共查询到20条相似文献,搜索用时 15 毫秒
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A flow-injection spectrophotometric method has been developed for the simultaneous determination of selenium(IV) and (IV + VI) at nanogram per milliliter levels. It is based on the catalytic effect of selenium(IV) on the photooxidative coupling of p-hydrazinobenzenesulfonic acid (HBS) with N-(1-naphthyl)ethylenediamine (NED) to form an azo dye (λmax = 538 nm). In this reaction, bromide acted as an activator for the catalysis of selenium(IV) and an reducer for selenium(VI) to selenium(IV) in an acidic medium which allowed the determination of selenium(IV + VI). A sample solution, being split by Y-piece into two portions, passed through the low-temperature coil (4 m, 25 °C) and the high-temperature coil (20 m, 100 °C). By monitoring the absorbance of the dye produced in the two portions, selenium(IV) and (IV + VI) in the range of 0.2–6 ng ml−1 were determined simultaneously. The relative standard deviations for 3 ng ml−1 selenium(IV) and (VI) (n = 10) were 1.2 and 1.3%, respectively. There were few interfering ions in the selenium determination. The proposed method was applied to the determination of selenium(IV) and (VI) in natural water samples. 相似文献
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M. H. Lee Y. J. Park W. H. Kim 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):375-382
Absorption spectroscopic properties for various Pu oxidation states in nitric and hydrochloric acid solutions were investigated
with UV-Visible spectrophotometry. As a result, it was confirmed that the intensities of the major absorption peaks had a
tendency to decrease for Pu(III), Pu(IV) and Pu(VI) in HCl and HNO3 media, and the major peak positions were shifted to longer or shorter wavelengths depending on the complexforming abilities
of Pu(III), Pu(IV) and Pu(VI) with the chloride or nitrate ion with increasing acid concentrations. The values of the wavelength
and the molar absorptivity for the principal peaks of Pu(III), Pu(IV) and Pu(VI) in NHO3 and HCl solutions were similar to those reported in other works. The values of the molar absorptivity for the principal peaks
of Pu(III), Pu(IV) and Pu(VI) in the HNO3 solution were a little higher than those in the HCl solution. 相似文献
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M. Kh. Umarakhunov U. A. Sadykova G. A. Khodzhaeva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(5):889-890
The sorption of molybdenum(VI) by KU-2 × 8 and AV-17 × 8 ionites from solutions in hydrochloric acid (1 × 10−5−6 N) was studied. Changes in the sorption of molybdenum(VI) by cationite and anionite were observed. The isoelectric point
of molybdenum in solutions in hydrochloric acid was determined from sorption and electrical migration measurements. 相似文献
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Nakayama M Tanaka T Tanaka M Chikuma M Itoh K Sakurai H Tanaka H Nakagawa T 《Talanta》1987,34(4):435-437
A new ligand-loaded anion-exchange resin has been developed which allows determination of Se(VI) and Se(IV) in mixtures of the two. The ligand is a sulphonic acid derivative of bismuthiol-II. 相似文献
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A procedure is developed for the selective photometric determination of selenium(IV) in bottled drinking water by the oxidation of Methylene Blue in 1 M HCl to colorless decomposition products and of selenium(VI) by its interaction with the specified reagent at pH 5–6 with the formation of a colored ion pair. The limits of detection are 1 and 0.8 µg/L, respectively. At the concentration of selenium(IV) 2 µg/L, the admissible weight ratios are: SeO42-, Br3- (1: 20); Br– (1: 60); I–, IO3- and IO4- (1: 100). At equal concentration of selenium(VI), the following species: SeO42-(1: 20); Br3-, Br–, I–, IO3-, and IO4- (1: 100) do not interfere with the determination. Other anions and cations present in highly mineralized waters do not interfere with the determination. The relative error of determination is 8–10% in the concentration range 2–10 µg/L of selenium(IV) and selenium(VI) and does not exceed 5% in their concentration range of 10–100 µg/L. 相似文献
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Speciation of inorganic selenium using hydride generation method is a widespread analytical method nowadays. However, a reduction step of Se(VI) to Se(IV) is necessary as the hydride-forming species is HSeO(3)(-) (oxydation state+IV). This paper describes the development of a batch assisted microwave system allowing a rapid (<5 min) conversion of Se(VI) to Se(IV). Hydride generation is performed by a flow injection system and detection by ICP/MS. Detection limits of 6 and 8 pg for Se(IV) and for Se(VI) (by using a sample loop of 200 mul) respectively have been achieved. This method has been validated by participating in a European certification exercise for inorganic Se speciation in aqueous solutions. 相似文献
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The extraction of vanadium(IV) from hydrochloric acid solutions by di-(2-ethylhexyl)-phosphoric acid
《Journal of Inorganic and Nuclear Chemistry》1978,40(5):853-856
The distribution of vanadium(IV) between hydrochloric acid solutions and solutions of di-(2-ethylhexyl)-phosphoric acid (DEHPA; HX) in organic solvent has been investigated under different conditions. Both the aqueous and organic phases have been examined spectrophotometrically. IR and electron spin resonance spectroscopies have been applied to the organic extracts. The mechanism of extraction is discussed on the basis of the results obtained. 相似文献
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C. Brunori M. B. de la Calle-Gunti?as R. Morabito 《Fresenius' Journal of Analytical Chemistry》1998,360(1):26-30
Parameters for the reduction of Se(VI) to Se(IV) in HCl medium by heating in a microwave oven have been optimized. The reduction
resulted to be quantitative applying 100% power, corresponding to 600 W heating for 2 min in 6 mol/L or for 3 min in 4 mol/L
HCl. The behavior of selenomethionine and selenocystine under the optimized reduction conditions was studied in order to evaluate
a possible interference of these selenium species in the determination of Se(VI). The final determination of Se(IV), and Se(VI)
were done by hydride generation-atomic absorption spectrometry. The analytical merits of the method are reported. The method
was applied to the selective determination of Se(IV), and Se(VI) in spiked river and lake water.
Received: 6 December 1996/Revised: 1 April 1997/Accepted: 3 April 1997 相似文献
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Summary The reaction between sulphurous acid and hexachloroiridate(IV) appears to take place through the formation of an intermediate complex followed by decomposition to give oxidation products. The rate is retarded as the hydrogen ion concentration increases. Thermodynamic parameters associated with the equilibrium step as well as with the slowest step have been calculated. The probable mechanism of the reaction is discussed. 相似文献
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Summary An oxychloroniobium(IV) complex was isolated for the first time by zinc reduction of NbCl5 in concentrated HCl solution. The product, an extremely moisture- and air-sensitive, intense blue solid was assigned a dimeric structure (H3O)2[Nb2O2Cl6] based on elemental analysis, i.r. and u.v.-vis spectroscopy as well as magnetic and conductometric measurements. 相似文献
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Pyrite was hydrothermally synthesized and used to remove Se(IV) and Se(VI) selectively from solution. Surface analyses of pyrite before and after contact with Se(IV) and Se(VI) were conducted using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). All solid samples were acquired by allowing 3.1 mmol/L of Se(IV) or Se(VI) to react with 1 g/L of pyrite for 1, 15, or 30 days. The XPS spectra were fitted using the XPSPEAK program that applies a Gaussian Lorentzian function. The fitted spectra indicate that Se(IV) more strongly reacts with the surface-bound S than with the surface-bound Fe of pyrite. However, there is no apparent evidence of surface reaction with Se(VI). Specifically, fitted XPS spectra showed the presence of sulfide and tetrathionate on the surface, indicating that sulfur (S(2)(2-)) at the surface of pyrite can be both oxidized and reduced after contact with Se(IV). This occurs via surface disproportionation, possibly resulting in the formation of surface precipitates. Evidence for the formation of precipitates was seen in SEM and AFM images that showed rod-like particles and a phase image with higher voltage. In contrast, there were no important changes in the pyrite after contact with Se(VI) over a period of 30 days. 相似文献
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Neutron activation analysis using shortlived77mSe (T=17.5 s) preceded by chemical pre-collection of Se on activated carbon (AC) has been applied to the fractional determination of Se(IV) and Se(VI) in natural water samples such as river water and sea water. Two chemical procedures were adopted: adsorption of Se(IV)/Bismuthiol-II complex on AC and adsorption of Se(VI)/Bismuthiol-II on AC after reduction of Se(VI) to Se(IV). It was shown that Se(IV) and Se(VI) can be determined at a <g l–1 (ppb) level in natural waters by the present method. 相似文献
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S. S. Sawant M. A. Anuse M. B. Chavan 《Journal of Radioanalytical and Nuclear Chemistry》1997,218(2):147-151
n-Octylaniline in bezene was used for the extractive separation of molybdenum (VI) from hydrochloric acid medium. Molybdenum(VI) was extracted quantitatively from 10 ml aqueous solution 1.5M in hydrochloric acid and 10M in lithium chloride into 10 ml of 10%n-octylaninline in benzene. It was stripped from the organic phase with 5% aqueous ammonia solution and estimated spectrophotometrically with thiocyanate at 465 nm. The interference of various ions has been studied in detail and conditions have been established for the determination of molybdenum(VI) in synthetic mixtures and alloy samples. 相似文献
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Iridium(IV) extraction with petroleum sulfoxides (PSO) from hydrochloric acid solutions is studied. Optimum conditions of
extraction are chosen. It is shown that in the investigated extraction systems for a phase contact time of 30 min, iridium(IV)
is extracted by the ion-associative mechanism. Electronic, 1H NMR, and IR-spectroscopy, and elemental analysis are used to establish the structure of the extracted compound. 相似文献
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Mild-hydrothermal reactions in acidic medium using 1,3-diaminopropane, 1,4-diaminobutane, and 1,5-diaminopentane as structure directing agents led to three-dimensional (3D) uranyl phosphates (CH?)?(NH?)?{[(UO?)(H?O)][(UO?)(PO?)]?} (C3U5P4), (CH?)?(NH?)?{[(UO?)(H?O)][(UO?)(PO?)]?} (C4U5P4) and (CH?)5(NH?)?{[(UO?)(H?O)][(UO?)(PO?)]?} (C5U5P4). The structures of (C4U5P4) and (C5U5P4) were solved in the space group Cmc2? using single-crystal X-ray diffraction data. The compounds are isostructural to the corresponding uranyl vanadates and contain the same 3D inorganic framework built from uranyl-phosphate layers of uranophane-type anion topology pillared by [UO?(H?O)] pentagonal bipyramids. In neutral or basic medium the alkyl diamines decompose to give ammonium uranyl phosphate trihydrate. In the same conditions by using ethylenediamine, unexpected reduction of uranium(VI) to uranium(IV) occurs leading to the formation of (CH?)?(NH?)?[U(PO?)?] (C2UP2) single crystals. C2UP2 undergoes a reversible phase transition from triclinic to monoclinic symmetry at about 230 °C. The structure of the two forms results from the stacking of inorganic layers (∞)1[U(PO?)?]2?, and organic layers containing ethylene diammonium ions, the two layers being linked by hydrogen bonds. Single crystals of (CH?)?(NH?)?[PO?OH] (C2HP) are formed by evaporation of the solution after filtering of C2UP2 single crystals. The structure of C2HP contains infinite (∞)1[PO?OH]2? chains connected by (CH?)?(NH?)?2? ions through hydrogen bonds. 相似文献
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A lamellar neptunium(IV) methylphosphonate, Np(CH3PO3)(CH3PO3H)(NO3)(H2O).H2O, has been prepared under hydrothermal conditions via the in situ reduction of NpVI to NpIV. The single crystal structure of this compound shows polar layers that are joined to one another via a hydrogen-bonding network involving interlayer water molecules. Magnetic susceptibility measurements demonstrate that the NpIV ions are magnetically isolated from one another. 相似文献
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N. G. Afzaletdinova E. R. Ibatova Yu. I. Murinov 《Russian Journal of Inorganic Chemistry》2006,51(6):971-976
The extraction of iridium(IV) by dihexyl sulfoxide from hydrochloric acid solutions was studied. Optimum conditions for the extraction of iridium(IV) were determined. It was found that an ion-association mechanism of iridium(IV) extraction took place in the test extraction systems at a phase contact time of 10 min. As the phase contact time was increased, the extraction took place by a mixed mechanism. One extractant molecule was incorporated into the inner coordination sphere of the iridium(IV) ion. This decreased the charge of the extracted complex to unity. 相似文献