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1.
The ability of the back-fill and the host rock materials to take up radioisotopes like 241Am, 85,89Sr and 137Cs has been examined as a function of contact time, pH, amount of sorbent, sorbate concentration, and the presence of complementary cations. A batch technique using actual borehole water from the granite formation has been utilized. In general, the uptake of nuclides by bentonite is much higher than that with granite. The sorption order of nuclides on bentonite is Am>Cs>Sr. The presence of complementary cations, Na+, K+, Ca2+ and Mg2+ depresses the sorption of Cs and Sr on bentonite. The sorption data have been interpreted in terms of Freundlich and Langmuir isotherm equations. Utilizing the Langmuir isotherm equation, the monolayer capacity, V
m
,and the binding constant, K, have been evaluated. The change in free energy for the sorption of nuclides on bentonite has also been calculated. 相似文献
2.
Saad Ali Khan 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(1):3-6
The sorption of long-lived radionuclides of cesium, strontium and cobalt (134Cs, 85Sr and 60Co) on bentonite under various experimental conditions, such as contact time, pH, sorbent and sorbate concentrations have been studied. The uptake of Cs and Sr was rapid and equilibrium was reached almost instantaneously in both the cases, while Co sorption was time dependent. The sorption of these nuclides increased by increasing pH. The uptake of Cs, Sr and Co increased with increasing the amount of the bentonite clay. The percentage sorption for Cs, Sr and Co decreased with increasing metal concentrations. The desorption studies with 0.01M CaCl2 and ground water at low-metal loadings on bentonite showed that about 95% of Cs, 85-90% of Sr and 97% of Co were irreversibly sorbed. These results could be helpful for nuclear waste management, for waste water effluents containing low concentrations of cesium, strontium and cobalt. 相似文献
3.
Distribution coefficients Kd for the sorption of Cs and Sr on mixtures of a clay mineral (Ca-saturated bentonite) and humic material (Ca-humate) have been measured and were compared with calculated values obtained from the Kd-values observed for the pure components. The concentration of Sr and Cs in the solution was varied between 1·10–6 and 0.01N and the distribution of the elements determined by using radioactive tracers. All experiments were carried out in pure water as well as in the presence of a supporting electrolyte (0.01N CaCl2). It was found that the differences between the observed and calculated Kd-values were, if present, always negative if Cs was sorbed, and positive if Sr was sorbed. 相似文献
4.
F. Macášek Ibrahim S. Shaban L. Mátel 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(3):627-636
The effect of Aldrich humic acid (HA) on the mobility of137Cs,85Sr,152Eu and239Pu radionuclides was studied in Ca-montmorillonite suspensions. Verified 2-sites-2-species (2s2s) models correspond to an
intensive interaction of all elements with humificated surface, what is in a remarkable contrast with the weak complexation
of cesium and even strontium in solutions — the neutral ligand interaction constants β (l/mol) are log β<−9.9 and 7.56±0.21
for Cs and Sr, respectively. The result for europium complexation in solution, log β=12.49±0.18 is in a good agreement with
literature data. For plutonium(IV) not only a high proton competitive constant in solution was obtained, log β β=(−0.67±0.32)+3pH,
but also a strong chemisorption, which at high concentrations of humic acid (above 0.05 g/l) indicates the formation of bridge
humate complexes of plutonium on the humificated surface. Logarithms of heterogeneous interaction constants (
24 l/g) of the elements with surface humic acid are 4.47±0.23, 4.39±0.08, and 6.40±0.33 for Cs, Sr, and Eu(III), respectively,
and the logarithm of the proton competitive constant (
24, l/g) for Pu(IV) −3.80±0.72. Distribution coefficients of humic acid and metal humates between 0.01 g HA/l solution and montmorillonite
were derived as logK
d(AH)=−1.04±0.11, logK
d(EuA)=1.56±0.11 and logK
d(PuA)=2.25±0.04, while the values for Cs and Sr were obtained with very high uncertainty. Speciation of the elements on montmorillonite
surface is illustrated as a function of equilibrium concentration of humic acid in solution and of pH. 相似文献
5.
Hwan-Seo Park In-Tae Kim Hwan-Young Kim Seung-Kon Ryu Joon-Hyung Kim 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(3):617-626
Summary Amorphous zirconium phosphate (Zr(HPO4)2.nH2O, AM-ZP) has been investigated as a material for selective removal of Cs or Sr from molten salt waste at aqueous state and
its ceramic waste form. NZP (MZr2P3O12, M=Li, Na, Cs, and Sr), was synthesized by three methods and evaluated their durability by the Product Consistency Test (PCT)
method. AM-ZP has a high selectivity on Cs and Sr even in the presence of Li with high concentration. From the leaching data,
the leached fractions (LF∞) of each product at a given time in infinite leachate volume can be calculated by a semi-empirical equation. The LF∞ of Li, Na, Cs and Sr on the product prepared by composition-adjusting process were 0.143, 0.078, 0.017, and 0.034, respectively.
It can be concluded that AM-ZP is an effective material for selective removal of radionuclides from molten salt waste and
its metal-loaded ZP can be changed into a durable waste form close to NZP structure by a composition-adjusting process. 相似文献
6.
The composition of nickel hexacyanoferrate(II) complexes depends on the ratios of sodium hexacyanoferrate(II) and nickel nitrate solutions mixed. The adsorption behavior of nickel hexacyanoferrate(II) is described; acid treatment of Ni2Fe(CN)6 accelerates the adsorption rate of cesium, but does not increase the adsorption capacity. The Ni—Cs exchange ratios of Ni2Fe(CN)6 are discussed. In concentrated salt solutions, the distribution coefficients of 59Fe, 60Co, 65Zn. 137Cs, 95Zr and 144Ce are determined together with those of 85Sr and 106Ru. A simple determination of 137Cs in sea water containing 59Fe, 60Co, 65Zn, 95Zr, 144Ce, 85Sr and 106Ru is described. 相似文献
7.
Synthetic Cs(VO2)3(TeO3)2 is built up from infinite sheets of distorted octahedral VVO6 groups, sharing vertices. These octahedral layers are “capped” by Te atoms (as parts of pyramidal [TeIVO3]2– groups) on both faces of each V/O sheet, with inter‐layer, 12‐coordinate, Cs+ cations providing charge compensation. Cs(VO2)3(TeO3)2 is isostructural with M(VO2)3(SeO3)2 (M = NH4, K). Crystal data: Cs(VO2)3(TeO3)2, Mr = 732.93, hexagonal, space group P63 (No. 173), a = 7.2351(9) Å, c = 11.584(2) Å, V = 525.1(2) Å3, Z = 2, R(F) = 0.030, wR(F 2) = 0.063. 相似文献
8.
The Reaction of Cyanide Ions with Trimethylgallium. The Crystal Structures of [Cs{CN(GaMe3)2}]n (1) and [Cs(toluene)2{CN(GaMe3)2}]n (2) CsCN reacts with GaMe3 in the molar ratio of 1 : 2 in the absence of additional solvent to the metalate [Cs{CN(GaMe3)2}] ( 1 ). 1 can be recrystallized from MeCN/toluene, forming [Cs(toluene)2{CN(GaMe3)2}] ( 2 ). If CsCN is treated with one equivalent GaMe3 in Et2O at 20 °C, the metalate [Cs(NCGaMe3)] can be isolated. 1 – 3 were characterized by NMR, IR, and MS techniques. In addition, X-ray structure analyses of 1 and 2 were prepared. According to the structural characterization 1 consists of a helix of Cs+ ions and side-on coordinated anions [Me3GaCNGaMe3]–, running along [010]. π-Electron-Cs+ contacts between Cs cations and toluene molecules are dominating the structure of 2 . The residual equatorial positions at the [Cs(toluene)2]+ sandwich-ion are occupied by Cs+-hydrogen(methyl) interactions. A three-dimensional network is the result of the contacts between cations and anions. 相似文献
9.
Saad Ali Khan Riaz-Ur-Reman M. Ali Khan 《Journal of Radioanalytical and Nuclear Chemistry》1995,190(1):81-96
The sorption of Cs(I), Sr(II) and Co(II) from aqueous solutions on alumina under various experimental conditions has been studied by batch techniques. Freundlich, Langmuir and Dubnin-Raduskevich equations have been used to interpret the sorption data. The values of various thermodynamic parameters have been determined. The sorption of Cs(I) and Sr(II) on alumina is exothermic in nature while that of Co(II) is an endothermic process. The H
o values for Cs(I), Sr(II) and Co(II) were–23.29 KJ/mol at 298K,–35.3 KJ/mol at 293 K and 13.49 KJ/mol at 293 K, respectively. Negative values of G
o show the spontaneity of the sorption processes; G
o values of Cs(I) and Sr(II) becomes less negative at higher temperatures while the G
o values of Co(II) become more negative with increasing temperature. At higher temperatures, less amounts of Cs(I) and Sr(II) and greater amounts of Co(II) are sorbed on alumina. The values of the mean free energies of sorption,E, for Sr(II) and Co(II) at various temperatures were within the range of 7–10 KJ/mol which show that these metals are sorbed on alumina predominantly by an ion-exchange process. 相似文献
10.
A. Zhang Y.-Z. Wei M. Kumagai T. Koyama 《Journal of Radioanalytical and Nuclear Chemistry》2004,262(3):739-744
A new type of silica-based chelating extraction resin, DtBuCH18C6/SiO2-P, was prepared by impregnating a crown ether derivative, 4,4,(5)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6), into the porous silica/polymer composite particles (SiO2-P). The adsorption of Sr(II) and some other fission product elements was investigated by a batch adsorption experiment in HNO3 medium. It was found that Sr(II) exhibits a strong adsorption onto the extraction resin, while the other fission product elements show almost no or only weak adsorption. The adsorption kinetics of Sr(II) was explained by assuming as the rate-controlling step the complex-formation reaction between Sr(II) and DtBuCH18C6 contained in the extraction resin. The rate equation of Sr(II) adsorption was determined as:-d[Sr(II)]/dt = k[Sr(II)][DtBuCH18C6][NO3
–]0.5. 相似文献
11.
Regularities of formation of nanocrystalline iron(III) oxides and oxyhydroxides via oxidation of iron(II) compounds in an
alkaline pH range (pH ≥ 12) were studied using pH and E
h
measurements, chemical analysis, electron microscopy, and X-ray diffraction. When the molar ratio [OH−]/[FeII] ∼ 2 (pH ∼ 12–12.5), the oxidation process yields cube-shaped magnetite Fe3O4 particles. An excess of an alkaline agent with an overstoichiometric concentration equal to or higher than 0.5 mol/L (pH
≥ 13.5) induces the formation of anisotropic particles of nanocrystalline goethite α-FeOOH over the entire range of the synthesis
parameters studied. Reaction products (Fe3O4 and/or α-FeOOH) are formed immediately as the initial Fe(OH)2 starts oxidizing by the dissolution-oxidation-precipitation mechanism near the surface of Fe(OH)2 precursor particles. Carbonate ions considerably change the structure and shape of newly formed α-FeOOH particles. 相似文献
12.
A new Cs(I) magnetic ion-imprinted polymer (Cs(I)-MIIP) aimed at the selective adsorption and separation of Cs(I) from salt lake brine was prepared. The Fe3O4@SiO2 was used as supporter, Cs(I) as template ion, and carboxymethyl chitosan as functional monomer. The product was characterized by Fourier transform infrared spectra, XRD, energy-dispersive spectrometry, scanning electron microcopy, thermogravimetric analysis, and vibrating sample magnetometer. The adsorption of the Cs(I)-MIIP in solution was investigated, which indicated the maximum adsorption capacity was 36.15?mg·g?1 under the optimum conditions. The pseudo-first-order kinetic model and the Freundlich isotherm model were applied to predict the adsorption process of Cs(I) onto Cs(I)-MIIP. Selectivity experiments showed that the relative selectivity coefficient (k′) were 24.995, 1.73, 1.43, 4.83, and 1.63 to Cs(I)/Li(I), Cs(I)/Na(I), Cs(I)/K(I), Cs(I)/Rb(I), and Cs(I)/Sr(II) binary solutions, higher than those of NIP, respectively. Furthermore, the Cs(I)-MIIP was successfully applied to the enrichment and separation of Cs(I) from the salt lake brine of Qinghai, with satisfactory Cs(I) recovery rates. 相似文献
13.
Hubert Gnaser 《Surface and interface analysis : SIA》2008,40(10):1367-1373
The incorporation of Cs atoms in silicon was investigated by dynamic computer simulations using the Monte‐Carlo code T‐DYN that takes into account the gradual change of the target composition due to the Cs irradiation. The implantation of Cs atoms at normal incidence was studied for four energies (0.2, 0.5, 1, and 3 keV) and three different Cs surface‐binding energies UCs (0.4, 0.8, and 2.4 eV). The total implantation fluences were 2 × 1017 Cs cm?2 for 0.2 keV, 1.5 × 1017 Cs cm?2 for 0.5 keV, and 1 × 1017 Cs cm?2 for 1 and 3 keV. At these values, a stationary state has been reached. The steady‐state Cs‐surface concentrations exhibit a pronounced dependence both on impact energy and UCs, varying between ~1 (at 0.2 keV and UCs = 2.4 eV) and ~0.13 (3 keV and UCs = 0.4 eV). Under equilibrium, the partial sputtering yield of Si, YSi, experiences little influence of UCs, but varies with the Cs energy: at UCs = 0.8 eV from 0.09 to 1.0 Si atoms/Cs projectile. For all irradiation conditions a strongly preferential sputtering of Cs atoms as compared to Si atoms is found, increasing from 1.8 (at 3 keV and UCs = 2.4 eV) to 13.3 (at 0.2 keV and UCs = 0.4 eV). Preferential sputtering of Cs increases with decreasing irradiation energy and decreasing UCs. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
14.
《Journal of Inorganic and Nuclear Chemistry》1981,43(9):1967-1975
The immobilization reactions of Cs, Sr, U and Mo from spent fuel elements (SFE) in the presence of basalts and basalt phases were investigated under hydrothermal, closed-system conditions. The exact Cs and Sr phases in SFE are not known with certainty, but Cs2MoO4, CsI, Cs2O, β-Cs2U2O7 and SrZrO3 are some of the predicted possibilities. These phases were mixed with basalts and basalt phases along with water, sealed in gold capsules and reacted at 100, 200 and 300°C under a confining pressure of 300 bars. The Cs and Sr concentrations of the product solutions were measured to determine the partitioning of these elements between the liquid and solid phases. Results varied substantially, depending on the particular basalt or basalt phase or Cs phase, the temperature and the duration of run. For example, a Deep Drill Hole (DDH-3) basalt-Cs2MoO4 reactions resulted in 15, 78 and 99% fixation of added Cs at 100, 200 and 300°C respectively. Fixation of up to 99.7 and 99.8% of the added Cs and Sr respectively were observed in some cases. X-Ray diffraction (XRD) analysis of the solid products revealed that Cs was immobilized by the formation of pollucite, (Cs, Na)AlSi2O6 in most cases and the formation of CsAlSiO4 in some cases. The interactions of basalts and basalt phases with Cs2MoO4 also resulted in the immobilization of Mo by the formation of powellite, CaMoO4 because Ca is available in the reaction mixtures. The U6+ in β-Cs2U2O7 was reduced to form uraninite, UO2 by the divalent iron component of basalts. The exact nature of Sr reaction with basalts is not clear because no new Sr phases could be detected by XRD. The reaction products, pollucite, CsAlSiO4, powellite and uraninite from SFE-basalt interactions serve to immobilize Cs, Mo and U because Cs in pollucite and CsAlSiO4 is difficult to exchange and Mo and U in powellite and uraninite are quite insoluble. 相似文献
15.
The phase diagrams of ACl/MoCl3 (A=Na, K, Rb, Cs) were elucidated by DTA measurements in sealed quartz ampoules in the range of 0–40 mol% MoCl3. The samples were prepared from alkali metal chlorides and the compounds A3MoCl6 or A3Mo2Cl9. The 31 compounds withA=Na, Rb, Cs were obtained by sintering mixtures of 3ACl+MoCl3; the enneachlorides A3Mo2Cl9 withA=K, Rb, Cs were precipitated from solutions of MoCl3·3H2O and ACl in formic acid. Congruently melting compounds A3MoCl6 exist in all four systems, incongruently melting enneachlorides A3Mo2Cl9 in systems withA=K, Rb, Cs. Still unknown structures were determined by analog-indexing powder patterns according to known structure families. Especially Cs3MoCl6 is isotypic with the recently found Cs3CrCl6 structure. Additionally, the unit cell parameters were determined for the compounds A3MoCl5·H2O (A=K, Rb, Cs) analogous to Cs2TiCl5·H2O, whose structure was determined by single crystal measurements.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthday 相似文献
16.
Babushkina T. A. Kovaleva E. V. Klimova T. P. Zemnukhova L. A. Krainova N. Yu. 《Russian Journal of Coordination Chemistry》2004,30(8):555-558
Aqueous solutions of bismuth(III) nitrilotriacetates BiNta · 2H2O and M3Bi(Nta)2 ·nH2O (M = Na, K, Rb, Cs, NH4, CN3H6, n = 0–4) and the K[Bi(Edta)(Tu)2] complex (Edta4– is the anion of ethylenediaminetetraacetic acid, Tu is thiocarbamide) are studied by the 1H NMR method at room temperature in the pH interval from 2 to 11. The formation of two types of bismuth nitrilotriacetate complexes in solutions is established. They are characterized by the presence (type 1) or absence (type 2) of the Bi–N bond. Their ratio, depending on the composition and pH of the solution, is determined. The K[Bi(Edta)(Tu)2] compound in solutions occurs as one form. The pH values at which the substance begins to decompose are determined for each compound. 相似文献
17.
S. Chitra S. Viswanathan S. V. S. Rao P. K. Sinha 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):955-960
Crystalline silicotitanate inorganic ion exchanger, with a sitinakite structure is candidate material for remediation of aqueous
nuclear waste streams. The syntheses of crystalline silicotitanate (CST) and Nb-substituted crystalline silcotitanate (Nb-CST)
were carried out under hydrothermal conditions and the products were characterized using techniques viz., XRD, SEM/EDS, DTA/TGA,
surface area respectively. Batch experiments were carried out to study the kinetics of uptake of 137Cs and 90Sr, to estimate the decontamination factor (DF) values and distribution coefficients (K
d) for the above synthesized CST and Nb-CST samples from actual radioactive waste solutions. The DF values for uptake of Cs
and Sr by Nb-CST after 24 h of equilibration was 355 and 136 whereas for CST it was found to be 40 and 176 respectively. The
K
d values for uptake of Cs and Sr for Nb-CST after 24 h of equilibration was found to be 35,490 and 13,500 mL/g respectively
whereas the K
d values for uptake of Cs and Sr for CST was found to be 4,025 and 17,525 mL/g respectively. The ion exchange capacity of Nb-CST
towards 90Sr and 137Cs was estimated to be 11.8 and 3.2 meq/g respectively whereas the ion exchange capacity of CST towards 90Sr and 137Cs was estimated to be 14.6 and 4.4 meq/g respectively. 相似文献
18.
P. Jurček V. Jedináková-Křížová P. Ivanová 《Journal of Radioanalytical and Nuclear Chemistry》1996,208(2):519-527
Retardation mechanisms of134Cs and85Sr have been investigated. Batch determination of distribution coefficientK
d
have been carried out for various values of factors affecting retardation such as solid-liquid ratio, particle size, composition of solid phase. Various types of bentonites and mixtures of bentonites with sand have been also studied. 相似文献
19.
Nagornyi O. V. Kolyshkin A. S. Vol'khin V. V. 《Russian Journal of Applied Chemistry》2003,76(8):1238-1241
Fe(CN)6
3
- and Fe(CN)6
4
- anions are sorbed from aqueous solutions of their potassium and cesium salts on -Ni(OH)2 by the mechanism of anion exchange with hydroxy groups. Alkali metal cations (K+, Cs+) are also partly sorbed on nickel(II) hydroxide in the form of anionic complexes (K,Cs)
z
Fe(CN)6
(n - z)-, where n = 3 or 4 (0 < z < n). The chemical composition of the new phase appearing in contact of nickel(II) hydroxide with aqueous potassium and cesium hexacyanoferrates(II, III) was determined by X-ray phase analysis and IR spectroscopy. 相似文献
20.
S. S. Yarovoi Yu. V. Mironov S. V. Tkachev V. E. Fedorov 《Russian Journal of Inorganic Chemistry》2009,54(2):299-304
Phase formation in the Re-Se-Br-MBr systems (M = K, Rb, Cs) was studied by NMR spectroscopy and powder X-ray diffraction.
The reactions taking place in alkali metal halide melts were found to give, among the series of cluster anions [{Re6Se8 − n
Br
n
}Br6](4 − n)− (0 ≤ n≤ 4), polymeric complexes Re6Se8Br 2 and M2Re6Se8Br4 (M = Cs, Rb) and salts containing cluster anions [Re6Se6Br8]2− and [Re6Se7Br7]3− as the major products. The effect of the alkali metal cation on the product composition and ratio was established.
Original Russian Text ? S.S. Yarovoi, Yu.V. Mironov, S.V. Tkachev, V.E. Fyodorov, 2009, published in Zhurnal Neorganicheskoi
Khimii, 2009, Vol. 54, No. 2, pp. 344–349. 相似文献