X-ray Florescence Spectroscopy Research Articles

Photocatalytic Performance of Sn–Doped TiO2 Nanopowders for Photocatalytic Degradation of Methyl Orange Dye

The tin-doped TiO2 powders obtained by sol-gel and microwave-assisted sol-gel methods were investigated. The synthesis took place in a basic medium (pH 10, ammonium hydroxide, 25%) starting from tetrabutyl orthotitanate in its parental alcohol. In the case of the dopant, Tin(II) 2-ethylhexanoate as SnO2 precursor was used in the amount of 1, 2, or 4 mol % SnO2. Based on thermal analysis data, the powders were thermally treated in air, at 500 °C. The comparative investigation of the structure and morphology of the nanopowders annealed at 500 °C was performed by scanning electron microscopy (SEM), high-resolution transmission electron microscopy with selected area electron diffraction (HRTEM/SAED), scanning transmission electron microscopy (STEM) coupled with EDX mapping, Fourier transmission infrared (FTIR), UV–Vis, Raman and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), and X-ray florescence spectroscopy (XRF). The obtained materials were tested for the photocatalytic removal of methyl orange dye from aqueous solutions. High degradation efficiencies (around 90%) were obtained by Sn doping after 3 h of UV light irradiation.

Anorganické zatížení říčních sedimentů řeky Olše a jejích významných přítoků

The main objective of research was to assess the current level of bottom sediment and water pollution of the Olše River and its tributaries. The Olše River is an important stream in the Upper Silesian Basin which was significantly affected by coal mining and industrial activities in the past (Martinec et al. 2006). Monitoring of the area by the Povodí Odry State Enterprise (the Odra River management) has shown that the water quality in the river has significantly improved due to the development of municipal wastewater treatment plants. Currently, saline waters from coal mines in the Karviná sub-basin are considered to be the biggest threat to the river environment. A total of 19 river sediment and 9 surface water samples were collected (Fig. 1). The elemental content was determined using X-ray florescence spectroscopy (XRF); for selected river sediments, the organic carbon content was determined using the Elementar Vario TOC CUBE device. The loading of river sediments by elements was evaluated using Igeo Class. The content of major ions (HCO3–, K+, Ca2+, Na+, Mg2+, SO42– and Cl–) in the surface water samples was determined in the laboratory. The water in the Olše River belongs to the hydrochemical type of Ca-HCO3. The water in the Karvina Creek near the mining works is highly mineralised and represents a single case of the Na-Cl hydrochemical type. Despite the significant mineralisation level, the water from this creek does not significantly affect the quality of the water in the Olše River. The highest enrichment of river sediments compared to the natural background was found for Zn (Table 1) at all sites. Zinc is one of the elements with rather high mobility and tends to be bound to hydrated Fe and Mn oxides that occur in rather large quantities on adjacent spoil heaps in the area and can thus enter the system very quickly. The Mn (340 to 2,553 mg/kg) as well as Sr (71 to 1,836 mg/kg) concentrations are elevated compared to those in global shales (850 mg/kg and 300 mg/kg, respectively; Turekian – Wedepohl 1961). Their contents in the Upper Silesian Coal Basin river sediments should be systematically monitored. The Olše River sediments were slightly to moderately contaminated with Cr and Pb (Table 1). This is not considered to be related to mining but rather to road runoffs and the fact that the river flows through industrial areas.

Determination of metals in children's plastic toys using X-ray florescence spectroscopy.

Children's toys may contain substances that children can be exposed to via multiple pathways. The aim of this study was to assess the presence of metals in children's plastic toys using X-ray florescence. Fifty-six children's plastic toys were purchased from several wholesale markets, supermarkets, and retail stores in the UAE, and fifty-four out of them were labeled "Made in China." X-ray fluorescence analysis was conducted on 442 samples from 56 toys to investigate the elemental composition of the toy material. The elements detected with higher frequencies were Ti (100%), Cl (78.6%), Zn (67.9%), Si (66.1%), Iron (48.2%), and Cu (16.1%). Chromium and nickel were detected only in one toy with low concentrations, while Pb was not detected in any of the toys analyzed. In conclusion, the analyzed plastic toys contain metals and the presence of these metals in some cases may pose a health risk to children. Chlorine presence in more than three quarters of toys may indicate that the toys were made of PVC. The study revealed the presence of titanium and silicon in toys. However, more research is needed to verify their role in toys and to identify associated health risks. The study did not reveal toxic elements such as Pb, Cd, and As.

Thermochemical Conversion of Waste Glass and Mollusk Shells into an Absorbent Material for Separation of Direct Blue 15 Azo Dye from Industrial Wastewater.

The objective of the presented work was to convert waste glass and mollusk shells into a porous material for separation of the direct blue 15 azo dye from industrial wastewater. The porous glass material of specific pore size and surface area was prepared through a thermochemical reaction by reacting waste glass with mollusk shells, soda, and rock salt. The optimal reaction conditions were determined by adjusting the reaction time, reaction temperature, and relative amount of the reactants. The surface morphology, elemental composition, and functional groups of the material were studied through scanning electron microscopy (SEM), X-ray florescence spectroscopy (XRF), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FT-IR). Barrett–Joyner–Halenda (BJH) and Brunauer–Emmett–Teller (BET) methods were used to determine the pore size distribution and surface area of the porous material. The material consisted of different types of flakes, oval-shaped particles, and granules. In addition to the functionalized char, the porous material contained Si–O–Si, Si–O–Al, and Si–OH groups. Relatively better yield and pore size distribution were obtained at a reaction temperature of 800 °C and reaction time of 90 min. The fully characterized material was used to separate the blue dye from industrial wastewater. This porous material absorbed about 2.66 mg/g blue dye from wastewater after 20 min of treatment time. The adsorption data fit the Freundlich isotherm better than the Langmuir isotherm. The correlation coefficient of Freundlich isotherm varied from 0.93 to 0.98, which was slightly higher than the correlation coefficient of Langmuir isotherm.

In Situ Failure Investigation of Weld Cracking in a Linz–Donawitz Vessel

Linz–Donawitz (LD) vessel is an integral part of the blast furnace–basic oxygen furnace route of steelmaking. Failures of the LD vessel can result in safety issues as well as production loss. In the event of any such failure, the thrust should be to carry out the investigation at the minimum lead time and suggest for corrective actions to prevent any recurrence in the future. For this purpose, an on-site or in situ nondestructive method of investigation can be extremely useful. Present work is a case study of analysis of cracking of the shell of a vessel. Visual observation revealed that a large crack of around 6.5 m length developed at the bottom of the top cone connected to the vertical portion of the vessel shell by means of welding. Crack had propagated along the weld. The investigation consisted of chemical analysis using portable x-ray florescence spectroscopy, hardness testing across the weld and replica technique for microstructural analysis. These were aided by detailed analysis of refractory wall thickness measurements and thermography data for over a year. The study revealed that the failure occurred in thermo-mechanical fatigue mode from the weld joint due to use of inferior welding electrode. In contrast to the micro-alloyed base metal, no precipitation strengthening was present at the weld zone that resulted in the onset of softening mechanism therein. Recommendations are provided to prevent similar failures in the future.

Provenance of the stones used in plinths of the Achaemenid palaces of Borazjan, South-Western of Iran

Following the discovery of the Achaemenid palace of Charkhab of Borazjan in south-western of Iran, an extensive survey was conducted to identify and introduce the other possible Achaemenid palaces in this region, which then results to the discovery of two other palaces, called Bardak-Siah and Sangh-Siah. In order to determine the source of the peony white stones used in the plinths of these palaces, physical and chemical characterization techniques including Polarized light microscopy, X-ray diffraction, and X-ray florescence spectroscopy were used and then, the results obtained were compared to that of the samples of ancient quarries in the eastern mountains of Borazjan region. Among the ancient quarries of this region, the samples of Tangh-Ghir and Puzeh-Palangi quarries were selected and studied to match to the stones used at the historic palaces of the region. Based on the results of petrography analysis, peony white stone samples of Charkhab, Bardak-Siah and Sangh-Siah palaces, consisted of micrite groundmass along with sparitic and quartz inclusions, were identified as identical with the samples of Puzeh-Palangi quarry samples. However, samples of Tangh-Ghir ancient quarry, which had a micrite groundmass along with many microfossils, did not match to samples of the palaces. The palaces samples have a layered structure of sparitic groundmass along with the small amount of micrite. The results of XRD analysis showed that the peony white stones of the Achaemenid palaces are identical to those of Puzeh-Palangi quarry, where the main component is calcite with low contents of dolomite and quartz. Moreover, elemental analysis of the samples by XRF technique confirmed that the source of the peony white stones used at these palaces is Puzeh-Palangi quarry.

The dating of French gilt bronzes with ED-XRF analysis and machine learning

ABSTRACTThis study presents a method for estimating the date of production of Parisian cast gilt bronze artifacts from the late seventeenth to the early twenty-first centuries based on their elemental composition as measured by energy dispersive X-ray florescence spectroscopy (ED-XRF). Gilt bronzes are notoriously difficult to date; however, during this time period in France, both metallurgy and trade in metals were in a state of continual transformation. These technological and commercial transformations drove changes in the elemental composition of gilt bronzes produced by Parisian craftsmen over time. These changes in turn allow estimation of the manufacture date of gilt bronzes of unknown provenance based on their elemental composition. The composition of undated French gilt bronzes can be compared to a database of compositions derived from well-dated examples. In this paper, a database of 466 such observations collected using ED-XRF is presented as a basis for comparison. The use of an ED-XRF calibration protocol designed to deliver accurate and reproducible quantitative results (CHARMed PyMca) allows for data collected on multiple instruments to be aggregated in the database and for data collected by similarly calibrated instruments to be evaluated. A method for estimating the date of manufacture for unknown samples is presented using two machine learning techniques, support vector regression (SVR) and random forest regression (RFR). By using a simple combination of both models, an estimate of the time of manufacture may be made within ±37 years with a confidence of approximately 90%. This level of precision can be useful for distinguishing eighteenth century castings from nineteenth century copies as well as from castings made in the twentieth century.

Synthesis of silicon nanocomposite for printable photovoltaic devices on flexible substrate

Renewed interest has been established in the preparation of silicon nanoparticles for electronic device applications. In this work, we report on the production of silicon powders using a simple ball mill and of silicon nanocomposite ink for screen-printable photovoltaic device on a flexible substrate. Bulk single crystalline silicon was milled for 25 h in the ball mill. The structural properties of the produced silicon nanoparticles were investigated using X-ray diffraction (XRD) and transmission electron microscopy. The results show that the particles remained highly crystalline, though transformed from their original single crystalline state to polycrystalline. The elemental composition using energy dispersive X-ray florescence spectroscopy (EDXRF) revealed that contamination from iron (Fe) and chromium (Cr) of the milling media and oxygen from the atmosphere were insignificant. The size distribution of the nanoparticles follows a lognormal pattern that ranges from 60 nm to about 1.2 μm and a mean particle size of about 103 nm. Electrical characterization of screen-printed PN structures of the nanocomposite formed by embedding the powder into a suitable water-soluble polymer on Kapton sheet reveals an enhanced photocurrent transport resulting from photo-induced carrier generation in the depletion region with energy greater that the Schottky barrier height at the metal-composite interface.

Painted textiles: knowledge and technology in the Andes

Many Andean textiles are painted, a tradition practiced across the Andes as early as the Lithic period (ca. 10000‒4000 B.C.E). Despite its prevalence and aesthetics, research into painted textile technology is limited. Recently, samples from nine painted Andean textiles were collected from different museums and analyzed at the Getty Conservation Institute in Los Angeles. The samples represent a range of cultures, locations, and times. Analytical techniques included polarized light microscopy and X-ray florescence spectroscopy. Due to the paucity of published data on painted textiles, a comparison is made with mural paintings. Results show that Andean painters used a range of pigments, including ocher and cinnabar, and that pigments were chosen based on their chemical and physical characteristics from at least the Early Horizon period (ca. 950 B.C.E.‒200 C.E.) onward, although there were also cultural preferences for specific pigments. The quality of the cinnabar pigment especially shows that Andean painters had great technical knowledge and skills, superior to what was previously suspected. Patterns of pigment choice and application indicate that painted textiles were primarily produced for funerary purposes.

Multi-element and biomolecular analyses of soils as a means of sustainable site structure research on hunter–gatherer sites: A case study from the Canadian Arctic

Analyses of large open-air spaces on northern hunter–gatherer sites face many difficulties. A central concern is that open-air tasks such as large scale animal processing may leave behind little or no macro evidence. Many tasks did, however, introduce chemical residues into underlying soils. Chemical surveys of these soils offer a minimally invasive, sustainable means of investigating large open-air spaces, which can provide evidence for the structured use of such spaces. Defining structuring in the use of space, in turn, contributes to clarifying site functions, seasonality, and residential mobility. Exemplifying this approach, we present results from ongoing soil chemistry studies at a 2000year old Taltheilei hunter–gatherer encampment in the Canadian Arctic. Samples were analyzed using X-ray florescence spectroscopy (XRF), inductively coupled plasma-mass spectroscopy (ICP-MS), and Fourier transform infrared spectroscopy (FTIR). Patterning in the data was highlighted using principal component analysis (PCA) and inverse distance weighted interpolation (IDW). Anomalous concentrations of CaO, MnO, P2O5, and Cu were discovered adjacent to dwellings, representing hearth cleaning episodes. Along with these, enrichments in K2O, MgO, Fe2O3, Sr, Sc, Y, Cr, Ni, and Pb provide support for the presence of open-air animal processing facilities. We have also identified several peaks in our FTIR spectra that reasonably indicate trans-fat derived from ruminant tissue. At this stage of research, anomalies are attributed to caribou processing and refuse disposal during late fall occupations. While we are hopeful that FTIR will continue to develop as a valuable means of identifying fats in archaeological contexts, additional work will strengthen our current argument for the presence of trans-fats in our samples.

Characterization of Cu(In,Ga)Se2 (CIGS) films with varying gallium ratios

Cu(In1−x,Gax)Se2 (CIGS) absorber layers were deposited on molybdenum (Mo) coated soda-lime glass substrates with varying Ga content (described as Ga/(In + Ga) ratios) with respect to depth. As the responsible mechanisms for the limitation of the performance of the CIGS solar cells with high Ga contents are not well understood, the goal of this work was to investigate different properties of CIGS absorber films with Ga/(In + Ga) ratios varied between 0.29 and 0.41 (as determined by X-ray florescence spectroscopy (XRF)) in order to better understand the role that the Ga content has on film quality. The Ga grading in the CIGS layer has the effect causing a higher band gap toward the surface and Mo contact while the band gap in the middle of the CIGS layer is lower. Also, a wider and larger Ga/(In + Ga) grading dip located deeper in the CIGS absorber layers tend to produce larger grains in the regions of the films that have lower Ga/(In + Ga) ratios. Moreover, it was found that surface roughness decreases from 51.2 nm to 41.0 nm with increasing Ga/(In + Ga) ratios. However, the surface roughness generally decreases if the Ga grading occurs deeper in the absorber layer.

Investigation of Surface Modifications of Metals with Low-Pressure Plasma System

The effects of plasma exposure and impingement of energetic particles are now widely used for substrate cleaning as well as to assist and control thin film growth and various applications. Plasma technology is a versatile green technology used for surface engineering technology. Plasma sources have become a very useful tool for surface modification and deposition of various materials. In this work, typical treatments of the surfaces of Mn, Fe, W and Cu metals were carried out using a low-pressure plasma system with argon gas and operating with an aluminum cathode. The plasma ignition was produced by flowing argon gas between two metal electrodes, and the maximum discharge voltage was 3 kV. All the treated metal samples were exposed to the plasma for a constant time of 2 hours. The modified metal surfaces were characterized by in situ X-ray florescence spectroscopy (XRF), contact angle measurements and scanning electron microscopy (SEM). The wetting behavior of the treated metal surfaces was studied by employing the contact angle method. The contact angle is found to be dependable on the surface layer properties of the metals which in turn is affected by the dose time.

Spatial distribution of physico-chemical properties and function of heavy metals in soils of Yelagiri hills, Tamilnadu by energy dispersive X-ray florescence spectroscopy (EDXRF) with statistical approach

Soil physico-chemical properties were thought to be important factors in obscuring clear identification of pollutant sources. In the present study physicochemical properties such as, pH, electrical conductivity, bulk density, porosity density, soil texture and color were determined to identify the pollution status using different conventional analytical methods in soils of Yelagiri Hills, Tamilnadu. Soil pH ranges from 5.39 to 8.43 which indicate that the soils are acidic to alkaline in nature. The concentrations of selected heavy metals were determined using energy dispersive X-ray florescence spectroscopy (EDXRF) technique. In all the locations Al is the most abundant metal and Co is the least amount in soil. The relationship between the physico-chemical properties and heavy metals were studied by Pearson correlation. The statistical technique shows that strong significant correlation among the heavy metals. The Chemometric approaches namely: principal component analyses (PCA), hierarchical cluster analysis (HCA), were used for identify the soil pollutant. Spatial distribution of physico-chemical properties of soil such as pH, soil texture (sand, silt, clay) electrical conductivity was studied by geo-statistical methods such as kriging identified areas. The heavy metal mapping also attempted to know the distribution pattern in soils.

A novel, effective and low cost electrocatalyst for direct methanol fuel cells applications

Electrocatalytic oxidation of methanol in alkaline solution on a NiCd/C catalyst chemically modified by a leaching process of Zn was investigated. Scanning electron microscopy (SEM), X-ray florescence spectroscopy (XRF) and atomic force microscopy (AFM) were used for coating characterization. The electrochemical properties and behaviors and also kinetic values of alkaline leached NiCdZn/C catalyst were characterized using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The electrocatalytic activity of the alkaline leached NiCdZn/C catalyst toward methanol oxidation is shown to strongly depend on the porous and larger structure of coating and increasing of electrocatalytic active sites. The prepared catalyst in the present work is the most promising system for use in direct methanol fuel cells.

Environmental survey in the Tuul and Orkhon River basins of north-central Mongolia, 2010: metals and other elements in streambed sediment and floodplain soil

Streambed sediment and subsurface floodplain soil were sampled for elemental analyses from 15 locations in river basins of north-central Mongolia during August 2010. Our primary objective was to conduct a reconnaissance-level assessment of potential inputs of toxicologically important metals and metalloids to Lake Baikal, Russia, that might originate from mining and urban activities within tributaries of the Selenga River in Mongolia. Samples were collected in triplicate from all sites, then dried, and sieved to <2 mm for analysis by portable X-ray florescence spectroscopy and by inductively coupled plasma mass spectrometry after digestion with concentrated nitric and hydrochloric acids. Arsenic, copper, and mercury were greatly elevated in sediment and floodplain soil collected from tributary streams located near two major mining operations. Lead and zinc were moderately elevated in streambed sediment and in floodplain soil obtained from a small tributary in the capital city of Ulaanbaatar, but those concentrations were considerably less than probable effects benchmarks. Historical and possibly present mining activities have led to considerable metal contamination in certain tributaries of the Orkhon River in north-central Mongolia; however, metals originating from those sources did not appear to be accumulating in sediments at our downstream-most sampling sites located near the border between Mongolia and Russia.

Electrocatalysis of Ni-promoted Cd coated graphite toward methanol oxidation in alkaline medium

The nickel–cadmium (Ni-promoted Cd) catalyst for using direct methanol fuel cell (DMFC) applications is electrochemically deposited on a graphite substrate. The activity of methanol oxidation is assessed by recording cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) techniques. The surface morphologies and chemical compositions of catalysts are determined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray florescence spectroscopy (XRF). Mean roughness of catalysts is measured by atomic force microscopy (AFM). Kinetic parameters of oxidation such as the anodic electron transfer coefficient (αa), cathodic electron transfer coefficient (αc) and charge transfer rate constant (ks) are calculated. The effect of methanol concentration and temperature on methanol oxidation is also investigated. The electrochemical measurements show that the addition of Cd to single coating enhances the electrocatalytic properties for methanol oxidation and Ni-promoted Cd/C has the best catalytic activity and stability.

Multifunctional silver coated E-33/iron oxide water filters: Inhibition of biofilm growth and arsenic removal

Bayoxide® E33 (E-33) is a widely used commercial material for arsenic adsorption composed of a mixture of iron oxyhydroxide and oxides. Primarily used to remove arsenic from water, it is a non-magnetic, iron oxyhydroxide/oxide used in fixed bed pressure filters that generally lack multi-functionality. Like other adsorptive media, it is subject to surface fouling by precipitates, including iron and manganese, and biofilms that can create diffusion limitations. Modifying the surface of E-33 with silver nanoparticles to enhance the material properties could add multi-functionality and be beneficial, providing that the original arsenic adsorption properties are not compromised. Commercially available arsenic adsorption media (E-33) was combined to create core-shell composites, i.e. silver coated goethite (in magnetic and non magnetic forms), that is capable of removing arsenic, acting as an antibacterial, and has magnetic properties. Several green approaches were developed to prepare the silver coated goethite and it was tested for arsenic removal and antibacterial activity. Samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray florescence spectroscopy (XRF), and inductively coupled plasma mass spectroscopy (ICP-MS).

Tuneability of Sm (1 − x) Ce xFeO 3 ± λ perovskites: Thermal stability and electrical conductivity

Trimetallic perovskite oxides, Sm (1 − x) Ce x FeO 3 ± λ ( x = 0–0.05), were prepared by thermal decomposition of amorphous citrate precursors followed by calcinations. The material properties of the substituted perovskites were characterized by X-ray diffraction (XRD), X-ray florescence spectroscopy (XRF), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The doped materials exhibited a single perovskite phase in air up to 1350 °C and have specific surface areas in the range of 2.696–8.665 m 2/g. In reducing atmosphere (5%v/vH 2/N 2), the unsubstituted perovskite ( x = 0) decomposed into two phases while the ceria stabilized materials ( x = 0.01, x = 0.03, x = 0.05) remained in a single phase as revealed by XRD analysis. Their conductivities were measured by the four point probe method in air and in dilute hydrogen (5%v/vH 2/N 2) separately. The ceria substituted materials show increased stability versus reduction and phase separation for a wide temperature range (up to 1000 °C). Although undoped SmFeO 3 has higher conductivity under oxidizing conditions than ceria doped SmFeO 3 due its p-type nature, the situation is reversed under reducing conditions. The ceria substituted perovskites (Sm (1 − x) Ce x FeO 3 ± λ , x = 0–0.05) showed higher conductivity in reducing than in oxidizing conditions, suggesting that ceria doping at the A-site has changed the SmFeO 3 from p-type to n-type semi-conducting behavior.

Polysilicon Encapsulation Gettering with Electric-Field-Enhanced Isothermal Annealing for Copper Impurities in Bulk Silicon

A metal gettering strategy for copper in silicon, combining polysilicon encapsulation, isothermal annealing, and an external dc electric field is proposed. Experimental results have shown faster gettering of copper at the polysilicon layer to a higher concentration level above the copper detection limits of total reflection X-ray florescence spectroscopy. The improvement in the observed gettering efficiency is attributed to the directional drift-diffusion of copper interstitials to the effective polysilicon gettering sites, under the influence of the applied potential gradient and the thermally induced gettering concentration gradient, respectively, providing a simple and effective method for minimizing and monitoring of Cu content in bulk silicon wafers. (C) 2004 The Electrochemical Society.