Energy Dispersive X-ray Diffraction Techniques Research Articles

Luminescent, sorptive and antibacterial potential of bismuth-organic framework

Metal organic frameworks are formed by the three-dimensional linkage of metal cores and organic linkers. In this work, bismuth-based metal organic framework (Bi-MOF) has been synthesized by using 5-hydroxyisophthalic acid (H2HIA) as linker via hydrothermal method. The said MOF was structurally characterized by UV/Vis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), 1H NMR, energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA) and X-ray diffraction technique. This MOF showed highly porous structure with surface area 1096 m2/g as determined by BET analysis. A model batch adsorption experiment was performed to evaluate the efficiency of methylene blue (MB) dye removal from aqueous media. It was found that monolayer adsorption capacity calculated from the Langmuir isotherm was 0.6240 mg/g. Bi-MOF was also screened for its antibacterial and luminescent behavior.
 
 KEY WORDS: Bismuth, Metal-organic Frameworks, Luminescence, Sorption
 
 Bull. Chem. Soc. Ethiop. 2021, 35(1), 119-128.
 DOI: https://dx.doi.org/10.4314/bcse.v35i1.10

One-pot synthesis of thiazole-2-imine derivatives by CoFe2O4@SiO2-PA-CC-Guanidine-SA MNPs as an efficient and recyclable catalyst

A novel and atom-economic protocol for the synthesis of thiazole-2-imine derivatives was developed. Synthesis of thiazole-2-imine derivatives from primary amines, phenyl isothiocyanate and phenacyl bromide derivatives by the CoFe2O4@SiO2-PA-CC-Guanidine-SA magnetic nanocatalyst in excellent yields was reported. This nanocatalyst is easily separated from the reaction mixture and can be reused for several times. For the characterization of the catalyst used of Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and vibrating-sample magnetometry (VSM) techniques.

Microstructural analysis and electrical behaviours of co-sputtered W–Ag thin films with a tilted columnar architecture

W–Ag thin films are produced by magnetron co-sputtering technique using glancing angle co-deposition configuration. Different samples are prepared with similar conditions (same pressure, thickness and tungsten target current) but with a variable Ag target current changing from 0 to 80 mA. The effect of the Ag target current on the film structure and electrical properties is investigated using scanning and transmission electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction and van der Pauw technique. Thin films with inclined columns are obtained and the columns section becomes more anisotropic for the films prepared with the lowest Ag target currents. The elemental composition of the films also changes as a function of the Ag target current, varying from tungsten-rich (at low current) to homogeneous (at high current). W–Ag thin films exhibit different crystallographic structures. If the fcc Ag phase is always present, the metastable A15 β-W is pointed out only at low Ag target current while at high current, only the bcc α-W phase is present. The microstructural analysis shows that the core of the columns is formed by W while Ag covers the columns as grains. Room temperature electrical resistivity decreases with Ag target current, whereas its anisotropy decreases. This behaviour correlates with the change in the columnar cross-section morphology.

Mn-DOPPED ZnS QUANTUM DOTS AS SENSITIVE SENSOR FOR DETERMINATION OF CIPROFLOXACIN IN PHARMACEUTICAL AND BIOLOGICAL SAMPLES

A simple and fast spectrofluorimetric method for determination of ciprofloxacin based on its quenching effect on the fluorescence intensity of colloidal water ­soluble TGA ­caped, Mn doped ZnS quantum dots (QDs) has been described. The QDs having characteristic fluorescence spectra with maximum excitation at 315 nm followed by an emission peak at 632 nm were characterized using Energy Dispersive X-Ray and X-ray Diffraction techniques. The effect of various parameters such as concentration of QDs, time, pH, common excipients and metal ions on the quenching phenomenon was investigated. Fluorescence quenching was found to be maximum with 10 µg mL­-1 of QDs at pH 8 and fluorescence intensity was observed to be constant upto 45 min. The Stern­-Volmer calibration plot of F0/F as a function of ciprofloxacin concentration was found to be linear in the range of 0.5-10 µg mL­-1 with r² = 0.993. Under optimal experimental conditions the method was found to be interference free. The percent relative standard deviation of the proposed method calculated against method blank was found to be 1.10%. The limit of detection (LOD) and the limit of quantitation (LOQ) for Cf (signal to noise ratio 3:1 for LOD and 10:1 for LOQ) were calculated to be 0.15 and 0.50 μg mL-1 respectively. Average percent recoveries (±SD) obtained for spiked commercial formulations; ciprol and ciproquine, and serum and urine samples were found to be in the range of 92.2±1.8% to 99.5±1.5%, 90.5±1.2% to 96.7±1.4% and 94.0±1.2% to 98.5±1.4% respectively. The data evidently prove the potential of the proposed sensor QDs in biological analysis.

Fabrication of a green and sensitive quantum dots based fluorescent probe for determination of sparfloxacin in biological samples and drug formulations

A simple and fast spectrofluorimetric method for determination of sparfloxacin (SPAR) based on fluorescence quenching of colloidal water soluble TGA caped, Mn doped ZnS quantum dots (QDs) has been described. The QDs having characteristic fluorescence spectra with maximum emission at 632 nm (Excitation at 315 nm) were characterized using Energy Dispersive x-ray and x-ray Diffraction techniques. The effect of various parameters such as concentration of QDs, time, pH, common excipients and metal ions on the quenching phenomenon was investigated. Fluorescence quenching was found to be maximum with 10 μg ml−1 of QDs at pH 7 with fluorescence intensity remaining constant upto 60 min. The Stern-Volmer calibration plot of F0/F as a function of sparfloxacin concentration was found to be linear in the range of 0.2–2.2 μg ml−1 with r2 = 0.995. Under optimal experimental conditions the method was found to be interference free. The percent relative standard deviation of the proposed method calculated against method blank was found to be 1.67%. The limit of detection and the limit of quantitation for SPAR (n = 3 and 10 respectively) were calculated to be 0.07 and 0.21 μg ml−1 respectively. Average percent recoveries (±SD) obtained were found to be 89.16 ± 0.03 to 94.44 ± 0.15 μg ml−1 for serum and 85.00 ± 0.10 to 97.77 ± 0.37 μg ml−1 for urine samples. In case of commercial formulations sparaxcin and spar, the maximum % recovery was found to 89.33 ± 0.54% while in case of Quspar the % recovery obtained was less than 71.83 ± 0.14%. The proposed method was statistically compared with reported chromatographic method and no significant difference was observed.

AN EGGSHELL HYDROXYAPATITE - GRAPHENE OXIDE NANOCOMPOSITE FOR THE REMOVAL OF HEAVY METALS FROM WASTE WATER

Heavy metal pollution is a serious environmental problem that can be remediated by various adsorbents. So, a new hydroxyapatite / graphene oxide nanocomposite (HAp/GO) material was synthesized from waste eggshell as a green and eco-friendly adsorbent for the effective removal of heavy metals (e.g., Cd, Pb, Cr, Ni, Co) from wastewaters. Nano-structured HAp was synthesized by calcination of the waste eggshell followed by hydrothermal treatment in the presence of phosphate solution. However, GO was synthesized using the Hummar’s method (Guerrero-Contreras and Caballero-Briones, 2015). The HAp/GO nanocomposite was synthesized from the HAp and GO precursors by ultrasonic treatment. The morphology, composition, crystal structure, functionality and stability of the synthesized sorbent were evaluated using Fourier transform infrared spectrophotometry (FTIR), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Raman spectrometry and N2-BET (Barrett–Emmett–Teller) surface area measurement techniques. The equilibrium concentrations of heavy metals were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The effect of the initial concentration of heavy metals, the dosage of HAp/GO, temperature effect and the solution pH on the adsorption capacity was investigated. The synthesized HAp/GO was adopted to achieve superior simultaneous removal efficiencies (≥ 90 %) for (Cd, Pb, Cr, Ni, Co) metal ions. .

Experimental Investigation of the Ni-V-Zn Ternary System

The 450 and 600 °C isothermal sections of the Ni-V-Zn ternary system have been investigated through Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and x-ray Diffraction (XRD) technique. Eight three-phase regions have been confirmed at the 450 °C section and nine three-phase regions exist at the 600 °C one. Experimental results indicate that it is difficult for Ni to dissolve in VZn3 and V4Zn5. The solid solubilities of V in γ(Ni2Zn11) and β1(NiZn) are 1.4 and 3.7 at.% at 450 °C, respectively, while V in γ and β1 are 2.5 and 4.0 at.% at 600 °C, respectively. The solid solubilities of Zn in Ni2V7, σ(Ni2V3), Ni2V and Ni3V are 0.5, 4.7, 2.3 and 2.6 at.% at 450 °C as well as 0.5, 9.5, 2.2 and 2.8 at.% at 600 °C, respectively. No ternary compound has been found in this work.

Cu-containing magnetic yolk-shell structured ionic liquid-based organosilica nanocomposite: A powerful catalyst with improved activity

A novel Cu-containing magnetic ionic liquid-based nanoporous organosilica composite with yolk-shell structure [Fe3O4@RF@void@PMO(IL)/Cu] was synthesized through nonsacrificial self-template strategy. The Fe3O4@RF@void@PMO(IL)/Cu nanosphere was characterized by using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) and powder X-ray diffraction (PXRD) techniques. The Fe3O4@RF@void@PMO(IL)/Cu was used as a powerful, recoverable and reusable nanocatalyst in the Chan-Lum coupling at room temperature under aerobic conditions. The recovery test was performed to study the stability of catalytic sites under applied conditions.

Liquid-solid phase reaction products formation in the diffusion welded joints made between Ti-6Al-4 V and AISI304L with brass interlayer

Abstract Liquid-solid phase reactions taken place at Ti-6Al-4 V-brass interface and brass-AISI304L stainless steel are presented in the current study. The liquid–solid phase reaction products formed in the diffusion welded (DW) samples made between Ti-6Al-4 V and AISI304L with brass interlayer were characterized with microscopy, energy dispersive X-Ray analysis and X-ray diffraction technique. Diffusion welding was performed by maintaining temperature 875, 900, 925 ⁰C and pressure 4, 8 and 12 MPa and welding time 20 and 40 min. Diffusion of ‘Cu’ and ‘Zn’ from the brass interlayer into base metals, and elements such as ‘Ti’, ‘Fe’, ‘Cr’, ‘Al’, ‘V’, ‘Ni’, ‘Mn’, ‘Si’ and ‘C’, diffused from the base metals into brass interlayer was observed. The maximum hardness values for the sample welded at 925 ⁰C, 12 MPa and 40 min were 595.2 VHN at the AISI304Lside and the Ti-6Al-4 V side, it was 612.4 VHN.

Hierarchically Au-functionalized derived ultrathin NiO nanosheets for highly sensitive electrochemical hydrazine detection

A highly sensitive hierarchical electrochemical sensing nanostructures have been successfully synthesized by hydrothermal and chemical deposition methods using Au nanoparticles (AuNPs)-functionalized Metal-organic frameworks (MOF) derived oxide nickel nanosheets (NiO NSs) on nickel foam (AuNPs@NiO NSs/NF). The morphological characterization of AuNPs@NiO NSs/NF nanomaterials was investigated by scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD) techniques. The electrochemical behaviors of AuNPs@NiO NSs/NF sensors were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometric response (i-t). The measured results of AuNPs@NiO NSs/NF sensor shows good electrochemical properties, including high sensitivity of 17.80 μA·μM−1·cm−2, wide linear range from 0.2 to 300 μM, a low detection limit (LOD) (S/N = 3) of 0.04 μM, limit of quantification (LOQ) of 0.13 μM and as well as great selectivity and long-time stability. Moreover, the electrochemical sensor has also been demonstrated excellent hydrazine properties in the real environmental samples. The excellent electrochemical performance of AuNPs@NiO NSs/NF sensor can be attributed to the hierarchical nanostructure of nickel-metal frameworks and synergistic catalysis effect of Au nanoparticles, which is promising as highly sensitive material for electrochemical sensor applications.

Novel bimetallic nano particles for sorption of mercury (II) from drinking water: Adsorption experiment and computational studies

The current study proposes fabrication of novel manganese and copper (Mn/Cu) based bimetallic nano particles (NPs) for adsorptive removal of mercury (Hg) ions from aqueous media and examines computational models for adsorption. The Mn/Cu bimetallic NPs were characterized for Atomic Force Microscope (AFM), Energy Dispersive X-rays Spectroscopy (EDS), X-Ray Diffraction (XRD) and Dynamic Light Scattering (DLS) techniques to investigate morphology, surface elemental composition and particle size analysis. Sorption of Hg was carried out using batch experiments in triplicate and residual Hg concentration after sorption was determined using cold vapor atomic absorption spectrometer (CV-AAS). The effect of various parameters such as pH, mass of nano particles, Hg concentration and contact time were optimized. Maximum removal efficiency was 95 % with 2.89 % RSD and maximum adsorption capacity (Q max) observed was 400 mg g-1. AFM images well separated morphology and mean grain size of 450 ± 50 nm of particles, DLS measured average particles size as 110 nm while XRD pattern and EDS results showed successful adsorption of Hg on Mn/Cu bimetallic surface. Ab initio based computational models for different geometries were optimized using semi empirical method through Gaussian software. Computational molecular models were optimized for structures before and after Hg sorption and important physical parameters such as electron spin, Root mean square (RMS) gradient, Adsorption energy, Mulliken charge density (Q) and bond lengths (BL) before and after adsorption were computed. It was concluded that Langmuir adsorption isotherm was favorable for this study and interaction of Hg was more favorable with Mn than Cu because of less adsorption energy (-112.48 eV) and stronger bond formation between them having bond length of 1.6433 Å.

Microstructure and phase composition of surface layers formed on aluminium alloys by plasma electrolytic oxidation

This paper presents elaboration and structural characterization of surface layers formed on aluminumalloys by plasma electrolytic oxidation (PEO). The electrolyte is a mixture consisting: sodium metasilicate and sodium hydroxide. The coatings obtained by PEO were investigated with: scanning electron microscopy (SEM) with Energy dispersive X-ray spectrometer (EDX) and X-ray diffraction (XRD)techniques.

From model to artefact: Versatile characterization of cinnabar, red lead and realgar red paints for rubrics and miniatures

This study focuses on the characterization of cinnabar, red lead and realgar paints, since the red colour was very often used for the illuminations and rubrics of medieval manuscript. The commercial pigments (cinnabar (HgS), red lead (Pb3O4), realgar (As4S4)) and binding media (gum Arabic, fish and parchment glue) were used for the preparation of analogous to historical paints. This work is on-going and at this stage, the resulting red paint samples were analysed to create a short data library that could be used to describe the various red paints and their compositions. The obtained paints were characterized before and after accelerated aging using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX), X-ray diffraction (XRD) and thermal (TG/DSC) analysis techniques. These results of versatile characterization are useful to develop red paint guidelines for the storage and how they affect current and future conservation of these objects.

Failure analysis of diesel engine piston in transport utility vehicles

Present work deals with the failure analysis of heavy-duty diesel engine piston used in transport utility vehicles. The piston under consideration has failed at 302763 km. Failure mode and effect analysis (FMEA) method is used to identify the engine component having significant contribution in failure. Identification of piston failure has been carried out using FMEA and risk priority number (RPN) for engine components. Experimental analysis of failed piston has been carried out using Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS) and X-Ray Diffraction (XRD) techniques. SEM was employed to speculate the type of failure of piston. Carbon deposition on the piston surface has been observed. EDS of failed piston has also been carried out to identify levels of unnormalized constituent elements contributing to piston failure. From EDS, presence of unnormalized carbon and oxygen is identified and reveal conformability with the failure analysis. Significant percentage of carbon and oxygen at different locations on the piston surface is observed, leading to conclusion of temperature variations inside the cylinder during working. Inferences drawn from piston failure analysis reveal the causes and consequences of failure reasons. The presence of excess carbon on the piston surface indicates the knocking and overheating phenomenon. Remedial measures in addition to periodic maintenance of engine and replacement of worn out gasket to avoid piston failures are presented in this research.

Manufacturing and Mechanical Characterization of Fly-Ash-Reinforced Materials for Furnace Lining Applications

Fly ash is the major wastes generated during the combustion of coal in thermal power plants. More than 110 million tons of fly ash produced in India annually. It leads to a significant disposal problem. An attempt has been made by numerous researchers to integrate the fly ash in the industry sector. The key applications include the manufacturing of bricks, production of cement, soil amelioration, mine backfilling, etc. Nevertheless, the refractory bricks for furnace lining are mainly formed from iron and steel, which are imported and are very expensive. Hence, to tackle this issue, the current study is focused on the synthesis of fly-ash-rich brick for high-temperature applications. In this investigation, fly ash material combined with minor additives such as granite powder, alite cement, and black sand were manufactured. The pellets of these materials with a varying additive percentage from 5 to 30% were prepared using hydraulic pressure. The heat-treated pellets were physically and mechanically characterized to ensure the brick properties suitable for furnace lining applications. Surface morphology of raw materials and particle–particle interaction after palletization were evaluated using scanning electron microscopy. Energy Dispersive x-Ray Analysis and x-ray diffraction technique were conducted to detect elemental analysis and phase evaluation of raw materials and fly-ash-rich brick after heat treatment. Microhardness of the samples was determined using a Vickers hardness tester. It is found that the formation of various complex compounds with respect to constituent composition, and pellet formation temperature has a great influence on the variation in hardness.

Promoted electrocatalytic performance of palladium nanoparticles using doped-NiO supporting materials toward ethanol electro-oxidation in alkaline media

Electrocatalyst support materials play significant role in the performance, durability and commercialization of fuel cells. This research work describes the preparation of metal oxide (nickel oxide (NiO), cobalt (Co) and copper (Cu) doped NiO) support materials on meshed titanium (Ti) substrate via a simple electro-deposition method for their application as novel support material for palladium (Pd) catalyst. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques are employed to study morphology, composition and structure of fabricated electrodes, respectively. The electrocatalytic performance of fabricated electrodes toward ethanol oxidation reaction (EOR) in alkaline solution is examined by the cyclic voltammetry (CV), chronoamperometry (CA) techniques. Low peak potential (−0.2 V), increased peak current density (62.54 mA cm−2) and large electrochemical active surface area (16.02 m2 g−1) were remarkable properties of Pd/Cu–NiO/Ti electrode. The results of other electrochemical measurements, CO-striping voltammetry, long-term stability and electrochemical impedance spectroscopy (EIS) revealed that the Pd/Cu–NiO/Ti electrode has the privileged electrocatalytic performance for EOR relative to other prepared electrodes. Accordingly, the Pd/Cu–NiO/Ti can be considered as a hopeful electrode for ethanol electro-oxidation reaction in DEFCs.

Characterization of natural rocks as filler materials for medium-temperature packed bed thermal energy storage system

Abstract Packed bed thermal energy storage system is a promising alternative to reduce the overall investment cost of a concentrating solar power plant. However, the choice of suitable filler materials depends on different steps and criteria in order to satisfy the requirements of the target application (e.g. operating temperatures, charging/discharging thermal power, thermal and mechanical stabilities, etc.). Most of the previous experimental investigations have focused on the lifetime stability of rocks at high-temperature up to 500°C. However, they have not discussed the suitability of the unsuccessful ones and their application for medium temperatures (up to 300°C). In this scope, the main aim of the present experimental work is to correlate the petrographic properties of the investigated rocks with their effect on their thermophysical properties, and their thermal stability for a medium-range temperature between 100°C and 300°C. To achieve this objective, four natural rocks (two varieties of pegmatite, cipolin and garnetite) are subjected to several experimental characterizations: At first, a petrographic analysis is done in order to identify the mineralogical composition and the texture of the samples. Secondly, chemical and structural analyses are conducted on the rocks using scanning electron microscopy, energy-dispersive x-ray and x-ray power diffraction techniques. Their thermophysical properties (density, specific heat capacity, thermal conductivity and diffusivity) are also measured. Finally, a thermo-gravimetric analysis is performed in order to test the thermal stability of the investigated rocks. The obtained results suggest that all the studied rocks are potential candidates to be used as filler materials in a packed bed configuration for a medium-range temperature.

Spark plasma sintering of Ti–Ni–TiCN composites: Microstructural characterization, densification and mechanical properties

Ti–Ni–TiCN composites with varying TiCN contents (5, 10 and 15 wt%) were consolidated using the novel spark plasma sintering technique at a sintering temperature of 1100 °C, for 10 min holding time under a vacuum condition of lower than 4 Pa, 100 °C/min heating rate and applied pressure of 50 MPa. The effects of Ni additive and TiCN nanoceramic reinforcement content on densification, microstructure and mechanical properties of the developed composites were investigated. Scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscope (EDS) and X-ray diffraction (XRD) techniques were employed to study the morphology and phases present in the developed composites. SEM results revealed the presence of undissolved particles and lamella arrangements of phases within the matrix of the sintered composites which were confirmed by the EDS and XRD results as undissolved TiCN particles, in-situ formed TiN and Ti2Ni intermetallic phases. The relative density of the sintered compacts decreased from 99.3% to 98.23% with increase in the reinforcement content. The hardness of the sintered composites was found to increase with increasing reinforcement content. Compressive test results indicated that Ti–Ni–TiCN composites displayed improved compressive strength than the pure Ti samples. The optimum properties were obtained in Ti–6Ni–10TiCN composite with Vickers hardness of 398 HV1.0, compressive yield and ultimate strengths of about 998 MPa and 1156 MPa respectively.

Binding of Polyethylene Glycol Imidazolium Hydrogen Sulfate to Magnetic Nanoparticles and Its Application as a Novel Recyclable Solid Acid Catalyst in the Friedländer Synthesis of Quinolines under Solvent-Free Conditions

For the first time, a new acidic imidazolium-based ionic liquid supported on magnetic nanoparticles (MNP@PEG-ImHSO4) was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDAX), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) techniques. Afterwards, its catalytic activity was investigated in the Friedländer synthesis of quinolines through a condensation reaction between 2-aminoaryl ketones and α-methylene ketones under solvent-free conditions. The catalyst could readily be separated from the reaction mixture using an external magnet and could be reused in subsequent reactions with no significant loss of activity.

Hexagonal boron nitride (h-BN) irradiated with 140 MeV protons

Hexagonal boron nitride was irradiated with 140 MeV protons to a fluence of ~6 1020p/cm2 at Tirr ~200 °C. Isotropic graphite was also irradiated alongside h-BN under similar conditions and fluence to enable direct comparison of the two similar structures. The effects of proton irradiation on dimensional stability and microstructure were studied using precision dilatometry and energy dispersive Xray diffraction techniques revealing by direct comparison to graphite that h-BN can better resist radiation damage from bombardment when irradiated with protons impinging normal to the crystallographic planes or along the crystallographic c-axis. X-ray diffraction experiments also revealed a preferred orientation of the crystallites in bulk samples near the sample surface, an orientation influenced by irradiation. Thermal studies using differential scanning calorimetry and thermogravimetric analysis to 740 °C, augmented by precision dilatometry, provided evidence of subtle phase transitions attributed to residual w-BN in the matrix. Irradiation appears to induce shifting of such transitions.