Cs Ions Research Articles

Coordination polymers of perylenetetracarboxylate with Cs(I) ions: 3D structures with 2D inorganic layers or triple coordination nets

The self-assembly of perylenetetracarboxylate (ptc) with Cs(I) ions at ambient temperature has been investigated with two coordination polymers being synthesized and structurally characterized. The diffusion of ethanol into a Cs-ptc solution led to the formation of compound 1 [(Cs4(ptc)(H2O)5·nH2O] displaying a compact three-dimensional (3D) structure constructed with 2D undulating layers of Cs polyhedra linked by ptc ligands in two types coordination modes. Extensive π···π interactions among stacking ptc ligands formed large hydrophobic organic channels between the inorganic layers. The addition of ethylenediamine (ED) to the reaction system afforded the formation of compound 2 [(H2ED)5Cs2(ptc)3(H2O)10] showing triple 2D coordination nets with protonated ethylene diammonium cations hydrogen-bonded to both non-bonded carboxyl oxygen and coordinated water molecules. The triple 2D nets are further linked via hydrogen bonding to form a 3D structure. The optical absorption, band gap analysis, vibrational modes and thermal stability of compound 1 were also investigated. Overall, the structural diversity was achieved in the studied self-assembly system at ambient temperature through varying Cs to ptc ratios by introducing ethylene diammonium as a non-metal cation.

Flexible Ion Adsorption Electrodes Using Natural Zeolite and Rice Husk Charcoal for FEM-EK Treatment

The Fukushima Daiichi nuclear power plant accident happened after the devastating earthquake in the Pacific coastal area of Japan on 11 March 2011. After the accident, radioactive materials spread out over a wide area in Japan. Radioactive materials were retained on soil surfaces, causing environmental problems. Among the radioactive materials, cesium (137Cs) has a long half-life of 30.2 years, and it remains near the surface soil; therefore, it is necessary to remove soil contaminated by 137Cs. The contaminated soil layer of inhabited areas in Fukushima was already removed before April 2020. However, the remediation method of Cs with other radioactive materials needs further study, as the large quantity of contaminated soil is not easy to preserve. Electrokinetic (EK) treatment is one of the soil remediation technologies that utilizes EK phenomena at the interface between contaminated soils by transferring ions from the soil. We have developed a new type of EK method in which a cathode is placed on the surface of the soil and an anode is place inside the soil. By applying DC voltage in between the electrodes, the Cs ions can be removed from the contaminated soil. The removed Cs ions are gathered near to the cathode, and if the cathode can adsorb the Cs ions, then only the cathode needs to be preserved, solving the problem of storing a large amount of soil. We have been working to prepare a new type of cathode that can be effective in adsorbing Cs ions and at the same time easier to store and handle. We used natural zeolite and rice husk charcoal (kuntan) to prepare this electrode, which showed good potential for adsorbing Cs ions. The electrode showed flexibility, which is helpful for storing it in the same way as pasture rolls. However, the experiments were conducted in the laboratory with non-radioactive Cs; field experiments and observations are needed for practical applications of this method, as well as the new electrodes.

Using Agricultural Mixed Waste as a Sustainable Technique for Removing Stable Isotopes and Radioisotopes from the Aquatic Environment

In the current study, dried ground mixed waste of olive waste and water hyacinth was subjected to the treatment of wastewater contaminated with stable or radioactive cobalt and cesium. Contact time, temperature, amount of adsorbent, metal ion concentration and pH-value were evaluated as the most potent factors that affect the adsorption process. Concentrations of Co and Cs ions before and after treatment are measured using ICP-OES technique. Moreover, kinetic and equilibrium isotherm parameters were investigated by explaining the equilibrium data by induction of two isotherms, “Langmuir” and “Freundlich”. Experimental results indicated that more than 85% of 60Co and 134Cs were efficiently removed from spiked wastewater after one hour of contact time by using 0.2 g of dried mixed waste. The optimal time to remove Cs+ and Co2+ was 50 and 90 min, respectively. The kinetic study showed that the adsorption of Cs+ and Co2+ were better suited to the second order. The most favorable pH value was at a range of 6–7 for Cs+ and 5–6 for Co2+. R2 values were higher at the Freundlich isotherm, indicating that the adsorption process was taking place according to Freundlich isotherm at all temperatures for Co2+ and Cs+ ions.

Energy transfer from self-trapped excitons to rare earth ions in Cs2ZrCl6perovskite variants

A series of Tb3+-doped Cs2ZrCl6perovskite variants are designed based on energy transfer, and the relationships among intrinsic self-trapped excitons, sub-band gap defects and rare earth ions Tb3+were established.

Optical Properties of Cu-Doped Perovskite Nanoplatelets

All inorganic perovskite nanocrystals (NCs) have been widely concerned for their unique optical properties. However, due to the rotation and inclining of the [PbX6]4− octahedron caused by Cs ions, such kind of materials usually have poor stability, which will hinder their commercialization. It is well known that using smaller divalent cations to replace Pb2+ can effectively improve the stability and luminescence properties of CsPbX3 NCs. In this work, Cu-doped CsPbBr3 nanoplatelets (NPs) are prepared, i.e., CsPb0.95Cu0.05Br3 NPs, and their temperature dependent emission properties have been investigated. The experimental results show that Cu-doping method can weaken the thermal expansion effect and electron-phonon interaction strength of perovskite NPs. Although the exciton binding energy of CsPb0.95Cu0.05Br3 NPs is smaller than that of CsPbBr3 NPs, it is still much larger than that of CsPbBr3 cubic NCs. Our experimental results will be of significance for the development of optoelectronic devices based on transition metal doped perovskite NPs.

Cesium salt of tungstophosphoric acid/mesoporous (zirconia-silica) composite for highly efficient synthesis of 7-hydroxy-4-methyl coumarin and removal of methylene blue.

The removal of harmful organic dyes from aqueous solutions has drawn the attention of scientists because of the substantial threat they pose to society's worldwide health. Hence, it is crucial to design an adsorbent that is both very effective in removing dyes and has the benefit of being inexpensive. In the present work, Cs salts of tungstophosphoric acid (CPW) supported mesoporous Zr-mSiO2 (mZS) with varying extents of Cs ions have been prepared by a two-step impregnation technique. Accordingly, a lowering in the surface acidity modes was observed after Cs exchanged protons of H3W12O40 and formed salts immobilized on the mZS support. After exchanging the protons with Cs ions, the characterization results revealed that the primary Keggin structure was unaltered. Moreover, the Cs exchanged catalysts had higher surface area than the parent H3W12O40/mZS, suggesting that Cs reacts with H3W12O40 molecules to create new primary particles with smaller sizes possessing inter-crystallite centers with a higher dispersion degree. With an increase in Cs content and thus a decrease in the acid strength and surface acid density, the methylene blue (MB) monolayer adsorption capacities on CPW/mZS catalysts were increased and reached an uptake capacity of 359.9 mg g-1 for Cs3PW12O40/mZS (3.0CPW/mZS). The catalytic formation of 7-hydroxy-4-methyl coumarin was also studied at optimum conditions and it is found that the catalytic activity is influenced by the amount of exchangeable Cs with PW on the mZrS support, which is in turn influenced by the catalyst acidity. The catalyst kept approximately the initial catalytic activity even after the fifth cycle.

Depth distribution of alkali metal ions on supported graphene in the presence of water

The interaction of alkali ions with multilayer graphene is critical in many applications, for example in energy storage devices. This requires a detailed understanding of ion interactions with carbonaceous layers. The mechanism of ion intercalation into graphene can be different from that observed for hard graphite. In this paper, we present an investigation of the vertical alkali ion (Na, K, Cs) distribution on multilayer graphene deposited onto SiO2 in vacuum and in the presence of water vapor using Standing Wave Ambient Pressure Photoemission Spectroscopy. It was found that Cs, K, and Na ions do not intercalate into multilayer graphene under vacuum conditions. The most likely reasons for this behavior are the reversibility of the process due to large inter-sheet spacing or lack of time for intercalation. When exposed to water vapor, Na ions intercalate soft carbon whereas Cs ions do not. This is a clear indication for the difference in the intercalation mechanisms on hard graphite and soft graphene.

Biosorption of Cs (I): Utilization of an eco-friendly adsorbent Dry Cowdung Powder

Dry Cowdung Powder (DCP) – a green biosorbent, has been demonstrated for Cs(I) removal from aqueous media using radiotracer technique. 100 mesh DCP was added to Cs(I) carrier solution spiked with radioactive Cs-137. Parameters like pH, biosorbent dose, agitation speed, contact time, temperature and Cs(I) ion concentration were optimized. Industrial effluents or other polluted water bodies contain different salts in varying proportions. To analyse the effect of these salts on adsorption of Cs(I), various sodium, potassium and ammonium salts were used. DCP characteristics pre and post biosorption of Cs(I) was analysed with EDAX spectra. The investigation reports a successful Cs(I) metal removal by following the principles of green chemistry.

Biosorption of Cs (I): Utilization of an eco-friendly adsorbent Dry Cowdung Powder

Dry Cowdung Powder (DCP) – a green biosorbent, has been demonstrated for Cs(I) removal from aqueous media using radiotracer technique. 100 mesh DCP was added to Cs(I) carrier solution spiked with radioactive Cs-137. Parameters like pH, biosorbent dose, agitation speed, contact time, temperature and Cs(I) ion concentration were optimized. Industrial effluents or other polluted water bodies contain different salts in varying proportions. To analyse the effect of these salts on adsorption of Cs(I), various sodium, potassium and ammonium salts were used. DCP characteristics pre and post biosorption of Cs(I) was analysed with EDAX spectra. The investigation reports a successful Cs(I) metal removal by following the principles of green chemistry.

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.

Single step wet-chemical deposition of cesium doped [formula omitted]-Ga2O3 nanostructured films for memristor application

Cesium doped gallium oxide (Cs-Ga2O3) nanostructured films are deposited using wet-chemical approach in single step process. Effect of different concentration of Cs (1% to 100 % molar concentration with respect to concentration of Ga precursor) on morphological, structural, optical and electrical properties of doped Ga2O3 nanostructured films are investigated. The morphology (diamond shaped nanostructures) remains intact for lower doping concentration of Cs (1 to 7.5% of Cs molarity with respect to Ga molarity in precursor solution) whereas when doping concentration is increased (10 to 100% of Cs with respect to Ga molarity in precursor solution) the morphology drastically changed to flower and clustered particles. The shift in diffraction pattern indicates the presence of Cs inside the Ga2O3 crystals. The high amount of Cs in precursors solution (half or equal molarity of Cs with respect to Ga molarity (50 to 100%)) in precursor solution results doping as well as formation of dicesium oxide. The doping of Cs is further confirmed by X-ray photoelectron spectroscopy. The electrical conductivity of doped Ga2O3 nanostructured films varies with variation in Cs ions concentration. The higher resistance is noticed in memristor device when the doping concentration is lesser. The RON/ROFF ratio is decreased after Cs doping and to be found only 101 orders but altering the switching speed of the memory device.

Highly selective adsorption and lattice process of cesium by cubic cyanide-based functional materials

Cesium (Cs) is a byproduct of nuclear bombs, nuclear weapons testing, and nuclear fission in nuclear reactors. Cs can enter the human body through food or air and cause lasting damage. Highly efficient and selective removal of 137Cs from low-level radioactive effluents (LLREs), which contain many radionuclides and dissolved heavy metal species, is imperative for minimizing LLRE volume, and facilitating their final disposal. Prussian blue analogs (PBAs) have received much attention as materials for the removal of radioactive Cs because of their affinity for adsorbing Cs+. In this study, an inexpensive and readily available cyanide-based functional material (PBACu) exhibiting high efficiency and excellent selectivity toward Cs capture was designed through a facile low-temperature co-precipitation process. Nano-PBACu, crystallizing in the cubic space group (Fm-3m (225)), has an average pore size of 6.53 nm; consequently, PBACu can offer abundant atomic occupation sites for capturing and incorporating Cs. Here, the pseudo-second-order kinetic model and Langmuir model fitted well with the adsorption of Cs + on PBACu, with a maximum capture capacity of 95.75 mg/g within 5 min, confirming that PBACu could rapidly capture Cs ions. PBACu strongly and selectively interacted with Cs even in a simulant containing large Na+, NH4+, Ca2+, and Mg2+ ion concentrations in an aqueous solution. The process of Cs + adsorption by cyanide-based functional crystals was confirmed to involve the entry of Cs+ into cyanide-based functional crystals to replace K+ and finally achieve the lattice incorporation of Cs. The current results broaden the lattice theory of radionuclide Cs removal and provide a promising alternative for the immobilization of Cs from radioactive wastewater.

Selective C-F Bond Etherification of Trifluoromethylalkenes with Phenols.

Selective functionalization of a single sp3 C-F bond of the CF3 group represents an appealing way to generate the pharmaceutically privileged difluoromethylene moiety. Herein, a novel protocol for the C-F bond etherification of trifluoromethylalkenes and phenols is reported. A variety of alkenyl difluoroaryloxy ethers are obtained with good chemoselectivity and functional group tolerance. DFT calculation results and control experiments suggest that metal ion Cs+ might be involved in this defluorooxylation. Furthermore, the desired product exhibits a good insecticidal activity.

Highly Emitting Perovskite Nanocrystals with 2-Year Stability in Water through an Automated Polymer Encapsulation for Bioimaging.

Lead-based halide perovskite nanocrystals are highly luminescent materials, but their sensitivity to humid environments and their biotoxicity are still important challenges to solve. Here, we develop a stepwise approach to encapsulate representative CsPbBr3 nanocrystals into water-soluble polymer capsules. We show that our protocol can be extended to nanocrystals coated with different ligands, enabling an outstanding high photoluminescence quantum yield of ∼60% that is preserved over two years in capsules dispersed in water. We demonstrate that this on-bench strategy can be implemented on an automated platform with slight modifications, granting access to a faster and more reproducible fabrication process. Also, we reveal that the capsules can be exploited as photoluminescent probes for cell imaging at a dose as low as 0.3 μgPb/mL that is well below the toxicity threshold for Pb and Cs ions. Our approach contributes to expanding significantly the fields of applications of these luminescent materials including biology and biomedicine.

Biosorption of Cs (I): Utilization of an eco-friendly adsorbent Dry Cowdung Powder

Dry Cowdung Powder (DCP) – a green biosorbent, has been demonstrated for Cs(I) removal from aqueous media using radiotracer technique. 100 mesh DCP was added to Cs(I) carrier solution spiked with radioactive Cs-137. Parameters like pH, biosorbent dose, agitation speed, contact time, temperature and Cs(I) ion concentration were optimized. Industrial effluents or other polluted water bodies contain different salts in varying proportions. To analyse the effect of these salts on adsorption of Cs(I), various sodium, potassium and ammonium salts were used. DCP characteristics pre and post biosorption of Cs(I) was analysed with EDAX spectra. The investigation reports a successful Cs(I) metal removal by following the principles of green chemistry.

Ag Nanocluster-Enhanced Scintillation Properties of Borophosphate Glasses Doped with CsPbBr3 Quantum Dots.

A novel and effective method to improve scintillation properties of glass-ceramics, such as intensity enhancement and decay-time shortening, is reported in this work. Compared with crystal scintillators, glass scintillators always have the problems of low efficiency and long decay; how to solve them has always been a scientific puzzle in the field of scintillation glass-ceramics. The plasma enhancement effect can be predicted to solve the above problems. Ag+ ions were diffused into glasses by ion exchange, and then Ag nanoparticles and CsPbBr3 quantum dots were formed by heat treatment. The structure of the CsPbBr3 perovskite consists of a series of shared corner PbBr6 octahedra with Cs ions occupying the cuboctahedral cavities. By using Ag and the plasma resonance effect, the photoluminescence intensity of CsPbBr3 quantum dot glasses was enhanced by 3 times, its radioluminescence intensity increased by 6.25 times, and its decay time was reduced by a factor of more than one. Moreover, the mechanism of photoluminescence and radioluminescence enhanced by Ag and plasma was discussed based on the experimental results and finite-difference time-domain method. We concluded that the increase in radioluminescence intensity was related to plasma enhancements and the energy exchange between Ag nanoclusters and CsPbBr3 quantum dots. Doping Ag is a valid means to improve the scintillation luminescence of CsPbBr3 quantum dot glasses, which can be applied in the field of scintillation.

Proton-Rich POM-Type K12Mo8O20(HPO4)8(PO4)Cl with Ion-Exchange Capabilities.

A proton-rich POM-type molybdenum phosphate K12Mo8O20(HPO4)8(PO4)Cl was successfully obtained. It crystallizes in a noncentrosymmetric tetragonal space group of P-4 (No. 81) with the unit cell parameters of a = 9.6580(4) Å, c = 14.2607(10) Å, and Z = 1. The occurrence and positions of the light element H in the structure are inferred from single-crystal X-ray diffraction and confirmed by DFT calculations. The hydrogen atoms are found to form hydroxyl bonds with O atoms from P(2)O4 and P(3)O4 constituting the [Mo4P4O26H4]4- layers but are only weakly bound to the isolated P(3)O4 group through hydrogen bonds. The title compound presents a POM-type framework of corrugated [Mo4P4O26H4]4- layers with four K+ ions and mixed ions (K4Cl3+ and isolated PO43-) orderly imbedding in the interlayer spaces with distances of 5.0396 (1) and 5.5966 (3) Å, respectively. The proton-rich nature and the structure feature were further verified by a series of experiments including 1H, 7Li, and 31P MAS NMR spectra, IR spectroscopy, and thermal analysis. Moreover, the weak bonding and large interlayer spaces make K+ and H+ ions susceptible to exchange with ions of Cs+, Ba2+, Zn2+, Pb2+, Cu2+, and Ni2+ commonly presented in chemical pollutants or nuclear wastes. In addition, the title compound shows a small second-harmonic generation signal, consistent with its noncentrosymmetric structure.

Temperature-Dependent Optical Properties of Perovskite Quantum Dots with Mixed-A-Cations.

In this work, metal halide perovskite quantum dots (QDs) with Formamidinium (FA) and Cs mixed cations were fabricated using a solution-processed method at room temperature. By controlling Cs doping ratios in a precursor, the optical properties of mixed-cation perovskite QDs were systematically studied. With the increase in Cs ion doping, the photoluminescence (PL) spectra of perovskite QDs were blueshifted, which was mainly due to the smaller radius of Cs ions than those of FA. Temperature-dependent PL spectra were conducted on mixed-cation perovskite QDs. As the temperature gradually increased from 4 K to 300 K, PL peaks were blue shifted, and full-width at half maximum (FWHM) was widened, which was directly related to lattice thermal expansion and the carrier-photon coupling effect under temperature variation. At the same time, excess Cs ion doping had a prominent influence on optical properties at low temperatures, which was mainly due to the introduction of detrimental defects in perovskite crystals. Therefore, it is particularly important to control doping concentration in the preparation of high-quality perovskite QDs and efficient photoelectric devices.

The approach of alkali ions towards an electrode surface – A molecular dynamics study

The approach of alkali ions from an aqueous solution towards a gold electrode has been studied by biased molecular dynamics. In accord with the Hofmeister series, Li+ and Na+ show signs of structure making, K+ and Cs+ of structure breaking. For all ions the potential of mean force at first rises, when the ion approaches the surface, passes through a maximum and then drops again to a local minimum. For the structure breaking ions Cs+ and K+ the solvation energies in the minima are the same as in the bulk, for Na+ and Li+ they are a little higher.

Novel Cesium Resistance Mechanism of Alkaliphilic Bacterium Isolated From Jumping Spider Ground Extract.

The radionuclide isotopes (134Cs and 137Cs) of Cesium (Cs), an alkali metal, are attracting attention as major causes of radioactive contamination. Although Cs+ is harmful to the growth of plants and bacteria, alkaliphilic bacterium Microbacterium sp. TS-1, isolated from a jumping spider, showed growth even in the presence of 1.2 M CsCl. The maximum concentration of Cs+ that microorganisms can withstand has been reported to be 700 mM till date, suggesting that the strain TS-1 is resistant to a high concentration of Cs ions. Multiple reports of cesium ion-resistant bacteria have been reported, but the detailed mechanism has not yet been elucidated. We obtained Cs ion-sensitive mutants and their revertant mutants from strain TS-1 and identified a Cs ion resistance-related gene, MTS1_00475, by performing SNP analysis of the whole-genome sequence data. When exposed to more than 200 mM Cs+ concentration, the intracellular Cs+ concentration was constantly lowered by MTS1_00475, which encodes the novel low-affinity Cs+/H+ antiporter. This study is the first to clarify the mechanism of cesium resistance in unexplained cesium-resistant microorganisms. By clarifying the new cesium resistance mechanism, it can be expected to be used as a bioremediation tool for treating radioactive Cs+ contaminated water.