XRF Measurements Research Articles

New complexes of 4-[(4-fluorophenyl)amino]-4-oxobut-2-enoic acid with selected transition metal ions: Synthesis, thermal, and magnetic properties

Complexes of 4-[(4-fluorophenyl)amino]-4-oxobut-2-enoic acid, HL, with Mn(II), Co(II), Ni(II), Cu(II), Nd(III), Gd(III), and Er(III) were synthesized and characterized by various physico-chemical methods: elemental analysis, FT-IR, TG, DTG, DSC, TG/FT-IR, XRF, XRD, and magnetic measurements using the Gouy’s method and a SQUID-VSM magnetometer. The complexes were found to be hydrates (except Er(III) complex) containing 1 to 4 molecules of water. The carboxylate groups acted as bidentate ligands.

Efficient reduction of nitric oxide using zirconium phosphide powders synthesized by elemental combination method

Zirconium phosphide (ZrP) powders were synthesized by elemental combination method via the direct reaction of zirconium powders with red phosphorus, and characterized by XRD, SEM, XPS, XRF, SAED and TEM measurements. The obtained ZrP powders were found to exhibit apparent activity in the ready eliminateion of nitric oxide (NO) via facile redox reactions, and the elimination dynamics was evaluated within the context of various important experimental parameters, such as reaction temperature and gas concentration. At a fixed amount of ZrP powders, an increasing amount of NO would be eliminated with increasing reaction temperature, and complete conversion of NO to N2 could be reached in the range of 700 to 800 °C. The addition of NH3 also facilitated NO elimination at a fixed reaction temperature. Furthermore, of the products of the elimination process, zirconia (ZrO2) powder is a kind of biocompatible material, red phosphorus can be used to produce safety matches, organophosphorous pesticide and phosphor bronze, and the produced N2 might be collected and used as a protective gas or be converted into liquid nitrogen for other purposes.

GEOMORPHOLOGY, SEDIMENTOLOGY AND GEOCHEMISTRY IN THE MARINE AREA BETWEEN SIFNOS AND KIMOLOS ISLANDS, GREECE

An extensive oceanographic survey was conducted in the marine area between Kimolos and Sifnos Islands, a rather poorly-studied sector of the Aegean Sea, in order to gain better understanding of submarine geomorphological features and associated sediment provenance. Multi-beam bathymetry and surface sediment sampling with a box corer were carried out on board R/V Aegaeo, followed by grain-size analysis, XRD and XRF measurements. A large circular depression was identified north of Kimolos reaching a water depth of 743 m, filled with fine grained sediments. Surface sediment distribution is characterized by gradual decrease in grain-size from silty sand to silt in a S-N direction. The mineralogical composition comprises calcite, Mgcalcite, aragonite, dolomite, quartz, K feldspars, plagioclase, amphiboles and clay minerals. Major sediment provinces identified were: (i) the shallow sector proximal to Kimolos, characterized by higher contents in Si, Al, K, Rb and Ba; (ii) the deep area west of Sifnos, including the large depression, characterized by higher contents in Fe, Ti, Na, Mg, S, Cr, Cu, Ni, V, Zn; and (iii) the south passage between Kimolos and Sifnos, which exhibits higher Ca, S, and Sr contents. Manganese enrichment was observed in and around the bathymetric depression, where Mn oxides act efficiently as scavengers of a suite of metals.

Glowing synthetic chlorohectorite: The luminescent features of a trioctahedral clay mineral

Clay minerals are versatile materials with numerous industrial applications. Their unique layered structure can act as a host for many optically active species. The synthesis and luminescence properties of chlorohectorite clays are now reported for the first time. The synthesized clays are composed of quasi-circular nanoparticles with diameters around 20–30nm showing blue/green emission and persistent luminescence with a duration of ca. 5s. The luminescence features are associated with titanium impurities in the chlorohectorite structure. It is shown that Ti can act as activator ion even at low concentrations: the XRF and ICP-MS measurements of the chlorohectorite materials indicate a Ti concentration around 60 ppm originating from the precursors. The XPS measurements of the clay materials showed the Ti 2p3/2 signals at 457.8 and 458.9eV associated with Ti3+ and TiIV, respectively. The excitation spectra confirm Ti3+ as the luminescent center in the chlorohectorites through the bands at 287 and 370nm, related to the e−(O2−(2p))→TiIV charge transfer and the electronic transitions from the t2g to eg levels of Ti3+, respectively. The persistent luminescence properties are due to structural defects common for layered silicates.

Synthesis and catalytic performance of bimetallic NiMo- and NiW-ZSM-5/MCM-41 composites for production of liquid biofuels

This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil (CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide (CTAB) surfactant with silica-alumina from ZSM-5 zeolite, prepared from natural kaolin by the hydrothermal technique. Subsequently, the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure, confirmed by XRD, SEM, TEM, EDX, NH3-TPD, XRF and N2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41 > NiW-ZSM-5/MCM-41 > Ni-ZSM-5/MCM-41 > Mo-ZSM-5/MCM-41 > W-ZSM-5/MCM-41 > NiMo-ZSM-5 > NiW-ZSM-5 > ZSM-5/MCM-41 > ZSM-5 > MCM-41. It was found that the bimetallic NiMo- and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products, identified by simulated distillation gas chromatography-flame ionization detector (SimDis GC-FID), are gasoline (150–200°C; C5–12), kerosene (250-300°C; C5–20) and diesel (350°C; C7–20). Moreover, the conversion of CPO to biofuel products using the NiMo- and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference (P> 0.05) at 95% confidence level, evaluated by SPSS analysis.

Bimetallic Au@Pt nanoparticles dispersed in conducting polymer—A catalyst of enhanced activity towards formic acid electrooxidation

Organic-inorganic hybrid system composed of bimetallic Au@Pt nanoparticles with diameter of a few nanometers uniformly dispersed in the conducting polymer matrix was synthesized by a simple electrochemical/chemical method on glassy carbon electrode. The elaborated catalyst demonstrates an enhanced specific catalytic activity (9.7Amg−1 Pt) in electrooxidation of formic acid. The reason of this improved performance is discussed in terms of the polymer structure used as the matrix for bimetallic catalyst and mechanism of formation of Au@Pt nanoparticles. Electrocatalytic activity of the hybrid systems obtained by means of two different procedures are compared to understand better the influence of the synthesis conditions on the properties of the catalyst. The composites are characterized by means HR-TEM, X-ray diffraction and X-ray fluorescence methods. Arrangement of nanoparticles in Au@Pt composite is determined by EDX elemental mapping. A new method of preparation of the samples embedded in thin polymer film for XRD and XRF measurements is proposed.

Waste dumpsites and public health: a case for lead exposure in Zimbabwe and potential global implications.

Most waste sites in Zimbabwe are not sanitary landfills but open dumps that indiscriminately receive waste from municipalities, industries, commercial establishments, and social services establishments. People, including children, who eke out a living through scavenging the dumps expose themselves to environmental pollutants at the dumps via inadvertent ingestion and inhalation of contaminated dust, and dermal absorption. The public is potentially being exposed to a slew of the pollutants via air, water, and food, all contaminated by uncontrolled leachates and aerially deposited dust and particulates from the sites. One of the unfortunate consequences of globalization is the sharing of contaminated food and the associated disease burdens; hence, regional contamination can have global impacts. We analyzed the levels of lead at two waste sites in Zimbabwe to assess the daily exposure levels of Pb to children and adults who scavenge the sites as well as determine levels of the heavy metal that are potentially contaminating air, water, soils, and food in the country. Levels of Pb ranged from 23,000 to 14,600,000µg/kg at one of the sites and from 30,000 to 1,800,000µg/kg at the other. Inadvertent daily exposure amounts that were calculated by assuming an inadvertent daily ingestion of 20-500mg of soil/dust were mostly higher than the provisional tolerable daily intake established by the World Health Organization for infants, children, and adults. The XRF measurements were validated using certified reference samples, 2710a (Montana soil) and 2781 (domestic sludge), from the National Institute of Standards and Technology.

Examinations of a Bronze Ingot Made of Fahlore

Abstract In Europe, the metallurgy of copper has been a tradition for thousands of years, which is also testified by relevant artifacts that can be found. A copper ingot of unknown origin was made available for the examinations. The surface of the ingot was characterized by a deposit of corrosion products from malachite and cuprite which could also be observed in cavities. XRF measurements resulted in Cu as the main component, up to 4 wt. % As, and 2.5 wt. % S, as well as smaller quantities of Sb, Ni, Fe, and Ag. This composition suggests the production from fahlores. A typical cast structure with copper dendritic areas and concentrations of the accompanying elements in the interdendritic areas could be observed. Delafossite crystals (Cu3Ni2SbO6) were verified on the ingot's top side (melt in contact with the air). The ingot is thus composed of an As bronze with a complex microstructure consisting of solid solutions, intermetallic phases, and sulfides.

A new composite sorbent based on SrBr2 and silica gel for solar energy storage application with high energy storage density and stability

The excellent matching between the sorption and desorption temperatures of hexahydrated SrBr2 and those required for solar heat storage for building applications, the high heat of reaction (67.5kJ/mol of water) coupled with the gain/loss of 5mol of water per mole of salt make this salt an appealing sorbent for solar thermal energy storage applications coupled to space heating. Due to the morphological instability of this salt, it is necessary to incorporate it in a porous matrix as a composite sorbent. A new composite material for thermochemical energy storage applications was developed. It consists of a mesoporous silica gel impregnated by strontium bromide with salt content equal to 58wt.%. The structure and the sorption properties of the composite were characterized by SEM-EDX, temperature dependent XRD, XRF, and N2 sorption measurements. The salt is homogeneously distributed inside the pores of the silica gel. Water sorption isotherms were measured between 20°C and 80°C, which enabled us to understand the sorption mechanism. A mathematical model was developed and used to fit the experimental data in order to predict the sorption behavior of the composite at different conditions (influence of temperature and pressure conditions on the cycle loading lift and energy storage density). The interest of using such a composite for thermal energy storage application is then discussed (thermal energy produced by solar collector and used for space heating). A high cycle loading lift of 0.22g/g is obtained corresponding to an energy storage capacity of 230Wh/kg and an energy storage density of 203kWh/m3 of packed bed composite (between 30°C and 80°C at 12.5mbar) is reported, with an excellent stability over 14 sorption/desorption cycles. The sorption kinetics of this composite is enhanced compared to pure salt. Test on a laboratory scale open type reactor gives a maximum specific thermal power of 200W/kg and a mean specific thermal power of 92W/kg at 30°C and 12.5mbar for an extent of reaction of 0.68.

Redistribution of elements between wastes and organic-bearing material in the dispersion train of gold-bearing sulfide tailings: Part I. Geochemistry and mineralogy.

Migration and redistribution of elements during prolonged interaction of cyanide wastes with the underlying natural organic-bearing material have been studied in two ~40cm deep cores that sample primary ores and their weathering profile (wastes I and II, respectively) in the dispersion train of gold-bearing sulfide tailings in Siberia. Analytical results of SR-XRF, whole-rock XRF, AAS, CHNS, and SEM measurements of core samples show high K, Sr, Ti, and Fe enrichments and correlation of P2O5 and Mn with LOI and Corg. Organic material interlayered or mixed with the wastes accumulates Cu, Zn, Se, Cd, Ag, Au, and Hg. The peat that contacts wastes II bears up to 3wt.% Zn, 1000g/t Se, 100g/t Cd, and 8000g/t Hg. New phases of Zn and Hg sulfides and Hg selenides occur as abundant sheaths over bacterial cells suggesting microbial mediation in sorption of elements. Organic-bearing material in the cores contains 10-30g/t Au in 2-5cm thick intervals, both within and outside the intervals rich in sulfides and selenides. Most of gold is invisible but reaches 345g/t and forms 50nm to 1.5μm Au0 particles in a thin 2-3cm interval of organic remnants mixed with wastes I. Vertical and lateral infiltration of AMD waters in peat and oxidative dissolution of wastes within the dispersion train of the Ursk tailings lead to redistribution of elements and their accumulation by combined physical (material's permeability, direction AMD), chemical (complexing, sorption by organic matter and Fe(III) hydroxides) and biochemical (metabolism of sulfate-reducing bacteria) processes. The accumulated elements form secondary sulfates, and Hg and Zn selenides. The results provide insights into accumulation of elements in the early history of coal and black shale deposits and have implications for remediation of polluted areas and for secondary enrichment technologies.

Unravelling the glass trade bead sequence from Magoro Hill, South Africa: separating pre-seventeenth-century Asian imports from later European counterparts

Excavations conducted between 2010 and 2012 at Magoro Hill, a site in South Africa’s Limpopo Province frequented or intermittently occupied by African farming communities since the first millennium AD, yielded a substantial glass bead assemblage. A selection of the beads was studied non-destructively by classifying them according to morphological attributes, supplemented by Raman analyses and XRF measurements. It became evident that a morphological classification of beads recovered from sites that include imports into Africa after the seventeenth century AD could be problematic due to apparent morphological similarities between earlier and later beads. This paper demonstrates the use and archaeological application of Raman and XRF measurements to separate earlier imported beads from later counterparts by identifying glass nanostructure, as well as pigments and opacifiers, which were not used in bead series pre-dating the seventeenth century AD. Results obtained from Raman and XRF measurements indicate that although some beads retrieved from Magoro Hill pre-date the seventeenth century and belong to the Indo-Pacific (K2, East Coast, Khami) and Zimbabwe series, the largest number of beads is from a later European origin. This ties in with the settlement history of the site, which suggests that it primarily served as a rendezvous for episodic rainmaking rituals before it became the stronghold and capital of a Venda chiefdom, headed by the Magoro dynasty, in the second half of the eighteenth century AD. The comparative analysis of the long bead sequence sheds new light on changing patterns in the availability, range, consumption and origin of glass trade beads imported into the northern interior of South Africa over a period of about 1000 years.

Preparation of Mo-Re-C samples containing Mo7Re13C with the β-Mn-type structure by solid state reaction of planetary-ball-milled powder mixtures of Mo, Re and C, and their crystal structures and superconductivity

Mo-Re-C compounds containing Mo7Re13C with the β-Mn structure were synthesized with high-melting-temperature metals Mo, Re, and C powders using a conventional solid state method with a planetary ball milling machine instead of the arc melting method. Use of the ball milling machine was necessary to obtain Mo7Re13C with the β-Mn structure using the solid state method. Almost single-phase Mo7Re13C with a trace of impurity were obtained using the synthesis method. By XRF and lattice parameter measurements on the samples, Fe element existed in the compound synthesized using the planetary ball milling machine with a pot and balls made of steel, though Fe element was not detected in the compound synthesized using a pot and balls made of tungsten carbide. The former compound containg the Fe atom did not show superconductivity but the latter compound without the Fe atom showed superconductivity at 6.1K.

Characterization and adsorption properties of the electrolytic carbon derived from CO2 conversion in molten salts

The amorphous carbon derived from a “molten salt CO2 capture and electrochemical transformation” process, was characterized and studied for the adsorption of aqueous solutes. XRF and TG measurements showed that the electrolytic carbon (E-carbon) had a higher purity than the commonly available biochars and activated carbons due to its unique growth mechanism in molten salts. The analysis on morphology, diameter distribution and porosity indicated that the E-carbon, with an inhomogeneous porous structure, exhibited an average particle size of 9.8 μm in aqueous solution, and a BET surface area of 614 m2 g−1. The major surface oxygen-containing functional group for E-carbon was carboxyl group, which was primarily due to the cathodic deoxygenation of carbonate ions and the surface modifying effect of melt. The spontaneous Cu(II) adsorption by E-carbon followed the pseudo-second-order kinetic model and the Langmuir isotherm. Through the surface complexation and surface-precipitation processes, the E-carbon exhibited a maximum adsorptive capacity of 29.9 mg g−1 for Cu (II) adsorption. It also showed a good performance on methylene blue adsorption due to its favorable adsorption-related features, such as high purity, porosity and having a large number of surface functional groups. The E-carbon is envisaged to be used as an adsorptive material for decontamination.

A combined XRF/Monte Carlo simulation study of multilayered Peruvian metal artifacts from the tomb of the Priestess of Chornancap

An innovative methodological approach based on XRF measurements using a polychromatic X-ray beam combined with simulation tests based on an ultra-fast custom-made Monte Carlo code has been used to characterize the bulk chemical composition of restored (i.e., cleaned) and unrestored multilayered Peruvian metallic artifacts belonging to the twelfth- and thirteenth-century AD funerary complex of Chornancap–Chotuna in northern Peru. The multilayered structure was represented by a metal substrate covered by surface corrosion patinas and/or a layer from past protective treatments. The aim of the study was to assess whether this new approach could be used to overcome some of the limitations highlighted in previous research performed using monochromatic X-ray beam on patina-free and protective treatment-free metal artifacts in obtaining reliable data both on the composition on the bulk metals and on surface layers thickness. Results from the analytical campaign have led to a reformulation of previous hypotheses about the structure and composition of the metal used to create the Peruvian artifacts under investigation.

X-ray fluorescence spectroscopy and Monte Carlo characterization of a unique nuragic artifact (Sardinia, Italy)

The chemical composition of a unique bronze artifact known as the “Cesta” (“Basket”) belonging to the ancient Nuragic civilization of the Island of Sardinia, Italy has been analyzed by combining X-ray Fluorescence Spectroscopy (XRF) with Monte Carlo simulations using the XRMC code. The “Cesta” had been discovered probably in the XVIII century with the first graphic representation reported around 1761. In a later draft (dated 1764), the basket has been depicted as being carried upside-down on the shoulder of a large bronze warrior Barthélemy (1761), Pinza (1901), Winckelmann (1776) . The two pictorial representations differed only by the presence of handles in the most recent one. XRF measurements revealed that the handles of the object are composed by brass while the other parts are composed by bronze suggesting the handles as being a later addition to the original object. The artifact is covered at its surface by a fairly thick corrosion patina. In order to determine the bronze bulk composition without the need for removing the outer patina, the artifact has been modeled as a two layer object in Monte Carlo simulations.

XRF measurements of tin, copper and zinc in antifouling paints coated on leisure boats

Tributyltin (TBT) and other organotin compounds have been restricted for use on leisure boats since 1989 in the EU. Nonetheless, release of TBT is observed from leisure boats during hull maintenance work, such as pressure hosing. In this work, we used a handheld X-ray Fluorescence analyser (XRF) calibrated for antifouling paint matrixes to measure tin, copper and zinc in antifouling paints coated on leisure boats in Sweden. Our results show that over 10% of the leisure boats (n = 686) contain >400 μg/cm2 of tin in their antifouling coatings. For comparison, one layer (40 μm dry film) of a TBT-paint equals ≈ 800 μg Sn/cm2. To our knowledge, tin has never been used in other forms than organotin (OT) in antifouling paints. Thus, even though the XRF analysis does not provide any information on the speciation of tin, the high concentrations indicate that these leisure boats still have OT coatings present on their hull. On several leisure boats we performed additional XRF measurements by progressively scraping off the top coatings and analysing each underlying layer. The XRF data show that when tin is detected, it is most likely present in coatings close to the hull with several layers of other coatings on top. Thus, leaching of OT compounds from the hull into the water is presumed to be negligible. The risk for environmental impacts arises during maintenance work such as scraping, blasting and high pressure hosing activities. The data also show that many boat owners apply excessive paint layers when following paint manufacturers recommendations. Moreover, high loads of copper were detected even on boats sailing in freshwater, despite the more than 20 year old ban, which poses an environmental risk that has not been addressed until now.

Mössbauer spectroscopy and X-ray fluorescence studies on sediments from the methanic zone of the Helgoland mud area, North Sea

57Fe Mossbauer spectroscopy (MS) and X-ray fluorescence spectroscopy (XRF) were used to determine the identity of iron(III) oxides in surface (top 30 cm ) and subsurface (> 30 cm – 500 cm)sediments from the Helgoland mud area in the German Bight of the North Sea. A 500 cm-long sediment core was cut in 25cm sections while only the top 10 cm of a 30 cm-long sediment core was sampled. Using a MIMOS spectrometer, MS spectra were recorded at 293K (RT) in backscattering geometry. At 80K and 5.5K, MS analysis was carried out in transmission geometry. At RT and 80K only illite was observed, but at 5.5K lepidocrocite was revealed in the MS spectra. The relation between Fe(III) and Fe(II) doublets of illite did not significantly vary with depth, but the relative amount of lepidocrocite increased with depth reaching about 24 % of iron phases, as revealed by MS. XRF measurements showed that the amount of Fe in the sediments varied with depth but was always less than 4 % of total elemental composition. The main component of the sediment was silica and its depth profile alternated with those of other elements, especially aluminium and iron. It was observed that elevated concentrations of dissolved iron in the subsurface sediment of the Helgoland mud area correlated with the depth-wise distribution of distinct microbial populations presumably due to microbial reduction of excess bioavailable iron minerals such as lepidocrocite. These results are thus, important in the context of microbe-mineral interactions in marine sediments as iron oxides are an electron acceptor for microbial anaerobic respiration.

Analyses archéométriques de figurines de Myrina : commentaire rétrospectif / Archaeometrical analyses of figurines from Myrina: some retrospective comments

În baza de date a Laboratorului de Ceramologie din Lyon, la secțiunea Grecia de Est, există o serie de rezultate ale unor analize făcute prin fluorescență X ; ele se referă la eșantioanele cu sigla KAS, identificate ca fiind un lot de figurine din teracotă de la Myrina, lot transmis de D. Kassab-Tezgör în anii 80, dar măsurate și publicate de alte laboratoare în cadrul unui program de teste comparative. Aceste rezultate sunt reexaminate de articolul de față.

Archaeometric investigation of the hoard from Bodrogolaszi, Hungary

The hoard from Bodrogolaszi is a very significant find, dating back to the 15th-16th centuries. Unfortunately only 73 coins have survived from the original 135. In our study we would like to present the site, the circumstances of finding the hoard, and also a short numismatic introduction to these coins. We used stereomicroscopy to investigate the surface of coins, searching for additional artificial interventions (breaking, cutting, and fillip). We discovered darker reddish brown spots on several coins. We applied Raman spectroscopy to determine the origin of the spots. The results revealed they are part of a lepidocrocite­goethite cover layer caused by exposure to the soil. XRF measurements were used to prove that the purity of the coins differs from historical data.

The tin content of the blue-glazed Hutterite and haban ceramics — Implications for the production technology based on results of the handheld XRF and electron microprobe analyses

The Hutterites and Habans produced coloured-glazed, mostly blue- and yellow-coloured vessels alongside their white-glazed faience ware. However, the production technology of the coloured-glazed vessels, specifically the nature of the glaze, is a matter of debate among scholars. Both coloured tin glaze and coloured engobe covered with a transparent lead glaze were thought to have been applied on the ceramics. Around 140 objects of blue-glazed Hutterite and Haban museum objects and archaeological artefacts were analysed using a handheld XRF spectrometer. In addition, small fragments of selected ceramics were studied by electron microprobe analysis (EMPA). According to the XRF measurements the blue glaze of all except one of the studied Hutterite and Haban ceramics contains tin in variable amounts (from about 0.015 wt% up to 13 wt%). The EMPA technique showed that tin in the form of tin oxide opacifier was deliberately added to the single-layered alkali– lead or lead–alkali glaze. These data confirm that the tin glaze technique was used during production of blue-glazed ceramics, and in this respect they can be regarded as faience. The blue glaze of the Haban vessels produced by a “mining town” workshop contains tin in very low concentrations (Sn <0.2 wt% by XRF), therefore the opacity of the glaze is mainly caused by the abundant silica and arsenate particles.