Scanning Electron Microscopy Coupled With Energy Dispersive X-ray Spectroscopy Research Articles

Innovative synthesis and practical application of graphitic carbon nitride/α-zirconium phosphate in visible light-activated Knoevenagel condensation

To advance the development of efficient photocatalysts activated by visible light for environmental applications. We employed a simple approach to synthesize g-C3N4/α-ZrP composite in different mass ratios, followed by comprehensive characterization through several techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM/EDS), and UV–Visible diffuse reflectance spectra (DRS). Furthermore, the g-C3N4/α-ZrP with mass ratio 6:1 was demonstrated high performance catalytic activity in Knoevenagel condensation (Yield 88 %–96 %) in a short reaction time (5–20 min) under visible light irradiation. The use of g-C3N4/α-ZrP has transformed the traditional synthesis of carbon–carbon double bonds, offering improved reaction rates and reduced by-products. These next-generation photocatalysts also exhibit remarkable properties that facilitate the activation of substrates under milder conditions, opening up new possibilities for green and sustainable synthesis. This advancement contributes to the development of environmentally friendly and efficient synthetic methodologies.

Macadamia nut residue-derived biochar: An eco-friendly solution for β-naphthol and Reactive Black-5 removal

The generation of liquid waste containing dyes and complex organic compounds is a problem in the textile industries. In this work, we evaluated the use of macadamia nut residue as a precursor of a biochar for the treatment of these effluents through the adsorption process. The macadamia nut endocarp undergoes a sequential treatment involving pyrolysis at 600 °C followed by physical activation with CO2 and H2O vapor at 700 °C. Characterization of the resulting macadamia nut residue-derived biochar (MB) is accomplished through various techniques, including X-ray diffractometry (XRD), thermogravimetric analysis (TGA), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), nitrogen physisorption analysis and the pH at the zero charge point (pHZCP). Performance studies reveal that pH exerts minimal influence on the adsorption phenomenon. The Elovich kinetic model effectively describes the adsorption kinetics for both β-naphthol and Reactive Black 5 (RB5), with adjusted coefficients of determination (R2adj) of 0.99 and 0.94, respectively. Further analysis using the intraparticle diffusion model demonstrates that β-naphthol adsorption kinetics involve multiple mechanisms, while RB5 adsorption is predominantly governed by intraparticle diffusion. Equilibrium adsorption data for both adsorbates fit well with the Sips isothermal model, yielding maximum adsorption capacities of qmax β-naphthol = 15.16 mg∙g−1 and qmax RB5 = 3.08 mg∙g−1 at 55 °C. The adsorption process for both compounds is spontaneous and endothermic, based on the enthalpy values, it can be inferred that the β-naphthol adsorption is governed by weak van der Waals forces, indicating physisorption. As for RB5, the enthalpy value suggests that the phenomenon occurs due to electrostatic interactions between the molecule and the surface groups with higher energy involved. This study highlights the potential of macadamia nut residue biomass as a precursor for biochar, demonstrating its favorable attributes for application as an effective adsorbent material in the removal of organic compounds such as β-naphthol and RB5 from wastewater streams within the textile industry.

Effectiveness and mechanism of microbial dust suppressant on coal dust with different metamorphosis degree.

The extraction of coal from open-pit mines significantly contributes to environmental degradation, posing grave risks to human health and the operational stability of machinery. In this milieu, microbial dust suppressants leveraging microbially induced carbonate precipitation (MICP) demonstrate substantial potential for application. This manuscript undertakes an exploration of the dust mitigation efficiency, consolidation attributes, and the fundamental mechanisms of microbial dust suppressants across coal dust samples with varying metamorphic gradations. Empirical observations indicate that, in resistance tests against wind and rain, lignite coal underwent mass losses of 7.43g·m-2·min-1 and 98.62g·m-2·min-1, respectively. The production of consolidating agents within the lignite dust, attributable to the microbial suppressants, was measured at 0.15g per unit mass, a value of 1.25 and 1.07 times greater than that observed in bituminous coal and anthracite, respectively. Scanning electron microscopy coupled with X-ray energy-dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) analyses illuminated that the consolidating products within the coal dust predominantly constituted calcite and vaterite forms of calcium carbonate. The consolidation mechanism of coal dust via microbial suppressants is articulated as follows: Subsequent to the application on coal dust, the suppressants induce the formation of carbonate precipitates with inherent adhesive properties. These carbonates affix to the surfaces of coal dust particles, progressively encapsulating them. Furthermore, they play a pivotal role in bridging and filling the interstices between adjacent dust particles, thereby culminating in the genesis of a dense, cohesive mass capable of withstanding erosive forces.

Revealing ancient yellow colorants in painted artworks along the silk Road (6th-10th century AD)

A comprehensive analytical protocol was undertaken to elucidate the yellow colorants employed in wall paintings from the Kizil Grottoes, the Taojia Tomb, the Baiyangzhai Tomb, and polychrome figurines from the Astana Tombs, all positioned along the historical Silk Road and dating to the 6th-10th centuries AD. To unequivocally identify these colorants, multi-analytical techniques were deployed, encompassing digital microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray fluorescence spectroscopy (XRF), micro-Raman spectroscopy, and ultra-performance liquid chromatography triple quadrupole time-of-flight mass spectrometry (UPLC-Triple TOF-MS/MS). This comprehensive approach facilitated the unambiguous identification of both inorganic pigments, specifically vanadinite, and plant-derived colorants, including gamboge (Garcinia sp.) and Chinese cork tree (Phellodendron chinense), within these archaeological artifacts. These findings not only significantly enhance our scientific understanding of the materials and techniques utilized in the creation of these wall paintings and polychrome figurines, but also shed light on the vibrant exchange of materials and technological advancements that flourished along the ancient Silk Road.

Material and Microstructure Analysis of Wood Color Paintings from Shaanxi Cangjie Temple, China.

Cangjie Temple was built to commemorate Cangjie, the legendary inventor of Chinese characters. It stands as one of the few remaining temples in China dedicated to the invention and creation of writing. In this study, the material properties of wooden paintings from the Cangjie temple were characterized using Polarized Light Microscopy (PLM), Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS), Micro-confocal Raman Spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC/MS). It was confirmed that the pigments of the paintings included cinnabar, lapis lazuli, lead white, Paris green, and carbon black. The proteinaceous glue was used as an adhesive in the pigment samples, with tung oil likely being utilized as a primer for the wooden structures before painting. This study not only provides valuable data support for the conservation and restoration of the architectural features of Cangjie Temple but also provides useful reference for the maintenance and inheritance of similar ancient buildings.

Eco-friendly engineering of micro composite-based hydroxyapatite bio crystal and polyaniline for high removal of OG dye from wastewater: Adsorption mechanism and RSM@BBD optimization

The presence of harmful substances such as dyes in water systems poses a direct threat to the quality of people's lives and other organisms living in the ecosystem. Orange G (OG) is considered a hazardous dye. The existing paper attempts to evaluate a low-cost adsorbent for the effective removal of OG dye. The developed adsorbent Polyaniline@Hydroxyapatite extracted from Cilus Gilberti fish Scale (PANI@FHAP) was elaborated through the application of the in situ chemical polymerization method to incorporate PANI on the surface of naturally extracted hydroxyapatite FHAP. The good synthesis of PANI@FHAP was evaluated through multiple techniques including X-ray diffraction (XRD), Scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM/EDS), Fourier Transforms Infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) coupled with thermal differential analysis (DTA) analysis. The results reveal a highly ordered disposition of PANI chains on FHAP, resulting in a well-coated FHAP in the PANI matrix. Furthermore, the presence of functional groups on the surface of PANI such as amine (-NH2) and imine (=NH) groups would facilitate the removal of OG dye from contaminated water. The adsorption of OG onto PANI@FHAP was conducted in batch mode and optimized through response surface methodology coupled with box-Behnken design (RSM/BBD) to investigate the effect of time, adsorbent dose, and initial concentration. The outcomes proved that OG adsorption follows a quadratic model (R2 = 0.989). The kinetic study revealed that the adsorption of OG fits the pseudo-second-order model. On the other hand, the isotherm study declared that the Freundlich model is best suited to the description of OG adsorption. For thermodynamic study, the adsorption of OG is spontaneous in nature and exothermic. Furthermore, the regeneration-reusability study indicates that PANI@FHAP could be regenerated and reused up to five successive cycles. Based on the FTIR spectrum of PANI@FHAP after OG adsorption, the mechanism governing OG adsorption is predominantly driven by π-π interaction, electrostatic interaction, and hydrogen bonding interactions. The obtained results suppose that PANI@FHAP adsorbent can be a competitive material in large-scale applications.

Influence of the concentration of KOH-based aqueous electrolyte on the electrochemical behavior of NiO thin film

In this research, we explored the influence of varying concentrations of KOH electrolyte (0.5, 1, and 2 M) on the electrochemical characteristics of Nickel Oxide (NiO) thin film. The deposition of NiO material onto glass and Fluor Tin Oxide (FTO) coated glass substrates was achieved through the chemical spray pyrolysis method. Subsequent examinations encompassed structural, morphological, optical, and electrochemical assessments, employing X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS), UV-VIS-NIR spectrophotometry, and cyclic voltammetry (CV), respectively. XRD analysis unveiled a polycrystalline cubic structure of NiO with a preference for orientation along the (111) plane. Raman spectroscopy confirmed the presence of the NiO phase, whereas SEM images depicted the emergence of interconnected nanograins with occasional minor cracks. EDS examination and elemental mapping further substantiated a homogeneous dispersion of elements. Optical analysis disclosed a band gap energy of 3.54 eV and an average transmittance of 71 % in the visible range. Electrochemical analysis indicated that the specific capacitance reached its peak at [1 M] (70 F. g−1). The [2 M] electrolyte exhibited the highest optical modulation (29 %), the most substantial charge density (Qi = 9.5 mC/cm2), and the most favorable switching kinetics. However, the coloration efficiency slightly decreased from 30.94 cm2/C in [1 M] to 30.47 cm2/C in the [2 M] solution, despite these improvements.

Extraction of metal values from iron-rich mine tailings via chloridized roasting and water leaching

The surge in mining and mineral processing to meet metal demand has led to accumulation of mining by-products like tailings, waste rocks, and acid mine drainage, containing high iron, copper, nickel, and zinc concentrations. These residues pose environmental threats. The concept of technospheric mining aims to repurpose these wastes for beneficial uses, reducing disposal and ecological impact while benefiting stakeholders. Within this context, the present investigation focuses on the discriminative retrieval of copper and nickel from mine tailings characterized by elevated iron content. This is achieved through formulation of an energy-efficient technique designed to surmount the challenge of iron co-extraction during hydrometallurgical processes aimed at extracting and recuperating metal values from intricate phases. The proposed method entails the amalgamation of mine tailings and solid NH4Cl in a stoichiometric ratio of 1:2, followed by roasting at 300 °C for a span of 1 h. Application of chloridized roasting orchestrates the transformation of copper and nickel into soluble metal chlorides, while concurrently inducing conversion of iron into a stable iron oxide state. Subsequent stages encompass the separation of copper and nickel from the water leach liquor, achieved through solvent extraction techniques utilizing LIX84I and Cyanex 272 as extractants. Rigorous characterization efforts, employing techniques such as X-ray Diffraction (XRD) and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS), are undertaken to elucidate the attributes of the raw material and solid residues. Remarkably, the comprehensive isolation of copper, nickel, and iron is realized without generation of any effluents, ensuring preservation of environmental equilibrium.

Interdisciplinary methodology for the characterisation of archaeological metal grave goods from the Museum of Patagonia by PIXE, DRX, and SEM/EDS

AbstractWe present a study of a selection of metal ornaments belonging to archaeological funerary goods from Patagonic Indigenous groups. They are part of the ‘Andrés Giai’ Collection, under the guard of the Museum of Patagonia (Nahuel Huapi National Park [PNNH]; National Parks Administration [APN]), Argentina. The absence of contextual information and its current conservation status motivated the design of an interdisciplinary methodology to develop an Integral Conservation Plan that considered the selection of analytical techniques. Here, we implemented complementary nondestructive characterisation techniques such as particle induced X‐ray emission (PIXE), X‐ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X‐ray spectroscopy (SEM/EDS). We developed a methodology enabling us to characterise each piece with respect to its metallic composition and degradation products, and in certain cases, their manufacturing process. These findings have contributed with essential information for the tailored conservation treatment proposal. Moreover, they provided key information in regard to the reconstruction of contextual data for each piece. In addition, the methodology proposed for the Integral Conservation Plan takes into account an optimisation of the techniques to be used in order to minimise unnecessary handling of goods whilst ensuring an appropriate use of technological and economic resources whilst minimising time on potentially unconclusive measurements and results.

Synergistic advantages of volcanic ash weathering in saline soils: CO2 sequestration and enhancement of plant growth

Carbon dioxide (CO2) is a primary greenhouse gas that has experienced a surge in atmospheric concentration due to human activities and lifestyles. It is imperative to curtail atmospheric CO2 levels promptly to alleviate the multifaceted impacts of climate warming. The soil serves as a natural reservoir for CO2 sequestration. The scientific premise of this study is that CO2 sequestration in agriculturally relevant, organically-deficient saline soil can be achieved by incorporating alkaline earth silicates. Volcanic ash (VA) was used as a soil amendment for CO2 removal from saline soil by leveraging enhanced silicate rock weathering (ERW). The study pursued two primary objectives: first, we aimed to evaluate the impact of various doses of VA, employed as an amendment for organically-deficient soil, on the growth performance of key cultivated crops (sorghum and mung bean) in inland saline-alkaline agricultural regions of northeastern China. Second, we aimed to assess alterations in the physical properties of the amended soil through mineralogical examinations, utilizing X-ray diffraction (XRD) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) analyses, quantifying the increase in inorganic carbon content within the soil. In the potting tests, mung bean plant height exhibited a noteworthy increase of approximately 41 % with the addition of 10 % VA. Sorghum plant height and aboveground and belowground biomass dry weights increased with VA application across all tested doses. At the optimal VA application rate (20 %), the sorghum achieved a CO2 sequestration rate of 0.14 kg CO2·m−2·month−1. XRD and SEM-EDS analyses confirmed that the augmented inorganic carbon in the VA-amended soils stemmed primarily from calcite accumulation. These findings contribute to elucidating the mechanism underlying VA as an amendment for organically-deficient soils and provide an effective approach for enhancing the carbon sink capacity of saline soils.

Investigating the Middle Iron Age ceramics of Van Fortress through multi-analytical techniques

This work presents the characterization results of Middle Iron Age pottery fragments excavated in Van Fortress, the historical capital of the Urartu Kingdom, located on the eastern coast of Lake Van in Turkey. A multi-analytical approach combining optical microscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR) has been employed to investigate the mineralogical composition of ceramics. Micro-Raman spectrometer was also used for the characterization of the pigments used for decoration. The data collected from the analyses offered information on the minerals that were discovered in the ceramics, as well as the temperature at which the ceramics were fired and the atmosphere that they were exposed to. The existence of hematite suggests that they were subjected to firing in an oxidizing environment, with the exception of one sample, which has a sandwich shape characterized by a red-edge and a black center, indicating exposure to both reducing and oxidative atmospheres during the fire process. The ceramics utilized in this investigation are hypothesized to have been crafted from elemental substances procured from two to three distinct clay origins.

Fabrication of peptide-encapsulated sodium alginate hydrogel for selective gallium adsorption

Peptides are recognized as promising adsorbents in metal selective recovery. In this study, the designed gallium-binding peptide H6GaBP was immobilized by the polysaccharide polymer sodium alginate (SA) for gallium recovery. The synthesized H6GaBP@SA microspheres exhibited a maximum adsorption capacity of 127.4 mg/g and demonstrated high selectivity for gallium at lower pH values. The adsorption process aligned well with the pseudo-second-order equation and Langmuir model. To elucidate the adsorption mechanism, a comprehensive characterization including molecular docking, scanning electron microscope coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and thermogravimetry analysis (TGA), were conducted. These analyses revealed that gallium ions were initially adsorbed through electrostatic interaction by H6GaBP@SA, followed by a cation exchange reaction between Ga(OH)2+ and Ca2+, as well as coordination between gallium and histidine residues on the peptide. Moreover, the H6GaBP@SA exhibited improved thermal stability compared to sole sodium alginate microspheres, and the coordination of gallium with peptides can also defer the decomposition rate of the adsorbents. Compared to other adsorbents, the peptide-encapsulated hydrogel microspheres exhibited superior gallium selectivity and improved adsorption capacity, offering an environmentally friendly option for gallium recovery.

Shrimp shell waste-modified natural wood and its use as a reservoir of corrosion inhibitor (L-arginine) for brass in 3% NaCl medium: Experimental and theoretical studies

The primary objective of this study is to harness the valuable properties of natural wood waste (NWW) and a shrimp shell extract known as chitosan (Cs). In this context, and in order to prevent rapid consumption of the L-arginine inhibitor (Arg), it was encapsulated in NWW by means of a chitosan polymer. The resulting modification was verified using X-ray diffraction (XRD), which revealed the presence of chitosan and reflections corresponding to arginine in the modified wood. Additional techniques, including Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS), were used for comprehensive characterization. The corrosion inhibition effect resulting from the application of NWW-Cs-Arg composite was investigated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The obtained results revealed that, at an optimal concentration of 2 g/L and under ambient temperature conditions (298 K), this composite demonstrated a high level of corrosion inhibition, reaching up to 75 %, exhibiting cathodic behavior. Quantum chemical calculations were also carried out to predict the active sites in the used inhibitor. The methodology employed was based on the B3LYP/6-311G++(d,p) theory in an aqueous environment. Parameters such as frontier molecular orbitals (HOMO and LUMO), global reactivity descriptors, molecular electrostatic potential (MEP), and Mulliken population have been studied to assess local reactivity and identify reactive centers and potential nucleophilic and electrophilic attack sites. Weak interactions were analyzed using topological approaches (ELF, LOL, and NCI). It is noteworthy that the arginine molecule interacts through hydrogen bonds between its guanidine group and the hydroxyl groups present in the wood and chitosan residues. Meanwhile, the amine groups of chitosan promote charge transfer between arginine and copper atoms, particularly through the NH groups in the alpha position relative to the C = O group.

Feroxyhyte - from synthesis and characterization to application.

Feroxyhyte (δ-FeOOH) was synthesized and characterized using X-ray diffractometry (XRD), simultaneous thermal analysis (STA), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), and low-temperature nitrogen adsorption-desorption measurements. Its potential application as adsorbent of an anionic and cationic dyes such as C.I. Acid Violet 1 (AV1) and C.I. Basic Blue 3 (BB3) was investigated by determining the adsorption capacities based on the Langmuir (36.6 mg/g for AV1 and 187 mg/g for BB3), Freundlich and Dubinin-Radushkevich isotherm models. Adsorption of AV1 and BB3 by δ-FeOOH drops with the presence of additives such as cationic and anionic surfactants (CTAB, SDS) and ionic polymers (PAA, PEI). The surface and electrokinetic properties of examined suspensions were also described. They include determination of the solid surface charge density and the zeta potential, as well as values of point of zero charge and isoelectric point of feroxyhyte particles without and with adsorbed layers of organic substances. Their analysis made possible to propose the most probable structure of electrical double layer formed at the iron mineral/aqueous solution interface.

Hydration mechanism of red mud-fly ash based geopolymer

Geopolymer is considered the most promising alternative to Portland cement due to its excellent performance and low cost. In this study, the hydration mechanism of red mud-fly ash based geopolymer (RFG) was analyzed using low-field nuclear magnetic resonance (LNMR), rheological tests, Fourier transform infrared spectrometry (FT-IR), isothermal calorimetry, and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS). The compressive strength of RFG falls with increasing dosages of red mud, and initially increased and subsequently decreased with the increment of SiO2/Na2O ratio. According to the results of LNMR and rheological tests, the geopolymerical hydration process of RFG is divided into three phases: an induction phase, an acceleration phase, and a stabilization phase. When the SiO2/Na2O ratio of the activator is lower than 2.4, it has an activation effect on the cementitious material, and the optimal value is 2.1. The hydration rate of the cementitious material decreases as the dosage of red mud is increased. The slurry transitions from the Herschel-Barkley model to the Bingham fluid model as the hydration reaction advances. The hydration products is verified with different red mud dosage and SiO2/Na2O ratio by SEM-EDS. The findings of this study enrich our understanding of RFG, promote its engineering applications, and improve the utilization efficiency of red mud.

Efficient extraction of platinum(IV) using tertiary-amine groups functionalized thiacalix[4]arene as extractant

In the present study, the extraction performance and complexation mechanism of p-di-ethyl-amino-methyl-thiacalix[4]arene (L) toward Pt(IV) in a hydrochloric acid system were investigated. The effects of various parameters including solution pH, L to Pt(IV) mole ratio, Cl− concentration, acidity and reaction time on the complexation process of L with Pt(IV) were systematically investigated. The experimental results indicated that L has excellent complexation ability toward Pt(IV) that about 90 % of Pt(IV) could be extracted within 2 min under the optimal conditions. Moreover, L could selectively extract Pt(IV) from the HCl system containing multiple competing ions such as Ce(III), Zr(IV), La(III), Fe(III), Ni(II), Mg(II), and Al(III). The complexation mechanism between L and Pt(IV) was further clarified by slope analysis, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), and proton nuclear magnetic resonance (1H NMR) titrations. Theoretical analysis of thermodynamics, complexation structure and intermolecular interactions between L and Pt(IV) during the solvent extraction process were performed through density functional theory (DFT) calculations. The results showed that the protonation of L occurs first to form the complex of L·2HCl, which further reacts with PtCl62− forming the complex of L·2H+·PtCl62− through anion-exchange, achieving the efficient and selective extraction of platinum.

Exploring the synergistic effects of calcium chloride modification on stem bark eucalyptus biochar for Cr(VI) and Pb(II) ions removal: Kinetics, isotherm, thermodynamic and optimization studies

In this study, stem bark eucalyptus was subjected to pyrolysis modification to produce modified biochar. The modified biochar (MSBEB) was characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray Diffraction (XRD), and Brunauer–Emmett–Teller (BET) techniques. The impact of adsorption process variables such as temperature, adsorbent dosage, pH and contact time on the metals ion removal efficiency were investigated. The optimum conditions for maximum removal of Cr(VI) and Pb(II) ions were determined as 45.20 °C, 0.12 g/L, and 120.5 min through optimization process. The excellent performance of the modified biochar can be attributed to its porous structure, surface area, surface chemistry and crystallinity as supported by SEM, BET, FTIR and XRD analysis. However, based on the high correlation coefficient (R2), low values of chi square (χ2) and sum of square error (SSE), the Freundlich isotherm and Pseudo-second order kinetics provided the best fit, suggesting chemisorption as the dominant mechanism. Thermodynamic analysis indicated an endothermic, spontaneous, and feasible reaction.

(Invited) Electrodeposition of Manganese Arsenides (MnxAs) as Promising Candidates in Spintronics

Spintronics is a new branch of electronics in which the spin of the electrons as well as their charge is manipulated to produce a desired outcome. Spintronic devices are particularly attractive for memory storage and magnetic sensor applications, and potentially for quantum computing where the electron spin would represent a bit of information. Nowadays many efforts are made to increase the efficiency and lower the production costs of these materials, among others the use of molecular inorganic compounds and cheap preparation techniques [1].Most of these layers are synthesized with physical and/or vapor phase techniques [2] which allow to obtain materials with a very few defects, but which are complex to manage and typically very expensive. For this reason, in this study we have searched for a way to electrochemically deposit a compound with interesting spintronic properties in the aqueous medium. In fact, electrodeposition is notoriously a very cheap, versatile and easily scalable technique.With this purpose Mn-As system was selected thanks to its good magnetic and transport properties to be used as building blocks for spin valve [3]. MnAs has potential applications in spintronics, for electrical spin injection into GaAs and Si based devices [4] and DFT simulations predict that Mn2As and Mn3As have a low magnetization saturation and a high spin polarization at the Fermi-level [5]. Starting from MnSO4 and NaAsO2 precursors solutions with various concentrations, supporting electrolytes and pH were tested.The electrochemical behaviour of the precursors was investigated with cyclic voltammetries and both potentiostatic as well as galvanostatic deposition were carried out. The deposits obtained were morphologically and compositional characterised with scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray fluorescence spectroscopy (XRF), the chemical states were analysed with X-ray photoelectron spectroscopy (XPS), the crystalline structure was investigated with X-ray diffraction measurements (XRD). The preliminary magnetic and transport measurements evidence the promising properties of this deposition process to provide spinfiltering materials.The authors acknowledge Regione Toscana POR CreO FESR 2014-2020 – azione 1.1.5 sub-azione A1 – Bando 1 “Progetti Strategici di ricerca e sviluppo” which made possible the project “RAM-PVD” (CUP 3647.04032020.157000057_1225).

Effective extraction of nickel and cobalt from sintered nickel alloy via reduction roasting and leaching

In this work, a carbothermic reduction technique is developed to improve the extraction of valuable metals from sintered nickel alloys by atmospheric acid leaching. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) analyses indicate that NiO in the sintered nickel alloy and the NiO coated by Ni2O3 hinders further dissolution of nickel. Nickel oxides can be transformed into easily leached metallic nickel by carbothermic reduction. The reduction roasting was investigated and optimized by thermodynamic analysis, thermogravimetry-mass spectrometry, XRD, and response surface methodology (RSM). The results show that the leaching efficiencies of nickel and cobalt are respectively increased from 80.34% and 69.92% to 98.65% and 96.71% after the reduction roasting under the optimized conditions: 935 °C of temperature, 50 min of time, and 29.9% of carbon dosage. The leaching of nickel was optimized by single-factor test method and the optimum conditions have been established as: 150 g/L of H2SO4 concentration, 25% of H2O2 dosage, 10 mL/g of liquid–solid ratio, 400 rpm of stirring speed, 80 °C of temperature, and 80 min of time. The kinetic analysis of leaching process shows that the activation energies of nickel and cobalt leaching are 20.71 kJ/mol and 16.33 kJ/mol, respectively, indicating that the leaching process is an internal diffusion control process. This study provides a feasible and effective approach to extract nickel from sintered alloys.

Role of Reservoir Brine and Rock in Modulating Asphaltene Stability: Insights from Experimental Analysis

Summary The stability of asphaltenes in crude oil is influenced by various factors, including interactions with reservoir components such as brine and rock formations. While previous research has focused on pressure and temperature effects, a comprehensive understanding of the combined impact of brine and reservoir rock on asphaltene stability is lacking. This study investigates the individual and combined influences of brine and rock formations on asphaltene stability. First, 11 crude oil samples from diverse locations were characterized using API gravity, viscosity, and saturates, aromatics, resins, and asphaltenes (SARA) fraction analysis. The elemental composition of the crude oils, including carbon, hydrogen, nitrogen, and various metals, was determined. The surface properties of asphaltenes were analyzed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). The interaction between asphaltenes and deionized water was examined through zeta potential, particle size, conductivity, and pH measurements. The behavior of asphaltenes in an 8,000 ppm NaCl solution was also investigated. The SEM analysis revealed the presence of inorganic content on the surfaces of asphaltenes, indicating interactions between asphaltenes and reservoir rock. A strong correlation between the zeta potential and sulfur content of asphaltenes was observed, highlighting the influence of sulfur compounds on surface charge and stability in heavy crudes. Additionally, the correlation between total dissolved solids (TDS) content and alkaline Earth metals and alkali metals in asphaltenes confirmed interactions between asphaltenes and reservoir brine. This interaction is likely influenced by the composition and properties of both the brine and reservoir rock. The presence of electrical charges on the asphaltene surfaces, as determined by zeta potential measurements, further supports the role of electrostatic interactions in asphaltene stability. The low precipitation tendency observed for most asphaltene samples, coupled with the abundance of negatively charged particles, underscores the importance of electrical charges in controlling stability. This study provides novel insights into asphaltene stability, highlighting the significance of surface charge and elemental composition. The results demonstrate the substantial impact of both reservoir brine and rock formations on asphaltene stability in crude oil. Further research is needed to unravel the complex mechanisms underlying these interactions and their implications in diverse reservoir environments.