Cs Adsorption Research Articles

Rapid determination of 135Cs and precise 135Cs/137Cs atomic ratio in environmental samples by single-column chromatography coupled to triple-quadrupole inductively coupled plasma-mass spectrometry

For source identification, measurement of 135Cs/137Cs atomic ratio not only provides information apart from the detection of 134Cs and 137Cs, but it can also overcome the application limit that measurement of the 134Cs/137Cs ratio has due to the short half-life of 134Cs (2.06 y). With the recent advancement of ICP-MS, it is necessary to improve the corresponding separation method for rapid and precise 135Cs/137Cs atomic ratio analysis. A novel separation and purification technique was developed for the new generation of triple-quadrupole inductively coupled plasma-mass spectrometry (ICP-MS/MS). The simple chemical separation, incorporating ammonium molybdophosphate selective adsorption of Cs and subsequent single cation-exchange chromatography, removes the majority of isobaric and polyatomic interference elements. Subsequently, the ICP-MS/MS removes residual interference elements and eliminates the peak tailing effect of stable 133Cs, at m/z 134, 135, and 137. The developed analytical method was successfully applied to measure 135Cs/137Cs atomic ratios and 135Cs activities in environmental samples (soil and sediment) for radiocesium source identification.

Quantitative Elucidation of Cs Adsorption Sites in Clays: Toward Sophisticated Decontamination of Radioactive Cs

For successful 137Cs decontamination from the soil environment, Cs adsorption sites for a saponite (i.e., a silicate clay of highly complex soil material) are highlighted based on the results of Fourier transform infrared (FT-IR) spectroscopy, 133Cs magic-angle-spinning nuclear magnetic resonance (MAS NMR), radiocesium interception potential (RIP), and a conventional elution experiment. Heavily adhesive Cs adsorption was found to originate from Cs chemisorption at nanosheet edges and Cs confinement in wedge-shaped parts available in the interior of local molecular structures, in which one- and two-nanosheets are inserted into the interlayer spaces. The multidisciplinary approach covering physical, chemical, and geochemical techniques successfully determines the concentrations of Cs-adsorption-associated nanosheet surfaces, nanosheet edges, wedge-shaped parts, and oncoming hexagonal cavities to be 322, 238, 9 × 10–2, and 207 mmol kg–1, respectively. Radioactive 137Cs that is not cleaned up after decontamin...

Study on adsorptive property of bentonite for cesium

Characterization and adsorption analysis of the bentonite samples were studied by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), Fourier transformed infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). SEM, EDS, FTIR, and XRD results showed that the ion exchange is one of the adsorption mechanisms of Cs+ onto bentonite and the Al–O–H and H–O–H groups of the bentonite might participate in the Cs+ adsorption process. The effect of the contact time, different concentrations of Cs+, pH value, and bentonite dosage on the adsorption of Cs+ onto bentonite were examined. The study results showed that cesium ions could be effectively adsorbed by bentonite. The adsorption equilibrium was established after 24 h. The distribution coefficient decreased from 1614.57 to 84.93 mL/g, but the adsorption capacity increased from 8.71 to 21.79 mg/g when the initial Cs concentration increased from 100 to 500 mg/L. The distribution coefficient and adsorption capacity for the cesium ions increased with an increase of solution pH in the range of 3 and 11 except for a little decrease at pH 7. The distribution coefficient increased from 66.54 to 3498.62 mL/g, but the adsorptive capacity decreased from 23.48 to 2.86 mg/g with an increasing amount of the adsorbent from 0.25 to 0.5 g. Adsorption isotherms fitted with Freundlich models well. Thermodynamic studies indicated that the sorption capacity of the sorption of cesium ions onto bentonite became weak with a temperature increase and showed the sorption of cesium ions onto bentonite was exothermic.

Evaluation of a cesium adsorbent grafted with ammonium 12-molybdophosphate

Abstract A fibrous cesium (Cs) adsorbent was developed using radiation-induced graft polymerization with a cross-linked structure containing a highly stable adsorption ligand. The ligand, ammonium 12-molybdophosphate (AMP), was successfully introduced onto the fibrous polyethylene trunk material. The resulting Cs adsorbent contained 36% nonwoven fabric polyethylene (NFPE), 1% AMP, 2% triallyl isocyanurate (TAIC) and 61% glycidyl methacrylate (GMA). The adsorbent's Cs adsorption capacity was evaluated using batch and column tests. It was determined that the adsorbent could be used in a wide pH range. The amount of desorbed molybdenum, which can be used as an estimate for AMP stability on the Cs adsorbent, was minimized at the standard drinking water pH range of 5.8–8.6. Based from the inspection on the adherence of these results to the requirements set forth by the Food Sanitation Act by a third party organization, it can be concluded that the developed Cs adsorbent can be safely utilized for drinking water.

Cesium growth on the SrTiO3(100) surface

We investigate Cs adsorption on the SrTiO3(100) surface at room temperature by means of Auger electron spectroscopy, low energy electron diffraction, electron energy loss spectroscopy, thermal desorption spectroscopy and work function measurements. Cesium grows in a single amorphous layer, showing different morphology from that on other insulating substrates. The Cs overlayer approximates a two-dimensional metallic phase. No indications for the reduction of the substrate and a Cs–O compound are found. Thermal annealing desorbs part of the metallic Cs, inducing at the same time the surface diffusion of the Cs adatoms to higher binding energy states. The growth and adsorption kinetics of Cs on the STO, shows substantial differences to that of other alkalis such as K and Li. The reasons for that are discussed.

The effect of hydroxylation on CNT to form Chitosan-CNT composites: A DFT study

The effect of types of CNTs (pristine and hydroxylated) on the synthesis of Chitosan-CNT (CS-CNT) composites was investigated theoretically. The adsorption energy (Eads) of CS on the pristine CNT and hydroxylated CNTs (CNT-OHn, n=1–6) as well as the structural and electronic properties of said composites have been investigated. Results show that the adsorption of CS on CNT and CNT-OHn is thermodynamically favored. The Eads of CS on CNTs was calculated to be −20.387kcal/mol from electrostatic interactions. For CS adsorbed into CNT-OHn, Eads ranges from −20.612 to −37.567kcal/mol. Hydroxyl groups on CNT are the main adsorption sites for CS loading onto CNT-OHn via hydrogen-bond interactions. The CS-CNT-OH3 is the most sable composite among tested complexes. The energy gap (ΔEgap) of CS-CNT-OH3 was calculated less than pristine CNT and CNT-OH3, indicative of the composites being more reactive than that of pristine CNTs and CNT-OH3. It was proved that CS can transfer electron to the hydroxylated CNTs, thus overcoming the drawbacks of CNTs being chemically inert.

The effect of graphene intercalation with alkali metal atoms on the field electron emission

The influence of adsorption and intercalation of alkali metal atoms (Cs, K, Na) on the field-electron emission from an iridium point emitter with surface graphene islands has been studied. It is established that the intercalation of graphene islands with alkali metal atoms does not lead to significant changes in the emission current. In the case of adsorption of Cs, K, and Na atoms on the emitter surface with graphene islands, the most pronounced decrease in the work function and localization of electron emission are observed for islands situated on the (100) and (111) faces of iridium.

A Study of the Adsorption Characteristics of Cobalt and Caesium from a Solution by Using Vietnamese Bentonite

Abstract The radioactive waste produced from the construction of a nuclear power plant is a controversial topic. The resulting radioactive waste contains 60Co and 137Cs isotopes that are the most difficult to remove. Bentonite is widely used as an adsorbent for heavy metals. An important factor is the safe operation of waste management at a nuclear power plant to be built in Vietnam. Therefore, a method of degrading complexes of radionuclides and the adsorption of radionuclides onto Vietnamese Bentonite was implemented in this study. In current literature, UV radiation and heating with oxidising substances are used in general for degrading complexes of radionuclides. The experimental results for the adsorption of Co(II) and Cs+ onto VNB suggest that VNB can be used in the future for large-scale liquid waste treatment due to its low cost, high efficiency, and environmentally friendliness.

Removal of Cs by Adsorption with IE911 (Crystalline Silicotitanate) from High-Radioactive Seawater Waste

This study was performed on the removal of Cs, one of the main high- radioactive nuclides contained in the high-radioactive seawater waste (HSW), by adsorption with IE911 (crystalline silicotitanate type). For the effective removal of Cs and the minimization of secondary solid waste generation, adsorption of Cs by IE911 (hereafter denoted as IE911-Cs) was effective to carry out in the m/V (ratio of absorbent weight to solution volume) ratio of 2.5 g/L, and the adsorption time of 1 hour. In these conditions, Cs and Sr were adsorbed about 99% and less than 5%, respectively. IE911-Cs could be also expressed as a Langmuir isotherm and a pseudo-second order rate equation. The adsorption rate constants (k2) were decreased with increasing initial Cs concentrations and particle sizes, and increased with increasing ratios of m/V, solution temperatures and agitation speeds. The activation energy of IE911-Cs was about 79.9 kJ/mol. It was suggested that IE911-Cs was dominated by a chemical adsorption having a strong bonding form. From the negative values of Gibbs free energy and enthalpy, it was indicated that the reaction of IE911-Cs was a forward, exothermic and relatively active at lower temperatures. Additionally, the negative entropy values were seen that the adsorbed Cs was evenly distributed on the IE911.

Potential application of a nanocomposite:HCNFe@polymer for effective removal of Cs (I) from nuclear waste

This study highlights new opportunities for the preparation of Cobalt Hexacyanoferrate(CoHCNF)@poly aniline nanocomposite as an adsorbent to efficiently remove Cs (I) ions from water. A chemical co-precipitation method was utilized to prepare CoHCNFe@poly aniline nanocomposite nanostructure. The TEM and SEM images of the product showed that it consists of semi-spherical particles with sizes ranging from 50 to 500 nm. Experimental parameters affecting Cs (I) sorption such as pH, adsorbent dosage, contact time, initial concentration of metal ion and temperature were studied. The maximum adsorption capacity (q) for cesium ions obtained from the Langmuir model at room temperature and 60 °C were 92.12 and 181.81 mg g−1 respectively. It is clear that this adsorbent has effective removal properties for adsorption of Cs(I) from radioactive waste compared with other adsorbents.The kinetic data were analyzed by the pseudo-first-order and the pseudo-second-order kinetic models; consequently, the pseudo-second-order model was the best to describe the adsorption of Cs (I) ions. The equilibrium data were fitted to the three isotherm models: Freundlich, Langmuir and Dubinin–Radushkevich (D–R), and as a result the Langmuir model produced the best fit for the experimental data. Thermodynamic parameters showed that the adsorption of Cs (I) ions onto the nanocomposite was endothermic and spontaneous. The mechanism of Cs (I) ions sorption was discussed.

Comparative study of the factors associated with the application of metal hexacyanoferrates for environmental Cs decontamination

Calcium alginate cohered beads of copper hexacyanoferrate (CuHCF), and iron hexacyanoferrate (FeHCF), were prepared and studied for their competence in the environmental Cs decontamination. The influence of temperature and solution pH, parameters which are crucial for effective decontamination are studied in detail. Kinetic study performed at varying temperatures showed that adsorption of Cs onto CuHCF is faster than on FeHCF, the difference observed mainly due to the difference in the adsorption capacities of the materials. Additionally, an important environmental issue, which is often omitted, the possibility of release of the ferrocyanide ion into the effluent solution, is discussed in detail. The concentration of total cyanide in the effluent solution passed through FeHCF is comparatively very high beyond pH 4. In contrary, it is lower than in CuHCF passed solution at pH below 4. Based on these results, FeHCF is a good option in highly acidic solutions, and for weakly acidic to slightly alkaline pH, CuHCF is effective.

The highly effective removal of Cs+ by low turbidity chitosan-grafted magnetic bentonite

Chitosan-grafted magnetic bentonite (CS-g-MB) was successfully synthesized via a plasma-induced method. The CS-g-MB composite shows good magnetic properties, low turbidity, and high stability in aqueous solution and exhibits significant adsorption capacity for Cs+ ions. The adsorption of Cs+ by CS-g-MB is dependent on both pH and ionic strength. In the presence of Mg2+, K+, Li+, and Na+ ions, the Cs+ exchange is constrained in the order of Li+≈Mg2+<Na+<K+, primarily as a result of the hydrated radii and hydration energies of these cations in aqueous solution. The stability of the CS-g-MB composite in simulated groundwater and in actual seawater was also investigated and this material was found to be a good candidate for the remediation of both types of water. These results demonstrate that enhanced coagulation achieved by plasma modification represents a viable yet advanced technology for wastewater management, and is capable of synthesizing new adsorbents that can be readily separated from solution and that avoid increasing the turbidity and color of the water being treated.

Incommensurate superstructure in heavily doped fullerene layer on Bi/Si(111) surface.

Cs adsorption onto the C60-covered Si(111)-β-√3×√3-Bi reconstruction has been studied by means of scanning tunneling microscopy and photoelectron spectroscopy. Unexpected increase in apparent size of every second C60 molecule has been detected, hereupon the close packed molecular array almost doubles its periodicity. The change affects only the fullerenes that are in direct contact with the metal-induced reconstruction and takes no place already in the second layer. Photoelectron studies have revealed that this incommensurate "2 × 2" superstructure of a heavily doped C60 monolayer remains in an insulating state regardless of doping level.

The possibly important role played by Ga2O3 during the activation of GaN photocathode

Three different chemical solutions are used to remove the possible contamination on GaN surface, while Ga2O3 is still found at the surface. After thermal annealing at 710 °C in the ultrahigh vacuum (UHV) chamber and activated with Cs/O, all the GaN samples are successfully activated to the effective negative electron affinity (NEA) photocathodes. Among all samples, the GaN sample with the highest content of Ga2O3 after chemical cleaning obtains the highest quantum efficiency. By analyzing the property of Ga2O3, the surface processing results, and electron affinity variations during Cs and Cs/O2 deposition on GaN of other groups, it is suggested that before the adsorption of Cs, Ga2O3 is not completely removed from GaN surface in our samples, which will combine with Cs and lead to a large decrease in electron affinity. Furthermore, the effective NEA is formed for GaN photocathode, along with the surface downward band bending. Based on this assumption, a new dipole model Ga2O3-Cs is suggested, and the experimental effects are explained and discussed.

Adsorption of Cs from Water on Surface-Modified MCM-41 Mesosilicate

Cs is a common radionuclide present in nuclear wastes and released from nuclear power plant accidents. It is hard to be removed from water with traditional technology. The current study aimed at developing of efficient cost-effective adsorbent for removing Cs with modified MCM-41 with specific functional groups –SH. Mesoporous material MCM-41 was selected due to its large surface area and tunable pore structure. Functional –SH groups were grafted into the pores of MCM-41 to enhance its capability of selective adsorption of Cs from multi-element (Co, Sr) water solution. The adsorption results showed that the maximum adsorption capacity was 29.24 mg/g. Both Langmuir and Freundlich models described the adsorption processes of Cs, indicating co-existence of both monolayer and multilayer adsorption in the surface and inner pores of the materials. TEM, FTIR, and Raman spectroscopy analyses indicated that –SH groups were successfully bounded into the pores of MCM-41. The present study approved the surface functional modified MCM-41 which might be a good alternative candidate for cleaning up of radionuclide Cs from nuclear power plant accidents and relevant nuclear accident events.

Adsorption of Cs+ at the Hydroxyapatite/Aqueous Electrolyte Interface

The aim of this paper is to discuss the changes in the double electrical layer at the hydroxyapatite/electrolyte solution interface during the adsorption of Cs+ and to establish the relationship between the time and adsorption on this material. The adsorbent was prepared by wet precipitation methods, and characterized by X-ray diffraction and low-temperature nitrogen adsorption–desorption methods. The specific surface area of the adsorbent was characterized and the suitable particle sizes were determined. Adsorption of 137Cs isotopes from ionic solutions was carried out at different concentrations and pH. The values of Cs+ adsorption on the hydroxyapatite were quantified and the effect of Cs on its grains (particles) size, morphology, surface charge density and zeta potential was discussed.

The sequestration of Sr(II) and Cs(I) from aqueous solutions by magnetic graphene oxides

The adsorption of Sr(II) and Cs(I) on magnetic graphene oxides was investigated by batch techniques. The adsorption kinetics indicated that adsorption of Sr(II) and Cs(I) on magnetic graphene oxides can be satisfactorily fitted by pseudo-second-order kinetic model. The adsorption of Sr(II) and Cs(I) on magnetic graphene oxides increased with increasing pH from 2.0 to 6.0, then high level adsorption of Sr(II) and Cs(I) was observed at pH>6.0. The maximum adsorption capacity of magnetic graphene oxides calculated from Langmuir model at pH4.0 and 293K was 14.706 and 9.259mg/g for Sr(II) and Cs(I), respectively. The thermodynamic parameters showed that the adsorption of Sr(II) and Cs(I) on magnetic graphene oxides was an exothermic and spontaneous process. According to surface complexation modeling, the adsorption mechanism of Sr(II) and Cs(I) on magnetic graphene oxides was cation exchange, whereas the inner-sphere surface complexation dominated the sorption mechanism of Sr(II) and Cs(I) on magnetic graphene oxides. The finding suggested that magnetic graphene oxides can be one of the promising adsorbents for the immobilization and preconcentration of radionuclides from aqueous solutions in environmental cleanup.

Design of Chitosan-Grafted Carbon Nanotubes: Evaluation of How the -OH Functional Group Affects Cs+ Adsorption.

In order to explore the effect of –OH functional groups in Cs+ adsorption, we herein used the low temperature plasma-induced grafting method to graft chitosan onto carbon nanotubes (denoted as CTS-g-CNTs), as raw-CNTs have few functional groups and chitosan has a large number of –OH functional groups. The synthesized CTS-g-CNT composites were characterized using different techniques. The effect of –OH functional groups in the Cs+ adsorption process was evaluated by comparison of the adsorption properties of raw-CNTs with and without grafting chitosan. The variation of environmental conditions such as pH and contact time was investigated. A comparison of contaminated seawater and simulated groundwater was also evaluated. The results indicated that: (1) the adsorption of Cs+ ions was strongly dependent on pH and the competitive cations; (2) for CNT-based material, the –OH functional groups have a positive effect on Cs+ removal; (3) simulated contaminated groundwater can be used to model contaminated seawater to evaluate the adsorption property of CNTs-based material. These results showed direct observational evidence on the effect of –OH functional groups for Cs+ adsorption. Our findings are important in providing future directions to design and to choose effective material to remedy the removal of radioactive cesium from contaminated groundwater and seawater, crucial for public health and the human social environment.

Synchrotron radiation photoemission study of the ultrathin Cs/InN interface

Abstract Electronic structure of the ultrathin Cs/n-InN interface has been studied in situ via synchrotron-based photoemission spectroscopy by excitation in the energy range of 70–400 eV. Changes in the In 4d, Cs 4d, Cs 5p, N 2s core level spectra and in the surface state spectra have been revealed under different cesium coverages. The intrinsic surface state for the clean InN surface at binding energy of 2.5 eV (SS1) is found to attenuate during the Cs adsorption. Simultaneously the Cs induced surface state at binding energy of 0.9 eV (SS2) arises. For the Cs/InN interface, the In 4d peak displays the strong core level shift and the appearance of an additional In 4d peak originated from In–Cs interface bonding. Change in the surface electronic structure of the InN caused by Cs adsorption is found to originate predominantly from suppression of the intrinsic surface state concerned with the local interaction of In dangling bonds and Cs adatoms.

Molecular Models of Cesium and Rubidium Adsorption on Weathered Micaceous Minerals

Understanding the adsorption mechanisms of metal cations onto soils and sediments is of critical importance in the protection of the environment, especially for the case of radioactive materials including the fission product (137)Cs. Mechanism-based adsorption models for the long-term interaction of chemical and radionuclide species with clay minerals are needed to improve the accuracy of groundwater reaction and flow models, as well as related simulations for performance assessment of waste sites and repositories. Toward this goal, molecular simulation using geometry optimization and molecular dynamics methods have been used to investigate the adsorption behavior of Cs(+) and Rb(+) cations at frayed edge wedges (a proxy for frayed edge sites, FES) and in the interlayer region formed as a result of the transformation of muscovite to Al-hydroxy interlayered vermiculite (HIV) during weathering and pedogenesis. Frayed edge wedges, formed both on individual smectite and illite phases and on the mica-HIV intergrade, have previously been recognized as significant sinks for the strong adsorption of Cs(+) and Rb(+). Atomic density profiles, interlayer adsorption site maps, radial distribution functions, and adsorption enthalpies derived from the equilibrated structural models are used to evaluate the optimal adsorption configurations and thermodynamics for Cs- and Rb-endmembers, a 50:50 Cs-Rb composition for the aqueous interlayer of vermiculite, and for the interlayer wedge zone as mica is transformed to HIV (i.e., HIV-mica wedge). Adsorption enthalpies for both cations are significantly larger for the frayed edge wedges (as represented by the HIV-mica wedge model) compared to values for the vermiculite and mica interlayers. Cesium cation binds more strongly than Rb(+) in the vermiculite interlayer, while Rb(+) binds more strongly than Cs(+) in the HIV-mica wedge. In all cases, the derived adsorption enthalpies for both cations indicate a preference for the wedge environment where electrostatic interaction is enhanced due to the presence of layer charge and the increased size of interlayer at the wedge accommodating cations larger than K(+).