Direct determination of uranium in sintered deeply depleted uranium oxide pellets by wavelength dispersive X-ray fluorescence spectrometry

This paper presents studies on direct non-destructive determination of uranium in sintered deeply depleted (DD) uranium oxide (UO₂) pellets by wavelength dispersive X-ray fluorescence (WDXRF) spectrometry. A special collet was designed and fabricated for holding the sintered DDUO₂ pellets for direct analysis, thus avoiding the sample preparation steps. The samples were analyzed using a calibration plot obtained from WDXRF spectra of matrix matched calibration standards. The WDXRF determined uranium values were found to be in very close agreement with titrimetric values and has reproducibility better than 0.05% (RSD, 1 s, n = 10) for the sintered DDUO₂ pellets having U: 86.81–88.04 wt%.

     

Analytical determination of colouring elements and of their compounds in glass beads from graveyards of the Merowings time

428 Monochrome beads from mainly female graves excavated at Groß-Gerau, Pleidelsheim and Weingarten (Germany) were examined by non-destructive methods, i.e. energy-dispersive X-ray fluorescence analysis (EDXRF), wavelength-dispersive X-ray fluorescence analysis (WDXRF) with fundamental parameter evaluation, and X-ray diffraction analysis. The results obtained by EDXRF were compared with those for beads from Donaueschingen and Eichstetten, published in former papers. In most cases the results obtained by WDXRF show very high contents of the colouring compounds, corresponding to a low glass quality. The diffraction measurements show crystalline colouring compounds at the surface of the glass beads that can be characterized as Pb₂SnSbO_6.5 for the yellow beads and as Cu₂O for the ochre beads.     

WDXRF, EPMA and SEM/EDX Quantitative Chemical Analyses of Small Glass Samples

Quantitative chemical analysis is a powerful tool for the classification and discrimination of small glass fragments in forensic and archaeometric analytical issues. In the choice of the analytical method the small dimensions and the irregular shape of the fragments must be accounted for. Several accurate and highly sensitive instrumental techniques successfully employed for the chemical analysis of small glass samples (AAS, ICP-AES and FAAS) are destructive, and therefore unacceptable for these applications. X-ray analytical techniques such as WDXRF, EPMA and SEM/EDX provide means for rapid, non destructive and sensitive multi-elemental analysis of glass fragments. In this study the analytical sensitivity and accuracy of WDXRF, EPMA and SEM/EDX for the analysis of small commercial glass fragments are investigated. The results are compared and discussed in order to establish a relation between the minimum size of glass samples and the accuracy and sensitivity of the analytical methods.     

Multielemental fast analysis of vegetation samples by wavelength dispersive X-ray fluorescence spectrometry: Possibilities and drawbacks

X-ray fluorescence spectroscopy (XRF) is universally recognized as a non-destructive method for rapid and sequential, or simultaneous analysis of elemental composition of a material. The use of this technique for the direct determination of chemical elements in plant matrices has increased over the last few years.In the present study, a wavelength dispersive X-ray fluorescence (WDXRF) method for the quantitative analysis of some major elements (Na, Mg, Al, P, S, K, Ca), trace elements (Mn, Fe, Co, Zn, As) and non-essential elements (Sr, Pb) in vegetation specimens has been developed. The method uses a quick and easy sample preparation procedure since only drying, pulverizing and pressing of the samples are necessary. The calibration procedure was established by employing four plant reference materials and several synthetic cellulose calibrators spiked with appropriate amounts of analytes. Matrix effects were corrected employing the method of the influence coefficients on the basis of the computerized routine program linked to the equipment.Trueness of the experimental procedure was checked by using the standard reference material GBW07602 “Bush branches and leaves”. In general, good agreement was achieved between certified values and the measured ones with recoveries ranging from 94% to 107%. Moreover, quality parameters, including repeatability and reproducibility of the developed method, were also evaluated.On the whole, from results obtained, WDXRF method proposed prove to be good and effective tool for environmental investigation and quality control processes in vegetation specimens.     

Nondestructive analysis of single crystals of selenide spinels by X-ray spectrometry techniques

The paper presents possibilities and difficulties in nondestructive analysis of small multielement single crystals performed by means of X-ray spectrometry techniques: micro-X-ray fluorescence spectrometry (μ-XRF), energy-dispersive electron probe microanalysis (ED-EPMA), and X-ray photoelectron spectroscopy (XPS). The capability of the X-ray spectroscopy techniques in elemental analysis is demonstrated with the single crystals of selenide spinels of the general formula M _x N _y Cr _z Se₄ (M⁺² and N⁺³ are, for example, Zn⁺², V⁺³, Ga⁺³, Cd⁺², In⁺³, and Sb⁺³). The results of the nondestructive analyses (μ-XRF, ED-EPMA, and XPS) are compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) and wavelength-dispersive X-ray spectrometry (WDXRF) following sample digestion. The present study shows satisfactory agreement between the results of μ-XRF analysis performed using the standardless fundamental parameter method and the results obtained with the WDXRF and ICP-OES analyses. If the measured single crystal is precisely positioned, the difference between μ-XRF and wet analysis (WDXRF and ICP-OES) does not exceed 5% rel. The reliable results of ED-EPMA can be obtained only if the measured area is sufficiently large, i.e., of 200 × 300 μm. Even if this condition is fulfilled, the relative difference between the ED-EPMA and the wet analysis may reach 10% rel. In case of the XPS analysis, the accuracy of results depends on the proper preparation of the sample surface. It should be free of contamination that can be obtained by scraping in situ in ultrahigh vacuum. The ion etching, commonly used for cleaning the surface, leads to preferential sputtering; therefore, the reliable results cannot be obtained.     

Determination of water content in silica nanopowder using wavelength-dispersive X-ray fluorescence spectrometer

A wavelength-dispersive X-ray fluorescence (WDXRF) technique that uses the scattered radiation of the X-ray tube lines and the fluorescence radiation of an element present in a powder sample is proposed as a non-destructive method for the determination of the water content in silica powder. Although direct X-ray fluorescence analysis of water using WDXRF is not adequate for the quantitative determination of water in powder, due to the very low fluorescence yield for hydrogen and oxygen, the fluorescence signal of silicon (Si) in silica powder is attenuated by water, and is shown to decrease in proportion to the water content in silica powder. In addition, it is demonstrated that the Compton- and Rayleigh-scattering of the X-ray tube lines is proportional to the water content. The coefficients of determination, R², of the linear regression equations obtained from the calibration curves for all individual scattered radiations and for the fluorescence radiation of Si were > 0.90. The sum of the peak intensities of the four scattering signals, i.e. the Rayleigh-scattered Rh K–L_2,3 and Rh K–M_2,3 lines, and Compton-scattered Rh K–L_2,3 and Rh K–M_2,3 lines, also showed fairly good linearity and sensitivity over a very wide range of water content from 0 wt.% to 61.5 wt.%. However, porosity had a significant effect on the X-ray signal at low water content, in the range from 0 wt.% to 7.5 wt.%, where the sensitivity for the silica nanopowder with well-defined mesopores (~ 3 nm in diameter) decreased to 0.40 kcps/wt.%, from 0.99 kcps/wt.% for the non-porous silica nanopowder. The use of the Si fluorescence signal along with the scattered radiation of the X-ray tube lines expands the applicability of conventional XRF spectrometers to the quantitative determination of water content in silica powder.     

Uncertainty measurement evaluation of WDXRF and EDXRF techniques for the Si and U<Subscript>total</Subscript> determination in U<Subscript>3</Subscript>Si<Subscript>2</Subscript> nuclear fuel

Uranium silicide (U₃Si₂), 20% ²³⁵U enriched powder, is an intermetallic compound used as nuclear fuel material, which is the state-of-the-art among nuclear fuel materials used in modern research reactors. It is produced by IPEN and used as nuclear fuel of the IEA-R1 reactor (IPEN/CNEN, São Paulo, Brazil); U₃Si₂ has 92.3 wt% U_total and 7.7 wt% Si. The qualification of this material requires chemical and physical tests such as Si and U_total content, isotope ratio, impurities, density, specific surface area and particle size determination. The Si and U_total were determined by gravimetric and volumetric procedures. Usually, these classical methods require a long time for analyses and are expensive. The objective of this study was to establish a fast and efficient analytical method to meet ISO/IEC 17025:2005 requirements in the Si and U_total determination. The X-ray fluorescence techniques (XRF) were chosen to allow a direct and non-destructive analysis, what is the main advantage compared to other instrumental techniques, since previous chemical treatments are not necessary. In this study, the performance of the wavelength dispersive (WDXRF) and energy dispersive (EDXRF) X-ray fluorescence techniques was evaluated. Furthermore, two different sample preparation procedures, plain powdered and pressed powdered, were evaluated. Statistical tools were used to evaluate the results and a comparison between these results and the conventional methods was done.     

Determination of small concentrations of hafnia in zirconia by selective excitation energy dispersive X-ray emission spectrometry

An energy dispersive X-ray fluorescence method is described for the determination of small concentrations of hafnia in zirconia. Bromine K X-rays from a secondary target in the form of a thick KBr pellet (excited by primary X-rays from a tungsten target X-ray tube) have been used to excite the analyte Hf L-lines selectively without exciting the matrix Zr K X-rays. The Hf L intensity vs. concentration relation was found to be linear in the concentration range 0.0–2.0 percent. The method gave a minimum detection limit of 45 ppm for 10 min (live) counting time. The results are discussed and the performance of this method is compared with those of WDXRF methods.     

Analysis of nuclear materials by energy dispersive X-ray fluorescence and spectral effects of alpha decay

Energy dispersive X-ray fluorescence (EDXRF) spectra collected from alpha emitters are complicated by artifacts inherent to the alpha decay process, particularly when using portable instruments. For example, ²³⁹Pu EDXRF spectra exhibit a prominent uranium L X-ray emission peak series due to sample alpha decay rather than source-induced X-ray fluorescence. A portable EDXRF instrument was used to collect qualitative spectra from plutonium and americium, and metal alloy identification was performed on a Pu-contaminated steel sample. Significant alpha decay-induced X-ray fluorescence peaks were observed in spectra obtained from the plutonium and americium samples due to the ²³⁵U and ²³⁷Np daughters, respectively. The plutonium sample was also analyzed by wavelength dispersive XRF (WDXRF) to demonstrate that alpha decay-induced X-ray emission has a negligible effect on WDXRF spectra.     

Analysis of Aluminum-Brass Corrosion Products in Sea Water and in Chloride Solutions

Abstract

A separation and chemical analysis method has been developed of corrosion products forming on aluminum brass surfaces immersed in sodium sulfate solutions at pH= 7.25 (simulating river water) and in sea water at pH= 8.2. This method is based upon a selective solubilization of various oxidation compounds with the aid of proper solvents (i.e. dissolving the metal matrix only to a negligible extent).

These analyses can be performed on oxidation films of more than 100 Å thickness. The following solvents were used:

1) Methanol for solubilization of Na⁺, Cu⁺⁺ and Zn⁺⁺ chlorides and sulfates;

2) Glycine to solubilize bivalent metal compounds:Cu and Zn oxydes oxysulfates, oxycarbonates, oxychlorides of Cu and Zn;

3) NH₄ OH to solubilize Cu⁺⁺ and aluminum compounds.

A fair agreement was observed between the formulae derived by stoichiometric calculation applied to chemical analyses and the values obtained by X-ray analysis.

Agreement was satisfactory for all compounds, except aluminum, determined by chemical analysis and identified by X-rays only in very thick oxidation films (≥ 10³ Å). The role of chemical analysis is therefore determinant to finalize the formation mechanism of aluminum brass passivation films.     

Stoichiometry determination of (Pb,La)(Zr,Ti)O3-type nano-crystalline ferroelectric ceramics by wavelength-dispersive X-ray fluorescence spectrometry

Analysis of small samples of lanthanum-doped lead zirconate titanate (PLZT) by wavelength-dispersive X-ray fluorescence spectrometry (WDXRF) is presented. The powdered material in ca. 30 mg was suspended in water and collected on the membrane filter. The pure oxide standards (PbO, La₂O₃, ZrO₂ and TiO₂) were used for calibration. The matrix effects were corrected using a theoretical influence coefficients algorithm for intermediate-thickness specimens. The results from XRF method were compared with the results from the inductively coupled plasma optical emission spectrometry (ICP-OES). Agreement between XRF and ICP-OES analysis was satisfactory and indicates the usefulness of XRF method for stoichiometry determination of PLZT.     

Application of multivariate calibration for simultaneous determination of major and minor constituents in U3Si2 by WDXRF technique

The aim of this work was to implement and to validate the multivariate calibration for simultaneous determination of major and minor constituents in uranium nuclear fuel by WDXRF technique. The method is nondestructive and involves no chemical treatments thus is possible to perform fast chemical analysis and produces no hazardous waste. The precision and accuracy achieved are statistically comparable to others sensitive techniques like ICP-OES for impurities determination.     

Investigation of tannery liming waste water using green synthesised iron oxide nano particles

ABSTRACT

The present study aimed that non-toxic, less expensive, easily available, safer to environment and previously unreported Eclipta prostrata leaf extract is used for the green synthesis of iron oxide nano particles. The iron oxide nanoparticles (NPs) were characterised by UV–visible, Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tannery effluents treated by photodegradation process and the removal efficiency of chemical oxygen demand (COD), biological oxygen demand (BOD) and sulphide were analysed. The maximum removal efficiency correlated with operating parameters was explained using response surface methodology with Boxmen Beckmen design.     

Determination of Hg from Cu concentrates by X-ray fluorescence through preconcentration on polyurethane foam

A methodology was developed for the separation and determination of microamounts of mercury from copper concentrate samples by wavelength dispersive X-ray fluorescence (WDXRF) after solid-phase extraction of mercury from iodide medium using polyurethane foam (PUF). The best sorption conditions for the Hg-KI-PUF system were settled using X-ray fluorescence technique after collection of ground PUF on a filter paper by vacuum filtration and direct measurement of the intensity signal of the sorbed mercury on PUF. The main parameters of sorption such as iodide concentration, pH, shaking time and sample dilution effect were studied. The system shows rapid kinetic sorption and maximum X-ray intensity signal was achieved after shaking for 2 min a 0.01 mol l⁻¹ iodide solution containing microamounts of mercury in the pH range from 1.0 to 9.0. Effective sorption up to a volume of 0.9 l allows preconcentration of mercury. A linear fit up to 50 μg mercury was obtained by the plot of the initial mercury mass in the bulk solution (0.5 l) vs. its respective XRF intensity signal measurement on ground PUF after the sorption process. The calibration sensitivity, quantification and detection limits found were 9.09 CPS μg⁻¹, 9.0 and 2.7 μg, respectively. The sorption of many elements was also evaluated under the best conditions. High concentrations of Cu(II) and Fe(III) interfere seriously. Mercury-selective separation could be achieved using citrate or EDTA as masking agent; no interference due to copper matrix samples was observed in citrate medium. This methodology was evaluated by recovery for mercury determination in copper concentrate ore samples supplied by a mining industry and copper sulfate salts; the results were between 98% and 106%.     

Characterization and differentiation of iron ores using X-ray diffractometry,k0 instrumental neutron activation analysis and inductively coupled plasma optical emission spectrometry

This study was aimed at developing methodology for the characterization and differentiation of iron ores from different ore deposits. X-ray diffractometry (XRD) was used for the determination of major and minor chemical phases in the ores, k₀-instrumental neutron activation analysis (k₀-INAA) and inductively coupled plasma optical emission spectrometry (ICP-OES) were employed for the determination of elemental profiles of iron ores. The quality of the ores was evaluated to establish their suitability to serve as a raw material for iron production. Principal component analysis was performed on the elemental data for the classification of ores. It was also shown that ores can be differentiated on the basis of rare earth elemental profiles. In this paper a new indicator, based on four elements (Ca, S, Sb, Yb), was proposed for the classification.

     

Chemical shifts of Kα and Kβ<Subscript>1,3</Subscript> X-ray emission spectra for oxygen compounds of Ti,Cr, Fe,Co, Cu with WDXRF

Chemical shifts and full widths at half maximum intensity (FWHM) of Kα and Kβ_1,3 X-ray emission lines and differences of full widths at half maximum intensity (ΔFHWM) using metallic element as reference for these emission lines were measured for oxygen compounds of elements in the range 22≤Z≤29 with a Wavelength-Dispersive X-Ray Fluorescence Spectrometer (WDXRF). It was also found larger chemical shifts and FWHM for Kβ_1,3 lines than those of Kα ones. It should be noted that the magnitude of the chemical shifts increases with increasing number of ligand atom.     

Determination of Mg, Ti and Cl in Ziegler-Natta catalysts by WDXRF

A method for determination of Mg, Ti and Cl in Ziegler-Natta (ZN) catalysts by wavelength dispersive X-ray fluorescence (WDXRF) spectrometry was developed. For comparative reasons, Ti was determined by spectrophotometry, Mg by complexometry and Cl by argentometric titration. Direct pressing was shown to be unsuitable for sample preparation due to catalyst decomposition. For Ti and Mg measurements, catalyst samples were calcinated at 1000 °C and pressed at 275 MPa. Their determination by the fundamental parameters based on the Ti Ka line measurement was shown to be equivalent to those results obtained by univariate calibration or by the classical methods. Cl was determined by aqueous extraction, followed by deposition on a support. Chloride loss was observed. Fixation of Cl as AgCl on polytetrafluoroethylene (FHLC) millipore membrane afforded the best results. Nevertheless, measurements by WDXRF were shown to be inferior to those obtained by argentometric titration.     

Preconcentration method for the determination of thorium in natural water by wavelength dispersive X-ray fluorescence spectrometry

The preconcentration of thorium from natural water and its determination directly by wavelength dispersive X-ray fluorescence spectrometry (WDXRF) were attempted. The first step consists of thorium preconcentration from slightly acid solutions on polyurethane foam (PUF) loaded with 2-etilhexylphosphonic acid (EHPA) reagent as solid phase. PUF held up to 50% (w/w) of the reagent and the preconcentration was maximum at the acidity of 0.25 mol^.l^-1 hydrochloric solution. Sorption on PUF had fast kinetics and 4.0 and 10 mg^.l^-1 detection and quantitation limits of thorium were achieved, respectively, as well as a R.S.D. of 4.2% at 21.7 mg^.l^-1. This method was successfully applied to natural water analyses. The results were in good agreement with reference values of water samples at 95% confidence level.     

Die Anwendung der Additionsmethode in der R?ntgenfluorescenzanalyse

Zusammenfassung Es wird eine Erweiterung der Additionsmethode in der Röntgenfluorescenzanalyse beschrieben, mit der gleichzeitig mehrere Elemente in Konzentrationen bis zu einigen Prozent bestimmt werden können. Dabei wird die Krümmung der in diesem Konzentrationsbereich nicht mehr linearen Eichkurve berücksichtigt.

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Application of the method of additions in X-ray fluorescence analysis

An extension of the method of additions in X-ray fluorescence analysis is described: it allows several elements in concentrations of up to a few percent to be determined simultaneously. Allowance is made for the non-linearity of the calibration curve at these concentrations.

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Herrn Prof. Dr. B. Timm zum 60. Geburtstag gewidmet.     

The determination of lead in total suspended air particulates by x-ray fluorescence spectroscopy

A method has been developed for the measurement of lead in air particulates collected on glass fiber filter paper with wavelength-dispersive x-ray fluorescence spectroscopy (WDXRF). Analyses conducted by both WDXRF and an EPA-approved procedure that employs acid sonication followed by analysis of the extract by atomic-absorption spectroscopy (AAS) shows excellent agreement between the two methods. WDXRF calibration was accomplished with standards prepared from known additions of Pb to unexposed glass fiber filter discs. Method equivalency has also been demonstrated by the analysis of several reference materials and the statistical analysis of quality control data. The WDXRF procedure has also been used to evaluate the distribution of Pb in the particulates across the surface of the filter.