微波消解-ICP-OES标准加入法测定钽炉灰中的钽

以氢氟酸和硝酸为溶剂通过微波消解对钽炉灰进行溶解,经分取、稀释后制得样品溶液. 对样品溶液进行半定量分析,保证校准溶液加入合适的钽量,制得系列校准溶液. 选择 Ta 240. 063 nm 为分析谱线,采用标准加入法消除测定过程中的基体效应,在电感耦合等离子体发射光谱（ ICP-OES）上对钽炉灰中的钽含量进行测定. 结果显示,绘制的工作曲线线性相关系数均在 0. 999 以上,测定结果的相对标准偏差（ n = 7）小于 0. 50%,加标回收率在94. 6% ~ 107. 9%之间.     

Ion exchange separation of trace amounts of uranium and thorium in tantalum for neutron activation analysis

Separation method of a few ppb of uranium and thorium in tantalum metal by ion exchange for neutron activation analysis was established. After dissolving tantalum metal by hydrofluoric acid, uranium and thorium were separated from tantalum using cation exchange resin column in 0.5M hydrofluoric –0.65M boric acid media. Both of the yields for uranium and thorium during separation were above 95% and the remaining amount of tantalum be lowered below 400 ng.     

Spektrophotometrische Bestimmung von Tantalspuren in Niob mit Malachitgrün

Traces of tantalum are separated from niobium by extraction from hydrofluoric acid solution with methylisobutyl ketone. The determination of the separated trace amounts of tantalum is based upon their conversion to a complex with malachite green, the absorbance of which is measured at 635 nm. 0.2 μg of tantalum can be determined in 0.5 g of niobium metal.     

Extraction Recovery of Tantalum(V) and Niobium(V) from Hydrofluoric and Hydrofluoric-Sulfuric Acid Aqueous Solutions with Octanol

Comparative study of extraction of tantalum(V) and niobium(V) with octanol and tributyl phosphate was made. The data on distribution of tantalum(V) and niobium(V) between octanol and hydrofluoric and hydrofluoric-sulfuric acid aqueous solutions were obtained. The flowsheet for preparation of pure tantalum and niobium oxides was developed.     

Spectrophotometric determination of niobium in tantalum metal

A new method for the determination of traces of niobium in tantalum metal has been developed. The niobium is separated from tantalum by solvent extraction with hexone from hydrofluoric acid-hydrochloric acid solution, and from molybdenum and tungsten by solvent extraction with oxine-chloroform solution from ammoniacal citrate solution. The niobium is then determined by the spectrophotometric thiocyanate method.     

Chemical separation procedure for the nuclide analysis of a tantalum target irradiated for 500 days with 800 MeV protons

A rapid radiochemical separation procedure has been developed for the determination of long-lived and stable nuclides produced by spallation and activation in a tantalum target irradiated for 500 days with 800 MeV protons. In this procedure the matrix element tantalum and simultaneously the¹⁸²Ta activity, built-up by activation of the matrix with themalized spallation neutrons is removed from many elements. About 50 mg of the sample is dissolved in a mixture of concentrated nitric and hydrofluoric acid. After dilution tantalum is extracted with a solution of 0.2M tetrahexylammonium bromide in methyl isobutyl ketone (MIBK). The residual amount of tantalum and the remaining¹⁸²Ta activity are 0.0003% and the recoveries of 27 investigated elements are in the range of 96.0–99.9%. A further 22 elements are quantitatively separated according to their chemical behavior. In the final aqueous fraction the separated long-lived and stable nuclides of 49 elements can be measured with high sensitivity by -ray spectrometry and mass spectrometry (ICP-MS).     

Extractive Recovery of Tantalum(V) and Niobium(V) with Octanol from Hydrofluoric Acid Solutions Containing Large Amounts of Titanium(IV)

Extractive recovery with n-octanol of tantalum(V) and niobium(V) from hydrofluoric acid solutions containing large amounts of titanium (up to 2-3 M) was studied. The conditions were found for separation of tantalum(V) and niobium(V) from titanium(IV), allowing recovery of 95.7 and 84.1% of tantalum and niobium fluoride complexes, respectively, in one extraction cycle, with 2.6% recovery of titanium.     

The quantitative separation and determination of tantalum and niobium using anion exchange chromatographY

A method is described for separating .and determining niobium and tantalum in mixtures of the two. A solution of the two elements in 3M hydrochloric.0.1M hydrofluoric acid is put on a column of Deacidite FF, the niobium is rapidly eluted with 3M hydrochloric.0.1M hydrofluoric acid and the tantalum is recovered by elution with 4M ammonium chloride-M ammonium fluoride. A complete separation is obtained and the two elements are recovered as their oxides after precipitation. The effecth of some other elements have been examined.     

Spectrophotometric determination of tantalum in ores and mill products with brilliant green after separation by methyl isobutyl ketone extraction of tantalum fluoride

A method for determining ~ 0.001% or more of tantalum in ores and mill products is described. After fusion of the sample with sodium carbonate, the cooled melt is dissolved in dilute sulphuric-hydrofluoric acid mixture and tantalum is separated from niobium and other matrix elements by methyl isobutyl ketone extraction of its fluoride from 1M hydrofluoric acid-0.5M sulphuric acid. The extract is washed with a hydrofluoric-sulphuric acid solution of the same composition to remove co-extracted niobium, and tantalum is stripped with dilute hydrogen peroxide. This solution is acidified with sulphuric and hydrofluoric acids and evaporated to dryness, and the residue is dissolved in oxalic-hydrofluoric acid solution. Tantalum is ultimately determined spectrophotometrically after extraction of the blue hexafluorotantalate-Brilliant Green ion-association complex into benzene from a 0.05M sulphuric acid-0.5M hydrofluoric acid-0.2M oxalic acid medium. The apparent molar absorptivity of the complex is 1.19 x 10(4) l.mole(-1).mm(-1) at 640 nm, the wavelength of maximum absorption. Common ions, including iron, aluminium, manganese, zirconium, titanium, molybdenum, tungsten, vanadium, tin, arsenic and antimony, do not interfere. Results obtained by this method are compared with those obtained by an X-ray fluorescence method.     

Niobium,tantalum, and titanium fluoride solutions

Parameters for the preparation of concentrated tantalum, niobium, and titanium fluoride solutions by dissolution of their oxides or hydroxides in hydrofluoric acid were studied. Anatase titania, niobium oxide, and tantalum oxide calcined to 900°C were found to have high dissolution rates. Solid phases separated upon the dissolution of niobium, tantalum, and titanium oxides in hydrofluoric acid were identified as NbO₂F, TaO₂F, Ta₃O₇F, and TiOF₂. Niobium hydroxide dissolution in an autoclave at the atmospheric pressure gave various complex salts: NH₄NbOF₄ and (NH₄)₃Nb₂OF₁₁.     

The separation and determination of niobium and tantalum by partition chromatography

A procedure is outlined for the separation and determination of niobium and tantalum by paper chromatography. A mixture of methyl isobutyl ketone and hydrofluoric acid was used as solvent and the metals were detected by means of 8-hydroxyquinoline. The minimum amount of each element detectable is 20 μg.

The procedure was applied successfully to the quantitative determination of small amounts of niobium and tantalum in a steel.     

Colorimetric determination of niobium in titanium alloys

There is need for a method for the determination of niobium in titanium alloys, since niobium-titanium alloys are becoming increasingly important. The determination of niobium in this type of alloy is an extremely difficult matter. Many approaches were tried before the problem was solved. In the method proposed in this paper the sample is dissolved in a mixture of hydrofluoric and nitric acids, the solution evaporated to a small volume, and boric acid added. Two tannic acid separations are then made to separate the niobium from the bulk of the titanium. The niobium, is determined colorimetrically by the thiocyanate method using a water-acetone medium. A study was made of the possible interference of elements that might be present in titanium alloys. It was found that the presence of tantalum causes two opposing tendencies. Tantalum can cause high results for niobium because it forms a complex with thiocyanate which is visually colorless but shows some absorption. Tantalum can cause low results for niobium by hindering the development of the niobium color. The resultant effect of the tantalum depends upon the amount of tantalum present, the amount of niobium present and the ratio of tantalum to niobium. The presence of more than one per cent. tungsten can lead to high results for niobium. Other elements that might be present in titanium alloys do not interfere with the method. The procedure is designed for titanium alloys containing 0.05 to 10 per cent. niobium. The method is reasonably rapid. Six determinations can be finished in two days. The method should be applicable to many other materials besides titanium alloys.     

Substoichiometric extraction of tantalum with diantipyrylmethane

Diantipyrylmethane is used for substoichiometric extraction of tantalum from 1—4M hydrofluoric acid into 1,2-dichlorethane. The selectivity of the method is good, niobium and antimony(V) being the main inteferences. The stoichiometric composition of the tantalum/diantipyrylmethane complex is 1:1. The method was usef for the determination of trace amounts of tantalum (0.52 ± 0.05 μ g^?1) in a lake sediment (Bodensee/Lake Constance) by neutron activation/μ-spectrometry. Tantalum was determined in niobium samples by an isotope dilution procedure after separation of the matrix on a polyurethane foam column loaded with diantipyrylmethane.     

Isolation of niobium,tantalum, and titanium complex fluoride salts with alkali metal cations

Fluoride and oxofluoride salts of niobium, tantalum, and titanium were isolated. They precipitated from aqueous solutions and upon washing of organic extracts with aqueous solutions of ammonium, potassium, and sodium salts. The compositions of the isolated compounds were studied. Different compositions were established for the niobium salts that precipitated upon the dissolution of unwashed niobium hydroxide in hydrofluoric acid under the atmospheric pressure, in an autoclave, and upon addition of sodium, potassium, and ammonium salts to purely fluoride solutions of niobium, as well as for the tantalum ammonium and sodium salts isolated from aqueous and organic solutions. The data obtained can be used for the synthesis of niobium, tantalum, and titanium complex fluoride salts with various compositions.     

Determination of niobium, tantalum, zirconium, and hafnium by atomic emission spectrometry using directed thermochemical reactions

A method is proposed for determining niobium, tantalum, zirconium, and hafnium in mineral stocks. It is based on the preliminary synthesis of analyte complexes in hydrofluoric acid containing cadmium oxide. It was shown by spectrographic measurements that the decomposition products of complexes in a small chamber electrode of an ac carbon arc are volatile individual analyte fluorides.     

Determination of trace impurities in tantalum powder and its compounds by inductively coupled plasma optical emission spectrometry using solvent extraction

A procedure was developed for the analysis of 18 trace impurity elements in capacitor-grade tantalum powder (Ta), potassium tantalum fluoride (K₂TaF₇), and tantalum pentoxide (Ta₂O₅) using inductively coupled plasma optical emission spectrometry (ICP-OES). The detection limits achieved were in the ppb levels. The samples were dissolved in hydrofluoric acid (HF) in a microwave digestion system and the Ta matrix was extracted using cyclo hexanone. The impurity traces remained almost completely in the aqueous phase. The text was submitted by the authors in English.     

Determination of nitrate in pickling baths with a nitrate-selective electrode and a standard addition procedure

A reverse addition method for the determination of nitrate in pickling baths is described. Calibration solutions of nitric acid were added to the standard solution so that the slope and intercept of the electrode response function could be determined. The standard deviation of the method was better than 1 %. Nitrate in pickling baths containing hydrofluoric and nitric acids was measured and compared to measured hydrogen ion concentrations as a function of running time for the bath. The effects of iron(III) and hydrofluoric acid on the results were studied.     

The analysis of chromium, cobalt, iron, nickel, niobium, tantalum, titanium and zinc in cemented tungsten carbides with cobalt as a binder by inductively coupled plasma atomic emission spectrometry

 Inductively coupled plasma atomic emission spectrometry (ICP-AES) was applied as a rapid routine method for the analysis of cemented tungsten carbides. Chromium, cobalt, iron, nickel, niobium, tantalum, titanium and zinc were selected as major, minor and trace constituents in the material investigated. In the first step, the sample was treated with hydrochloric and orthophosphoric acid. The second step consisted of the simultaneous addition of hydrofluoric and nitric acids. Cemented tungsten carbides dissolved completely, leaving only minor quantities of carbon in the solution. Multiple linear regression proved to be very effective in the search for interfering elements. Using simple acid based standards, all the elements investigated could be determined individually from the complicated matrix using an appropriate method of calculation. The method described was successfully applied to real type commercial samples. The advantages of the ICP-AES method in comparison with the XRF-method are discussed. Received: 15 February 1996/Revised: 22 April 1996/Accepted: 2 May 1996     

Radiochemical multielement neutron activation analysis of tungsten

A radiochemical neutron activation technique for the detemination of 19 elements in high purity tungsten has been developed. It is based on extraction with diantipyrylmethane (for tantalum and antimony), substoichiometric extraction of molybdophosphate (for phosphorus) and anion-exchange chromatography (other elements) in hydrofluoric acid medium. The results obtained and achievable limits of detection are given. The effects of self-shielding and nuclear interfering reactions are discussed.     

Trace characterization of tantalum by NAA involving pre- and post-irradiation separations

Three different methods for pre-irradiation separation of the tantalum matrix combined with preconcentration of trace elements for NAA were developed. They involve selective extraction of tantalum with diantipyrylmethane, and anion- and cation-exchange from hydrofluoric acid medium. The role of the blank as the limiting factor for limits of detection and accuracy was one of the main aspects of this investigation. A conventional radiochemical NAA based on post-irradiation separation of the matrix radionuclides was also applied. The trace elements considered were Ag, Ba, Ce, Co, Cr, Cu, Eu, Hf, K, La, Mn, Mo, Na, Rb, Re, Sc, W, Y, Zn, Zr. The methods were used for the analysis of tantalum materials of different purity grades. The advantages and disadvantages of each technique are discussed and the achievable limits of detection are given.