Selective Removal Of Cesium Research Articles

Silica-Reinforced AMP-Calcium Alginate Beads for Efficient and Selective Removal of Cesium from a Strong Acidic Medium.

Due to the significant selectivity for Cs+, ammonium molybdophosphate (AMP) possesses potential to uptake radiocesium from high-level liquid waste (HLLW), whereas its micro-crystalline structure and fine powder morphology limit its industrial application. Although the granulation method with alginate is prospective for the preparation of an AMP exchanger, the mechanical strength of obtained beads may be insufficient for application. In this context, we prepared silica-reinforced AMP-calcium alginate (ACS) beads and evaluated their performance for Cs+ removal from strong acidic solutions. It was found that the addition of silica in the fabrication significantly improved the mechanical strength of the beads in comparison to those without silica. Notably, the beads with an AMP/silica mass ratio of 1.0 exhibited an exceptional mechanical strength, surpassing that of ACS beads composed of other components. The batch experiment results indicated that the Cs+ adsorption follows a non-linear pseudo-second-order rate equation. The distribution coefficient of Cs+ was high even in extreme acidic conditions (∼1.6 × 102 mL/g in 8.0 mol/L HNO3 solution). The Cs+ adsorption can be well fitted with the Langmuir model, and the estimated maximum exchange capacity in 3.0 mol/L HNO3 could reach 23.9 mg/g. More importantly, ACS beads showed excellent selectivity toward Cs+ uptake over eight co-existing metal ions in simulated HLLW, with separation factor values all above 145. The column experiment exhibited that the beads can serve as the stationary phase in columns to effectively remove Cs+. The findings of this study are significant as they provide insights into the development of efficient materials for radiocesium removal from high-level liquid waste. The results demonstrate the potential of silica-reinforced ACS beads for Cs+ adsorption, with promising applications in industrial settings.

A facile synthesis of polyacrylic acid–ammonium phosphomolybdate microspheres for the highly selective removal of cesium

A facile synthesis of polyacrylic acid–ammonium phosphomolybdate microspheres for the highly selective removal of cesium

Selective removal of cesium by magnetic biochar functionalized with Prussian blue in aqueous solution

Selective removal of cesium by magnetic biochar functionalized with Prussian blue in aqueous solution

Readily regenerated porous fiber-supported metal tin sulfide for rapid and selective removal of cesium from wastewater

The removal of Cs from radioactive wastewater remains a great challenge due to the presence of a large number of coexisting ions. Herein, a novel porous fiber-supported metal tin sulfide named PVC-[Me2NH2]2Sn3S7 was designed. Specifically, four tin sulfides were prepared by the one-pot method in different solvents. Water was the most suitable solvent since it was essential for converting amides to cations. When three amides were used as precursors, [Me2NH2]2Sn3S7 prepared with DMF showed the best adsorption performance. Five polymers were then comprehensively evaluated around physicochemical stability, hydrophilicity, and cost to facilitate the engineering application of adsorbents. Finally, polyvinyl chloride (PVC) was selected as the support material. The optimized porous PVC-[Me2NH2]2Sn3S7 fiber with 50 wt% [Me2NH2]2Sn3S7 percentage can reach adsorption equilibrium within 30 min, has a wide active pH range of 2–12, and has a high adsorption capacity of 419.01 mg g−1. When applied to simulated wastewater, the separation coefficients of Cs+ and coexisting ions were above 1 × 104. The Cs + adsorption enthalpy change was obtained by calorimetric study and simulation calculation. Even after 50 consecutive cycles, the removal efficiency barely decayed. The Cs+ concentration could be enriched to 259.93 times that of the geothermal water. The above advantages make PVC-[Me2NH2]2Sn3S7 a promising adsorbent for selective Cs + removal from wastewater.

Rapid and highly selective removal of cesium by Prussian blue analog anchored on porous collagen fibers

Removing radioactive cesium from wastewaters is necessary for sustainable development of nuclear energy. In this study, a novel adsorbent (PBA-CFs) was successfully fabricated by securely anchoring Prussian blue analog on porous collagen fibers (CFs) crosslinked with Zr4+. PBA-CFs showed low pH sensitivity and high adsorption capacity (qe) for cesium, with an optimal adsorption pH range of 2–10 and a maximum of 1.32 mmol g−1. The novel adsorbent also displayed high selectivity for Cs+ in the presence of competing ions (K+, Na+, Ca2+, Mg2+, Sr2+, or Co2+). They could effectively remove above 98 % Cs+ from tap water, lake water, and mineral water and more than 75 % of Cs+ in seawater at the Cs+ concentration of 10–60 mg/L. The adsorption process could rapidly reach equilibrium within 30 min and satisfy the pseudo-second-order kinetics model. Adsorption thermodynamics further indicated the process was exothermic, feasible, and spontaneous. Significantly, PBA-CFs exhibited superior adsorption performance in the continuous column process, with qo of 1.53 mmol g−1. One gram of PBA-CFs could effectively treat 4.03 L (666 BV) of water at a flow rate of 0.3 mL min−1, with a removal rate beyond 95 %, superior to other common adsorbents. Moreover, 0.1 mol/L NH4Cl solution with pH 2 could rapidly regenerate the saturated PBA-CF column. PBA-CFs demonstrated notable irradiation stability after exposure to 10–350 kGy of 60Co γ-ray. These results demonstrate PBA-CFs are a highly effective and promising adsorbent for the removal of radioactive 137Cs from wastewater. This work not only provides a feasible method for Cs+ removal to facilitate the environmental protection and sustainable development of nuclear energy but also extends the effective application and circular development of CFs as a reproducible biomass resource.

Highly selective and easily regenerated porous fibrous composite of PSF-Na2.1Ni0.05Sn2.95S7 for the sustainable removal of cesium from wastewater

The removal of 137Cs from radioactive wastewater remains a huge challenge due to the interference of many coexisting ions. Several tin chalcogenides (X2Sn3Y7, XNa, K; YTe, Se, S) were synthesized and screened for highly selective cesium removal from radioactive wastewater. It was found that Na2Sn3S7 showed the best adsorption performance for low cesium concentrations. Especially after nickel doping, the adsorption capacity and thermal stability of the adsorbent were significantly enhanced. Its maximum adsorption capacity reached 436.72 mg·g−1 within only 5 min and adsorption performance kept active in the pH range of 2–12. After being coated with a porous polysulfone (PSF) fiber, the developed PSF-Na2.1Ni0.05Sn2.95S7 was applied to natural complex water with cesium concentration of 17.58 mg·L−1. The separation factors between Cs+ and competitive ions ranged from 625.21 to 13123.21. It is noteworthy that NaNO3 was an efficient regenerating agent and can be easily separated from the CsNO3 mixture for cyclic utilization. Remarkably, only 45 min in each cycle of adsorption and desorption toward cesium was realized, and the adsorption properties hardly decreased even after 50 consecutive cycles. The above advantages make the proposed material an excellent candidate for efficient Cs+ removal and enrichment from wastewater.

An Aluminum-Based Metal-Organic Cage for Cesium Capture.

Metal-organic cages are a class of supramolecular structures that often require the careful selection of organic linkers and metal nodes. Of this class, few examples of metal-organic cages exist where the nodes are composed of main group metals. Herein, we have prepared an aluminum-based metal-organic cage, H8[Al8(pdc)8(OAc)8O4] (Al-pdc-AA), using inexpensive and commercially available materials. The cage formation was achieved via solvothermal self-assembly of solvated aluminum and pyridine-dicarboxylic linkers in the presence of a capping agent, acetic acid. The obtained supramolecular structure was characterized by single-crystal X-ray diffraction (SCXRD), thermogravimetric analysis, and NMR spectroscopy. Based on crystal structure and computational analyses, the cage has a 3.7 Å diameter electron-rich cavity suitable for the binding of cations such as cesium (ionic radius of 1.69 Å). The host-guest interactions were probed with 1H and 133Cs NMR spectroscopy in DMSO, where at low concentrations, Cs+ binds to Al-pdc-AA in a 1:1 ratio. The binding site was identified from the crystal structure of CsH7[Al8(pdc)8(OAc)8O4] (Cs+⊂Al-pdc-AA), and a binding affinity of ∼106-107 M-1 was determined from NMR titration experiments. The Al-pdc-AA showed improved selectivity for cesium binding over alkali metal cations (Cs+ > Rb+ > K+ ≫ Na+ ∼ Li+). Collectively, the study reports a novel aluminum cage that can serve as a promising host for efficient and selective cesium removal.

Highly selective cesium removal under acidic and alkaline conditions using a novel potassium aluminum thiostannate

The pH values of nuclear wastewater are extremely low or high, which make the efficient removal of 137Cs a major concern among the issues for safety management and environmental remediation. Existing metal sulfides for Cs+ adsorption have shown poor performance at acidic and alkaline conditions, and the reason has not been revealed yet. Herein, a novel potassium aluminum thiostannate (KAlSnS-3) adsorbent was designed and its Cs+ adsorption mechanism over a wide pH range was investigated. We hypothesized that Al3+ dopant on Sn4+ sites would allow stable adsorption for Cs+ upon its partial release at acidic and alkaline conditions. As a result, KAlSnS-3 demonstrated excellent adsorption performance across a broad pH range (1–13), and high selectivity toward Cs+, even under high salinity conditions (in tap water Kd = 3.12 × 104 mL/g; and in artificial seawater Kd = 3.42 × 103 mL/g). KAlSnS-3 also exhibited rapid adsorption kinetics (R = 97.6% in the first minute), a remarkable adsorption capacity (259.31 mg/g), and a high distribution coefficient (2.09 × 105 mL/g) toward Cs+. In addition, the high reusability of KAlSnS-3 was observed, suggesting its potential for real-world applications. The mechanism for enhancing performance at low and high pH values was discussed with the evidence of crystallinity, elemental concentrations, and binding energy of electrons based on the concept of electrostatic interactions and chemical affinity. In summary, this work provides insights into the mechanism of Cs+ removal under a wide pH range, and the impressive Cs+ adsorption performance indicates the application potential of KAlSnS-3 in wastewater treatment.

Highly Selective Cesium Removal Under Acidic and Alkaline Conditions Using a Novel Potassium Aluminum Thiostannate

Highly Selective Cesium Removal Under Acidic and Alkaline Conditions Using a Novel Potassium Aluminum Thiostannate

Stabilization of Prussian blue analogues using clay minerals for selective removal of cesium

Numerous Prussian blue analogues (PBAs) and their application in cesium elimination have been conducted. However, those were practically impossible to use in alkaline solution and seawater, due to the low stabilization of PBAs in alkaline solution and quickly decompose to create toxic cyanide contamination. In this research, potassium zinc hexacyanoferrate (PZH), one kind of PBAs was chosen, and the stability of PZH in the alkaline solution was remedied by incorporating magnetic rectorite (MR) and evaluated by XRD, XPS and cyanide analysis. Effect of pH value and the water systems on the crystalline and chemical stability were studied. The adsorption performance for Cs+ in high pH solution and the biological toxicity of the PZH/MR composite were also evaluated. The composite material exhibits significant adsorption capacity for Cs+ ions (215.128 mg/g, 293 K, increased over 20% than pristine PZH) and low cytotoxicity in human hepatic cells (HepG2 cells), indicating its potential application Cs+ adsorption in waste-water and Cs+ decorporation from body. The stability and safety mechanism in a wide pH range (from 2 to 11) were explained. The stabilization method on PBAs is an advanced yet and effective feasible mean with applications for internal and external cesium remediation. This research opens up a wide range of novel applications for PB-based adsorbents or decorporation, particularly in the field of the cesium remediation in high pH value.

Securely anchored Prussian blue nanocrystals on the surface of porous PAAm sphere for high and selective cesium removal

Prussian blue (PB) has been well known as a pigment crystal to selectively sequestrate the radioactive cesium ion released from aqueous solutions owing to PB cage size similar to the cesium ion. Because the small size of PB is hard to deal with, the adsorbents containing PB have been prepared in the form of composites causing low sequestration efficiency of cesium. In this study, securely anchored PB nanocrystals on the surface of millimeter-sized porous polyacrylamide (PAAm) spheres (PB@PAAm) have been prepared by the crystallization of PB on the Fe3+ adsorbed PAAm. The securely anchored PB nanocrystals have been demonstrated to be selective and efficient adsorbents for sequestration of the radioactive cesium. The well-interconnected-spherical pores and millimeter-sized diameter of the PB@PAAm adsorbents facilitated permeation of Cs+ into the adsorbent and ease of handling respectively. Especially the well-interconnected-spherical pores allowed that PB@PAAm showed 90% of its maximum Cs+ adsorption capacity within 30 min. The PB@PAAm showed an outstanding Cs+ capture ability of 374 mg/g, high removal efficiency of 85% even at low concentration of Cs+ (10 ng/L), and superior selectivity of Cs+ against interference ions of Na+, K+, Mg2+, and Ca2+.

Selective removal of cesium by ammonium molybdophosphate-magnetic Fe3O4-chitosan composites

Selective removal of cesium by ammonium molybdophosphate-magnetic Fe3O4-chitosan composites

Sulfur-encapsulated zeolite micromotors for the selective removal of cesium from high-salt water with accelerated cleanup times

Bubble-propelled sulfur-encapsulated NaX zeolite (S-NaX) micromotors were developed for the selective removal of cesium from high-salt conditions with accelerated cleanup times. NaX was first modified with sulfur to provide additional Lewis acid−base interactions with Cs+ for enhanced Cs+ selectivity, and then Pt was half-deposited on S-NaX for bubble propulsion via the catalytic decomposition of H2O2. The average velocity of the resulting S-NaX/Pt micromotors in 5 wt% H2O2 is 39.7 ± 17.1 μm/s, which is higher than that of a previously reported Cs adsorbent micromotor (35.4 μm/s). The Cs+ ion-exchange kinetics of the S-NaX micromotor is 1.32 times higher than that of the NaX micromotor in a 5 wt% H2O2 solution where the molar ratio of Na+ to Cs+ is 200, even though the sulfur in the S-NaX micromotor causes an adverse effect on the propulsion speed due to the sulfur poisoning effect. Moreover, the S-NaX micromotor in simulated groundwater also exhibited excellent Cs+ removal performance with distribution coefficient (Kd) values at least 3.2 times higher than those of the nonpropelled S-NaX and NaX micromotor, demonstrating the great potential for the treatment of radioactive Cs+-contaminated water.

Highly Selective Cesium Removal Under Acidic and Alkaline Conditions Using a Novel Potassium Aluminum Thiostannate

Highly Selective Cesium Removal Under Acidic and Alkaline Conditions Using a Novel Potassium Aluminum Thiostannate

In situ assembly of PB/SiO2 composite PVDF membrane for selective removal of trace radiocesium from aqueous environment

A non-toxic and applicable surface-modified polyvinylidene fluoride (PVDF) membrane consisting of Prussian blue (PB) and aminating silica (A-SiO2) nanoparticles was fabricated for the selective removal of trace radionuclide cesium (Cs) from water. The modified membrane denoted as PB/A-SiO2/PVDF exhibited high selective removal of cesium with a high permeate flux of more than 800 L/h∙bar∙m2 in a wide pH range from 3 to 9. The adsorption experiments showed that the Langmuir isotherm model and the pseudo-second order model fitted well with the experimental results. The maximum adsorption capacity was 10.95 mg-Cs/g-membrane (i.e. 78.21 mg-Cs/g-PB sorbent on membrane) for the membrane at an initial Cs concentration of 50 mg/L. Based on the high Cs adsorption capacity of PB, the membrane could remove more than 97.5% Cs in the presence of the coexisting ions and organic matter for more than 10 h. The filtrated membrane could be effectively regenerated by NH4Cl, H2O2 and HNO3 solution with negligible decrease in removal efficiency after repeated use. With the high membrane flux and selective removal efficiency, the fabricated membrane can be potentially applied in Cs contaminated water treatment.

Highly effective prussian blue-coated MXene aerogel spheres for selective removal of cesium ions

Two-dimensional titanium carbide MXene (Ti3C2Tx) incorporated with Prussian blue aerogel spheres (PBMXsphere) were designed and fabricated by a simple synthesis method for selective cesium removal in different matrices. The synthesized micro spheres exhibited unique internal structure and high porosity. They were enriched with oxygenated functional groups of Ti3C2Tx and offered selective binding sites of Prussian blue. The synthesized PBMXsphere can thus be used as a unique adsorbent for radionuclide Cs+ removal in water. Analytical techniques such as PXRD, FT-IR, FE-SEM, and XPS were utilized to investigate the material characteristics and structural changes after cesium ion adsorption. The PBMXsphere spheres unveiled an exceptional adsorption capacity of 315.91 mg/g for Cs+, which is amongst the highest values reported for similar adsorbents. PBMX-IIIsphere was capable for removing cesium ions at the ppb level with a distribution coefficient of 3.42 × 1005 mL/g in the presence of coexisting ions such as Na+, K+, Mg2+, and Ca2+. The PBMXsphere spheres were highly efficient for Cs+ removal under extreme pH values (pH 2–12). Furthermore, PBMX-IIIsphere offered exceptionally high removal efficiency in 1 M HCl and 5 M NaNO3 solution matrices. For practical applications, extraordinary Cs+ capturing behavior was observed in simulated seawater.

Magnetized Activated Carbon Prepared by Oak Shell Biowaste and Modified with Nickel Hexacyanoferrate for Selective Removal of Cesium

The activated carbon synthesized by biowaste materials was magnetized by Fe3O4 nanoparticles and then impregnated with nickel hexacyanoferrate. The magnetize composite was identified by various methods including; XRD, FT-IR, TG, VSM and SEM technique and then employed for separation of cesium from aquatic systems. The adsorption capacity was optimized by evaluating different experimental variables including time, pH, dose, and concentration, and the maximal uptake of 135.28 mg g−1 was obtained. Evaluation of adsorbent selectivity was performed with co-existing cations including Mg2+, Ca2+, Na+, K+ and NH4+. The results revealed that removal process was endothermic, spontaneous, with fast kinetic. The adsorption data was evaluated using Langmuir, Freundlich, Sips, and Redlich-Peterson isotherm models. The data was well described by the Langmuir model. The pseudo first-order, pseudo second-order, Intra-particle diffusion equation and Elovich kinetic models were used to evaluate the kinetic data. The used sorbent regenerated by use of nitric acid solution retained most of its initial capacity.

Fabrication of a novel polyvinylidene fluoride membrane via binding SiO2 nanoparticles and a copper ferrocyanide layer onto a membrane surface for selective removal of cesium.

A novel polyvinylidene fluoride (PVDF) membrane was fabricated through chemical binding SiO2 nanoparticles (NPs) and copper ferrocyanide (CuFC) layers onto a membrane surface simultaneously to improve the removal efficiency of Cs. The results indicated that the SiO2 NPs were strongly deposited onto the membrane surface, and the CuFC layer was firmly attached on the surface of SiO2 NPs and the membrane. CuFC/SiO2/PVDF membrane remained stable after the acidic solution and sonication stress treatments. CuFC/SiO2/PVDF membrane showed good permeate flux and high selectivity on removal of Cs, and adsorbing capacity reached 1440.4 mg m-2 for Cs. The membrane remained high rejections of Cs in a wide pH, and could be regenerated well by H2O2 and N2H4. Selective adsorption and electrostatic interaction govern the rejection of Cs. The coexisting cations decreased the rejection of Cs mainly in accordance to the order of cations' hydration radii as K+ > Na+ > Ca2+ > Mg2+. In addition, the rejection of Cs could still reach 99.4% in 8 h in the filtration of humic acid solution and natural surface water. The membrane could removal of Cs from water effectively by directly rapid filtration, suggesting it can be applied as promising technology for radioactive wastewater treatment.

Highly stable Prussian blue nanoparticles containing graphene oxide–chitosan matrix for selective radioactive cesium removal

In this work, a Prussian blue (PB)/graphene oxide (GO)/chitosan (CS) organic-inorganic composite was successfully synthesized and utilized as an adsorbent for the selective removal of cesium (Cs+) ions. Taking the advantage of synergistic effect GO, CS and PB nanoparticles, the PB/GO/CS composite exhibited maximum adsorption capacity of 48.35 mg g−1 for Cs+ ions. In the presence of competitive monovalent cations (K+ and Na+), PB/GO/CS showed excellent selectivity (86%) for Cs+ ions and had a 6-fold higher distribution coefficient (Kd) than GO/CS. This enhanced adsorption capacity with high selectivity of PB/GO/CS for Cs+ ions may have been attributed to (i) the presence of carboxylic, hydroxyl and amino functional groups on GO/CS matrix which strongly bind Cs+ ions through electrostatic attraction and chelation, and (ii) the trapping of Cs+ ions by the voids of the FCC-structured PB lattice whose size is equivalent to the hydration radius of Cs+ ions. Due to its low-cost, facile preparation, high adsorption capacity, and superior Cs+ ions selectivity, PB/GO/CS is a promising material for the selective removal of the Cs+ ions from the environment and for protecting ecosystems from the radiation hazards.

Selective removal of cesium and strontium by crystalline silicotitanates

Crystalline silicotitanate ion exchanger (58.5 mmol Ti, and 620 mmol Na) with 6 mmol of SiO2 after 10 days of hydrothermal synthesis was optimized for selective removal of 90Sr. Studies on X-ray diffraction, scanning electron microscope and energy dispersive spectroscopy revealed that the silicotitanate is highly crystalline with bright cubic and rod like morphology with varying amounts of Ti, Si, Na, and O. The decontamination factor and distribution coefficient values for uptake of 137Cs and 90Sr from actual radioactive waste solutions by the ion exchanger after 24 h of equilibration was found to be 40 and 176 and 4025 ml g−1 and 7525 ml g−1, respectively. The exchange capacity for 90Sr and 137Cs was estimated to be 14.6 and 4.4 meq g−1, respectively.