共查询到20条相似文献,搜索用时 437 毫秒
1.
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
2.
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
3.
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
4.
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
5.
D. Nayak M. Nag S. Banerjee R. Pal S. Laskar S. Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):337-340
Summary The
bioaccumulation of 198Au radionuclide, by Rhizoclonium riparium
a member of Chlorophyceae has been studied. It has been observed that
accumulation of gold on Rhizoclonium is almost pH independent and
slightly higher at basic pH. Accumulation of gold was studied with 198Au
radiotracer, 0.1, 1 and 5 ppm concentrations of gold. It has been concluded
from the biochemical analysis that the gold accumulation is due to adsorption
in the cellulose and not in protein, fat and carbohydrate. Accumulated gold was
recovered when washed with conc. HNO3.</p>
</p> 相似文献
6.
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
7.
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
8.
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
9.
The preparation, spectroscopic characterization and thermal stability of neutral complexes of uranyl ion, UO2
2+, with phosphonate ligands, such as diphenylphosphonic acid (DPhP), diphenyl phosphate (DPhPO) and phenylphosphonic acid (PhP)
are described. The complexes were prepared by a reaction of hydrated uranyl nitrate with appropriate ligands in methanolic
solution. The ligands studied and their uranyl complexes were characterized using thermogravimetric and elemental analyses,
ESI-MS, IR and UV–Vis absorption and luminescence spectroscopy as well as luminescence lifetime measurements. Compositions
of the products obtained dependent on the ligands used: DPhP and DPhPO form UO2L2 type of complexes, whereas PhP forms UO2L complex. Based on TG and DTG curves a thermal stability of the complexes was determined. The complexes UO2PhP·2H2O and UO2(DPhPO)2 undergo one-step decomposition, while UO2PhP · 2H2O is decomposed in a two-step process. The thermal stability of anhydrous uranyl complexes increases in the series: DPhPO < PhP < DPhP.
Obtained IR spectra indicate bonding of P–OH groups with uranyl ion. The main fluorescence emission bands and the lifetimes
of these complexes were determined. The complex of DPhP shows a green uranyl luminescence, while the uranyl emission of the
UO2PhP and UO2(DPhPO)2 complexes is considerably weaker. 相似文献
10.
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
11.
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
12.
H. A. El-Boraey F. A. El-Saied S. A. Aly 《Journal of Thermal Analysis and Calorimetry》2009,96(2):599-606
UO2(VI), Sn(IV), Th(IV) and Li(I) complexes of 4-azomalononitrile antipyrine (L) have been isolated and characterized based on
IR spectra, 1H NMR, elemental analyses, molar conductance and thermal analysis (DTA/TG). The study revealed that the ligand behaves as
a neutral bidentate one and coordination takes place via the carbonyl atom of pyrazolone ring >C=O and the azomethine nitrogen
>C=N. The thermal stability of the metal complexes were investigated by thermogravimetry (TG), differential thermal analysis
(DTA) techniques and infrared spectra, and correlated to their structure. The thermal study revealed that Th(IV) complexes
show lower thermal stability than both UO2(VI) and Sn(IV) complexes. 相似文献
13.
Summary Macroporous
methyl methacrylate polymeric resin (XAD-7) was investigated incorporating both
acidic organophosphorous extractant (cyanex-301) and one neutral extractant
from the followings: dibenzo 18 crown 6 (DB18C6), 18 crown 6 (18C6) and 15
crown 5 (15C5). The sorption behavior of the solvent impregnated resin (SIR)
towards thorium ion, including batch equilibrium, and kinetic operation are
described. Different factors affecting the uptake of metal ions and hence, the
separation efficiency of the impregnated resins were investigated. The maximum
uptakes of Th4+ were found to be 62.9, 66.7 and 92.6% for DB18C6,
18C6 and 15C5, respectively. Synergistic extraction of various CE towards
thorium ion was tested with cyanex-301 to enhance the sorption capacity as well
as the selective separation efficiency. A relatively high capacity of the
chelating resin towards tetravalent thorium was found. The capacities of the
co-impregnated resins were found to be 2.11, 2.42 and 3.85 mmol/g for DB18C6,
18C6 and 15C5, respectively. The impregnated resin containing cyanex-301 and
15C5 can be utilized for selective separation and pre-concentration of thorium
ion from nitrate medium in the presence of several interfering metal ions.</p>
</p> 相似文献
14.
M. Yu. Shilova A. V. Vologzhanina L. B. Serezhkina V. N. Serezhkin 《Russian Journal of Coordination Chemistry》2009,35(2):153-156
The single crystals of [UO2(C2O4){CONH2N(CH3)2}2] were synthesized and studied by X-ray diffraction. The crystals are monoclinic, a = 7.461(2) Å, b = 8.828(2) Å, c = 11.756(2) Å, β = 107.21(3)°, space group Pc, Z = 2, R = 2.94%. The structure comprises infinite chains [UO2(C2O4){CONH2N(CH3)2}2] extended along [001] and corresponding to the AT11M 2 1 crystallochemical group (A = UO 2 2+ , T11 = C2O 4 2? , M1 = N,N-CONH2N(CH3)2) of uranyl complexes. The chains are connected into a three-dimensional framework by hydrogen bonds involving the oxygen atoms of oxalate and uranyl ions and the N,N-dimethylcarbamide methyl groups. 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.
A. V. Marukhnov E. V. Peresypkina A. V. Virovets D. V. Pushkin L. B. Serezhkina 《Russian Journal of Coordination Chemistry》2009,35(1):42-46
Single crystals of (NH4)(CN3H6)[UO2(SeO3)2] (I) are synthesized and studied by X-ray diffraction analysis. The compound crystallizes in the triclinic crystal system with the unit cell parameters: a = 7.0051(2) Å, b = 9.4234(3) Å, c = 9.5408(3) Å, α = 88.727(1)°, β = 70.565(1)°, γ= 77.034(1)°, space group P 1, Z = 2, R = 0.0224. The main structural units of crystals I are the [UO2(SeO3)2]2? chains of the crystal-chemical group AB2B11 (A = UO 2 2+ , B2= SeO3 2?, B11= SeO3 2?) of the uranyl complexes. The uranium-containing complexes are joined into a three-dimensional framework by the ammonium and guanidinium ions and a system of hydrogen bonds. 相似文献
17.
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
18.
M. Yu. Shilova A. V. Vologzhanina L. B. Serezhkina S. A. Novikov V. N. Serezhkin 《Russian Journal of Inorganic Chemistry》2011,56(10):1555-1560
A new complex [UO2CrO4{CH3CON(CH3)2}2] (I) was studied by thermal analysis, IR spectroscopy, and X-ray crystallography. The crystals are monoclinic: a = 13.8108(11) Å, b = 8.6804(7) Å, c = 13.0989(10) Å, β = 104.777(1)°, V = 1518.4(2) Å3, space group P21/c, Z = 4, R = 2.39%. The structure of I contains infinite chains of the [UO2CrO4{CH3CON(CH3)2}2] composition running along [001]; the complex belongs to the AT11M1 2 crystal-chemical group (A = UO 2 2+ , T11 = CrO 4 2? , M1 = CH3CON(CH3)2) of uranyl complexes. The chains are linked into a three-dimensional framework due to hydrogen bonds between oxygen atoms of chromate ions and hydrogen atoms of methyl groups of the dimethylacetamide. 相似文献
19.
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
20.
Structural and spectroscopy studies of complexes of the uranyl ion with 2,2′-bipyridine-N,N′-dioxide
2,2′-Bipyridine-N,N′-dioxide (bypO2 = L) complexes of the composition [UO2(bypO2)2(NO3)2]·2H2O (UO2–L2–NO3), [UO2(bypO2)2H2O](ClO4)2 (UO2–L2–ClO4) and [UO2bypO2(H2O)2SO4] (UO2–L–SO4) have been prepared by the reactions of the respective hydrated uranyl salts with the bypO2 ligand in water. The structures of the complexes were elucidated using elemental and thermal analyses, IR and luminescence spectroscopy as well as luminescence lifetime measurements. The IR spectra show that the bonding between uranium and bypO2, as well as uranium and water or a counter ion (NO3− and SO42−) is formed. The nitrate or sulfate groups coordinate to the central metal ions in a monodentate manner. From TG–DTA curves, the nature of the water molecules present in the complexes and the decomposition temperature of the dehydrated uranyl complexes were determined. The thermal stability of the anhydrous uranyl complexes increases in the series: (UO2–L2–NO3) < (UO2–L2–ClO4) < (UO2–L–SO4). All the compounds show green-yellow intense luminescence. The main fluorescence bands and the emission lifetimes in these complexes were determined. The luminescence spectra of all the prepared complexes differ from each other with respect to their peak maxima positions. The luminescence lifetimes also vary. The structure of the (UO2–L–SO4) complex was determined by X-ray single-crystal analysis. 相似文献