共查询到20条相似文献,搜索用时 20 毫秒
1.
2.
The distribution of 27 metal ions between zirconium and titanium arsenophosphate and demineralized water, perchloric acid and nitric acid has been studied. On the basis of the results, several binary and ternary separations can be designed. The data have been used in application of these materials to the analysis of certain alloys and rocks. 相似文献
3.
In acidic solution only molybdenum(VI), tungsten(VI), vanadium(V), niobium(V) and tantalum(V) form stable, anionic complexes with dilute hydrogen peroxide. This fact has been used in developing an analytical method of separating molybdenum(VI), tungsten(VI) and vanadium(V) from other metal ions and from each other. Preliminary investigations using reversed-phase paper chromatography and solvent extraction led to a reversed-phase column Chromatographic separation technique. These metal-peroxy anions are retained by a column containing a liquid anion-exchanger (General Mills Aliquat 336) in a solid support. Then molybdenum(VI), tungsten(VI) and vanadium(V) are selectively eluted with aqueous solutions containing dilute hydrogen peroxide and varying concentrations of sulphuric acid. 相似文献
4.
There are opposite opinions as to the geometrical structure of U(IV)-β-diketonate in solution. From the result of both PMR spectra and magnetic susceptibility in solution, a square antiprism with higher symmetry than a dodecahedron is considered to be the structure in solution. 相似文献
5.
Zu-Ming Zhou Ying-Jie Zhang Hui-Fang Du 《Journal of Radioanalytical and Nuclear Chemistry》1994,188(3):177-187
The kinetics of oxidation of U(IV) in nitric acid solution by nitrous acid and air oxygen have been studied. The effects of concentrations of U(IV), nitric acid, hydrogen ion and nitrous acid in aqueous solution or oxygen in gas on the oxidation rate have been examined. The oxidation rate increases with increasing temperature and the activation energies are 47 kJ mol–1 for nitrous acid and 91 kJ mol–1 for oxygen. The mechanisms for both oxidation reactions are discussed. 相似文献
6.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1979,35(3):213-216
The compositions of the equilibrium vapors above U(BH4)4 and U(BD4)4 at 23° were analyzed by mass spectrometry and only monomeric molecular ions, U(BH4-x)y+, were detected. Infrared spectra for the molecules were recorded in the frequency range 4000-200 cm−1 for vapors contained in a variable path (1–20m) cell at 23°, from inert gas, low temperature matrices and low temperature thin-films. The data collected in this study are correlated with previously recorded data from vapors of U(BH4)4 generated at 40–50°. Several spectral features pertinent to the eventual complete vibrational spectroscopic definition of U(BH4)4 and U(BD4)4 are discussed. 相似文献
7.
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
8.
9.
Liu Mouwu Wang Yanfei Ma Zhili Luo Yige 《Journal of Radioanalytical and Nuclear Chemistry》2019,319(1):279-288
Poly(cyclotriphosphazene-co-phloroglucinol) (PCPP) microspheres, a new solid phase extraction for extracting uranium(VI), synthesized via one-pot precipitation copolymerization. The PCPP microspheres were characterized by FT-IR, SEM/EDS, zeta potential and N2 adsorption/desorption isotherms. Through the extraction experiment to evaluate the extraction behavior of the PCPP microspheres for uranium(VI). The extractant can achieve the optimal effect under the conditions of contact time with 60 min, pH = 3.5, initial concentration 100 mg L−1 and extractant dosage 0.70 g L−1. The extraction behavior obeyed with the pseudo second-order model and Langmuir isotherm model.
相似文献10.
11.
Zu-Ming Zhou Wan-Chun Wang Jian-Suo Wang Hui-Fang Du Ming-Lu Ye 《Journal of Radioanalytical and Nuclear Chemistry》1998,227(1-2):167-169
The cold solution of a pyrophosphate kit was prepared and dispensed into 2-ml fractions which were stored at −20°C for one
week. The solution was prepared by using two protection methods. The first was nitrogen purging to exclude air and the second
one the addition of the well known antioxydant ascorbic acid. The aim was to determine the stability of99mTc(Sn)-PyP obtained by labeling these fractions prepared under the given experimental conditions. The content of99mTc-pertechnetate in the unprotected samples raises with time. Nitrogen purging provides some protection but already after
a few days the content of pertechnetate exceeds 5%. The addition of ascorbic acid gave good results. The content of pertechnetate
was 1–2% after seven days in the presence of 50 μg of acid per ml of the cold kit. 相似文献
12.
13.
Shen Chao-Hong Bao Bo-Rong Wang Gao-Dong Qian Jun Bao Ya-Zhi Cao Zheng-Bai 《Journal of Radioanalytical and Nuclear Chemistry》1992,162(2):207-216
Extraction of uranium(VI), thorium(IV) from nitric acid has been studied with N-octylcaprolactam and N-(2-ethyl)hexylcaprolactam. Distribution coefficients of U(VI), Th(IV) and HNO3 as a function of aqueous NHO3 concentration, extractant concentration and temperature have been studied. The compositions of extracted species, thermodynamic parameters of extraction have been evaluated. Third phase formation in extraction of U(VI) has been studied. Back extraction behavior of U(VI) and Th(IV) from the organic phase has also been tested. The results obtained are compared with those obtained by using TBP under the same experimental conditions. 相似文献
14.
15.
16.
(Micellar) electrokinetic chromatography: an interesting solution for the liquid phase separation dilemma 总被引:2,自引:0,他引:2
High-performance liquid chromatography (HPLC) is a well-established method in modern analysis. The method is simple, very robust and is applicable to the majority of components to be analyzed in contrast to gas chromatography. Low efficiency and small peak capacity are sore points of HPLC when complex mixtures have to be separated. The reason for this dilemma is the small diffusion coefficient of the analytes in the liquid mobile phase compared to a gaseous phase. This review, complemented by exemplary calculated data and some latest results of our own research, illustrates the dilemma of liquid phase chromatography to achieve high efficiencies under reasonable conditions. It is shown that (micellar) electrokinetic chromatography, offering fast and efficient separations, is a very promising solution for this dilemma. Additional features of this method are possibilities of on-line analyte concentration, coupling to mass spectrometry and the easy change of selectivities by applying various separation additives. The pros and cons of electrokinetic chromatography are pointed out and some application examples are given. 相似文献
17.
18.
19.
Thorium is quantitatively extracted with 4% Amberlite LA-1 or LA-2 in xylene, from 0.01M malonic acid medium at pH 3.0 and stripped from the organic phase with 1M hydrochloric acid, then determined spectrophotometrically at 545 nm as its complex with thoron. It is separated from other elements by selective extraction and stripping. 相似文献
20.
2,6-Diacetylpyridine bis(benzoylhydrazone) (H2DPBH) is proposed as a ligand for the extraction of uranium(VI). Complete extraction from aqueous solutions into dichloromethane is achieved with a ligand/metal mole ratio of < for 10?5?10?4 M uranyl ion. Potentiometric measurements indicate that the extracted species is UO2 (DPBH). Uranium can be determined in the extract by spectrophotometric measurements at 420 nm and by differentail pulse polarography (Ep = ?0.67 V) with tetraethylammonium bromide as supporting electrolyte. For both methods, the detection limit is about 2 × 10?6 M in the extract. 相似文献