Sr) contaminants in seawater have been a serious problem since the Fukushima accident in 2011 due to their long-term health risks. For the effective and simultaneous removal of radioactive cesium (137Cs) and strontium (90Sr) from seawater, a Prussian blue (PB)-immobilized alginate aerogel (PB–alginate aerogel) was fabricated and its adsorption performance was evaluated. PB nanoparticles were homogeneously dispersed in the three-dimensional porous alginate aerogel matrix, which enabled facile contact with seawater. The PB–alginate aerogel exhibited Cs+ and Sr2+ adsorption capacities of 19.88 and 20.10 mg/g, respectively, without substantial interference because Cs+ and Sr2+ adsorption occurred at different adsorption sites on the composite. The Cs+ and Sr2+ adsorption onto the PB–alginate aerogel was completed within 3 h due to the highly porous morphology of the aerogel. The Cs+ and Sr2+ adsorption behaviors on the PB–alginate aerogel were systematically investigated under various conditions. Compared with Cs+ adsorption, Sr2+ adsorption onto the PB–alginate aerogel was more strongly influenced by competing cations (Na+, Mg2+, Ca2+, and K+) in seawater. 137Cs and 90Sr removal tests in real seawater demonstrated the practical feasibility of the PB–alginate aerogel as an adsorbent.

Effective washing removal of radioactive cesium from soils using adsorbents: a proposed adsorbent-coexistence method

Effective washing removal of radioactive cesium from soils using adsorbents: a proposed adsorbent-coexistence method

Radioactive Cs Removal from Aqueous Solutions by Biochar-Immobilized Potassium Nickel Hexacyanoferrate Prepared Using Ball Mill

Biochar-immobilized potassium nickel hexacyanoferrate (KNiFC) as a sorbent for removal of radioactive cesium (Cs) from aqueous solutions was prepared using a novel method. Japanese cedar sawdust loaded with NiSO4 using a ball mill was carbonized at various temperatures. The resultant Ni-loaded biochar was immersed in a K4[Fe(CN)6]·3H2O solution, and biochar-immobilized KNiFC was obtained. For comparison, Ni-loaded biochar was also prepared using the impregnation method. The loading of Ni using the ball mill resulted in a higher Ni amount in the biochar compared with the impregnation method. The carbonization at 400 °C was suitable for Cs adsorption on biochar and synthesis of KNiFC. Consequently, KNiFC immobilization on biochar improved the Cs sorption performance in aqueous solutions with Na+, K+, Ca2+, Mg2+, and Cs+. The sorption performance was selective in aqueous solutions with radioactive Cs and other cations of high concentration. Low-cost Cs adsorbent was prepared using a novel method from bioresource and KNiFC. The application of ball mill was effective for loading Ni on biochar. Immobilization of KNiFC on biochar improved Cs sorption performance. Removal of 134Cs and 137Cs using biochar-immobilized KNiFC was selective.