This study aims to determine the magnetic properties of Fe3O4 synthesized from rope bamboo and natural iron sand. In this study, natural magnetic bio-char of bamboo and iron sand was synthesized by ...the co-precipitation method at a calcination temperature of 500oC. Then it was characterized through several tests, namely XRD and VSM. The results of the XRD test showed that the synthesis of natural bamboo + iron sand produced HKL peaks that were identical to Fe3O4 where these peaks were the peaks of magnetite and hematite. Magnetic properties were tested using VSM through a hysteresis curve with samples classified as soft magnets.
PEO/PVA blends have been prepared to investigate the effect of gamma rays on the structural, morphological and photoluminescence properties. The studies of non-irradiated and irradiated samples with ...radiation doses of 10 kGy were examined by using XRD, ATR-FTIR, Optical microscopy and PL. Gamma photons induced important chemical rearrangements, especially by PVA hydroxyl groups. We found that the crystallinity rate is strongly influenced by radiation. In this context, one could predict that the immiscibility of PVA with PEO and the interactions between the chains are of the electrostatic type. A structural-scale disturbance due to the radical formation leads to spherulitic texture modifications of the PEO. Due to the luminescence properties, the blend samples behave like core-shell nanoparticles. This phenomenon is due to the fact that the PVA polymer played the role of shell. Irradiation makes it possible to obtain well-ordered spherulites and to get a high pore density. The irradiated blend showed a higher quantum yield. The significant chemical and morphological changes caused by gamma radiation favored the optical recombination of hydroxyl groups.
The dry reforming of methane was systematically studied over a series (2-30 wt%) of Co (~5nm in size) loaded CeO2 catalysts, with an effort to elucidate the behavior of Co and ceria in the catalytic ...process using in-situ methods. For the systems under study, the reaction activity scaled with increasing Co loading, and a 10 wt% Co-CeO2 catalyst exhibiting the best catalytic activity and good stability at 500 °C with little evidence for carbon accumulation. The phase transitions and the nature of active components in the catalyst were investigated during pretreatment and under reaction conditions by ex-situ/in-situ techniques including X-ray diffraction (XRD) and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). These studies showed a dynamical evolution in the chemical composition of the catalysts under reaction conditions. A clear transition of Co3O4 → CoO → Co, and Ce4+ to Ce3+, was observed during the temperature programmed reduction under H2 and CH4. However, introduction of CO2, led to partial re-oxidation of all components at low temperatures, followed by reduction at high temperatures. Under optimum CO and H2 producing conditions both XRD and AP-XPS indicated that the active phase involved a majority of metallic Co with a small amount of CoO both supported on a partially reduced ceria (Ce3+/Ce4+). We identified the importance of dispersing Co, anchoring it onto ceria surface sites, and then utilizing the redox properties of ceria for activating and then oxidatively converting methane while inhibiting coke formation. Furthermore, a synergistic effect between cobalt and ceria and the interfacial site are essential to successfully close the catalytic cycle.
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Faba bean (high- and low-tannin) protein isolates were water extracted followed by dialysis or micellization in comparison to concentrates from conventional alkali extraction + acid precipitation, ...and salt-based extraction (1% NaCl) + dialysis. Protein fractions were characterised for secondary structure conformational changes, crystalline structure, particle size distribution in aqueous suspension and thermal properties. Mild water or salt extraction did not influence particle size distribution. Based on XRD, FTIR and CD, β-sheet structures were the most abundant secondary structures and water extraction + dialysis had minimal impact on their native conformation. DSC results showed an association between protein purity, glass transition temperature and endothermic enthalpy. High melting temperature above glass transition confirms the suitability of faba bean proteins for thermal/extrusion processing. Fractionation method was a more significant determinant of physicochemical characteristics compared to the cultivar. Further exploration of the techno-functional characteristics of faba bean proteins is essential for value-added food applications.
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•Faba bean proteins were concentrated/isolated from water and NaCl extracts.•Water based extraction had minimal impact on faba bean protein secondary structure.•β-Sheet structures were the most abundant secondary structures of faba bean proteins.•Faba bean protein purity was positively correlated to the enthalpy of denaturation.•Faba bean proteins from mild extraction have the potential for extrusion processing.
An artificial patina on weathering steel produced with a 10% sulphuric acid solution and a natural patina formed over a period of 2 years in an urban environment were compared with a 44-year-old ...natural patina on an outdoor weathering steel sculpture. The samples and sculpture are exhibited and studied in two of the most polluted Croatian cities, Zagreb and Sisak. Various techniques used to examine the patina included scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR) and in-situ electrochemical impedance spectroscopy (EIS) using a paste electrolyte cell. A widely accepted criterion for the protective effect of the patina on weathering steel, the ratio of goethite to lepidocrocite (α/γ), was found to be 0.10 < 0.38 < 0.71 for 2-year-old natural, 2-year-old artificial and 44-year-old natural patina on the investigated sculpture. Equivalently, the corrosion rates determined by EIS were approximately 37, 22 and 12.5 μm year-1. The in-situ EIS technique allowed confirming the efficiency of artificial patination by H2SO4 in immediately attaining about twice as protective patina than that formed naturally after 2 years. It also confirmed about three times as efficient protection offered by a 44-year-old patina except on the moss-covered surface.
•Materials studied lie in the Na3/4(Mn-Al-Ni)O2 pseudo-ternary system.•P3/P2 phase fraction was manipulated by adjusting the calcination temperature.•Superior electrochemical performance of P3/P2 ...biphasic cathodes.•Absence of the P3 to O3 phase in the Al-substituted P3-type compounds.
Layered oxide cathodes, a promising avenue for Na-ion batteries, hold the highest potential for commercialization. Herein, we delve into the structural and electrochemical properties of Al-substituted layered oxides in our quest to pinpoint the optimal cathode composition in the Na3/4(Mn-Al-Ni)O2 pseudo-ternary system. The cathode materials investigated were synthesized in three distinct phase configurations, which include two monophasic configurations with P3 and P2-type structures and a third biphasic cathode with equal proportions of P3 and P2 phases. The fractions of the P3 and P2 type phases in the cathode materials were manipulated by adjusting the calcination temperature. The varying concentration of Mn3+ and Mn4+, confirmed by X-ray photoelectron spectroscopy, was found to impact the cyclic stability of these materials significantly. During electrochemical testing, the P3 cathodes showed impressive rate performance and exhibited an excellent specific capacity of 195 mAh g−1 at 0.1C. Regarding cyclic performance, the biphasic cathodes consistently outperformed their monophasic counterparts, with P3/P2-Na0.75Mn0.50Ni0.25Al0.25O2 exhibiting 82 % capacity retention after 300 cycles. Analysis of operando Synchrotron XRD data revealed an absence of P3 to O3 type phase transition in the cathodes even at low voltages where large structural variations to the unit cell structure were observed. The absence of P3 to O3 transformations and the superior electrochemical performance of Na0.75Mn0.50Ni0.25Al0.25O2 underlines the importance of Al substitution and P3/P2 biphasic structure in enhancing the electrochemical performance of layered oxides.
A conceptual design for a handheld X‐ray diffraction (HHXRD) instrument is proposed. Central to the design is the application of energy‐dispersive XRD (EDXRD) in a back‐reflection geometry. This ...technique brings unique advantages which enable a handheld instrument format, most notably, insensitivity to sample morphology and to the precise sample position relative to the instrument. For fine‐grained samples, including many geological specimens and the majority of common alloys, these characteristics negate sample preparation requirements. A prototype HHXRD device has been developed by minor modification of a handheld X‐ray fluorescence instrument, and the performance of the prototype has been tested with samples relevant to mining/quarrying and with an extensive range of metal samples. It is shown, for example, that the mineralogical composition of iron‐ore samples can be approximately quantified. In metals analysis, identification and quantification of the major phases have been demonstrated, along with extraction of lattice parameters. Texture analysis is also possible and a simple example for a phosphor bronze sample is presented. Instrument formats other than handheld are possible and online process control in metals production is a promising area. The prototype instrument requires extended measurement times but it is argued that a purpose‐designed instrument can achieve data‐acquisition times below one minute. HHXRD based on back‐reflection EDXRD is limited by the low resolution of diffraction peaks and interference by overlapping fluorescence peaks and, for these reasons, cannot serve as a general‐purpose XRD tool. However, the advantages of in situ, nondestructive and rapid measurement, tolerance of irregular surfaces, and no sample preparation requirement in many cases are potentially transformative. For targeted applications in which the analysis meets commercially relevant performance criteria, HHXRD could become the method of choice through sheer speed and convenience.
Energy‐dispersive X‐ray diffraction implemented in a back‐reflection geometry has unique characteristics, particularly its insensitivity to sample morphology. The potential to develop a handheld X‐ray diffraction instrument based on this technique is explored with the help of a prototype instrument adapted from a handheld X‐ray fluorescence device.
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•Asphaltene of Azerbaijani oil is dominated by molecules with island architecture.•Vanadium porphyrin dominates in the asphaltene of Zagli oil.•Asphaltene molecule is thermostable up ...to 406 °C.
The lack of information about the chemical composition and structure of asphaltenes in crude oil, which has a sufficient share in the economy of Azerbaijan, complicates its processing and use. As a first attempt, this research is devoted to the detailed analysis of the average molecular structure and properties of asphaltenes isolated from crude oil samples collected from the Zaglı oil field using the integrated application of high-sensitivity devices such as Nuclear Magnetic Resonance (NMR), Ultraviolet–Visible (UV–Vis), Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction analysis, Elemental analysis, Scanning Electron Microscope (SEM), Differential Thermal Analysis (DTA), Dynamic Light Scattering (DLS). The average molecular formula of asphaltene monomer was determined to be C49.5H55O3.04N0.95S2. An island architecture with one polycyclic aromatic hydrocarbon (PAH) in each molecule of this compound is predominant. Amorphous asphaltene molecule contains vanadium-based porphyrins, –COOH group, disulfide (−S-S-) linkage. It was found that asphaltene of crude oil is stable up to 406 °C. The three-stage pyrolysis process in the temperature range of 406–818 °C resulted in the formation of 12.58 % coke. Due to the absence of free radicals in the range of 25–100 ℃, the asphaltene sample is dielectric. The decrease of monodispersity with particle growth in asphaltene compound in different solvents was analyzed by dynamic and static light scattering. The HOMO-LUMO energy gap of the asphaltene molecule was 2.666 eV, indicating high stability. The knowledge gained about the chemical composition and molecular structure of asphaltenes can help prevent problems arising in oil production and refining processes.
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