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1.
Liquid–liquid extraction and separation studies of uranium have been carried out from sodium salicylate media using cyanex
272 in toluene. Uranium was quantitatively extracted by 1 × 10−3 M sodium salicylate with 5 × 10−4 M cyanex 272 in toluene. The extracted uranium(VI) was stripped out quantitatively from the organic phase with 1.0 M hydrochloric
acid and determined spectrophotometrically with arsenazo(III) at 660 nm. The effect of concentration of sodium salicylate,
extractant, diluents, metal ion and strippants has been studied. Separation of uranium(VI) from other elements was achieved
from binary as well as from multicomponent mixtures. The method was extended for the separation and determination of uranium(VI)
in geological samples. The method is simple, rapid and selective with good reproducibility (approximately ± 2%). 相似文献
2.
M. Eskandari Nasab S. A. Milani A. Sam 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):677-683
In this study, the effects of various extraction parameters such as extractant types (Cyanex302, Cyanex272, TBP), acid type (nitric, sulfuric, hydrochloric) and their concentrations were studied on the thorium separation efficiency from uranium(VI), titanium(IV), lanthanum(III), iron(III) using Taguchi??s method. Results showed that, all these variables had significant effects on the selective thorium separation. The optimum separations of thorium from uranium, titanium and iron were achieved by Cyanex302. The aqueous solutions of 0.01 and 1 M nitric acid were found as the best aqueous conditions for separating of thorium from titanium (or iron) and uranium, respectively. The combination of 0.01 M nitric acid and Cyanex272 were found that to be the optimum conditions for the selective separation of thorium from lanthanum. The results also showed that TBP could selectively extract all studied elements into organic phase leaving thorium behind in the aqueous phase. Detailed experiments showed that 0.5 M HNO3 is the optimum acid concentration for separating of thorium from other elements with acidic extractants such as Cyanex272 and Cyanex302. The two-stage process containing TBP-Cyanex302 was proposed for separation thorium and uranium from Zarigan ore leachate. 相似文献
3.
M. Eskandari Nasab A. Sam S. Alamdar Milani 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):239-245
Solvent extraction of thorium was studied using Taguchi method. The effect of various parameters such as acid types (sulfuric,
nitric, hydrochloric, sulfuric + nitric) and their concentrations from 0.001 to 4 M, initial thorium concentration (0.0001,
0.001, 0.01, 0.1 M) and solvent type (TBP, D2EHPA, Cyanex921, Cyanex272) in the ranges of 0.001 to 1 M on thorium extraction efficiency were investigated. The maximum
extraction of thorium was obtained while 0.001 M hydrochloric acid, 0.001 or 0.01 M thorium and Cyanex272 were used. Under
these optimum conditions, the extraction percent and distribution coefficient of thorium were 98.7% and 73.8, respectively.
Compared with the hydrochloric aqueous solution, the nitric acid system showed less variation in the extraction of thorium.
The proposed process has been applied for the separation of Th(IV), U(VI), La(III), and Ce(III) from synthetic solution same
as thorium ores (monazite). 相似文献
4.
Nandita Panda Nihar Bala Devi Sujata Mishra 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(3):1205-1211
The extraction of Nd(III) using binary mixtures of Cyanex 272 (HA), Cyanex 921/Cyanex 923 (B) in kerosene from nitric acid medium has been investigated. The effect of aqueous phase acidity, extractant concentration, nitrate ion concentration and diluents on the extraction of Nd(III) has been studied. On the basis of slope analysis results, extracted species are proposed as Nd(NO3)A2·3HA and Nd(NO3)2·A·3HA·B using Cyanex 272 and its mixture with Cyanex 921/Cyanex 923, respectively. With the mixture of 0.1 M Cyanex 272 and 0.1 M Cyanex 923 in kerosene, the extraction of 0.001 M Nd(III) from 0.001 M HNO3 solution was found to be 83.3 % whereas it was 73.3 % when 0.1 M Cyanex 921 used as synergist under same experimental conditions. The stripping data of Nd(III) from the loaded organic phase containing 0.1 M Cyanex 272 and 0.1 M Cyanex 921/Cyanex 923 with different acids indicated sulphuric acid to be the best stripping agent. 相似文献
5.
Extraction behavior of 1 × 10−2–0.1 M U(VI) from aqueous phases containing 0.86 M Th(IV) at 4 M HNO3 in 1.1 M tributyl phosphate (TBP) and 1.1 M N,N-dihexyl octanamide (DHOA) solutions in different diluents viz. n-dodecane, 10% 1-octanol + n-dodecane, and decahydronaphthalene (decalin) was studied. Third-phase formation was observed in both the extractants using
n-dodecane as diluent. There was a gradual decrease in Th(IV) concentration in the third-phase (heavy organic phase, HOP) with
increased aqueous U(VI) concentration [0.71 M (no U(VI))–0.61 M (0.1 M U(VI)) for TBP; 0.27 M (no U(VI))–0.22 M (0.1 M U(VI))
for DHOA]. The HOP volume in case of DHOA was ~2.2 times of that of TBP. Uranium concentration in HOP increased with its initial
concentration in the aqueous phase [from 1.8 × 10−2 M (0.01 M U(VI))–0.162 M (0.1 M U(VI)) for TBP; from 1.4 × 10−2 M (0.01 M U(VI))–0.14 M (0.1 M U(VI)) for DHOA] suggesting that Th(IV) was being replaced by U(VI). An empirical correlation
was developed for predicting the concentrations of uranium and thorium in HOP for both the extractants. No third-phase appeared
during the extraction of uranium and thorium from the aqueous phases employing 10% 1-octanol + n-dodecane, or decalin as diluents, and therefore, were better choices as diluent for alleviating the third-phase formation
during the reprocessing of spent thorium based fuels, and for the recovery of thorium from high-level waste solutions. 相似文献
6.
Maha El-Tohamy Sawsan Razeq Magda El-Maamly Abdalla Shalaby 《Central European Journal of Chemistry》2010,8(4):937-945
The construction and performance characteristics of phenytoin sodium selective electrodes are detailed. Two types of electrodes:
plastic membrane I and coated wire II, were constructed based on the incorporation of phenytoin sodium with tungstosilicic
acid. The influence of membrane composition, kind of plasticizer, pH of the test solution, soaking time and the electrodes’
foreign ions were investigated. The electrodes showed a Nernstian response with a mean calibration graph slope of 30.9±0.1
and 28.9±0.1 mV decade−1 at 25°C for electrode I and II respectively, over a phenytoin sodium concentration range of 5×10−3−5×10−6 M and 1×10−3−1×10−6 M with a detection limit 1.3×10−6 M and 2.5×10−7 M for electrode I and II, respectively. The electrodes gave average selective precision and were usable within the pH range
6–10. Interference studies from common cations, alkaloids, sugars, amino acids and drug excipients are reported. The results
obtained by the proposed electrodes were also applied successfully for the determination of the drug in pharmaceutical preparations
and biological fluids. 相似文献
7.
A simple method is described for the solvent extraction of thorium. Thorium is extracted quantitatively from 5·10–3M sodium salicylate solution at pH 2.5–3.25 using 2.16·10–2M triphenylphosphine oxide as an extractant dissolved in toluene. The extracted metal ion is stripped with hydrochloric acid (0.1M) and determined spectrophotometrically with Thoron-1 at 540 nm. The method permits separation of thorium from lanthanum, cerium, neodymium, samarium and uranium from binary mixtures and is applicable to the analysis of monazite sand. The method is precise, accurate and selective. 相似文献
8.
M. Eskandari Nasab 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1739-1747
The extraction of thorium(IV) and uranium(VI) from nitric acid solutions has been studied using mixtures of bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272 or HA), and synergistic extractants (S) such as tri-butylphosphate (TBP), tri-octylphosphine oxide (TOPO) or bis(2,4,4-trimethylpentyl)thiophosphinic acid (Cyanex301). The results showed that these metallic ions are extracted into kerosene as Th(OH)2(NO3)A·HA and UO2(NO3)A·HA with Cyanex272 alone. In the presence of neutral organophosphorus ligands TBP and TOPO, they are found to be extracted as Th(OH)2(NO3)A·HA·S and UO2(NO3)A·HA·S. On the other hand, Th(IV), U(VI) are extracted as Th(OH)2(NO3)A·HA·2S and UO2(NO3)A·HA·S in the presence of Cyanex301. The addition of neutral extractants such as TOPO and TBP to the extraction system enhanced the extraction efficiency of both elements while Cyanex301 as an acidic extractant has improved the selectivity between uranium and thorium. The effect of TOPO on the extraction was higher than other extractants. The equilibrium constants of above species have been estimated by non-linear regression method. The extraction amounts were determined and the results were compared with those of TBP. Also, it was found that the binding to the neutral ligands by the thorium–Cyanex272 complexes follows the neutral ligand basicity sequence. 相似文献
9.
Chitosan was modified by grafting 2-pyridyl-ethyl moieties on the biopolymer backbone for the synthesis of a Platinum Group
Metal (PGM) sorbent. The sorbent was tested for Pd(II) and Pt(IV) sorption from HCl solutions. Stable for HCl concentrations
below 0.5 M, the sorbent reached sorption capacities as high as 3.2 and 2.6 mmol metal g−1 for Pd(II) and Pt(IV), respectively. Metal sorption mainly proceeds by electrostatic attraction in acidic solutions, though
a contribution of complexation mechanism cannot be totally rejected. The resistance to intraparticle diffusion is the main
controlling mechanism for uptake kinetics. While agitation speed has a limited effect on kinetics, metal concentration and
sorbent dosage have a greater effect on the kinetic profiles. The intraparticle diffusivity varies between 3 × 10−11 and 4.5 × 10−10 m2 min−1. Thiourea (combined with HCl solution) is used for Pd(II) and Pt(IV) desorption. The resin could be desorbed and recycled
for a minimum of five cycles maintaining high efficiencies of sorption and desorption. 相似文献
10.
Scandium can be extracted from 5.0 × 10−2 mol/1 sodium salicylate solution, adjusted to pH 4.0–5.0 with 0.5% triphenylphosphine oxide dissolved in toluene as an extractant.
After stripping from the organic phase with 0.5 mol/1 HCl it can be subsequently determined spectrophotometrically with Alizarin
Red S. The method permits a separation of Sc(III) from Ti(IV), V(V), Cr(VI), Fe(III), Y(III), La(III), Ce(III), Nd(III) and
Sm(III) in synthetic mixtures. The method is fast, simple and selective. 相似文献
11.
Summary Th(IV) was quantitatively extracted from 1 . 10-3M HNO3 using 1 . 10-3M Cyanex302 in xylene and was stripped from the organic phase with 5M HCl. The effect of different parameters affecting the
extraction was systematically studied to achieve optimum conditions for the extraction of thorium. Based on the data some
separations of thorium from binary and complex mixtures and its recovery from monazite sand were achieved. The method is reproducible
with a relative standard deviation of 0.4%. 相似文献
12.
Neetu Bansal 《Transition Metal Chemistry》2010,35(4):483-490
A kinetic method for the determination of organosulfur compounds by UV spectrophotometry is described. Organosulfur compounds
have been shown to inhibit the Hg(II)-catalyzed substitution of cyanide in hexacyanoferrate(II) by 2-methylpyrazine (2-Mepz).
The inhibitory effect is proportional to the concentration of inhibitor and can be used as the basis for the determination
of trace amounts of organosulfur compounds such as cysteine, 2,3-dimercaptopropanol (DMP) and thioglycolic acid (TGA). Both
the influence of the reaction variables and interference of a variety of ions have been studied. A mechanism for the inhibition
process is proposed. The determination range depends on the amount of Hg(II) added and stability of the Hg(II)–ligand complex.
Kinetic parameters were determined from Lineweaver–Burk plots, obtained in the absence and presence of the inhibitor. Excellent
linearity is observed for all analytes over their respective concentration ranges with correlation coefficient >0.9. The condition
calibration curves were linear in the range of 5 × 10−6–15 × 10−6 M for cysteine, 1 × 10−7–7 × 10−7 M for DMP and 1 × 10−6–10 × 10−6 M for TGA. The detection limits were 1.18 × 10−7 M for cysteine, 4.16 × 10−8 M for DMP and 1.30 × 10−7 M for TGA. The effects of amino acids that can interfere in the determination of cysteine were studied. 相似文献
13.
A. R. Joshi Nijith Sebastian K. G. Kate D. R. Ghadse 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):115-119
Coated wire ion selective electrode for thorium ion selective potentiometry was developed. Thorium ion selective coated wire
electrodes were prepared by depositing a membrane comprising of Aliquat-336 loaded with Th(NO3)62− ions and poly vinyl chloride in varying proportion. A linear near-Nernstian response with a slope of −29.5 ± 0.3 mV over
thorium concentration range of 1 × 10−1–3 × 10−5 M in constant total nitrate concentration of 6 M was obtained for the electrodes of almost all the composition studied. In
spite of small drift in response potential from composition to composition, day to day as well as from electrode to electrode,
the slope of potential response line was constant within experimental error. Moreover, the electrode once prepared could be
conveniently used over a period of one and half month. 相似文献
14.
R. B. Kadam G. G. Mali B. S. Mohite 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):501-511
A selective and effective chromatographic separation method for thorium(IV) has been developed by using poly [dibenzo-18-crown-6] as stationary phase. The separations are carried out from glycine medium. The sorption of thorium(IV) was quantitative from 1 × 10?2 to 1 × 10?4 M glycine. The elution of thorium(IV) was quantitative with 2.0–8.0 M HCl, 4.0–7.0 M HBr, 1.0–2.0 M HClO4 and 5.0 M H2SO4. The capacity of poly [dibenzo-18-crown-6] for thorium(IV) was found to be 0.215 ± 0.01 mmol/g of crown polymer. The effect of concentration of glycine, metal ion, foreign ion and eluents has been studied. Thorium(IV) was separated from a number of cations in ternary as well as in multicomponent mixtures. The applicability of the proposed method was checked for the determination of thorium(IV) in real as well as geological sample. The method is simple, rapid, and selective with good reproducibility (approximately ±2 %). 相似文献
15.
The liquid-liquid extraction of zirconium(IV) from acidic chloride solutions was carried out with Cyanex 272 as an extractant diluted in kerosene. An increase of the acid concentration decreased the percentage extraction of metal, which indicates that the extraction follows ion exchange-type mechanism: MO2+(aq) + 2(HA)2(org) <--> MO (HA2)2(org) + 2H+(aq), where, M = Zr(IV); HA = Cyanex 272. The extraction of Zr(IV) increases with an increase of the extractant concentration. In a plot of log D vs. log[extractant], M is linear with a slope of approximately 2, indicating the association of two moles of extractant with the extracted metal species. On the other hand, the extraction decreases with an increase of the H+ ion concentration. A plot of log D vs. log[H+] gave a straight line with a negative slope of 1.7, indicating the exchange of two moles of hydrogen ions for every mole of Zr(IV). The effect of the Cl- ion concentration at a constant concentration of [H+] did not show any change in the D values. The addition of sodium salts enhanced the percentage extraction of metal, and followed the order of NaSCN > NaNO3 > Na2SO4 > NaCl. The stripping of metal from the loaded organic (L.O) with different acids indicated sulfuric acid to be the best stripping agent. An increase of the temperature during the extraction and stripping stages increases the metal transfer, showing that the process is exothermic. The synergism, regeneration and recycling capacity of Cyanex 272; the extraction behavior of associated elements, such as Hf(IV), Ti(IV), Al(III), Fe(III); and IR spectra of the extracted Zr-Cyanex 272 complex were studied. 相似文献
16.
A. K. Dinkar Suman Kumar Singh S. C. Tripathi P. M. Gandhi R. Verma A. V. R. Reddy 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(1):707-715
Present studies deal with supported liquid membrane (SLM) technique for the separation of thorium from hydrochloric acid (HCl) medium using Cyanex 923 as a carrier. Effects of feed acidity, strippant, and membrane pore size and membrane thickness on the transport of thorium have been studied in detail. The optimized parameters were applied for separation of thorium from a radioanalytical waste. Stability of the membrane and membrane support was investigated. Transport of thorium increased from 78.3 to about 93.7 % with increase in acidity from 0.5 to 2 M using 0.3 M Cyanex 923 in n-dodecane as carrier and 2 M ammonium carbonate as stripping phase. The transport of thorium decreased above 2 M HCl. An attempt was made to model the physicochemical transport of thorium in SLM and understand the mechanism of thorium transport. 相似文献
17.
An “off–on” rhodamine-based fluorescence probe for the selective signaling of Cr(III) has been designed by exploiting the
guest-induced structure transform mechanism. This system shows a sharp Cr(III)-selective fluorescence enhancement response
in 100% aqueous system under physiological pH value and possesses high selectivity against the background of environmentally
and biologically relevant metal ions including Cr(VI), Al(III), Fe(III), Cd(II), Co(II), Cu(II), Ni(II), Zn(II), Mg(II), Ba(II),
Pb(II), Na(I), and K(I). Under optimum conditions, the fluorescence intensity enhancement of this system is linearly proportional
to Cr(III) concentration from 5.0 × 10−8 to 7.0 × 10−6 mol L−1 with a detection limit of 1.6 × 10−8 mol L−1. 相似文献
18.
Muhammad Haleem Khan Akbar Ali 《Journal of Radioanalytical and Nuclear Chemistry》1996,203(1):161-167
The solvent extraction of thorium(IV) (4.3·10–4M) from nitric acid solution by bis-2-(butoxyethyl ether) (butex or DBC) has been studied. It has been investigated as a function of nitric acid, extractant and metal ion concentration. The effect of equilibration time, diverse ions and salting-out agent on the extraction has also been examined. Among anions, fluoride, phosphate, oxalate and perchlorate have reduced the extraction. Cations such as Na(I), K(I), Ca(II), Zn(II), Al(III), Ti(IV), Zr(IV) except Sr(II) and Pb(II) do not interfere in the extraction. The extraction is enhanced upto 97% in three stages at 6M HNO3 having 2.94M NaNO3 as salting-out agent. The extraction is found to be independent of thorium concentration in the range studied (4.3·10–4–4.3·10–2M). The temperature (18–45°C) has an adverse effect on the extraction. A 1% solution of ammonium bifluoride is found to be a good stripping solution and recovery of thorium is >98%. 相似文献
19.
M. Mazloum Ardakani P. Ebrahimi M. R. Mansournia 《Russian Journal of Electrochemistry》2008,44(9):1065-1072
A new salicylate-selective electrode based on the complex (2,3;6,7;10,11;14,15-tetraphenyl-4,9,13,16-tetraoxo-1,5,8,12-tetraazacyclohexadecane)
copper(II) [CuL] as the membrane carrier was developed. The electrode exhibits a good Nernstian slope of −60.9 ± 1.0 mV/decade
and a linear range from 1.0 × 10−6 to 1.0 × 10−1 M for salicylate. The detection limit is 5.0 × 10−7 M. The electrode has a fast response time (5–15 s) and can be used for more than three months. The selective coefficients
were determined by the fixed interference method (FIM) and separate solution method (SSM). The salicylate-selective electrode
could be used in the pH range 3.5–10.5. It was employed as an indicator electrode for direct determination of salicylate in
pharmaceutical samples.
Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 9, pp. 1147–1154.
The text was submitted by the authors in English. 相似文献
20.
We have optimized the conditions for the separation and quantification of a mixture of heteroaromatic thioamides, potential thyreostatics: pyridine-2-thione (I), 5-trifluoromethylpyridine-2-thione (II), pyrimidine-2-thiol (III), 4-trifluoromethylpyrimidine-2-thiol (IV) by capillary zone electrophoresis using a 60 cm × 75 μm capillary (effective length of 50 cm), 15-kV voltage, and borate buffer solution (pH 9.18) as the running electrolyte. The procedure provides the estimation of analyte concentrations in the range from 6.7 × 10?6 to 1.0 × 10?4 M with the detection limits (by electrophoretic peak areas) 0.72 (I), 0.47 (II), 0.43 (III), and 0.76 (IV) μg/mL. 相似文献