共查询到20条相似文献,搜索用时 609 毫秒
1.
D. Bontea C. Mita D. Humelnicu 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):305-311
Summary Three
silylcellulosic derivatives with different substitution degree were examined as
sorbents for uranyl ions. The adsorption rate and capacity of cellulose and
modified cellulose were investigated in aqueous media, at various pH and
temperature values. The polymer - metal complexes of UO22+
were characterized by infrared and electronic spectra, and thermogravimetry.
The thermal behavior of cellulose (C), trimethylsilyl - cellulose (tmsc, SD=
2.85) and triphenylsilyl - cellulose (TPSC1, SD=2.89 and TPSC2, SD
=2.70) and their complexes with
uranyl ions in atmospheric air has been studied between room temperature and
600 °C. The Coats-Redfern method was applied to estimate the kinetic
parameters. The results revealed that the complexation of C and TMSC with UO22+
increases the thermal stability.</p>
</p> 相似文献
2.
P. Mell J. Megyeri L. Riess Z. Máthé J. Csicsák K. Lázár 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):405-410
Summary Sorption of60Co,85Sr, 137Cs and125I have been studied on samples
originated from Boda (siltstone-) claystone formation (BCF) (Hungary). The
distribution of Kdvalues have been determined in static batch
experiments using natural groundwater. The order of sorption of isotopes was
Co>Cs>Sr>I, where iodine exhibits sorption properties in a modest
extent. The sorption isotherm was determined for Cs from measurements carried
out in 10-5-10-1M initial concentration range. The
isotherm can be described with non-linear Freundlich approximation in the range
of</o:p></p>
10-7-10-4M equilibrium concentration. At
concentrations >10-2M the isotherm achieves saturation. Hence, it is suggested that sorption
of Cs on BCF is dominated by cation-exchange reactions on the illite mineral
component. In the case of Co and Sr, precipitation reactions occurred during
the experiments performed with carrier-containing solutions. This can be
attributed to the low values of solubility product constants of SrCO3, SrSO4and Co(OH)2, formed from anions present in the
natural groundwater.</p>
</p> 相似文献
3.
K. M. Abd El-Rahman A. M. El-Kamash M. R. El-Sourougy N. M. Abdel-Moniem 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):221-230
Summary The
batch removal ofCs+, Sr2+, Ca2+and Mg2+ions from aqueous solutions using synthetic
zeolite A was investigated. The influence of the initial ion concentration, pH
and temperature was studied. The obtained isotherm data have been correlated
with Langumir, Freundlich, and Dubinin-Radushkevich(D-R) isotherm models. The effect of the temperature on the equilibrium
distribution values has been utilized to evaluate the standard thermodynamic
parameters such as free energy (DG), enthalpy (DH) and entropy (DS). Based on the D-R
isotherm expression, the maximum ion-exchange capacity and the mean free energy
of each studied ion has been determined. The selectivity sequence, deduced from
the equilibrium isotherm data is: Sr2+>Ca2+>Mg2+>Cs+>Na+.</p>
</p> 相似文献
4.
H. Kazemian H. Zakeri M. S. Rabbani 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):231-236
Summary Potassium
nickel hexacyanoferrate, KNiFC, was incorporated in the porous matrix of
zeolites by successive impregnation with Ni(NO3)2 and</o:p></p>
K4Fe
(CN)6.1 CFC and PFC exchangers were first prepared by
impregnating the potassium nickel hexacyanoferrate into the clinoptilolite and
the synthetic P zeolite, respectively. Ion-exchange isotherms and breakthrough
curves were plotted. Results showed that the CFC sorbent is suitable for
removal of Cs+ where PFC is more suitable for Sr2+.
Negative effect of Na+ as a competing ion in these exchangers was
less than in the parent zeolites. Isotherm plots fitted the Langmuir equation.</p>
</p> 相似文献
5.
Pratibha Sharma Renu Tomar Pankaj Sharma Radha Tomar 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):329-336
Summary Sorption
and desorption of UO22+, Th4+ and Ru3+
on the synthetic analogue of the mica mineral muscovite has been studied by a
batch technique. The synthesized gel was characterized by XRD, EDXRFS, FTIR,
TGA and SEM and was found to have a composition K1.4Al4.2(Si6Al2O20)(OH)4
. 2H2O. Different parameters like acid concentration, contact
time, amount of gel, composition of gel: OPC admixture, effect of temperature,
desorption of metal ions from loaded muscovite and effect on crystal morphology
due to loading of metal ions were studied. The results has been expressed in
terms of distribution coefficient (Kd).</p>
</p> 相似文献
6.
A. Bhattacharyya P. K. Mohapatra P. N. Pathak V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):323-328
Summary Sorption
behavior of Th and U on cation-exchange resins was investigated from nitric
acid medium by both batch and column methods. The cation-exchange studies
involved the sorption of UO22+ and Th4+ and
their cationic complexes onto Dowex 50Wx8 and Dowex 50Wx4 resins (50-100 mesh).
The batch data yielded a separation factor (Kd,Th/Kd,U)
value of >100 for the cation-exchanger, Dowex 50Wx4 at 1-2M HNO3.
Separation of uranium from thorium was also carried out by column method in
nitric acid medium using cation-exchangers, Dowex 50Wx4 as well as Dowex 50Wx8.
While uranium elution was possible at 1M HNO3, Th could be eluted
only at higher concentration of nitric acid (>6M). The stripped solution
emanating from a mixer settler employing di-2-ethyl hexyl isobutyramide as
extractant and feed solution similar to THOREX process comprising 350 mg/l U
and 380 mg/l Th in 0.75M HNO3 was loaded on the column and the
decontamination factor value for U in the product was >1000.</p>
</p> 相似文献
7.
Chien C. Lin C. F. Wang Y.C. Sun J. H. Chao C. L. Tseng 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):419-424
Summary Exploratory
experiments have been carried out to investigate the effects of gamma-radiation
on iodine aerosols under various chemical conditions. The results indicate that
iodide ions (I-) in aerosol can be readily oxidized to I2
and HIO, and some iodide ions may be converted to organic iodine when organic
additives are present in the KI solution from which the aerosol is generated.
The results also suggest that the chemical transformation of irradiated iodine
aerosol depends on the chemical environment both carrier gas and iodide
solution.</p>
</p> 相似文献
8.
A. S. Al-Hobaib K. M. Al-Sulaiman D. M. Al-Dhayan A. A. Al-Suhybani 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):425-431
Summary Sand
filters are used in water treatment stations to remove particulate matter from
underground water, where iron and manganese are collected forming thin oxide
films. These oxides of iron and manganese adsorb radium from underground water.
Radium concentration increases in time on the filters, and consequently the
level of radioactivity increases in the station. The removal of adsorbed radium
on sand using inorganic acids was studied. Good efficiency of radium removal
was obtained by controlling different parameters like temperature, time, pH,
addition of competitive cations and anions. It was found that hydrochloric acid
is the best for radium removal from sand filters. Maximum removal obtained was
about 60% at 5M BaCl2 and 2M HCl at 50 °C for 180-minute contact
time. Kinetic parameters of the removal process were studied and compared with
literature data.</p>
</p> 相似文献
9.
Adel M. El-Menshawy M. E. Khalifa 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):341-348
Summary Duolite
C20 resin modified with trimethylammonium acetosalycoylhydrazone has been
developed, for the selective separation and/or preconcentration of uranium. The
modified resin was characterized by elemental analysis and infrared spectra.
Batch and column modes were applied. The newly designed resin quantitatively
sorbs uranium ion at pH 3 when the flow rate equals to 2 ml . min
-1 . The sorption capacity was 0.750 mmol . g-1 for
uranium ion, whereas its preconcentration factor was 200. The lower limit of
detection was 5 ng . ml-1 and its desorption was
effective with 5 ml of 3 mol . l-1 HCl or HNO3
prior to detection spectrophotometry. The modified resin was highly
ion-selective in nature even in the presence of large concentrations of
electrolyte or organic media, with a preconcentrating ability for uranium ion.
The modified resin was tested on its utility with synthetic, real and certified
ore samples, showed RSD values of <2% reflecting the accuracy and
reproducibility of the newly modified resin.</p>
</p> 相似文献
10.
M. S. Al-Masri A. Nashawati Y. Amin B. Al-Akel 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):289-295
Summary Transfer
of 226Ra, 85Sr and 137Cs from cow and sheep
milk to various Syrian dairy products has been evaluated. Dairy products
include Kashkivan cheese, braided cheese, Haloom cheese, Sircassian cheese,
liquid cheese, native cheese, cottage, thick yogurt, butter and milk cream. The
results showed that the percentage of 226Ra, 85Sr and 137Cs
transferred from cow milk to milk cream (Pt=food
processing retention factor′processing efficiency′100%) has reached 32%, 16% and 7%,
respectively. Butter and liquid cheese were found to have the lowest percentage
of transferred 226Ra, 85Sr and 137Cs.
Most of the obtained Pt values of the studied radionuclides
in thick yogurt were relatively low in spite of the high processing
efficiencies of thick yogurt. Moreover, the transfer, Pt, of
the studied radionuclides from cow milk to the prepared cheese was higher than
those values determined for sheep milk. This is due to differences in chemical
compositions of each type of milk. On the other hand, the treatment of Native
cheese, most commonly consumed cheese in Syria, with different concentrations
of NaCl solutions showed that 137Cs was completely removed from
cheese soaking in 5% NaCl solution (soaking time of 48 hours), while 40% of 226Ra
and 80% of 85Sr were also decontaminated using 0-2.5% NaCl solutions
and soaking time of 48 hours. Based on the obtained results, industrialization
processes of the dairy products that resulted the removal of radionuclides have
been identified.</p>
</p> 相似文献
11.
E. A. A. El-Shazly R. R. Sheha H. H. Someda 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):255-260
Summary 8-Hydroxyquinoline
in benzene, xylene, chloroform and toluene diluents was used to modify silica
gel as a solid phase extractant (SPE) for the sorption of Eu(III) in batch
extraction techniques. Influences of solid/liquid ratio, pH, metal ion
concentration, particle size and temperature were studied. The optimum initial
pH is 4.2, while the maximum sorption capacities for the prepared impregnated
resins in benzene, xylene, chloroform and toluene diluents are 18.52, 14.98,
14.79 and 5.94 mg . g-1, respectively. The sorption
process is found to be affected by both metal ion concentration and particle
size of the impregnated resin. Thermodynamic parameters for the sorption of
Eu(III) were determined and the reaction is found to be exothermic and spontaneous
with enthalpy-14.23
and-23.71
kJ . mol-1 for benzene and xylene as diluents. Release of
the element from the loaded solid particles into 0.01M HNO3 is@85% and@53% from
8-HQ/benzene/silica gel and 8-HQ/xylene/silica gel.</p>
</p> 相似文献
12.
Sh. Yu X. Li A. Ren D. Shao Ch. Chen X. Wang 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):387-392
Summary The
removal of heavy metal ion Co(II) from aqueous solution was studied usingg-Al2O3
by batch technique. The experiments were performed at T=20±2 °C, in 0.01M
NaNO3 solutions and under aerobic conditions. The effect of pH,
ionic strength, fulvic acid (FA) and alumina amount on the sorption of Co(II)
on alumina were also investigated. The pH affected the sorption of Co(II)
significantly as compared with the effect of FA and ionic strength. The results
indicated that strong chemical bonds are formed between Co(II) and functional
groups of the bare or FA coated alumina, and a precipitation of Co(II) takes
place on the alumina surface, induced by a transition from the adsorption to
surface. The addition sequences of Co/FA on Co(II) sorption were also studied:
the sorption of Co(II) in the ternary system was found independent of addition
sequences.</p>
</p> 相似文献
13.
J. Solecki 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):357-364
Summary Results
of studies of Na+, K+ and Cs+ influence on the
adsorption of 85Sr on soil samples of the different types of
successive horizons are presented. It was proved that the adsorption isotherms
in log-log coordinates are of straight-line type and may be described by the
Freundlich equation. Monovalent cations influence the coverage degree of the
soil surface by 85Sr (most often lowering it) in the following order
K+3Na+3Cs+.
The investigation of pH influence proved its essential meaning in the process.
The plateau of surface coverage degree versus pH lies above pH 5.5 or 6.5
depending on the soil type. Generally, in the studied system, the size of 85Sr
adsorption depends on the concentration of the isotope, pH of the solution,
type of monovalent cation, and on the soil properties.</p>
</p> 相似文献
14.
M. D. Engelmann L. A. Metz N. E. Ballou 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):201-204
Two
methods capable of near complete recovery of technetium adsorbed on charcoal
are presented. The first involves liquid extraction of the technetium from the
charcoal by hot 4M nitric acid. An average recovery of 98% (n=3) is
obtained after three rounds of extraction. The second method involves dry
ashing with air in a quartz combustion tube at 400-450 °C. This method yields
an average recovery of 96% (n=5). Other thermal methods were attempted, but
resulted in reduced recovery and incomplete material balance.</p>
</p> 相似文献
15.
Shuddhodan P. Mishra Diwakar Tiwari Shailesh Kumar Prasad R. S. Dubey Manisha Mishra 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):191-199
Summary The
uptake of indigenously synthesized amorphous stannic and zirconium phosphate
was assessed for, one of the important fission fragment, cesium from aqueous
solutions using a radiotracer technique. A virtual increase in sorptive
concentration (from 1.0 . 10-8 to 1.0 . 10-2
mol . dm-3) and pH (from 2.4 to 10.2) and temperature
(from 303 to 333 K) enhanced the uptake of cesium on stannic phosphate.
However, the extremely high degree of uptake of cesium on zirconium phosphate
was almost unaffected with the dilution beyond 10-5 mol .
dm-3 and pH (i.e., from 2.4 to 10.2) and temperature (from 303 to
323 K). Irreversible uptake occurring for these solids follow the Freundlich
adsorption isotherm and the presence of several complexing agents viz.,
sulphate, phosphate, glycine and EDTA did not affect appreciably the uptake of
cesium on zirconium phosphate but it did affect for stannic phosphate system.
Both these solids showed good radiation stability towards a 11.1 GBq Ra-Be
neutron source having neutron flux ca. 3.2 . 106 n .
cm-2 . s-1 and associated with a nominalg-dose of ca.
1.72 Gy/h, at least for the uptake of cesium.</p>
</p> 相似文献
16.
Mixed-valence
state of optically active 1',1'”-bis(2-phenylpropyl)-1,1”-biferrocenium salts</p>
</p>
Summary The
mixed-valence state of 1',1'”-bis(2-phenylpropyl)-1,1”-biferrocenium
polyiodides was studied for (R,R), (S,S), (R,S) isomers
and the DL modification. The effect of cation symmetry appeared differently
from 1',1'”-bis(2-phenylbutyl)-derivatives, while similar packing effect was
observed.</p>
</p> 相似文献
17.
Summary A
rapid separation of microamounts of Sr2+ from Y3+ using
HCl, 15-crown-5 (15C5) and hydrogen dicarbollylcobaltate (H+B-)
in the two-phase water - nitrobenzene extraction system was developed. The
reached separation factor a(Sr/Y) was approximately 10. 5.4</p>
__</p> 相似文献
18.
H. J. Ding Y. N. Niu Y. B. Xu W. F. Yang S. G. Yuan Z. Qin X. H. Zhou 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):433-436
Summary The
extraction of protactinium with Aliquat 336 (methyl-tri-caprylyl ammonium
chloride) in toluene, cyclohexane and chloroform from HCl, HNO3, H2SO4,
HClO4, HF and mixed HCl-HF media was investigated by radioactive
tracer technique. Distribution ratios of protactinium between the aqueous
solution and the organic phase were determined as a function of shaking time,
concentrations of acid in aqueous solution phase, extractant concentration and
type of diluents in the organic phase. Aliquat 336 can almost quantitatively
extract protactinium from strong HCl solution. At the same time, small amounts
of HF in HCl solutions have a strong effect on Pa distribution.</p>
</p> 相似文献
19.
Summary A
tail-made polymer matrix is proposed to remove strontium ions from aqueous
solutions. The removal behavior of strontium ions on a crosslinked copolymer
containing methacrylic acid as functional groups was investigated as a function
of sorptive concentration, time, temperature and pH. It was observed that an
increase of these parameters enhanced the removal of Sr(II) ions from aqueous
solution. It is found that a maximum adsorption of Sr(II) ions can be obtained
on the crosslinked copolymer after 30 minutes and at pH 8. The increase of
Sr(II) ion concentration in the solution resulted in an increase in the amount
of Sr(II) ions adsorbed on the crosslinked copolymer containing methacrylic
acid as functional groups. However, after a maximum of Sr(II) concentration in
the solution, the percentage of adsorbed Sr(II) ions decreased. The adsorption
data are well represented by the Freundlich, Langmuir and Dubinin-Radushkevich
(D-R) isotherms. The adsorption capacity of the copolymer and the free energy
change were calculated by using the D-R isotherm. For the adsorption of Sr(II)
ions on the crosslinked copolymer the thermodynamic parameters (DH°,DS° andDG°) were
calculated.</p>
</p> 相似文献
20.
D. Yokoyama K. Namiki Y. Yamada 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):283-288
Summary Pyrite
FeS2 was laser-deposited onto Al substrates at various temperatures,
and the M?ssbauer spectra of the films were measured. The yields and the
M?ssbauer parameters of FeS2 and FeS changed depending on the
formation temperature, because of the sulfur deficiency in the lattice
structures. In addition, hematite Fe2O3 was employed as a
laser-ablation target, and FeO and Fe2O3 were deposited
on SiO2/Si substrates. It was shown that laser-deposition of
compounds can produce films that have different chemical species than the
laser-evaporated materials.</p>
</p> 相似文献