共查询到20条相似文献,搜索用时 31 毫秒
1.
D. K. Das P. N. Pathak S. Kumar V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):449-455
Sorption behavior of 241Am (~10−9 M) on naturally occurring mineral pyrite (particle size: ≤70 μm) has been studied under varying conditions of pH (2–11),
and ionic strength (0.01–1.0 M (NaClO4)). The effects of humic acid (2 mg/L), other complexing anions (1 × 10−4 M CO3
2−, SO4
2−, C2O4
2− and PO4
3−), di- and trivalent metal ions (1 × 10−3 M Mg2+, Ca2+ and Nd3+) on sorption behavior of Am3+ at a fixed ionic strength (I = 0.10 M (NaClO4)) have been studied. The sorption of 241Am on pyrite increased with pH from 2.8 (84%) to 8.1 (97%). The sorption of 241Am decreased with ionic strength at low pH values (2 ≤ pH ≤ 4), but was insensitive in the pH range of 4–10, suggesting the
formation of outer-sphere complexes on pyrite surface at lower pH, and inner-sphere complexes at higher pH values. The sorption
of 241Am increased in the presence of (i) humic acid (5 < pH < 7.5), and (ii) C2O4
2− (2 < pH < 3). By contrast, other complexing anions such as (carbonate, phosphate, and sulphate) showed negligible influence
on 241Am sorption. The presence of Mg2+, Ca2+ ions showed marginal effect on the sorption profile of 241Am; while the presence of Nd3+ ion suppressed its sorption significantly under the conditions of present study. The sorption of 241Am on pyrite decreased with increased temperature indicating an exothermic process. 相似文献
2.
Chuan-Pin Lee Yi-Lin Jan Pei-Lun Lan Yuan-Yaw Wei Shi-Ping Teng Chun-Nan Hsu 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(1):145-151
This study is focused on sorption and determination of distribution ratios (R
d) of cesium and selenium on mudrock, which is the potential host rock for waste disposal in Taiwan. Batch tests including
sorption kinetic and isotherms tests have been performed in synthetic groundwater at aerobic and anaerobic conditions which
might be found in the deep geologic environment. It is found that R
d for sorption of cesium did not have an obvious difference in both conditions with various contact time. However, R
d in anaerobic condition for sorption of selenium was greater than that in aerobic condition. Selenium is a redox sensitive
element and its solubility in reducing conditions is controlled by the formation of metallic or precipitable selenium. It
demonstrated variation of R
d with time in both conditions for Se sorption kinetic experiments was equal (10 ml/g) and indicated a part formation (10%)
of precipitable selenium (Se0, FeSe or FeSe2) in the solution. Moreover, it was not enough to form precipitable selenium completely in reducing condition as to insufficient
experimental period (2 weeks) and in the presence of Fe2+. The Freundlich and Langmuir isotherm for the concentration ranges (i.e., 10−3–10−7M) conducted in both conditions seem to be adequate to quantitatively describe the sorption of cesium and selenium, respectively. 相似文献
3.
S. M. Steinberg G. M. Kimble G. T. Schmett D. W. Emerson M. F. Turner M. Rudin 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(1):185-191
Previous studies have shown that iodine (including 129I) can be strongly retained in organic-rich surface soils and sediment and that a large fraction of soluble iodine may be
associated with dissolved humic material. Iodate (IO3−) reacts with natural organic matter (NOM) producing either hypoiodous acid (HIO) or I2 as an intermediate. This intermediate is subsequently incorporated into the organic matter. Based on reactions of model compounds,
we infer that iodine reacts with peat by aromatic substitution of hydrogen on phenolic constituents of the peat. Alternatively,
the intermediate, HIO or I2, may be reduced to iodide (I−). The pH (and temperature) dependence of the IO3− reaction (reduction) has been explored with sphagnum peat, alkali lignin, and several model compounds. The incorporation
of iodine into NOM has been verified by pyrolysis gas chromatography/mass spectrometry (GC/MS). Model compound studies indicate
that reduction of IO3− to HIO may result from reaction with hydroquinone (or semiquinone) moieties of the peat. 相似文献
4.
Enzo Curti Laure Aimoz Akira Kitamura 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):1655-1665
79Se is a major dose-determining redox-sensitive nuclide in safety analysis of radioactive waste disposal sites. In aqueous solutions, selenium forms soluble anionic species (SeIVO3 2? and SeVIO4 2?) that hardly sorb on negatively charged surfaces of common host-rock minerals. However, Se is known to have a strong affinity with sulphides and interacts with pyrite, a common minor mineral of argillaceous rocks being considered as host formations for radioactive waste repositories. In this study, we present micro- and bulk X-ray spectroscopy data (μ-XRF, μ-XANES, and EXAFS) showing that, under nearly anoxic conditions, dissolved SeO3 2? and SeO4 2? sorb directly onto the pyrite surface and are subsequently reduced to Se0 with increasing ageing time (up to 8 months). These results suggest that the mobility of 79SeIV released from radioactive waste could greatly decrease through uptake on the pyrite surface followed by transformation into a sparingly soluble reduced form. 相似文献
5.
D. S. McKinney D. L. Hesterberg 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):289-297
Iodide retention by AgCl, a potential sorbent in high-level waste (HLW) storage systems, was determined. The kinetics and
steady state sorption of iodide were determined in single and mixed electrolytes of NaNO3, and NaCl at ionic strengths of 25 and 50 mM. Iodide retention involved the conversion of AgCl to AgI. This conversion increased
rapidly within 0.02 hours, and retention maxima of 0.92 and 1.0 mol·l·mol−1 Ag occurred for low and high ionic strengths, respectively. These short-term studies indicated that AgCl would be an effective
scavenger of I− in HLW containment systems. 相似文献
6.
Š. Palágyi K. Štamberg H. Vodičková 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(3):629-636
Transport and sorption of water-soluble 85Sr2+ and 125I− in the columns with beds of crushed crystalline rocks from synthetic groundwater has been studied under dynamic flow conditions.
Samples of crystalline rocks: diorite-I, diorite-II, gabbro, granite and tonalite, having the grain size between 0.25 and
0.80 mm, were used. Plastic syringes of 8.8 cm length and 2.1 cm in diameter were applied as columns. The synthetic groundwater
was pumped downward through the columns with a seepage velocity of about 0.2 cm/min and the given radioactive nuclide was
added into the water stream individually in a form of a short pulse. In case of 85Sr, desorption from diorite-I was also studied using an artificial acid rainfall and then, the longitudinal distribution of
the residual 85Sr activity along the bed was measured. Retardation, distribution and hydrodynamic dispersion coefficients were determined
by the evaluation of respective breakthrough curves. A corrected integral form of a simple advection–dispersion equation was
derived and used for fitting the experimental data. The K
d-parameters resulting from dynamic experiments were also compared with the results of static sorption experiments. 相似文献
7.
Mamdoh R. Mahmoud Hanan H. Someda 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1391-1400
In the present study, Mg–Al layered double hydroxide intercalated with nitrate anions (LDH-NO3) was synthesized, modified with the anionic surfactant, sodium lauryl sulfate, and applied for the removal of 152+154Eu from aqueous solutions. Modification of the as-synthesized Mg–Al layered double hydroxide was carried out at surfactant
concentration of 0.01 M (the organo-LDH produced denoted LDH-NaLS). The as-synthesized and surfactant-intercalated LDHs were
characterized by FT-IR and energy-dispersive X-ray spectroscopy techniques. The effect of some variables such as solution
pH, contact time and sorbate concentration on removal of 152+154Eu was investigated. The kinetic data obtained were well fitted by the pseudo-second-order kinetic model rather than the pseudo-first-order
model. Intraparticle diffusion model showed that sorption of 152+154Eu proceed by intraparticle diffusion together with boundary layer diffusion. Experimental isotherm data were well described
by Langmuir model. Organo-LDH was found to have higher capacity (156.45 mg g−1) for europium than the as-synthesized LDH-NO3 (119.56 mg g−1). Comparing LDHs capacities obtained for Eu(III) in the present work with other sorbents reported in literature indicated
that LDHs have the highest capacities. Application of the developed process for removal of 152+154Eu(III) from radioactive process wastewaters was also studied and the obtained results revealed that these LDHs are promising
materials for treatment of radioactive wastewaters. 相似文献
8.
Theoretical study on the complexation of bambus[6]uril with the chloride, bromide, and iodide anions
Petr Toman Emanuel Makrlík Petr Vaňura 《Monatshefte für Chemie / Chemical Monthly》2011,286(1):881-884
Abstract
By using quantum mechanical DFT calculations, the most probable structures of the bambus[6]uril·Cl−, bambus[6]uril·Br−, and bambus[6]uril·I− anionic complex species were derived. In these three complexes, each of the considered univalent halide anions, included in the center of the macrocyclic cavity, is bound by 12 weak C–H⋯X− (X− = Cl−, Br−, I−) hydrogen bonds between methine hydrogen atoms on the convex face of the glycoluril units and the respective anion. The lengths of the C–H⋯X− hydrogen bonds increase in the order Cl− < Br− < I−. 相似文献9.
P. Rajec F. Macášek M. Féder P. Misaelides E. Šamajová 《Journal of Radioanalytical and Nuclear Chemistry》1998,229(1-2):49-55
The sorption of caesium and strontium from its aqueous solutions by ten clinoptilolite-and mordenite-containing sedimentary
materials from Slovakia, Bulgaria, Ukraine and Greece was investigated by batch-type procedure and radiotracer techniques.
The concentration of the solutions, that were performed in and without the presence of competing cations (0.005 mol·dm−3 KCl) varied between 1·10−4 and 5·10−2 mol·dm−3. The uptake and distribution coefficient (K
d
) values determined for the materials of the different origin, were correlated with their mineralogical composition and gross
cation exchange capacity (CEC). The identification of the specific uptake sites was attempted on the basis of the sorption
isotherms and the content of exchangeable cations. The experimental results provide information on the suitability of the
individual materials for the treatment of radioactive wastes and their application as backfills in potential nuclear waste
repositories. 相似文献
10.
O. S. Oleneva T. A. Shestimerova A. V. Olenev E. V. Dikarev A. V. Shevelkov 《Russian Chemical Bulletin》2007,56(10):1948-1952
New double mercury silver phosphide iodide Hg12Ag41P88I41 (1) was synthesized and its crystal structure was established. Compound 1 crystallizes in the cubic system. The characteristic feature of the crystal structure 1 is the presence of the anionic cage clusters P11
3−, which have been previously found in alkali metal compounds only. The well-ordered P11
3− clusters form a system of polyhedra, which encapsulate various disordered α-AgI-type fragments.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1882–1886, October, 2007. 相似文献
11.
N. K. Tunali H. N. Erten S. Kinikoğlu Ş. Gümüş 《Journal of Radioanalytical and Nuclear Chemistry》1979,49(2):225-237
The extraction of iodine and bromine under various conditions from their saturated aqueous solutions by CCl4, C6H6 and o-xylene has been studied. The data obtained from the experiments carried out at various temperatures, for H2O(I2)−CCl4 and H2O(I2)−C6H6 systems, exhibit an Arrhenius behaviour. The overall activation energy calculated for the extraction in the H2O(I2)−CCl4 system, 650±50 cal·mol−1 is lower than that of H2O(I2)−C6H6, 3600±300 cal·mol−1. The use of the solubility parameter for the interpretation of the data in the extraction of iodine is investigated. The
data obtained in multiple extractions are treated by using the analogy between extraction and radioactive decay. The half
number of extraction for each system is determined. The complex curves obtained in the H2O(I2)−CCl4 and H2O(I2) −Br2)−CCl4 systems are resolved into two components. 相似文献
12.
Adsorption of iodide ions at the Bi(111) and Cd(0001) electrodes from the aqueous solutions with constant ionic strength 0.1x M KI + 0.1(1−x) M KF and 0.1x M KI + 0.033(1−x) M K2SO4 has been studied by impedance spectroscopy. It was found that, to a first approximation, the classical Frumkin–Melik–Gaikazyan
equivalent circuit with the slow diffusion-like and adsorption steps can be applied for fitting the experimental impedance
data for iodide ions adsorption on Bi(111) and Cd(0001) from aqueous solutions with constant ionic strength. The modified
Grafov–Damaskin circuit can be used in the region of electrode potentials, where parallel faradic processes (electroreduction
of protons, oxygen traces) are probable. The more complicated Ershler equivalent circuit, taking into account the slow diffusion-like,
adsorption and charge transfer steps, is not applicable for characterization of the adsorption process of I− at Bi(111) and Cd(0001) electrodes. 相似文献
13.
Sultan Şahin Fatih Külahcı Mahmut Doğru 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):313-318
In this study, 90Sr (540 keVβ −), 129I (150 keVβ −) and the gross beta radioactivity concentrations were determined for the samples of tea as the most leading consumed hot
drink in the markets (processed and packaged for sale) in our country. Furthermore, the obtained data were statistically analyzed.
For determination of 129I (150 keVβ−), 90Sr (540 keVβ−) and gross radioactivity concentrations in tea samples, a sensor system consisting of scintillation detector with BP4 probe
sensitive to beta radiation and a radiation meter (ST7) configurable for windows at desired power was used. 相似文献
14.
Radhey M. Naik Raj K. Tiwari Pradeep K. Singh Shiv Bali S. Yadav Abhas Asthana 《Transition Metal Chemistry》2008,33(5):615-623
It is observed that Ag(I) catalyzes the rate of substitution of phenylhydrazine (PhNHNH2) into hexacyanoferrate(II), producing a cherry red colored complex, [Fe(CN)5PhNHNH2]3−. The reaction was monitored at 488 nm leading to the formation of the complex under the conditions: [Fe(CN)6]4− (5.0 × 10−3 mol dm−3), PhNHNH2 (2.0 × 10−3 mol dm−3), temperature (25 ± 0.1 °C), pH (2.8 ± 0.02), and ionic strength, I (0.02 mol dm−3), (KNO3). Under optimum conditions, absorbance at fixed times (A
t
) is linearly related to Ag(I) in the concentration range 10.79–97.08 ng cm−3, in the presence of several diverse ions. The highest percentage error and relative standard deviations in the entire range
of Ag(I) determination are found to be 2.5% and 0.16, with a detection limit of 8.75 ng cm−3 of silver(I). The experimental accuracies expressed in terms of percentage recoveries are in the range of 97.87–102.50. The
method was successfully applied for the determination of Ag(I) in a few synthetic samples and found to be in good agreement
with those obtained from atomic absorption spectrophotometry (AAS). The validity of the proposed method has also been tested
for Ag(I) determination in spiked drinking water samples. The present catalytic kinetic method (CKM) is highly sensitive,
selective, reproducible, and inexpensive. A review of recently published catalytic spectrophotometric methods for determination
of Ag(I) has also been presented for comparison. 相似文献
15.
V. V. Sharutin V. S. Senchurin O. K. Sharutina B. B. Kunkurdonova 《Russian Journal of Inorganic Chemistry》2011,56(9):1384-1389
Complexes [Me3EtN]2+[CoI4]2− (I) and [Me3EtN]2+[CoI4]2− (II) were synthesized by reacting trimethylalkylammonium iodide with cobalt(II) iodide in acetone. According to X-ray diffraction
data, complexes I and II consist of tetrahedral tetraalkylammonium cations (for I, N-C is 1.481(5)–1.590(8) CNC is 107.3(3)°–111.6(3)°; for II, N-C is 1.485(8)–1.506(10) ? and CNC is 106.9(7)°–111.7(5)°) and [CoI4]2− anions (for I, Co-I is 2.5951(5)–2.6127(5) ? and ICoI is 104.67(2)°–113.23(2)°; for II, Co-I is 2.5914(8)–2.5943(9) ? and ICoI is 107.05(2)°–114.42(5)°). 相似文献
16.
Sorption and desorption of radioiodine and radioselenium on calcareous soil and its solid components
Wang Xiangke Dong Wenming Yao Jie Tao Zuyi 《Journal of Radioanalytical and Nuclear Chemistry》1999,242(3):815-820
This paper is an extension of previous papers1–3. The breakthrough curves and the displacement curves of125I− and75SeO3 on the calcareous soil, the treated soil to remove CaCO3 and the treated soil to remove organic matter were determined at pH 7.8, at 20°C and in the presence of 1·10−3 or 1·10−4 mol/l CaCl2. These results from column experiments and from batch experiments in the previous papers1,2 were mutually complementary. It can be definitely concluded that iodide is retained to a very small degree and tetravalent-selenium
is retained to a small degree by calcareous soil and that organic matter in calcareous soil acts as a significant trap of
iodide and CaCO3 acts as a trap of tetravalent selenium. Iodide and tetravalent-selenium would be expected to have relatively high dissemination
in calcareous soil. 相似文献
17.
N. A. Udalova S. I. Karpov V. F. Selemenev I. A. Sharmar 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(6):1006-1011
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. 相似文献
18.
Photoelectrochemical corrosion of n-type α-PbO electrodes in aqueous Fe(CN)6
3−/4− and I−/I3
− electrolytes using the rotating ring-disk electrode technique has been investigated. The α-PbO thin film is found to be more
stable in I−/I3
− (48%) than in Fe(CN)6
3−/4− electrolyte (10%). Preferential adsorption of iodide ions decreases the photocorrosion reaction of holes with α-PbO. Addition
of CsI (0.4 mM) to the I−/I3
− electrolyte decreases the photocorrosion from 48% to less than 10%. Cs+ ions perhaps nullify the effect of negatively charged surface states of α-PbO, thus minimizing the trapping of holes at the
surface of α-PbO and hence decrease the possibility of photocorrosion of lead oxide with holes.
Received: 30 June 1998 / Accepted: 20 April 1999 相似文献
19.
As part of a mass spectrometric investigation of the binding properties of sulfonamide anion receptors, an atmospheric pressure
chemical ionization mass spectrometric (APCI-MS) method involving direct infusion followed by thermal desorption was employed
for identification of anionic supramolecular complexes in dichloromethane (CH2Cl2). Specifically, the dansylamide derivative of tris(2-aminoethyl)amine (tren) (1), the chiral 1,3-benzenesulfonamide derivatives of (1R,2S)-(+)-cis-1-amino-2-indanol (2), and (R)-(+)-bornylamine, (3), were shown to bind halide and nitrate ions in the presence of (n−Bu)4N+X− (X− = Cl−, NO3−, Br−, I−). Solutions of receptors and anions in CH2Cl2 were combined to form the anionic supramolecular complexes, which were subsequently introduced into the mass spectrometer
via direct infusion followed by thermal desorption. The anionic supramolecular complexes [M+X]−, (M=1–3, X−=Cl−, NO3−, Br−, I−) were observed in negative mode APCI-MS along with the deprotonated receptors [M−H]−. Full ionization energy of the APCI corona pin (4.5 kV) was necessary for obtaining mass spectra with the best signal-to-noise
ratios. 相似文献
20.