Sorption Of Cesium Research Articles

Kinetic features of cesium sorption onto a polyfunctional ferrocyanide sorbent

The kinetics of cesium sorption onto mixed nickel potassium ferrocyanide supported on hydrated titanium dioxide were studied in different ranges of cesium concentrations. At the cesium concentration in solution from 2 × 10−7 to 5 mg L−1, the sorption rate is determined by external diffusion of cesium ions in solution, heterogeneous ion-exchange reaction, and internal diffusion of cesium in the pore space of the sorbent. The slowest step is the breakdown of sorption colloids and uptake of the released cesium ions by the sorbent. At the cesium concentration in solution higher than 50 mg L−1, the rate-determining step is the precipitation of mixed nickel cesium ferrocyanide in the pore space of the sorbent.

Sorption properties of nanostructured potassium aluminosilicate

The ability of synthetic nanostructured potassium aluminosilicate (PAS) KAlSi3O8·1.5H2O with the specific surface area of 105 ± 5 m2 g−1 to take up cesium ions was studied. The maximal sorption capacity of PAS in sorption of Cs+ ions from cesium carbonate solutions containing no other salts is ∼3.7 mmol g−1. In Cs+ sorption from solutions containing no other salts, the sorption capacity is the lowest at pH 1; it increases with pH, reaching a maximum at pH 10.8. The effect of salt background (various concentrations and ratios of KCl and NaCl) on the sorption properties of PAS was examined. The sorption capacity decreases to the greatest extent (to 0.25 mmol g−1) in solutions containing the K+ and Na+ ions simultaneously at concentrations of 68 and 517 mM, respectively. The dependence of the cesium sorption on the concentration of nitrates (NaNO3, KNO3, NH4NO3) and the kinetics of the cesium sorption from aqueous NaNO3 solution were studied with the 137Cs tracer. The highest distribution coefficients (up to 12000 mL g−1) are observed in 137Cs sorption from NaNO3 solutions. The degree of the 137Cs sorption reaches a maximum (92 ± 4%) in sorption from 0.01 M NaNO3 solutions at the sorption time of 4 h.

Cesium sorption intensification by complex natural sorbents from liquid radioactive media

The studies have shown a growth (up to 90%) in the sorption degree of strontium ions by composite sorbents based on the modified titanium oxide of bentonite rocks and montmorillonite in a ratio of 1: 1. Optimum hydrodynamic regimes (350 rev/min), which increase the emergence effect of complex natural sorbents were determined. Intensification of external diffusion of cesium from liquid radioactive waste was calculated using the theory of local isotropic turbulence, taking into account the flow turbulence hydrodynamics and geometric parameters of mixers. The diffusion coefficient of strontium in the model solution, computed using the Wilkie and Chang dependence allows to predict the kinetics of external diffusion mass transfer of cesium ions in liquid medium based on the theoretical values of mass transfer coefficient. For a correlation of experimental and theoretical data of mass transfer coefficient during external diffusion mass transfer process, correction factor kβ (1,1-1,25) was calculated, which takes into account the radial distribution heterogeneity of solid dispersion particles in the system center and near the walls of the device depending on the particle size distribution and the size of the device.

The usage of zeolites for dynamic sorption of cesium from waste waters of nuclear power plants

Experiments have been made to determined the effect of various confounding factors (foreign ions, organic compounds entering into the composition of detergents) on the dynamic sorption of cesium by zeolites (natural and synthetic). On the basis of the results obtained, a few ways were proposed for reducing the influence of the various confounding factors on the degree of cesium sorption on zeolites. Among those ways, the usage of the sorption facility consisting of several sorption columns has appeared to be most efficient. For the quantitative determination of cesium used nuclear-physical methods of analysis using a beam of charged particles.

Sorption behavior of cesium from aqueous solution on magnetic hexacyanoferrate materials

The rapid development of the nuclear power plant in China leads to increasing attention to the treatment of low-level radioactive wastewater (LLRW). One of possibilities is the application of inorganic adsorbent like potassium titanium hexacyanoferrate (PTH), which can exhibit the effective adsorption of cesium. In this paper, the PTH material was optimized by means of being loaded on magnetite substrate. The synthesized material (magnetic PTH, M-PTH), with a particle size of less than 100nm, can offer a high capacity and favorable kinetic performance, however, without difficulties of separation from the LLRW due to its magnetic characterizations. The batch experiments demonstrate that cesium sorption isotherm of M-PTH coincide well with Langmuir model. The calculated capacity amounts to 0.517mmol/g, approximately 1.5 times the capacity of zeolite materials. The sorption process follows the pseudo-second-order sorption model. In the initial phase the rate-controlling step is intraparticle diffusion. With the Cs accumulation on the particle surface, external diffusion performs an important role together with intraparticle diffusion.

Modeling of cesium sorption on biotite using cation exchange selectivity coefficients

Abstract For the modeling of cesium sorption on biotite, samples of natural biotite separated from gneissic rocks were converted into monoionic potassium, sodium, and calcium forms, and sorption isotherms for Cs/K, Cs/Na and Cs/Ca exchange were determined at pH 6 and 8 in E-4–E-8 M Cs solutions. Selectivity coefficients for Cs/K, Cs/Na, and Cs/Ca ion exchange reactions were calculated from the isotherm data, using the Gaines-Thomas convention. At Cs loadings below 1% of the total ion exchange capacity, the overall selectivity coefficient for Cs/Ca exchange was approximately five and seven orders of magnitude higher than those for Cs/Na and Cs/K exchange, respectively. Based on the selectivity coefficients, the ion exchange isotherms were modeled with the U.S. Geological Survey PhreeqC program, assuming three different types of ion exchange site: sites on the basal planes on biotite crystal surfaces with 95% site abundance, probable interlayer sites on crystal edges [frayed edge sites (FESs)] (0.02%) and third-type sites (5%), the physical background of which is unclear. Of these three types, the FES sites were superior in Cs selectivity, while the planar sites exhibited the lowest selectivity, and the third-type sites had selectivity between these two. The functionality of the model was successfully verified by modeling the Cs sorption isotherms on crushed mica gneiss rock in saline groundwater. Determination of the exchangeable ions K, Na, Ca, and Cs on the basal plane and edge surfaces by scanning electron microscopy-energy-dispersive x-ray spectroscopy (SEM-EDX) supports the results of modeling: edge sites highly prefer Cs ions and also Ca and Na ions but not K ions.

Gamma radiation induced preparation of organic-inorganic composite material for sorption of cesium and zinc

A novel composite material, poly(acrylamide-acrylic acid-acrylonitrile)-N,N′-methylenediacrylamide/silicon oxide-zirconium oxide [P(AM-AA-AN)-DAM/SiO2-ZrO2], was prepared by γ-radiationinduced template copolymerization of acrylic acid (AA) with acrylonitrile (AN) on polyacrylamide P(AM) as a template polymer in presence of N,N′-methylenediacrylamide (DAM) as cross-linker in aqueous solution with water-insoluble mixed oxide of silicon and zirconium. The composite material was characterized by Fourier transform IR spectroscopy and by thermal analysis (synchronized TGA-DTA). The sorption of 134Cs and 65Zn(II) onto the prepared composite material was investigated using batch equilibrium technique with variation of pH, adsorbent weight, initial sorbate concentration, contact time, and temperature. The sorption equilibrium data were fitted with the Langmuir and Freundlich isotherm models. The isotherm is successfully fitted by the Langmuir equation over the entire concentration range studied. Lagergren pseudo-first- and pseudo-secondorder kinetic models were tested to describe the reaction mechanism. The experimental data are fitted well the pseudo-second-order model. The thermodynamic functions (free energy ΔG0, enthalpy ΔH0, entropy ΔS0) of the sorption were calculated. These quantities show that the sorption of 134Cs and 65Zn onto the composite material is spontaneous and endothermic.

Radiocesium Adsorption By Zeolitic Materials Synthesized From Coal Fly Ash

Brown coal fly ash derived from the combustion of brown-coal in power plant ENO Nováky (Slovak Republic) was used as raw material for synthesis of zeolitic materials ZM1 and ZM3 by hydrothermal alternation with 1M NaOH and 3M NaOH, respectively. Fly ash and synthesized products were characterized using XRF and SEM-EDX analysis. Subsequently, zeolitic materials were tested as sorbents to remove Cs+ ions from aqueous solutions using radiotracer technique. Sorption of cesium by both types of zeolitic materials obeys Langmuir adsorption isotherm model. The maximum sorption capacities Qmax at pH 6.0 calculated from Langmuir isotherm were 1203 ± 65 μmol Cs+/ g for ZM1 and 1341 ± 66 μmol Cs+/ g for ZM3. The results showed that alkali treated fly ash can be used as effective sorbent for radiocesium removal from contaminated solutions.

Immobilization of metal hexacyanoferrates in chitin beads for cesium sorption: synthesis and characterization

Five metal-potassium hexacyanoferrate/chitin composites (based on Cu, Ni, Zn, Co or Fe co-metal) have been prepared and characterized, using SEM-EDX, TEM, X-ray diffraction and FT-IR, before being compared for Cs(I) and 137Cs(I) sorption. The Zn-ion exchanger was characterized by a much larger crystal size of about 250 nm compared with a few tens of nm for other ion-exchangers. The ion-exchangers are well distributed in the whole mass of the composite and they are fully accessible to Cs(I), as evidenced by Cs(I) distribution after metal sorption. Uptake kinetics can be modeled using both the pseudo-second order rate equation and the Crank equation (resistance to intraparticle diffusion coefficient). Sorption isotherms showed substantial differences in the sorbents that can be ranked as Cu > Ni > Zn > Co > Fe. However, based on 137Cs Kd values, the sorbents can be ranked as Co ≫ Fe ≫ Cu ≫ Ni > Zn. Taking into account the cost and toxicity of metals (both in terms of manufacturing and potential metal release) a Prussian Blue based sorbent (i.e., iron-potassium hexacyanoferrate/chitin composite) sounds to be a good composite for Cs(I) recovery from radionuclide-containing effluents.

セシウム吸着機能付ジオシンセティックスの除染区域への適用事例（第二報）

セシウム吸着機能付ジオシンセティックスの除染区域への適用事例（第二報）

Synthesis, Characterization, and Cesium Sorption Performance of Potassium Nickel Hexacyanoferrate-Loaded Granular Activated Carbon

GAC has been modified by loading of potassium nickel hexacyanoferrate (KNiCF) as a new adsorbent for cesium adsorption. The potassium nickel hexacyanoferrate-loaded granular activated carbon (KNiCF-GAC) was characterized using powder x-ray diffraction (XRD) and nitrogen adsorption-desorption isotherm data, infrared spectroscopy, and its cesium adsorption performance in aqueous solution was investigated. The effect of the various parameters such as initial pH value of the solution, contact time, temperature, and initial concentration of the cesium ion on the adsorption efficiencies of KNiCF-GAC have been studied systematically by batch experiments. The adsorption isotherm of KNiCF-GAC was studied and the fitted results indicated that the Langmuir model could well represent the adsorption process. The maximum adsorption capacity of Cs+ onto KNiCF-GAC was found to be 163.9 mg · g−1.

Ionic strength and pH dependent multi-site sorption of Cs onto a micaceous aquifer sediment

Caesium-137 (t1/2=30years) is a common contaminant at nuclear legacy sites. Often the mobility of 137Cs in the environment is governed by its sorption to charged sites within the sediment. To this end it is important to understand the sorption behaviour of caesium across a wide range of environmental conditions. This work investigates the effect of varying solution composition (pH and competing ions) on the sorption of caesium to micaceous aquifer sediment across a large concentration range (1.0×10−11 – 1.0×10−1molL−1 Cs+). Experimental results show that Cs+ exhibits three distinct sorption behaviours at three different concentration ranges. At very low concentrations<1.0×10−6molL−1 Cs+ sorption was unaffected by competition with Na+ or H+ but significantly reduced in high ionic strength K+ solution. Secondly between 1×10−6 and 1.0×10−3molL−1 Cs+ is strongly sorbed in a neutral pH, low ionic strength background but sorption is significantly reduced in solutions with either a high concentration of Na+ or K+ ions or low pH. At high concentrations>1.0×10−3molL−1 Cs+ sorption is reduced in all systems due to saturation of the sediment’s sorption capacity. A multi-site cation exchange model was used to interpret the sorption behaviour. From this it was determined that at low concentrations Cs+ sorbs to the illite frayed edge sites only in competition with K+ ions. However, once the frayed edge sites are saturated the Cs+ sorbs to the Type II and Planar sites in competition with K+, Na+ and H+ ions. Therefore sorption of Cs+ at concentrations>1.0×10−6molL−1 is significantly reduced in both high ionic strength and low pH solutions. This is a significant result with regard to predicting the migration of 137Cs+ in acidic or high ionic strength groundwaters.

Immobilization of inorganic ion-exchanger into biopolymer foams – Application to cesium sorption

Nickel–potassium ferrocyanide (along with other ferrocyanide sub-products, as shown by mineralization, SEM–EDX and XRD analyses) has been immobilized in highly porous discs of chitin for the sorption of Cs(I) from near neutral solutions. The immobilization process allows synthesizing stable materials that can bind up to 80mg Csg−1 (i.e., 240mg Csg−1 ion-exchanger). Cesium sorption is hardly affected by the pH between pH 2 and 8. The sorbent is selective to Cs(I) even in the presence of high concentrations of Na(I), K(I), Rb(I) or NH4+. The pseudo-second order rate equation fits well kinetic profiles: the rate coefficient increases with the flow rate of recirculation (to force the access to potentially non-interconnected pores), as an evidence of the control of uptake kinetics by diffusion properties. In fixed-bed columns, the breakthrough curve is accurately described by the Clark model and the sorption capacity (at sorbent saturation) is consistent with the values obtained in sorption isotherms. Preliminary tests performed on 137Cs spiked solutions confirm the efficiency of the material for the treatment of effluents bearing radionuclides.

Influence of the concentrations of potassium, sodium, and ammonium ions on the cesium sorption with mixed nickel potassium ferrocyanide sorbent based on hydrated titanium dioxide

The effect of single-charged cations (Na+, K+, NH +4 ) on the cesium sorption with mixed nickel potassium ferrocyanide sorbent based on hydrated TiO2 was studied. The K+ and Na+ ions exert no effect at their concentrations of up to 0.5 M; the Cs+ distribution coefficients from KCl and NaCl solutions are (1.1 ± 0.5) × 105 and (8 ± 3) × 104 mL g−1, respectively. The sorbent is highly specific to Cs+ in the presence of ammonium ions. The sorption mechanisms were studied. The concentration ranges in which Cs+ and NH +4 are sorbed by independent mechanisms (Cs+, by the ferrocyanide phase; NH +4 , by the phase of hydrated TiO2) and in which the Cs+ distribution coefficient decreases owing to competitive filling of the ferrocyanide phase with ammonium ions were determined. At cesium concentrations in solution exceeding 50 mg L−1, Cs+ and NH +4 are absorbed jointly owing to coprecipitation in the mixed ferrocyanide phase in the pore space of the sorbent.

Sorption of cesium and iodide ions onto KENTEX-bentonite

The sorption of cesium and iodide ions onto KENTEX-bentonite was investigated using batch test and in-diffusion test methods. The cesium ions were highly sorbed on the bentonite, and the experimental data fit the Freundlich isotherm well. The distribution coefficient, K d, of the cesium ions was variably affected by the chemical conditions of the solution (initial ion concentration, pH, salinity) and temperature. An increasing pH of solution increased the K d. However, there were different K d values that decrease with an increase in the initial ion concentration, salinity, and temperature. The iodide ions, on the contrary, were negligibly sorptive. The K d values obtained from the in-diffusion tests were quite lower than those from the batch tests, which could be explained by changes in the pore water chemistry and surface area available for sorption.

Peculiarities of sorption isotherm and sorption chemisms of caesium by mixed nickel–potassium ferrocyanide based on hydrated titanium dioxide

Sorption isotherm of caesium from tap water by mixed nickel–potassium ferrocyanide based on hydrated titanium dioxide is obtained for a wide range of concentrations of caesium. It is shown that there are three types of specificity to caesium sorption sites in this sorbent. Sorption chemisms of caesium are studied, factors conditioned high sorption capacity of the sorbent are revealed. It is shown that occupation of sorption sites I and II is well approximated by Langmuir equilibrium and this process can be described within the bounds of theory of ion exchange. The expected sorption chemism of caesium by sorption sites III at high concentrations of caesium (>50 mg L−1) is precipitation of mixed nickel–caesium ferrocyanide in pore space of the sorbent.

Effect of organic complexing agents on the interactions of Cs+, Sr2+ and [formula omitted] with silica and natural sand

Sorption processes play a key role in controlling radionuclide migration through subsurface environments and can be affected by the presence of anthropogenic organic complexing agents found at contaminated sites. The effect of these complexing agents on radionuclide–solid phase interactions is not well known. Therefore the aim of this study was to examine the processes by which EDTA, NTA and picolinate affect the sorption kinetics and equilibria of Cs+, Sr2+ and UO22+ onto natural sand. The caesium sorption rate and equilibrium were unaffected by the complexing agents. Strontium however showed greater interaction with EDTA and NTA in the presence of desorbed matrix cations than geochemical modelling predicted, with SrNTA− enhancing sorption and SrEDTA2− showing lower sorption than Sr2+. Complexing agents reduced UO22+ sorption to silica and enhanced the sorption rate in the natural sand system. Elevated concentrations of picolinate reduced the sorption of Sr2+ and increased the sorption rate of UO22+, demonstrating the potential importance of this complexing agent. These experiments provide a direct comparison of the sorption behaviour of Cs+, Sr2+ and UO22+onto natural sand and an assessment of the relative effects of EDTA, NTA and picolinate on the selected elements.

Preparation of Modified Kaolin Filler with Cesium and Its Application in Security Paper

In this study, cesium was added intentionally during paper manufacture for protecting the papers against forgery and counterfeiting by sorbing cesium ions (Cs+) on kaolin, used as special filler in papermaking. The sorption of cesium from aqueous solution by kaolin was studied as a function of pH, shaking time, cesium initial concentration, and mass of kaolin using batch technique. The results showed that a solution containing 10 mg/L Cs+and 250 mg of kaolin at pH 6 can be used to modify the kaolin. Paper handsheets were prepared containing various percentages of the modified kaolin. The mechanical and optical properties of paper handsheets were studied. The prepared paper handsheets were irradiated by gamma irradiation using different doses. Fourier transform infrared (FTIR) spectroscopy was used to study the effect of kaolin modification by cesium and gamma irradiation on paper handsheets properties. The results indicated that modified kaolin enhanced the mechanical and optical properties of paper handsheets. Electron spin resonance (ESR) spectroscopy and laser-induced breakdown spectroscopy (LIBS) were also used. They provided rapid, sensitive and nondestructive techniques in differentiating between different questioned documents. This study presents a new concept in manufacturing security papers and anticounterfeiting applications.

Removal of cesium by spherical resorcinol–formaldehyde resin beads: Sorption and kinetic studies

Batch equilibrium studies were conducted at 20 ± 0.5 °C with indigenously synthesized spherical resorcinol–formaldehyde resin beads, using radioanalytical technique, to determine their capacity for sorption of cesium ions from alkaline medium. Equilibrium isotherm studies were carried out, by varying the initial concentrations of cesium from 0.1 to 50 mM. The liquid-to-solid phase ratio of ~100 ml:1 g was maintained for all the sorption experiments. The equilibrium data were fitted to Langmuir and Freundlich isotherm models. It was observed that Freundlich isotherm explains sorption process nicely. The effect of resin size on percentage cesium ion uptake was also investigated, and 20–40 mesh size was found to be the optimum particle size. The cesium sorption capacity of the beads was determined to be ~238 mg/g. The kinetics of the sorption was studied at different initial cesium ion concentrations, and the kinetics data were fitted into various kinetics models. The kinetics of the cesium ion sorption was found to be pseudo second-order. The mechanistic steps involved were found to be complex, consisting of both film diffusion and intraparticle diffusion with film diffusion as the rate limiting step.

The study of sorption of caesium radionuclides by “T-55” ferrocyanide sorbent from various types of liquid radioactive wastes

The sorption of caesium by T-55 sorbent from different types of liquid radioactive wastes is studied. It is shown that the sorbent can be used for extraction of caesium from high level acidic and saline solutions and also for decontamination of caesium contaminated waters containing surfactants and EDTA.