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1.
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
2.
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
3.
Sorption is often quantified by a distribution coefficient, K
d
, which is the equilibrium ratio between species sorbed to the rock and species in solution. Traditionally K
d
-values are determined in batch experiments from equilibrium concentrations. 相似文献
4.
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
5.
Summary The sorption of Cs(I) and Sr(II) on bentonite and magnetite was experimentally studied and numerically simulated using surface
complexation (SCM) and ion-exchange (IExM) models. The empirical system consisted of: (1) synthetic granitic water with a
given ionic strength (0.1 or 0.01 NaNO3), (2) radionuclides studied (10-6M CsCl or SrCl2 . 6H2O spiked with 137Cs or 85Sr), and (3) bentonite pre-treated with the aim to remove carbonates, and magnetite as a representative of steel canister
corrosion products. The parametric study covered, e.g., the influence of pH, bentonite to magnetite ratio and volume-liquid
ratio on the values of selectivity coefficients and Kd. 相似文献
6.
《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):787-791
A sorption ability of titanium silicates (TiSi) and iron oxides towards Cs, Sr, Pu and Am was tested using the laboratory
batch method. The obtained results are expressed as distribution coefficients (Kd). TiSi synthesised using TiOSO4 revealed better sorption ability towards all studied radionuclides in comparison with TiSi produced on the basis of TiCl4. The Kd values ranged from 3.9 × 102 to 1.6 × 105 mL g−1 for Sr, from 6 to 4.1 × 104 mL g−1 for Cs, from 2.2 × 102 to 2.6 × 105 mL g−1 for Pu and from 50 to 1.6 × 104 mL g−1 for Am. The highest Pu Kd values (9 × 103–6.2 × 104 mL g−1) and better kinetics were found for iron oxides. 相似文献
7.
Radiotracer batch ion‐exchange experiments were employed to investigate the uptake of 90Sr and 137Cs radioisotopes by various cation‐exchanged forms of a 30% cross‐linked macroporous 1‐vinyl‐2‐pyrrolidone–divinylbenzene cation‐exchange resin with 1.37 ml g?1 pore volume, 0.0232 µm pore diameter and 271.2 m2 g?1 surface area. The uptake of 90Sr and 137Cs was determined by taking liquid aliquots at various time intervals from solutions over solids. The volume‐to‐solid ratio was kept at 200. The results of kinetic experiments for the carrier‐free 90Sr and 137Cs were evident in all cationic forms of the resin. The percentage uptake and distribution coefficient Kd values with carrier (0.005 M SrCl2 and 0.01 M CsCl) concentrations were also determined, and the best results were obtained from the Li+ and H+ forms of the resin. Cerenkov counting (β?‐counting) was used to observe the initial and final radioactivity in the liquid phase. All the experiments were carried out at room temperature and the radioactivity in each case was corrected for the background counts. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
8.
The radionuclides54Mn,60Co,90Sr,95Nb,95Zr,103Ru,106Ru,125Sb,131I,134Cs,137Cs,140Ba,144Ce,226Ra and228Ac have been studied in the Sava River environment since the Chernobyl accident in 1986. The measured periphyton concentration ratios (CR) for each radionuclide were correlated with the measured sediment distribution coefficients (Kd) for that radionuclide. The Kd-CR relationships obtained were defined by the equation ln Kd=–0.5 ln CR +7.4. These Kd-CR relationships were assumed to be referable to the Sava River ecosystem and were used to predict the missing soil Kd values and/or the missing CR values for the wide range of radionuclides, respectively. Moreover, the Kd-CR relationship characteristic for the Sava River ecosystem was compared with the Kd-CR relationship proposed by Baes1 and by Shepard2. The characterization of the partition coefficients in the Sava River environment and understanding of the mechanisms affecting radionuclide retardation and bioaccumulation are required for the planning of radioactive waste depositories in the area. 相似文献
9.
U. K. Thakur Poonam Verma D. J. Shah R. M. Sawant B. S. Tomar 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(1):121-124
A method based on ion-chromatography has been developed for determination of Cs and Sr in high level waste (HLW) without matrix separation. The acidity of HLW (3 M HNO3) was decreased to 0.01 M by addition of NaOH. Chromatographic separation of Cs+ and Sr++ in presence of bulk Na+ has achieved using methane sulphonic acid as mobile phase in isocratic and gradient mode. The calibration plot was linear for the concentration range of 0.5–12 mg/L for Cs and 0.025–6 mg/L for Sr with regression coefficients close to 1. RSD obtained for Cs and Sr was 1 and 5 % respectively. Detection limit calculated as 3(S/N) was found to be 20 μg/L for Cs and 30 μg/L for Sr. The standard addition procedure was used to validate the developed method. The samples received from PREFRE, Tarapur and WIP, BARC were analyzed by the new method and the results are presented. 相似文献
10.
Chuan-Pin Lee Y. Y. Wei S. C. Tsai S. P. Teng C. N. Hsu 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(3):761-768
In this study, the diffusion behavior of cesium and selenium with 10−4M concentration in mudrock was studied by trough-diffusion tests and summarized in order to provide confidence on long-term
performance assessment of nuclear waste repositories. The diffusion process of Cs and Se reached equilibrium after 60 and
500 days, respectively. Besides, it also displays that the distribution coefficients (K
d
) of Se in through-diffusion tests is higher than that of Cs in agreement with that obtained from the batch method. The K
d
value (15.14±1.99 mL/g) of Cs by diffusion techniques is equivalent to that of batch method (15.10±0.40 mL/g) because sorption
of Cs was assumed to fast sorption step. However, the K
d
value of Se (137.58±12.20 mL/g) derived from the diffusion technique is higher than that from batch tests (76.72±2.96) and
showed an obvious variation with K
d
of Cs. The difference of K
d
between diffusion and batch methods resulted from the fact that 14 days were not long enough to reach equilibrium or stable
state in the batch method. 相似文献
11.
M. H. Baik S. S. Kim J. K. Lee S. Y. Lee G. Y. Kim S. T. Yun 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):337-345
Sorption experiments for radionuclides such as 14C, 99Tc, 137Cs, 90Sr, 63Ni, and 241Am were conducted using two different groundwaters (GM-1 and SS-5) and solid materials (granodiorite and fracture-filling
material) sampled from the Wolsong low- and intermediate-level radioactive waste (LILW) repository, Gyeongju, Korea. The distribution
coefficients of the radionuclides, K
d’s, were obtained and their sorption properties were discussed for each radionuclide. For all sorbing radionuclides, the K
d values for the fracture-filling material were observed to be higher than those for granodiorite regardless of the groundwater.
The K
d values were increased in the sequence 99Tc < 14C < 90Sr < 137Cs < 63Ni < 241Am regardless of sorbent types implying that the sorption of radionuclides onto geological media is affected by their chemical
behavior in accordance with geochemical environments. Anionic radionuclides such as 14C and 99Tc showed very low K
d values both for the granodiorite and fracture-filling material. The mineralogical composition of the geological media and
groundwater conditions was also observed to be important in the sorption of sorbing radionuclides, especially in the case
of strongly sorbing radionuclides. 相似文献
12.
A. Dyer N. U. James N. J. Terrill 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(2):589-592
Pillared clays were characterised by thermal analysis and small-angle X-ray scattering. They were then examined for their
ability to take up137Cs and90Sr/90Y isotopes as a function of concentration and competing cations (Na+, K+, NH4
+, Ca2+, Mg2+) in the concentration range 10−1 to 10−4 M. The radioisotope uptakes were quantified byK
d
(ml/g) measurements. 相似文献
13.
P. Jurček V. Jedináková-Křižová 《Journal of Radioanalytical and Nuclear Chemistry》1998,229(1-2):57-60
Sorption and diffusion processes with134Cs and85Sr in natural bentonites have been investigated. The distribution coefficients (K
d
) have been determined by a batch method. Various factors affecting theK
d
value as water-to-bentonite ratio, concentration of the competitive cations in the aqueous phase or bentonite-to-sand ratio
in the mixed sorbents have been evaluated. A comparison of the sorption and diffusion data has been made. 相似文献
14.
Chuan-Pin Lee Shih-Chin Tsai Yuan-Yaw Wei Shi-Ping Teng Chun-Nan Hsu 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(1):115-119
This study focused on sorption mechanism of Cs and Se in mudrock by batch techniques. Batch kinetics tests have been conducted
with carriers 10−
4M CsCl and SeO2 by using individual and coupling radiotracers of 137Cs and 75Se. The distribution coefficients (K
d
) of Cs in synthetic groundwater (GW) and seawater (SW) showed that there is no interference between individual and coupling
value (13 and 6 ml/g). Moreover, individual and coupling K
d
) (80 and 40 ml/g) of Se in GW and SW are in agreement with Cs. It is quite clear that the sorption mechanisms of Cs and Se
on mudrock are independent and different by using radiotracer’s technique. 相似文献
15.
S. Chitra R. Sudha S. Kalavathi A. G. S. Mani S. V. S. Rao P. K. Sinha 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):607-613
Crystalline silicotitanate inorganic ion exchanger, with a sitinakite structure is a candidate material for remediation of aqueous nuclear waste streams. Niobium substituted crystalline silicotitanates (Nb-CST) with varying concentrations of Nb (2, 4, 8, 12 and 24 mmol) and with constant concentrations of Ti-12 mmol, Si-16 mmol, Na-165 mmol were prepared hydrothermally 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 Cs137 and Sr90, to estimate the decontamination factor (DF) values and distribution coefficients (K d) for the above synthesized Nb-CST samples from actual radioactive waste solutions. The DF values for uptake of Cs and Sr by Nb-CST for the optimized Nb-concentration of 4 mmol after 24 h of equilibration was 355 and 136 respectively. The K d values for uptake of Cs and Sr for Nb-CST (Nb-4 mmol) after 24 h of equilibration was found to be 35,490 and 13,500 ml/g respectively. The ion exchange capacity of Nb-CST (Nb-4 mmol) towards Sr 90 and Cs137 was estimated to be 11.8 and 3.2 meq/g respectively. 相似文献
16.
The distribution coefficients Kd for the sorption of95mTc by peat as well as the corresponding rates of sorption and desorption were determined as a function of the concentration of the supporting electrolyte (CaCl2), the amount of dissolved oxygen and the pH of the solution. The results show that the Kd-values of Tc (added as Tc(VII)-pertechnetate) increase, if the concentration of CaCl2 or the amount of dissolved oxygen is decreased. The sorption was reversible with respect to the replacement of Tc by a CaCl2 solution. The half-times for the rates of sorption and desorption depend on the concentration of CaCl2 and dissolved oxygen and were in the range of 20–60 minutes and 500–900 minutes for the sorption and desorption processes, respectively. 相似文献
17.
Removal of some radionuclides from contaminated solution using natural clay: bentonite 总被引:1,自引:0,他引:1
A. F. Seliman Y. F. Lasheen M. A. E. Youssief M. M. Abo-Aly F. A. Shehata 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(3):969-979
Clays and specially bentonite are widely used as natural adsorbents for wastewater treatment and as a barrier in landfills to prevent the contamination of subsoil and groundwater by leachates containing radioactive materials. The adsorption of four radionuclides, 134Cs(I), 90Sr(II), 133Ba(II) and 152Eu(III) by an Egyptian bentonite (Bent) and its modified Na+ form (Na-Bent) collected from a deposit within Alexandria governorate was investigated as a function of different parameters. The batch equilibrium technique was used and the kinetic results showed that the equilibrium was mostly reached within 10 min and the kinetic data fit well to the pseudo-second order model. The Langmuir model fits well the experimental data of all metals adsorption on Bent and Na-Bent except for adsorption of 133Ba on Bent, while 152Eu adsorption on Na-Bent fits better to the Freundlich model rather than to the Langmuir. Both Bent and Na-Bent fit well to the D-R model with adsorption energy of E > 8 kJ mol?1 that means that the adsorption reaction is expected to be controlled by both cation exchange and surface complexation reactions. At lower concentrations, the values of distribution coefficient (K d), follow the order of 152Eu > 90Sr > 134Cs > 133Ba for Bent and Na-Bent. The K d of 152Eu is higher than that of 134Cs in Bent up to 150 mg L?1. This order changes at higher concentration where the K d of 134Cs becomes higher than 152Eu after 150 mg L?1 for Bent and after 200 mg L?1 for Na-Bent. Na-Bent is preferred than Bent for the uptake of 90Sr and 134Cs especially at high concentration. 相似文献
18.
J. Rais P. Selucký V. Jiråsek F. Šebesta 《Journal of Radioanalytical and Nuclear Chemistry》1977,35(2):351-359
New type of sorbent, based on the complexing properties of polyethyleneglycols, with high selectivity for Ba and Sr is described.
The dependences of Kd on the initial concentration of HNO3 for Ba, Sr, Eu, Ce, Cs and Na were studied. The capacity of two model sorbents for uptake of Cs and Sr is given. The properties
of the sorbents are compared with those of the ammonium salts of heteropolyacids. 相似文献
19.
A silica-based adsorbent, (DtBuCH18C6 + dodecanol)/SiO2-P, which is used for selective separation of Sr(II) from high level liquid wastes, against temperature and gama-irradiation was investigated. The adsorption characteristics of Sr(II), Ba(II), La(III), Nd(III), Gd(III) and Dy(III) under varying nitric acid concentration at different temperatures were measured by batch method. The adsorbent showed higher distribution coefficients (K d) for Sr(II) compared to other tested metal ions, and the K d values of Sr(II) decreased with increasing temperature. Thermodynamic parameters of the adsorption process were calculated. The related parameters in adsorption isotherm models were obtained using a non-linear fitting. Uptake capacity from 0.38 to 0.43 mmol g?1 was obtained for Sr(II) in the temperature range of 298–323 K by the Langmuir equation fitting. The leakage of total organic carbon was below 120 ppm at 298 K and 180 ppm at 323 K, respectively. The degradation of the adsorbent irradiated in 2 M HNO3 was investigated. It is found that the adsorbed dose of γ-ray more than 50 KGy has a strong influence on K d of Sr(II). The K d values of Sr(II) decrease about 3 times ranged from 50 to 500 KGy. 相似文献
20.
M. V. Balarama Krishna J. Arunachalam M. S. Murali Surendra Kumar V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2004,261(3):551-557
The efficiency of immobilized moss as a bio-sorbent for the removal of 137Cs and 90Sr radionuclides from actual low-level radioactive waste (LLW) solutions was investigated. Preliminary batch experiments with
the moss (Funaria hygrometrica) for the sorption of Cs and Sr have shown a pH dependent binding trend from pH 1–13, with maximum binding between pH 5–10.
Time dependence of the batch studies showed that a contact time of 30 minutes was sufficient to reach equilibrium. Column
experiments for the sorption of Cs and Sr by moss after immobilizing in polymer silica matrix demonstrated that the sorbent
is capable of removing considerable amounts of Cs and Sr from actual LLW solutions under constant flow conditions. The adsorption
capacity was estimated to be 8.5 mg/g for Cs and 15 mg/g for Sr. These sorbed metal ions from the column could be leached
out using 0.20M nitric acid. The regenerated sorbent exhibited relatively the same initial binding capacity of both Cs and
Sr even after 3 cycles of reuse.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献