X-ray Fluorescence Analysis Research Articles

Cost-effective synthesis and thermomechanical processing of AlxCoCrFeNiCuy (x&y=0.5,1) high-entropy alloys

This study investigates the cost-effective synthesis and thermomechanical processing of AlxCoCrFeNiCuy (x&y = 0.5,1) high-entropy alloys through cold (CR) and hot rolling (HR). The alloys were synthesized using a thermochemical modelling-assisted aluminothermic non-centrifugal, self-propagating high-temperature synthesis (SHS) method, which is reported for the first time in the literature. Remelting and suction casting were conducted via vacuum arc melting upon the compositional verification through x-ray fluorescence (XRF) and energy dispersive spectroscopy (EDS) analyses. The deformabilities and hardness values of the alloys were correlated with microstructural changes that were analysed through scanning and transmission electron microscopy (SEM, TEM). Among the master alloys, FCC-A1 based Al0.5CoCrFeNiCu0.5 (Al0.5Cu0.5) and Al0.5CoCrFeNiCu (Al0.5Cu1.0) alloys exhibited highest cold deformability (145% and 170%, respectively), accompanied by significant work hardening (114% and 108% increase in hardness, respectively), primarily attributed to dislocation-dislocation interactions. It has been demonstrated for the first time that equiaxed single phase (FCC-A1) Al0.5CoCrFeNiCu0.5 high-entropy alloy can be obtained through the CR + annealing. The alloys exhibited reduced hot formability (62% and 85%, respectively) partly due to the formation of Cr-rich sigma phase instead of the Al-Ni rich B2 phase, most notable in the Al0.5Cu0.5 alloy, contrary to the CALPHAD simulations. This led to increased hardness in the alloys through precipitation hardening, achieving similar hardness values as those obtained through cold rolling (CR) with less deformation. The findings support the conclusion that the presented integrated processing strategy offers a cost-efficient means of producing Al0.5CoCrFeNiCuy alloys with enhanced mechanical and chemical properties for various engineering applications by the selection of cold and hot rolling routes.

Elemental distribution patterns in rock samples from Egypt using neutron activation and complementary X-ray fluorescence analyses

The study utilized instrumental neutron activation analysis (INAA) and X-ray fluorescence (XRF) to accurately analyze the elemental composition of 28 felsite (rhyolite), rock samples. Statistical approaches, including bivariate and multivariate analysis, were employed to characterize the rocks and determine their origin. Major findings include significantly high levels of silicon (297000 ± 4000) mg/kg and low levels were noticed for gold (0.10 ± 0.01) mg/kg. The dominant major elements in the rocks were ranked as follows: silicon > aluminum > potassium > sodium > zirconium > calcium > zinc > manganese. A comparison with the upper continental crust (UCC) revealed higher levels for most elements, except for a few. The study also identified substantial amounts of uranium and thorium. Variations in elemental composition were observed both between different profiles and within felsite (rhyolite) rock samples, indicating heterogeneity and varying origins of the rocks. The findings contribute valuable baseline data for the area and highlight its economic significance for Egypt. Additionally, the study addresses the integration of results from different analytical methods, providing a comprehensive answer to this issue.

Nickel and/or platinum modified crystalline silicon–carbon composites and their electrochemical behaviour towards the hydrogen evolution reaction

Generation of hydrogen is very important, as it is one of the most desired alternatives to fossil fuels. Moreover, designing of cheap and stable electrocatalysts is the task for the efficient generation of hydrogen with reasonable activity. Materials hybridization can be considered a tool for engineering different material properties. Composites of modified silicon such as C–Si, Ni/(C–Si), Pt/(C–Si), and Pt–Ni/(C–Si) were prepared (in weight percent) and studied as electrocatalysts for the hydrogen evolution reaction (HER) in 0.5 M H2SO4 solution. The surface morphologies and chemical compositions of the composites were confirmed using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray fluorescence analysis (XRF), elemental mapping, and BET surface analysis. The electrochemical measurements of linear sweep voltammetry (LSV), Tafel plots, chronoamperometry, and electrochemical impedance spectroscopy (EIS) were used to study the behaviour of the prepared electrodes toward the hydrogen evolution process. Among the various prepared composites, [7%Pt–3%Ni]/[C–Si (1:1)] composite shows the best catalytic activity with the highest HER rate (940.95 µA cm−2 s−1), the lowest overpotential [0.358 V vs. (Ag/AgCl) ≈ 0.161 V vs. (RHE)] at 10 mA cm−2, and the lowest charge transfer resistance (2.657 Ω) compared to other prepared electrodes. In addition, it gives the highest values of 4.219 × 10−3 s−1 turn over frequency (TOF) and 642 mA g−1 mass activity. It shows good stability towards the hydrogen evolution reaction as the current density reaches about 34.28 mA cm−2 after 5 h.Graphical abstract

A field‐based evaluation of portable XRF to screen for toxic metals in seafood products

AbstractPortable X‐Ray Fluorescence (XRF) has become increasingly popular where traditional laboratory methods are either impractical, time consuming, and/or too costly. While the Limit of Detection (LOD) is generally poorer for XRF compared to laboratory‐based methods, recent advances have improved XRF LODs and increased its potential for field‐based studies. Portable XRF can be used to screen food products for toxic elements such as lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), manganese, (Mn), zinc (Zn), and strontium (Sr). In this study, 23 seafood samples were analyzed using portable XRF in a home setting. After XRF measurements were completed in each home, the same samples were transferred to the laboratory for re‐analysis using microwave‐assisted digestion and Inductively Coupled Plasma Tandem Mass Spectrometry (ICP‐MS/MS). Four elements (Mn, Sr, As, and Zn) were quantifiable by XRF in most samples, and those results were compared to those obtained by ICP‐MS/MS. Agreement was judged reasonable for Mn, Sr, and As, but not for Zn. Discrepancies could be due to (1) the limited time available to prepare field samples for XRF, (2) the heterogeneous nature of “real samples” analyzed by XRF, and (3) the small beam spot size (~1 mm) of the XRF analyzer. Portable XRF is a cost‐effective screening tool for public health investigations involving exposure to toxic metals. It is important for practitioners untrained in XRF spectrometry to (1) recognize the limitations of portable instrumentation, (2) include validation data for each specific analyte(s) measured, and (3) ensure personnel have some training in sample preparation techniques for field‐based XRF analyses.

Research and development of gold ore processing technology

This paper presents the results of technological studies of two samples of gold-bearing ore from the gold-bearing deposit of Kazakhstan deposits 1 and 2. A comprehensive analysis of ore samples by X-ray fluorescence, X-ray phase, chemical, and mineralogical methods was carried out. The calculated initial gold content was determined, and X-ray fluorescence analysis showed that the main elements that make up the ore are oxygen up to 51% and silicon up to 33%. X-ray phase analysis showed the presence of more than 95% quartz and muscovite in the samples. The form of finding gold in the ore, according to the results of mineralogical analysis, is defined as free gold and gold in iron hydroxide. Silver is present in the studied samples in the form of various types of halides. An ore beneficiation scheme has been developed and presented, including gravity and flotation. Gravity enrichment was carried out in two stages, with the production of concentrate and tailings, with the maximum recovery of gold in concentrate up to 91%, flotation enrichment using butyl xanthate reagents and a blowing agent, was carried out in two stages with the production of main and control concentrates and final flotation tailings. The subsequent hydrometallurgical study of the ore was carried out to assess the effect of sodium cyanide on the extraction of gold, tests were performed on the leaching of the initial samples of the ore and the obtained flotation and gravity concentrates in the agitation mode, it was found that cyanide leaching is an effective method for processing the mineral raw materials of the gold-bearing deposit of Kazakhstan, and the obtained flotation concentrates, with the recovery of gold into solution under optimal conditions up to 98%. The results obtained make it possible to predict the effectiveness of the main technological stages in the ore processing scheme, technology optimization, and maximum gold recovery.

TiO2 coatings on titanium obtained by anodising in a 2% Na2SiO3 solution at various voltages

Commercially pure titanium is recognised as one of the most biocompatible materials used in everyday medicine, particularly in prosthodontics. However, its high reactivity with oxygen and low thermal expansion makes titanium difficult to process, making it less popular as a material for porcelain fused to metal substructures. Analysing the available literature studies, both positive and negative effects of the oxide layer on the titanium-ceramic bond have been found. The given work attempted to anodically create oxide coatings in a 2% Na2SiO3 solution on commercially pure titanium, which could serve as substructures for crowns and dental bridges.Grade 2 titanium discs (diameter 20 mm, height 5 mm) were ground and polished. The alloy composition was determined by X-ray fluorescence analysis. The samples were divided into six groups and subjected to anodic oxidation in a 2% Na2SiO3 solution at constant voltages: 230 V, 270 V, 300 V, 350 V, 400 V, and a time of t = 1 min. The obtained oxide layers were examined by X-ray diffraction, chemical composition analysis, and SEM observation.Coating thicknesses ranging from 0.65 μm to 13.2 μm were obtained. Besides titanium oxide, an amorphous phase is present in the anodised layer.It is crucial to provide the ideal voltage directly related to the employed solution to maintain the useable thickness of the oxide layers. Variations in oxide layer thickness beyond optimal value may lead to exfoliating if it exceeds 1 μm or present fractures if it subceeds 1 μm.Titanium oxide layers obtained by anodic oxidation are mainly tested on their biocompatibility and tissue integration so important in implantology. However, the given paper focuses on creating oxide layers that may strengthen the bond between titanium and dental ceramics.

Investigation of the Biodistribution of Gd0.5La0.5F3:Eu Nanoparticles in the Internal Tissues of Laboratory Mice Using X-Ray Computed Tomography and X-Ray Fluorescence Analysis

Investigation of the Biodistribution of Gd0.5La0.5F3:Eu Nanoparticles in the Internal Tissues of Laboratory Mice Using X-Ray Computed Tomography and X-Ray Fluorescence Analysis

X-ray Fluorescence Analysis of the Composition of the Alloy of Rare Figural Weights of the 5th Century with an Image of the Emperor on the Throne

X-ray Fluorescence Analysis of the Composition of the Alloy of Rare Figural Weights of the 5th Century with an Image of the Emperor on the Throne

A NEW FIND OF A KUBAN-TYPE HELMET FROM THE NORTHWEST CAUCASUS

The article publishes the discovery of a new cast helmet of the “Kuban type” of the Early Scythian culture. The helmet is considered against the background of other similar cast helmets from the territory of Eastern Europe dating from the 7th–6th centuries BC. The authors discuss an assumption of the origin of East European cast helmets from the prototypes of the Zhou period from Northern China. Special attention is paid to the typological similarity and difference of East European specimens from similar finds from Central and East Asia. The paper proposes a variant for the reconstruction of the technology of mould manufacturing and casting of the product. The authors provide the results of X-ray fluorescence analysis of the metal in the published helmet and compare them with data on other known finds of Kuban type helmets. The comparison shows the difference in the composition of metal which they were made from.

Determination of Pozzolanic Activity of Buffalo Dung Ash to Utilize as Cement Replacement Material in Concrete

Increasing construction activity around the globe has raised the demand for cement to 4.4 giga-tonnes/year, making it costlier, and its consumption second to water. Meanwhile, a tonne of clinker produces a tonne of CO2 on a large consumption of natural resources of raw materials and energy of 10–11 EJ/year, which is why an affordable and environmentally sustainable substitute for cement is needed today. Pakistan possesses more than 30 million buffalos. Each can produce up to 15 kg of dung per day, resulting in 450 million kg of dung produced in Pakistan alone. This research aims to investigate the pozzolanic activity of Buffalo dung ash and determine the optimum conditions for developing the ash, along with the optimum dosage as cement replacing material in Normal concrete. For this purpose, five buffalo dung ash samples were prepared by calcining the dung in a muffle furnace for a 1-hour duration at 400°C, 500°C, 600°C, 700°C, and 800°C, and after cooling, sieving through a No. 100 sieve. The Strength Activity Index was determined as per ASTM C311. The results showed that developed ash at 600oC has a maximum Strength Activity Index of 94.2%, meeting the ASTM C618 standards for pozzolanic material, which was further confirmed by X-ray Fluorescence analysis. Furthermore, when 5%, 10%, 15%, and 20% of this ash were used as cement substitutes in concrete, the compressive strength increased by 11.2% on 10% substitution compared to the control mix. Based on the parameters investigated, it was found optimal to replace 10% of the cement in the concrete with buffalo dung calcined at 600°C for 1 hour.

Mineralogical and physico-chemical characterization of alluvial clays from Bamendou-Balessing (West Cameroon): Suitability for ceramics

The alluvial clays of Bamendou-Balessing (West Cameroon) are characterized to evaluate their potential for ceramic products. Four representative samples collected in the study area were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), differential thermal analysis (DTA) coupled with thermogravimetry analysis (TG), X-ray fluorescence (XRF) and physical analyses (particle size distribution and consistency limits). Firing properties of the specimens making from alluvial clays were determined. The alluvial clays are composed of clay minerals (45–64 wt%) dominated by kaolinite (92–98 wt%) with variable contents of illite (1–7 wt%) and vermiculite (0–2 wt%). The non-clay mineral phases are quartz (19–38 wt%) associated with variable proportions of K-feldspar (1–17 wt%) gibbsite (2–5 wt%) and goethite (1–12 wt%). The thermal behavior of the clayey samples shows dehydration of gibbsite and goethite at 281–288 °C and dehydroxylation of kaolinite at 521–524 °C. SiO2 (34.5–47.4 wt%), Al2O3 (25.4–29 wt%) and Fe2O3 (4.8–15.2 wt%) are the main major oxides. Samples G and YG present the most suitable physico-mechanical properties for fired bricks between 850 and 1100 °C (i.e. water absorption 19–29%, bulk density 1.49–1.81 g/cm3, compressive strength 12–23 MPa, metallic sonority, good cohesion). On the contrary, the samples R and B show poor physico-mechanical properties during firing due to their low fluxing agent (feldspar) content and high Fe2O3 content (9–15 wt%). The neoformation of mullite, spinel and cristoballite at 1100 °C occurs in specimens favoring the densification of the ceramic body.

Investigation of the Elemental Composition of Components of the Cutters of a Cold Miller by the Method of X-Ray Fluorescence Analysis

Purpose. Establishment of the elemental and quantitative composition of alloys - components of road milling cutters, which are used as working bodies for milling the road surface, by X-ray fluorescence analysis.Methods. To establish the chemical composition of alloys - components of cutters of a road milling cutter, WIRTGENW6/20X cutters and their domestic counterpart KZTS A6/20 were studied. The X-ray fluorescence method was chosen to study the elemental composition of the components of the road milling cutters. This method, based on the interaction of X-ray radiation with the analyzed substance, is the most effective and efficient method of analysis, which allows obtaining complete and reliable information about the elemental composition of complex samples in a minimum period of time without destroying them, while maintaining all the physicochemical properties, as well as without using a reference sample. The method is based on the correlation between the X-ray fluorescence intensity and the element concentration in the sample. As a result of irradiating the sample with an X-ray flux, a characteristic emission of atoms is created, which is proportional to their concentration in the sample. With the help of an express analyzer of metals and alloys - the Niton GOLDD spectrometer, experimental data were obtained on the composition of alloys - components of cutters of a road milling machine.Results. During the study, it was revealed that the components of the cutters are made from the following alloys:1. Cutter WIRTGEN W6/20X:- tip made of hard sintered alloy VK8;- housing made of structural alloyed steel 32G2;- spring sleeve of the cutter made of structural carbon steel 08ps;- washer made of structural quality carbon steel 60.2. Cutter KZTS A6/20:- tip made of hard sintered alloy VK8;- housing made of structural alloyed steel 38XV;- spring sleeve made of structural quality carbon steel 40;- washer made of structural alloyed steel 45G.Conclusion. The obtained research results can be used for subsequent processes of hardening or restoration of cutters of road milling machines.

Obsidian in the Valley of Volcanoes, Peru

The Andagua Valley in the Department of Arequipa of southern Peru has only recently seen systematic archaeological investigations, revealing ancient agricultural communities that, despite apparent geographic isolation, were integrated economically with the wider Andean world. Portable x-ray fluorescence analysis of 137 obsidian artifacts recovered from sites in the lower Andagua Valley identifies the transfer of obsidian from Peru’s three largest sources, with > 90% of the analyzed artifacts coming from the Alca-1 source northwest of the valley. In addition to Alca-1 obsidian, small amounts of obsidian from the distant sources of Chivay and Quispisisa appeared in distinct contexts associated with local pre-Inka occupations, corresponding with the Middle Horizon and Late Intermediate Periods (600 – 1000 and 1000 – 1400 Common Era). Obsidian from the Alca-4 and Alca-5 sources, originating on the adjacent plateau, was also transported to Andagua during these periods, possibly continuing under Inka imperial expansion after 1400 CE.Because there is no archaeological evidence of either Wari or Tiwanaku states in the lower Andagua Valley, the probable mechanisms of obsidian transfer include direct or down-the-line exchange between plateau-based camelid pastoralists and valley farmers. Therefore, at least some long-distance obsidian transfers in southern Peru were carried out without direct oversight from Wari or Tiwanaku, though these transfers may have been facilitated by region-scale economic integration during the Middle Horizon and Late Intermediate Period. Tracing the distribution of obsidian in the Andagua Valley highlights both intra-valley and inter-zonal relationships between the Valley of the Volcanoes and specific areas of the high-elevation Andean plateau while illuminating dynamic economic and social connections along the central Andes in the pre-Hispanic past.

Bulk Compositional Influence on Diverse Metapelitic Mineral Assemblages in the Whetstone Lake Area, Ontario

Abstract Understanding the interplay between bulk composition and metamorphic grade underpins our interpretations of metamorphism in orogenic belts. The focus of this study is the regional garnet–staurolite–kyanite–sillimanite metamorphic sequence of the Whetstone Lake area, southeastern Ontario. In the kyanite and lower sillimanite zones of this area, there is exceptional diversity in metapelitic mineral assemblages that cannot be accounted for by differences in metamorphic grade. We present a data set of petrographic observations, phase proportions, whole-rock geochemical compositions, and mineral compositions, from thirty-two samples that encapsulate the range of assemblages found in these zones. Differences in bulk composition are the primary control on mineral assemblage development. Whole-rock XMg = molar MgO/(MgO + FeO) and ${\textrm{X}}_{\textrm{Fe}^{3+}}=\kern0.5em \textrm{molar}\ 2\times{\textrm{Fe}}_2{\textrm{O}}_3/\left(2\times{\textrm{Fe}}_2{\textrm{O}}_3+\textrm{FeO}\right)$ exert the greatest control on the observed mineral assemblages, whilst variation in MnO, K2O, and Al2O3 have a secondary influence. We use a set of quality factors ( Duesterhoeft & Lanari, 2020) to test the ability of thermodynamic models to reproduce the observed mineral assemblages, modal abundances, and mineral compositions in the diverse bulk compositions at Whetstone Lake. Eight samples were selected for phase equilibrium modelling, for which two bulk compositions were calculated for each sample: (1) a whole-rock bulk composition based on an X-ray fluorescence analysis and (2) a carefully considered local bulk composition based on combining mineral proportions with representative mineral compositions, as obtained from a single thin section. Our modelling uses thermodynamic data set 6.2 ( Holland & Powell, 2011) and the solution models of White et al. (2014a, 2014b) that incorporate several Fe3+ end members needed to model the natural data. Modelling in both types of bulk composition broadly predicted mineral assemblages that match those observed. In addition, predicted mineral assemblage fields overlap within uncertainty between 620°C and 675°C and between 6.5 and 7.5 kbar, consistent with the limited range of grade represented by the natural rocks. Predicted modal abundances better match those observed when phase diagrams are constructed using local bulk compositions compared to whole-rock bulk compositions. Despite the acceptable agreement between predicted and observed mineral assemblages, consistent discrepancies are found between predicted and observed mineral compositions. These include overestimation of ${\textrm{X}}_{\textrm{Mg}}^{\ast }$ in garnet, staurolite, and cordierite, overestimation of Ti in staurolite and biotite, underestimation of Si in biotite, and overestimation of Al and underestimation of Fe3+, Fe2+, and Mg in muscovite. The Whetstone Lake suite of this study will be useful to test the predictive capability of future thermodynamic models.

Natural and thermally stimulated aging of nanosized powders of cobalt ferrospinel

This article presents the production of nanosized powders of cobalt ferrospinel through mechanochemical synthesis, resulting in an average particle size ranging from 3 to 15 nm. The elemental composition of the nanopowders, analyzed using X-ray fluorescent analysis, is found to be nonstoichiometric and can be represented by the formula: Co0.7±0.05Fe2.3±0.05O4 . When the duration of mechano­chemical synthesis exceeds 25 min, the spinel phase constitutes approximately 90 vol. % in the samples. Additionally, the samples contain hematite phases, the beta modification of iron hydroxide, and an X-ray amorphous phase. Natural aging at room temperature leads to significant changes in the phase composition of the nanopowders. Specifically, there is an increase in the content of spinel phase, while the content of hematite and the amorphous phase decrease significantly. Furthermore, the saturation magnetization and effective field of anisotropy of the cobalt ferrospinel nanopowders exhibit noticeable increments. Consequently, thermal aging of the powders accelerates the changes in phase composition, structural parameters, and magnetic properties, as well as enhances the transformation extent during the formation of cobalt ferrospinel.

Integrated analysis approach of water and solids for root cause of injectivity decline of water injection well – A case study

Accurate sampling and analysis of injection and flow back water and solids are pivotal to identify the root causes of injectivity decline of water injection well. The present paper is focussed on case study of detailed characterization of injection and flowback water and solids using combination of techniques such as X-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy, inductively coupled plasma optical emission spectroscopy, ion chromatography and water isotope analyser in investigating the cause of injectivity decline. The present study emphasizes the effect of pressurized and non-pressurized water sampling on water analysis results, their scaling tendencies and correlation with compositions of solids encountered. Surface pressurized injection water sample pH result was found acidic with a higher dissolved iron and lower total suspended solids (TSS). Non-pressurized water samples showed comparatively higher pH due to release of CO2. Langelier saturation index (LSI) and ScaleSoftPitzer™ program SI of pressurized water sample showed lower scaling tendency than the non-pressurized water sample. Non-pressurized water samples contained significantly higher concentrations of TSS than the pressurized water sample indicated precipitation of salts in non-pressurized sample. Composition of TSS revealed presence of iron-based compounds, calcite and gypsum. Geochemical and water isotope analysis showed identical composition of injection and flowback water. XRD and XRF analysis of trapped solids revealed different forms of iron oxides and iron sulphides as major phase along with appreciable amount of calcite and quartz. XRF analysis also showed traces of Cr, Mo, and Ni in trapped solids indicated corrosion of tubing/pipes. Solid composition correlates with scaling tendency predicted by ScaleSoftPitzer™ program SI. Presence of iron in pressurized injection water and iron compounds in solids indicate iron-based scale/corrosion as key reason for reduction in injectivity of the well. Systematic sampling, accurate and integrated analysis of water and solids can help to find the dominant causes of injectivity decline and direct oilfield engineers at well site to take appropriate remedial and preventive action.

Are Twin Pregnancies at Higher Risk for Iron and Calcium Deficiency than Singleton Pregnancies?

The aim of this study was to compare the iron and calcium status in singleton and twin pregnancies and to assess whether there is an increased risk for iron and calcium deficiency in twin gestation. The study included 105 singleton and 9 twin pregnancies at or above 35 weeks of gestation. Information on prenatal supplementation with iron or calcium was acquired, and adverse perinatal outcomes were recorded. Biosamples from all 114 mothers and 73 newborns (61 singleton and 12 twin newborns) were finally analyzed. Total iron and calcium concentrations in serum were measured through total reflection X-ray fluorescence analysis. The results indicated no significant differences in maternal serum iron and calcium concentrations between singleton and twin pregnancies. Similarly, iron and calcium concentrations in newborn umbilical cord serum samples were not different between singleton and twin pregnancies. The comparison of total iron and calcium between mothers and umbilical cord serum indicated significantly lower concentrations in the mothers, with the differences being not homogenous but rather pair-specific. A significant positive correlation between maternal serum and umbilical cord serum calcium concentration was noticed. Prenatal iron supplementation was associated with higher iron concentrations in both mothers and newborns, supporting the efficiency of supplementation and the quality of the study methods. Collectively, the data indicate no significant differences in serum iron and calcium concentrations with regard to singleton or twin pregnancies and the efficiency of iron supplementation during pregnancy for increasing iron status.

Human health risk assessment of potentially toxic elements in soil and air particulate matter of automobile hub environments in Kumasi, Ghana

Rapid urbanization and uncontrolled industrial activities in developing countries have raised concerns about potentially toxic metal contamination of the environment. This study assessed the levels of potentially toxic elements in soil and airborne particulate matter in the Suame and Asafo areas in the Kumasi metropolis, characterized by a high concentration of auto mechanic workshops and residential settlements. X-ray fluorescence analysis and inductively coupled plasma-mass spectrometry were used to determine the metal concentrations in the samples. The results showed high concentrations of potentially toxic elements in the soil and air samples, indicating contamination from automotive activities. Metals such as Co, Ni, Pb, and Zn were found to be present at concentrations (13.42–6101.58 mg/kg and 14.15–11.74 mg/kg for Suame and Asafo respectively) that pose potential health risks to exposed populations. Mathematical models such as pollution indices were used to assess the extent of contamination and determine the potential sources of the metals - the automotive repairs. The findings highlight the urgent need for environmental management and remediation strategies to mitigate the health risks of exposure to potentially toxic elements in the Kumasi metropolis automotive hub.

Solidification treatment of rare earth tailings by a renewable biological cementation method

Rare earth mineral is a kind of polymetallic co-associated mineral, in addition to containing iron, rare earth, niobium, and a certain amount of thorium and uranium. The tailings after wet leaching of rare earth are both a kind of hazardous waste and a kind of potential strategic resource. Therefore, the treatment and disposal of rare earth tailings should not only achieve the purpose of risk control, but also cannot affect the subsequent reuse. Microbially induced calcium carbonate precipitation (MICP) as an environmentally friendly biological cementation technique, it can solidify the tailings and stabilize the polluting elements. The valuable elements in the tailings can be further recovered after the sample solidified by MICP is decomposed by acid. In this study, a strain of urease-producing bacteria (K-1) with excellent performance was screened by dilution culture method from rare earth tailings. Through physiological and biochemical analysis and 16 s rDNA analysis, the strain K-1 belonged to the genus Lysinibacillus. In the mold, strain K-1 was used to induce the formation of calcium carbonate for cementing rare earth tailings, the strength of the cured body after cementation can reach 1.73 MPa after 28 d. There was a significant reduction in the leaching of heavy metals and radionuclides in the cured body. The results obtained from the scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicated that strain K-1 induced a large amount of calcium carbonate, whose crystal forms are vaterite and calcite. The calcium carbonates cemented the rare earth tailings together for tighter texture and reduced porosity. The X-ray fluorescence (XRF) analysis of the rare earth tailings before and after solidification and after acid decomposition showed that the loss of rare earth elements in rare earth tailings after MICP treatment was small. Moreover, the cured body was relatively easy to dissociate, which facilitated the recovery and reuse of potential valuable elements in the tailings. This study provides technical support for the long-term storage of rare earth tailings and the sustainable development of the rare earth industry.

An augmented approach for the determination of the particle size effect on energy dispersive X-ray fluorescence analysis outcomes for alumina-based refractory materials

The chemical compositions of refractory materials, such as high-alumina concrete, bricks, and putty, were analyzed using an energy-dispersive X-ray spectrometer (EDXRF). An improved methodology for investigating the effect of particle size on the outcomes of EDXRF chemical analysis is presented. Eight independent refractory samples (refractory concrete, brick, and putty) were pulverized utilizing seven milling times (30, 60, 120, 180, 240, 300, and 360 s) and compared to non-pulverized samples. Thus, sixty-four refractory samples were obtained and analyzed using EDXRF. The method for measuring the fundamental EDXRF characteristics was then tested with ten certified reference materials. The acquired data were compared using inductively coupled plasma atomic emission spectrometry (ICP-OES). Univariate and multivariate statistics are used to evaluate EDXRF data. The particle size of the tested samples affected the z-scores of SiO2, Al2O3, Fe2O3, TiO2, CaO, MgO, Na2O, K2O, and P2O5 concentration measurements. Grinding times for refractory concrete, brick, and putty samples were determined in order to validate the robustness of the EDXRF technique and provide reliable chemical analyses. The ideal milling times for the samples studied ranged from 180 to 360 s, depending on the type of refractory material.