Rapid method to determine 89/90Sr in steel samples

The sorption and diffusion behavior of cesium was studied to support the interpretation of the ongoing in-situ experiments in the Olkiluoto test site. The distribution coefficients of cesium in the Olkiluoto pegmatitic granite, veined gneiss and their main minerals were obtained by batch sorption experiments and the diffusion of cesium was studied in rock cubes. The results were modelled with PHREEQC and Comsol Multiphysics. The distribution coefficients of cesium were largest in biotite and veined gneiss. The effective diffusion coefficients of cesium from the diffusion model were 3 × 10⁻¹³ m² s⁻¹ for veined gneiss and 4 × 10⁻¹³ m² s⁻¹ for pegmatitic granite.

     

Effect of grain size on the sorption and desorption of 137Cs in crushed granite columns and groundwater system under dynamic conditions

In this work, the sorption of ¹³⁷Cs⁺ dissolved as ¹³⁷CsNO₃ in the solution of 10^?6?M CsNO₃ in SWG, and its desorption by solution mentioned, were investigated under dynamic conditions in columns with crushed granitic materials of various grain sizes, namely, of pure granite and, of corresponding filling materials. It aims at the quantification of the influence of grain size on the retardation and distribution coefficients of ¹³⁷Cs, as well as on the other transport parameters (Peclet numbers and dispersion coefficients). For their determination, model based on erfc-function was used, assuming reversible equilibrium linear or non-linear sorption/desorption isotherms. By means of both model approaches, the experimental BTC _S were fitted using non-linear regression procedure, in the course of which the parameters mentioned were sought. The obtained results also validated the applicability of the linear equilibrium isotherms of the ¹³⁷Cs⁺ sorption/desorption in the studied transport processes and systems. Depending on the grain size, the retardation coefficients were between 40?C93 in pure granite and 140?C200 in filling materials. These values correspond to distribution coefficients of 11?C34?cm³/g and 40?C69?cm³/g, respectively. It was found that both retardation and distribution coefficients increase with decreasing grain size.     

Effect of grain size on the sorption and desorption of SeO4 2− and SeO3 2− in columns of crushed granite and fracture infill from granitic water under dynamic conditions

The sorption of 2 × 10^?5 mol/dm³ Na₂SeO₄ and Na₂SeO₃ dissolved in synthetic granitic water (SGW) were investigated in columns of crushed granite and fracture infill (clay minerals) of various grain sizes. Desorption was studied using pure SGW. The goal of study was the quantification of the effect of grain size on the retardation and distribution coefficients of SeO₄ ^2? and SeO₃ ^2?, as well as on the other transport parameters (Peclet number and hydrodynamic dispersion coefficient). A model based on the erfc-function, assuming a non-linear reversible equilibrium sorption/desorption isotherm, was used for evaluation of sorption/desorption and transport parameters. The determination of selenium was performed using an ICP-MS technique. The experimental breakthrough curves were fitted using non-linear regression procedure, in the course of which the parameters mentioned were sought. Summing up, no sorption was recorded in the case of SeO₄ ^2? under these conditions. The values of retardation coefficients were practically one for all studied grain sizes. On the other hand, significant sorption was found for SeO₃ ^2?: depending on the grain size, the retardation coefficients varied between 1.6–8.7 in pure granite and 1.8–37.2 in infill materials. These values correspond to distribution coefficients of 0.2–2.5 and 0.2–12.7 cm³/g, respectively. The both parameters have similar values in a case of desorption which reflects the reversible character of sorption process. It was found that retardation and distribution coefficients and sorption capacity for SeO₃ ^2? also increase with decreasing grain size.     

Study of ion exchange selectivity of organic ions by using (31)P NMR spectroscopy

Ion exchange distribution of the phenylphosphoric acid has been studied on various types of chloride form strong base resins as a function of pH at 25 °C, at 0.1 M ionic strength. Equilibrium measurements were supplemented by the study of pH dependence of the ³¹P NMR spectra of the resin-phase phenylphosphate species. Equations were derived to describe the pH dependence of the overall distribution coefficient and the chemical shift of the resin-phase solute species. Experimental data were evaluated by using these model equations and the values of the individual distribution coefficients, ion exchange selectivity coefficients and the resin-phase ³¹P chemical shifts of the mono- and divalent ions have been calculated. Comparison of distribution data of the individual species corroborated the significance of the role of hydrophobic interaction in the selectivity of organic ion exchange processes. A well-defined correlation between the ion exchange selectivity and the resin-phase ³¹P NMR chemical shift data has been pointed out.     

Retention of Cs on zeolite, bentonite and their mixtures

The sorption behavior of cesium on zeolite and bentonite minerals and their mixtures was studied by means of a batch method and a tracer technique. All experiments were carried out in the presence of CsCl spiked with ¹³⁷Cs and NaCl as a supporting electrolyte in varying concentrations. The distribution coefficients (K _D) did not show significant differences at low Cs⁺ loadings while they decreased in the high loading region. Freundlich and D-R isotherms were applied to the adsorption data of zeolite and bentonite. Adsorption capacities and mean energies calculated from D-R isotherm parameters decreased by increasing ionic strength on both minerals. The identification of the specific uptake sites was attempted on the basis of the Freundlich isotherm. Experimentally observed distribution coefficients of Cs on two mineral mixtures were smaller than theoretically calculated values, except at the highest NaCl concentration.     

Adsorption of fission products onto soils using a fission multitracer

The adsorption behavior of fission products to various soils was studied using a multitracer. The multitracer was prepared by neutron irradiation of ²³⁵U. Distribution coefficients of fission products were obtained for seventeen kinds of Japanese soils. It was found that zirconium, niobium, and rare earth elements show high distribution coefficients for all soil samples, however, elements like alkali metals show varied values.     

The influence of distribution coefficients on the separation factor of lithium isotopes

The influence of distribution coefficients on the separation factor of lithium isotopes was studied with Dowex 50W-X8, 200–400 mesh, ammonium form, strongly acidic cation exchanger by changing the pH and EDTA concentration of the eluent. It was found that the larger the EDTA concentration in the buffer solution, the smaller the distribution coefficients were. The separation factor was increased with decreasing EDTA concentration. The separation factor of lithium isotopes linearly increased up to a distribution coefficient value of 30, and gradually increased above 30. The optimum value of distribution coefficient of lithium to separate litihium isotopes was about 30. The distribution coefficient was increased with increasing pH, but the separation factor of lithium isotopes has no relation with pH.⁶Li concentrated on the resin phase, and⁷Li in the solution phase.     

The sorption of quercetin by high-basicity anion exchangers

The sorption of quercetin on anionites with various porosities in the OH⁻ and Cl⁻ forms was studied under static conditions. The equilibrium (distribution coefficients K _p) and kinetic (effective diffusion coefficients D _eff) parameters of quercetin sorption on AV-17-2P and AV-17-6M anionites in the Cl⁻ and OH⁻ forms were calculated. The mechanism of quercetin interactions with the anion exchangers was studied by electron microscopy and IR spectroscopy. Original Russian Text ? N.A. Udalova, S.I. Karpov, V.F. Selemenev, I.A. Sharmar, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 6, pp. 1143–1149.     

Pressure effect on cation exchange distribution of some fission products on a strongly acidic cation exchanger of sulfonic acid type in nitric acid

Distribution coefficients of fission products on a cation exchanger in 1M nitirc acid were measured as a function of the pressure by means of the column method. The distribution coefficients were found to decrease with the pressure, and this became more pronounced with increasing charge of the ions. The distribution coefficients of yttrium and RuNO³⁺ decreased with the pressure to a relatively greter extent than lighter lanthanides, and RuNO³⁺ appeared at a separate peak from europium in the elution chromatogram as the pressure was increased up to 900 kg/cm².     

Interaction of 3H+ (as HTO) and 36Cl− (as Na36Cl) with crushed granite and corresponding fracture infill material investigated in column experiments

The transport of ³H⁺ (as HTO) and ³⁶Cl^? (as Na³⁶Cl) was investigated in the dynamic system, i.e., in the columns filled with crushed pure granite and fracture infill of various grain sizes. The aim of column experiments was to determine important transport parameter, such as the retardation, respectively distribution coefficients, Peclet numbers and hydrodynamic dispersion coefficients. Furthermore, the research was focused to quantification of the effect of grain size on migration of studied radionuclides. The experimental breakthrough curves were fitted by a model based on the erfc-function, assuming a linear reversible equilibrium sorption/desorption isotherm, and the above mentioned transport parameters were determined. The results showed that influence of grain size on sorption of ³H⁺ and ³⁶Cl^? was negligible. Retardation and distribution coefficients of both tracers converged to one and zero, respectively, in case of all fractions of crushed granite and infill material. Generally, the presumed ion exclusion of ³⁶Cl in anionic form was proved under given conditions, only very weak one seems to exist in a case of infill material. In principal, both radionuclides behaved as non-sorbing, conservative tracers. On the other hand, the influence of grain size on Peclet numbers value and on dispersion coefficient was observed for both crystalline materials, namely in agreement with theoretical suppositions that the values of Peclet numbers decrease with increasing grain size and values of dispersion coefficient increase.     

Characterization of Poly(N-Vinylcarbazole) Obtained via Asymmetrical Polymerization

Abstract

The characterizations of poly(N-vinylcarbazole) (PVCZ) obtained via asymmetrical polymerization have been studied by using ¹H-NMR spectrum, UV spectrum, DSC, and GPC analysis. The tacticities, i.e., the isotactic diad mole fractions, were found to increase when using the initiator AIBN to the catalyst (?)Sp?⁺(+)CSA?^?, and the extinction coefficients to decrease. Bimodal molecular weight distribution (MWD)s were caused by two propagating species of the free ions and the ion-pairs during the polymerization process.     

Distribution of dopant metals between PbTiO3 crystals and PbO-B2O3 flux

Single crystals of lead titanate PbTiO₃ doped with silicon, calcium, chromium, manganese, cobalt, nickel, copper, zinc, and cadmium were grown. The compositions and crystallographic parameters of the crystals were studied. The lowest distribution coefficients of dopants between PbTiO₃ crystals and flux were observed with Mn⁺² and Co⁺² and the highest, with Ca⁺². Doping with niobium leads to the formation of solid solutions with the pyrochlore structure A₂B₂O₇ and even higher distribution coefficient. A correlation was found between dopant concentrations and crystal cell parameters.     

Sorption selectivity of cobalt(II), nickel(II), and copper(II) ions by KB-2E macroreticular carboxylic cation exchanger from aqueous-salt solutions of alkali metals

Sorption selectivity of copper(II), nickel(II), and cobalt(II) ions by KB-2E macroreticular carboxylic cation exchanger in the Na-form from dilute solutions was studied in the target concentration range (0.52.6) 103 M. The equilibrium distribution coefficients of Co²⁺, Ni²⁺, and Cu²⁺ were calculated. The role played by hydration of ions in their sorption by KB-2E cation exchangers is analyzed with consideration for IR spectroscopic, thermal analysis, and scanning electron microscopic data.     

Influence of the matrix on the complexation of metal ions by chelating ion exchangers

Summary Chelating ion exchangers show distribution coefficients that are considerably lower than those expected from complexation equilibria with the corresponding free ligands in solution. Furthermore, dependence of distribution coefficients on the concentration of exchanging ions in solution is observed. Both effects are due to the influence of the surrounding matrix on the anchor groups. The distribution coefficients of Fe³⁺, Ni²⁺, Cu²⁺, Pb²⁺ and UO ₂₊ ² on two cellulose exchangers carrying different anchor groups are investigated as function of the concentration in solution. In case of the anchor group of high flexibility a strong increase of the distribution coefficients with decreasing concentration in solution is measured. This is explained by the fact that the anchor groups located at the surface are less affected by interactions with the matrix, with the result of higher distribution coefficients. The explanation is in agreement with the sorption isotherm.

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Einfluß der Matrix auf die Komplexierung von Metallionen durch chelatbildende Ionenaustauscher

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Dedicated to Prof. Dr. G. Tölg on the occasion of this 60th birthday     

Physico-chemical Properties of the Molten CuCl–CuCl<Subscript>2</Subscript> System: Experiment,Thermodynamics and Molecular Dynamics Simulations

The molten CuCl–CuCl₂ system was studied by means of the maximum bubble pressure method, thermodynamics and molecular dynamics simulations at temperatures of 835, 866, 905 and 943 K. The equilibrium constant of CuCl₂ decomposition has been determined with thermodynamic simulation. The density and molar volume of the CuCl–CuCl₂ system were established as a function of composition. Some evidence of ideality of CuCl–CuCl₂ solutions was observed. The molar volumes of pure liquid CuCl₂ are equal to 44.64, 46.23, 46.55 and 46.81 cm³·mol^?1 at 835, 866, 905 and 943 K, correspondingly. Radial distribution functions, coordination numbers, self-diffusion coefficients and trajectories of motion were obtained by molecular dynamics simulation. For this reason a new pair potential for Cu²⁺–Cl^? pair has been designed. The coordination number of Cu²⁺ by Cl^? is about 4. This value corresponds to literature data with regards to this coordination. The self-diffusion coefficients are close to diffusion coefficients measured in molten salts solutions.     

Americium(III) sorption from multicomponent solutions by macrocyclic polyester-based sorbents

Americium sorption by crown-ether-impregnated polymeric sorbents from nitric acid solutions and multicomponent nitrate solutions that model process solutions was studied. Sorption of ballast elements by the unimpregnated Porolas-T support was studied. The sorption coefficients K _d of these elements on Porolas-T do not exceed 0.01. Sorption of the same elements by crown-ether-impregnated sorbents was also studied. Dicyclohexano-18-crown-6 (DCH18C6) and its alkyl derivatives were used. Sorption coefficients were determined for all ballast elements. At the final stage of the study, ²⁴¹Am sorption coefficients of from multi-component solutions were determined. The data obtained signify the utility of crown-ether-impregnated sorbents for recovering ²⁴¹Am from multicomponent technological solutions.     

The uptake of radioisotopes onto clays and other natural materials

The ability of natural and simulated soils to take up radioisotopes of cesium, strontium and ruthenium was examined. Uptakes were assessed by distribution coefficients measured in the presence of different concentrations of Na, Ca, Mg and HN₄ cations, and from synthetic groundwaters. Peat was included in similar studies for comparison purposes. Conclusions were drawn as to the effect of soil and ground water compositions on isotope uptake taking into account the results described in Part 1 of this series¹ which estimated the distribution coefficients for¹³⁷Cs,⁸⁹Sr and¹⁰⁶Ru (as chloride or nitrosyl) shown by illite and montmorillonite clays. These, or similar, clays were soil components in this study.     

Sorption of Cs<Superscript>+</Superscript> and Sr<Superscript>2+</Superscript> by ion exchanger based on titanium phosphate

Sorption capacity of a composite ion exchanger based on titanium phosphate for Cs⁺ and Sr²⁺ cations was studied. The effect of pH and concentration of salts and, in particular, sodium chloride in solution on the sorption efficiency and distribution coefficient was analyzed. The diffusion coefficients were calculated for the Cs⁺ and Sr²⁺ cations and the time of half-exchange of the Na⁺ cation for the Cs⁺ and Sr²⁺ cations was found.     

The gibbs energies of transfer of nicotinamide from water to water-ethanol mixtures and formation of the nicotinamide-silver(I) complex

The distribution coefficients of nicotinamide (NicNH₂) and solubility products of nicotinamide-silver perchlorate were determined by the distribution and solubility methods over a wide range of water-ethanol (EtOH) solvent compositions. The Gibbs energies of transfer of NicNH₂ and the AgNicNH ₂ ⁺ complex cation from water into water-ethanol mixtures were calculated. The influence of H₂O-EtOH solvent compositions on the stability of the nicotinamide-Ag⁺ complex was studied potentiometrically at a 0.25 ionic strength of the medium (NaClO₄) and 25.0 ± 0.1°C. The stability of complexes increased as the concentration of ethanol in mixtures grew. Reagent solvation contributions to complex formation equilibrium shifts were analyzed.     

The preparation of gold nanoparticles in triton N-42 reverse micelles after preliminary concentration from acid sulfate-chloride solutions

The distribution of Au(III) between an acid (3 mol/l HCl) aqueous phase and a micellar Triton N-42 solution in n-decane was studied as a function of the concentration of Na₂SO₄ (0–3.55 mol/l). The high distribution coefficients (200–500) allow 50-fold absolute concentration to be performed at a 90% extraction. Au⁰ nanoparticles were obtained by the injection solubilization of a reducing agent (hydrazine) into micellar extracts. At low solubilization capacities (≤1 vol %) and high reducing agent concentrations (≥0.2 mol/l) in Triton N-42 micelles, stable systems of Au⁰ nanoparticles suitable for the spectrophotometric determination of gold were obtained. At high solubilization capacities and low hydrazine concentrations, reduction was accompanied by coagulation and sedimentation processes. These processes were studied by spectrophotometry and the static and dynamic light scattering methods.