Carrier Distillation Research Articles

A Comprehensive Investigation alongwith the Statistical Evaluation for the Characterization of Ilmenite Mineral by X‐ray Fluorescence Spectrometry and Optical Emission Spectrometry

AbstractA comparative investigation on characterization of ilmenite manuscript was performed by energy dispersive X‐ray fluorescence spectrometry (EDXRF) and carrier distillation direct current arc atomic emission spectrometry (D.C. Arc AES) along with the statistical evaluation of the data obtained. 5 % AgCl was used as carrier in AES to avoid spectral interference arising out of the emission rich matrix elements. An exercise was performed to evaluate the total uncertainty associated with the methodology for characterization of base reference materials. The developed methodologies were validated using synthetic samples. ∼30 % Fe and ∼35 % Ti as major elements alongwith Ca, Mg, Cr, Si, Al, Ni, Mn, V, Zr, Eu, Mo, Na and Cd as minor and trace level were reported in real ilmenite samples. Student t test was performed at 95 % confidence limit with 10 degrees of freedom revealed that the null hypothesis persisted, i. e. the data obtained by both the methods are reliable and within the limit of statistical fluctuation. The F test on variance revealed that all the variance estimated for all the analytes were less than the critical value (Fc=2.98) and hence the variance is also within the statistical fluctuation

Development of Methodologies for the Chemical Quality Control of Zircon, A Precursor for Zirconium Production

AbstractMethodologies have been developed for the chemical quality control of zircon mineral by EDXRF and D.C.Arc carrier distillation technique. EDXRF technique was found to be preferred for major and minor constituents including non‐metal analytes, while D.C.Arc carrier distillation OES was found to be good for minor and trace metallic constituents including low Z elements. A comparative evaluation of the analytical performance (detection limit, sensitivity, precision, linear dynamic range) was performed. A multipoint standardization was carried out using the base material of 1 : 1 SiO2 : ZrO2 powder mixture to establish calibration curves for the analytes after identification of interference free and the best performed emission and X‐ray analytical lines. In zircon sample, Si, Zr and Y were found to be present as major constituent, with Ga, Ca, Ru, Rh, Fe, Mn, Mg, I, S as minor and Zn, Cr, Sn, Li as trace constituents. The total uncertainty of the EDXRF measurements was evaluated. The statistical t‐test analysis was carried out for 10 degrees of freedom with 95 % confidence interval. The experimentally obtained t‐values were found to be lower compared to the corresponding tcri value revealing the reliability of the measurements. Elemental distributions of the analytes were also investigated using five different zircon samples.

Direct non-destructive total reflection X-ray fluorescence elemental determinations in zirconium alloy samples.

The development of a direct non-destructive synchrotron-radiation-based total reflection X-ray fluorescence (TXRF) analytical methodology for elemental determinations in zirconium alloy samples is reported for the first time. Discs, of diameter 30 mm and about 1.6 mm thickness, of the zirconium alloys Zr-2.5%Nb and Zircalloy-4 were cut from plates of these alloys and mirror polished. These specimens were presented for TXRF measurements directly after polishing and cleaning. The TXRF measurements were made at the XRF beamline at Elettra synchrotron light source, Trieste, Italy, at two different excitation energies, 1.9 keV and 14 keV, for the determinations of low- and high-Z elements, respectively. The developed analytical methodology involves two complementary quantification schemes, i.e. using either the fundamental parameter method or relative sensitivity based method, allowing quantification of fifteen minor and trace elements with respect to Zr with very good precision and accuracy. In order to countercheck the TXRF analytical results, some samples were analyzed using the DC arc carrier distillation atomic emission spectrometry technique also, which shows an excellent agreement with the results of the TXRF-based methodology developed in this work. The present work resulted in a non-destructive TXRF elemental characterization methodology of metal and alloy samples avoiding the cumbersome dissolution and matrix separation which arenormally required in other techniques and traditional methods of TXRF determination. In addition, the production of analytical waste could also be avoided to a large extent. Although the work was carried out for specific applications in the nuclear industry, it is equally suitable for other such samples in different industrial applications.

Determination of Major, Minor and Trace Metallic Constituents in Sillimanite: Comparative Evaluation of EDXRF and D. C. Arc Carrier Distillation AES

Determination of Major, Minor and Trace Metallic Constituents in Sillimanite: Comparative Evaluation of EDXRF and D. C. Arc Carrier Distillation AES

Development of an AES based analytical method for the determination of trace metallic impurities in uranium silicide dispersion fuel: from precursors to end products

An analytical method was developed based on the D.C. arc carrier distillation atomic emission spectrometric (D.C. Arc AES) technique for determination of trace metallic impurities (Al, Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Na, Ni, Si, Sn, Ti, V and Zn) in uranium silicide samples.

Etermination of Trace Metallic Constituents in Nuclear-grade BeO Matrix by D.C. Arc Carrier Distillation and ICP-AES: A Comparative Evaluation

etermination of Trace Metallic Constituents in Nuclear-grade BeO Matrix by D.C. Arc Carrier Distillation and ICP-AES: A Comparative Evaluation

Determination of analytes at trace level in uranium matrix by ICP-AES without chemical/physical separation

Determination of trace metallic constituents in nuclear materials e.g. U, Pu, Am, Zr etc. by Atomic Emission Spectroscopy requires the separation of the major matrix without the loss of analytes at trace level. For DC Arc carrier distillation technique, carrier is used to separate the matrix physically according to the volatility of the analytes while appropriate extractant in suitable diluent is used for chemical separation in inductively coupled plasma atomic emission spectroscopy (ICP-AES). In the present study an attempt was made to develop a methodology for the determination of B, Cd, Mg, Zn, Al, Sr and Sc at trace level (up to 0.1 μg/mL) in uranium matrix without any chemical or physical separation. It involves identification of suitable analytical lines of uranium for its ICP-AES determination; study the spectral interference of uranium to choose interference free analytical lines, optimization of instrumental and experimental parameters etc. The method was validated using synthetic samples.

THE USE OF DIGITAL IMAGE PROCESSING IN ANALYSIS OF BORON, CADMIUM IN THORIUM OXIDE WITHOUT CARRIER DISTILATION WITH EMISSION SPECTROGRAPH METHOD

THE USE OF DIGITAL IMAGE PROCESSING IN ANALYSIS OF BORON, CADMIUM IN THORIUM OXIDEWITHOUT CARRIER DISTILLATION EMISSION SPECTROGRAPH METHOD. The use of digital imageprocessing in direct determination elements of highly absorption cross-section of thermal neutron such as B andCd in nuclear fuel ThO2 without carrier distillation was described. Working and counter electrode should bemodified because volume of the sample was larger than the traditional one. Firstly, analysis of B and Cd in ThO2was recorded by X-ray film for thorax and then was proceeded by mini digital camera. All files in mini digitalcamera were transferred to computer and read by digital image processing of Matlab software. It was found thatall line spectra became Gaussian shape. Since couple of camera position and lightening system had not beendone successfully yet, therefore, quantitative analysis could not been done yet, meanwhile qualitative analysishad already been done by analysis spectra after image processing. It is easier to analysis B and Cd qualitativelyuse of image processing than densitometer instrument.Keywords : Thorium Oxide, Carrier Distillation, Image Processing, Digital Camera

Recovery of americium from analytical solid waste containing large amounts of uranium, plutonium and silver

Trace metallic impurity analysis by spectroscopic techniques is one of the important steps of chemical quality control of nuclear fuel materials. Depending on the burn-up and the storage time of the fuel, there is an accumulation of 241Am in plutonium based fuel materials due to β decay of 241Pu. In this paper, attempts were made to develop a method for separation of 241Am from 1.2 kg of analytical solid waste containing 70% U, 23% Pu, 5% Ag and 1–2% C as major constituents along with other minor constituents generated during trace metal assay of plutonium based fuel samples by d. c. arc carrier distillation atomic emission spectrometry. A combination of ion exchange, solvent extraction and precipitation methods were carried out to separate ~45 mg of 241Am as Am(NO3)3 from 15 L of the analytical waste solution. Dowex 1×4 ion exchange chromatographic method was used for separation of Pu whereas 30% TBP–kerosene was utilized for separation of U. Am was separated from other impurities by fluoride precipitation followed by conversion to nitrate. The recovery of Pu from ion exchange chromatographic separation step was ~93% while the cumulative recovery of Am after separation process was found to be ~90%.

Glycerol production by microbial fermentation: A review

Microbial production of glycerol has been known for 150 years, and glycerol was produced commercially during World War I. Glycerol production by microbial synthesis subsequently declined since it was unable to compete with chemical synthesis from petrochemical feedstocks due to the low glycerol yields and the difficulty with extraction and purification of glycerol from broth. As the cost of propylene has increased and its availability has decreased especially in developing countries and as glycerol has become an attractive feedstock for production of various chemicals, glycerol production by fermentation has become more attractive as an alternative route. Substantial overproduction of glycerol by yeast from monosaccharides can be obtained by: (1) forming a complex between acetaldehyde and bisulfite ions thereby retarding ethanol production and restoring the redox balance through glycerol synthesis; (2) growing yeast cultures at pH values near 7 or above; or (3) using osmotolerant yeasts. In recent years, significant improvements have been made in the glycerol production using osmotolerant yeasts on a commercial scale in China. The most outstanding achievements include: (1) isolation of novel osmotolerant yeast strains producing up to 130 g/L glycerol with yields up to 63% and the productivities up to 32 g/(L day); (2) glycerol yields, productivities and concentrations in broth up to 58%, 30 g/(L day) and 110–120 g/L, respectively, in an optimized aerobic fermentation process have been attained on a commercial scale; and (3) a carrier distillation technique with a glycerol distillation efficiency greater than 90% has been developed. As glycerol metabolism has become better understood in yeasts, opportunities will arise to construct novel glycerol overproducing microorganisms by metabolic engineering.

Trace Metal Assay of Uranium Silicide Fuel

A comprehensive trace metal assay of uranium silicide, a fuel for nuclear research reactors that employs low-enrichment uranium, is carried out by atomic spectrometry. Of the list of specification elements, 21 metallic elements are determined by a direct current (dc) arc carrier distillation technique; the rare earths yttrium and zirconium are chemically separated from the major matrix followed by a dc arc/inductively coupled argon plasma (ICP) excitation technique in atomic emission spectrometry (AES); silver is determined by electrothermal atomization-atomic absorption spectrometry (ETA-AAS) without prior chemical separation of the major matrix. Gamma radioactive tracers are used to check the recovery of rare earths during the chemical separation procedure. The detection limits for trace metallics vary in the 0.1- to 40-ppm range. The precision of the determinations as evaluated from the analysis of the synthetic sample with intermediate range analyte concentration is better than 25% relative standard deviation (RSD) for most of the elements employing dc arc-AES, while that for silver determination by ETS-AAS is 10% RSD. The precision of the determinations for four crucially important rare earths by ICP-AES is better than 3% RSD.

Preparation and Certification of Uranium Oxide (U3O8) Spectrometric Reference Materials

Abstract This paper describes the preparation, provisional certification, and certification of reference materials for the trace element analysis for uranium oxide (U3O8). The reference materials were prepared by the addition of solution pools containing the trace elements to a dry base of high-purity uranium oxide (U3O8) with subsequent mixing, drying, milling, and blending. Provisional certification was accomplished through an interlaboratory program in which four different laboratories analyzed the reference materials by carrier distillation d-c arc emission spectroscopy. The full certification of these reference material requires concordant results by two independent methods of analysis. Newer methods of analysis, such as graphite-furnace atomic absorption spectrophotometry and inductively-coupled plasma emission spectrometry, unavailable when the last reference material of this type was certified, have figured prominently in the certification of newer reference materials, a project now nearing completion.

Trace metal assay of thorium oxide by atomic emission spectrometry

An Atomic Emission Spectrometric (AES) method has been developed for the direct determination of twenty-two metallic elements at trace concentrations in thorium oxide. The method is based on the use of a d.c. arc — carrier distillation technique with 12% composition of a mixed carrier, viz. AgCl+SrF2 in 5:1 proportion, and is equally applicable to both volatile and refractory analytes. A direct reading emission spectrometer with computerised data acquisition and processing facility has been used in these studies. The standardisation procedure includes study of volatilisation/excitation characteristics of the analyte elements to optimise choice and proportion of the carrier and signal integration time apart from optimisation of other experimental parameters such as arc current, viewing position of the arc plasma, sample charge etc. The detection limits for the analytes lie in the range 0.1–50 ppm while the precision of determinations is better than 15% for most of the elements as evaluated from the repetitive analyses of spiked samples.

The Determination of Impurities in Plutonium Metal by Anion Exchange and ICP/AES

The determination of trace-metal impurities in plutonium metal was investigated with the use of anion exchange separation and analysis by inductively coupled plasma/atomic emission spectrometry. Data on recoveries and independent measurements for some 30 elements show precisions and accuracies in the 1–10% range, values that are a significant improvement over those of traditional carrier distillation techniques. Americium can be determined on the same sample aliquot, with figures of merit rivaling those of nuclear counting procedures.

Emission spectrographic determination of volatile trace elements in geologic materials by a carrier distillation technique

Trace levels of chalcophile elements that form volatile sulfide minerals are determined in stream sediments and in the nonmagnetic fraction of a heavy-mineral concentrate of stream sediments by a carrier distillation emission spectrographic method. Photographically recorded spectra of samples are visually compared with those of synthetic standards for the two sample types. Rock and soil samples may also be analyzed by comparison with the stream-sediment standards. A gallium oxide spectrochemical carrier/buffer enhances the early emission of the volatile elements. Detection limits in parts per million attained are: Sb 5, As 20, Bi 0.1, Cd 1, Cu 1, Pb 2, Ag 0.1, Zn 2, and Sn 0.1. A comparison with other methods of analysis, total-burn emission and atomic absorption spectroscopy, shows good correlation for standard reference for materials and samples from a variety of geologic terranes.

Convenient method for the determination of trace elements in solid samples using an inductively coupled plasma

A method for the determination of trace elements in solid samples is described. The sample is loaded into a graphite cup, which is inserted horizontally into the tail region of the inductively coupled plasma. Application of the method to carrier distillation analysis of impurities in uranium oxide shows that detection limits in the range 0.02–5 µg g–1 with a relative standard deviation of 4–12% are obtainable.

Spectrographic analysis of high-purity calcium oxide by a carrier distillation technique

Spectrographic analysis of high-purity calcium oxide by a carrier distillation technique

Selective volatilisation of trace metals from refractory solids into an inductively coupled plasma

Feasibility studies have been carried out on the use of a graphite electrode assembly for the introduction of U 3O 8 solid samples into a continuously running low-powered argon inductively coupled plasma for the assay of trace metallic elements in uranium. The d.c. arc carrier distillation procedure has been adopted here for the selective volatilisation of analyte elements from the refractory matrix by injecting analyte vapours into the central zone of the plasma using Scribner-Mullin electrodes covered with a graphite lid having a central opening. The experimental parameters have been optimised for the direct determination of B, Be, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Na, Ni and Pb in U 3O 8 powders. The analytical performance of the method has been checked by analysing spiked U 3O 8 samples and is seen to be comparable to or better than d.c. arc methods for these analytes. These results indicate that the carrier-distillation-ICP combination shows promise as a sensitive and precise method for analysis of trace metallic elements in a refractory matrix with a complex spectrum.

Carrier distillation-ICAP approach for trace metal assay of U3O8 powder

A new approach for the trace metal assay of U3O8 powder has been described. The carrier distillation technique used for selective volatilization of trace metals in U3O8 with d.c. arc excitation is adapted for the release of analytes from the solid sample into the ICAP source by inductively heating the sample. The experimental parameters have been optimised for the direct determination of Cd, Cu, K, Na, Ni and Pb. The performance of the method developed here is tested for the precision and accuracy of determinations by analysing spiked U3O8 samples and NBL U3O8 reference standards (standard deviation 2–9%). The method appears promising to be developed as a highly precise analytical optical emission spectrometric method as it adds to the ingenuity of the carrier distillation method, the advantages of ICAP.

Spectrographic determination of traces of B, Be, Cd, Si and Co in U3O8 by the d.c. arc cathode-region method

The cathode region of the d.c. arc emission of U3O8 has been photographed (0.6 mm below the cathode) from 2,200 to 3,400 A, using Scribner-Mullin carrier distillation electrodes. Along with the elemental spectra of trace impurities in U3O8, a well resolved Mulliken band (1Σ u + → 1Σ g + ) of the C2 molecule has been observed in the 2,300 A region and its intensity has been found to follow the excitation conditions of the arc. Using some of the well resolved rotational lines in the Mulliken band of C2 molecule as internal standard lines, the trace impurities with analytical lines in 2,200 –2,500 A region (B, Be, Cd, Si and Co) have been satisfactorily determined. This method offers several advantages compared to the well established “carrier distillation” and also the “cathode region” method described by Avni as it has a “built-in” internal standard.