Energy Dispersive X-ray Diffraction Techniques Research Articles

Spectroscopic and antibacterial activities of cobalt and nickel nanoparticles: a comparative analysis

This study aimed to compare the spectroscopy, morphological, electrocatalytic properties, and antibacterial activities of cobalt nanoparticles (CoNPs) with nickel nanoparticles (NiNPs). Cobalt nanoparticles and NiNPs were prepared via a chemical reduction approach and characterized utilizing transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD) techniques. The result from XRD and TEM analysis revealed that the synthesized nanoparticles exhibit face-centered cubic with smooth spherical shape, having average particles size of 12 nm (NiNPs) and 18 nm (CoNPs). The electrochemical properties of the nanoparticles were examined via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The CV results showed that GCE-Ni (35.6 μA) has a higher current response compared to GCE-Co (10.5 μA). The EIS analysis revealed that GCE-Ni (1.39 KΩ) has faster electron transport capability compared to GCE-Co (2.99 KΩ) as indicated in their Rct values. The power density of the synthesized nanoparticles was obtained from their "knee" frequency (f°) values, with GCE-Ni (3.16 Hz) having higher f° values compared to GCE-Co (2.00 Hz). The antibacterial activity of the nanoparticles was evaluated against multidrug-resistant Escherichia coli O157, Escherichia coli O177, Salmonella enterica, Staphylococcus aureus, and Vibrio cholerae. The result from the antibacterial study revealed that at low concentrations both CoNPs and NiNPs have significant antibacterial activities against E. coli O157, E. coli O177, S. enterica, S. aureus, and V. cholerae. NiNPs showed better antibacterial activities at low concentrations of 61.5, 61.5, 125, 61.5, and 125 µg/mL compared to CoNPs with minimum inhibitory concentrations of 125, 125, 250, 61.5, and 125 µg/mL against E. coli O157, E. coli O177, S. enterica, S. aureus, and V. cholerae, respectively. These promising antibacterial activities emphasize the potential of CoNPs and NiNPs as effective antibacterial agents, which could aid in the development of novel antibacterial medicines.

Optimization of methyl orange decolorization by bismuth(0)-doped hydroxyapatite/reduced graphene oxide composite using RSM-CCD.

In the current study, the catalyst for the decolorization of methyl orange (MO) was developed HAp-rGO by the aqueous precipitation approach. Then, bismuth(0) nanoparticles (Bi NPs), which expect to show high activity, were reduced on the surface of the support material (HAp-rGO). The obtained catalyst was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. The parameters that remarkably affect the decolorization process (such as time, initial dye concentration, NaBH4 amount, and catalyst amount) have been examined by response surface methodology (RSM), an optimization method that has acquired increasing significance in recent years. In the decolorization of MO, the optimum conditions were identified as 2.91min, Co: 18.85mg/L, NaBH4 amount: 18.35mM, and Bi/HAp-rGO dosage: 2.12mg/mL with MO decolorization efficiency of 99.60%. The decolorization process of MO with Bi/HAp-rGO was examined in detail kinetically and thermodynamically. Additionally, the possible decolorization mechanism was clarified. The present work provides a new insight into the use of the optimization process for both the effective usage of Bi/HAp-rGO and the catalytic reduction of dyes.

Green synthesis of silver nanoparticles using mature-pseudostem extracts of Alpinia nigra and their bioactivities

Abstract Green synthesis of silver nanoparticles (AgNPs) employing agricultural wastes as plant extracts to improve environmental benignity and also economic value added is the highlight of this research. The mature pseudostem of Alpinia nigra is an unbeneficial raw material discarded from several food ingredients and medicinal formulas. Therefore, this research focused on condition optimization for AgNP synthesis with ecofriendly techniques using A. nigra mature-pseudostem extracts and evaluation of their antioxidant, antibacterial activities, and toxicity with brine shrimp lethality assay (BSLA). The optimal reaction conditions were achieved by using 5 mM silver nitrate (AgNO3) solution with a volume ratio of 2:8 for the extract to AgNO3 at pH 12 under room temperature. The morphology and crystalline phase of the generated AgNPs were characterized using UV–visible spectrophotometry, field emission-scanning electron microscope (FE-SEM), energy dispersive X-ray, X-ray diffraction, and Fourier transform-infrared (FTIR) techniques. The FE-SEM analysis exposed spherical shapes with an average diameter of approximately 49 nm. The XRD analysis indicated their face center cubic structure, and the FTIR spectra confirmed that phytochemicals from A. nigra extract promoted the synthesis of AgNPs. In particular, the biosynthesized AgNPs presented potential antibacterial activity against both Staphylococcus aureus and Escherichia coli and effective antioxidant capacity using the DPPH radical scavenging assay. Additionally, non-toxic desired AgNPs were confirmed with BSLA.

Copper-Plated Nanoporous Anodized Aluminum Oxide for Solar Desalination: An Experimental Study

Currently, there is a shortage of potable water in several regions. Various alternative methods exist for producing purified water; however, one particular technology known as solar desalination is gaining prominence as a sustainable and environmentally friendly solution. Solar desalination harnesses solar energy to produce fresh water in regions with abundant sunlight. This study involved the fabrication of a nanostructured porous material composed of copper using anodization, followed by copper electroplating. In order to create three distinct nanoporous structures, we utilized three anodization periods of 40 min, 60 min, and 80 min. Subsequently, these structures underwent a copper deposition process for 30 min using the copper electroplating technique. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDAX), and X-ray diffraction (XRD) techniques were utilized to analyze the characteristics of the copper-plated nanoporous structure. Three distinct samples were utilized in solar desalination experiments, employing solar stills over a span of three consecutive days, with each sample being tested on a separate day. All three samples underwent desalination, unlike the standard solar still, which did not include any sample. Our observation revealed that the sample, which underwent 60 min of anodization followed by copper electroplating, had a significantly greater evaporation rate of 22.22% compared to the conventional still.

Calcium-, magnesium-, and yttrium-doped lithium nickel phosphate nanomaterials as high-performance catalysts for electrochemical water oxidation reaction

Abstract Electrochemical water oxidation reaction (WOR) lies among the most forthcoming approaches toward eco-conscious manufacturing of green hydrogen owing to its environmental favors and high energy density values. Its vast commoditization is restricted by high-efficiency and inexpensive catalysts that are extensively under constant research. Herein, calcium, magnesium, and yttrium doped lithium nickel phosphate olivines (LiNi1−x M x PO, LNMP; x = 0.1–0.9; M = Ca2+, Mg2+, and Y3+) were synthesized via non-aqueous sol-gel method and explored for catalytic WOR. Lithium nickel phosphates (LNP) and compositions were characterized via Fourier transform infrared, scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray diffraction techniques for the structural and morphological analyses. Glassy carbon electrode altered with the LNMPs when studied in a standard redox system of 5 mM KMnO4, displayed that yttrium doped LNP, i.e. LNYP-3 exhibits the highest active surface area (0.0050 cm2) displaying the lowest average crystallite size (D avg) i.e. ∼7 nm. Electrocatalytic behavior monitored in KOH showed that LNMP-2 offers the highest rate constant “k o,” value, i.e. 3.9 10−2 cm s−1 and the largest diffusion coefficient “D o,” i.e. 5.2 × 10−5 cm2 s−1. Kinetic and thermodynamic parameters demonstrated the facilitated electron transfer and electrocatalytic properties of proposed nanomaterials. Water oxidation peak current density values were indicative of the robust catalysis and facilitated water oxidation process besides lowering the Faradic onset potential signifying the transformation of less LNP into more conducive LNMP toward water oxidation.

Discriminating organic carbon from endokarstic moonmilk-type deposits by LIBS. The case of a natural carbonated Martian analogue

Moonmilk-type deposits exemplify carbonated Martian analogues existing in the subsurface of Earth, an endokarstic speleothem with a possible biochemical origin composed principally by carbonates, mainly huntite and dolomite. In this work, samples of moonmilk located in Nerja Cave (southern Spain) have been studied by LIBS with the aim of identifying carbon of biogenic origin by establishing a relationship between a molecular emission indicator, CN signal, and the organic carbon content. The characterization of this kind of carbonate deposit with a multiple mineralogical composition has been completed using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction techniques for qualitative and semi-quantitative analysis. The information attained from LIBS regarding energy thresholds and time-resolved kinetics of CN emissions provides useful insight into the identification of different molecular emitters, namely organic and inorganic CN, depending on the laser irradiance and time settings conditions. These promising results are of application in the search and identification of biosignatures in upcoming planetary missions with astrobiological purposes.

Aluminum Alloys as Anodes for Aluminum Batteries

The manuscript investigates the synthesis and characterization of Aluminum alloys, comprising Si, Ti and B as alloying elements, as anodes for Al-ion batteries. Deposition/stripping measurements, impedance spectroscopy, metallographic, energy dispersive X-ray spectroscopy (EDXS) and X-ray diffraction (XRD) techniques unveil the complex interplay existing between the microstructures of the alloys and the obtained electrochemical performance. Prototype cycling and post-mortem battery failure analysis are performed as well. It is demonstrated that a remarkable improvement in the: a) oxidation/reduction currents and overvoltages; and b) interfacial stability with the electrolyte; can be obtained, with respect to a conventional Al anode.

Fabrication of magnetic biochar-MIL-68(Fe)-supported cobalt composite material toward the catalytic reduction performance of crystal violet

A magnetic biochar-MIL-68(Fe)-supported cobalt composite material (Co@MIL-68(Fe)@Fe3O4@CM-BC) was synthesized and used as a novel and effective catalyst for the catalytic reduction of crystal violet (CV) in aqueous environments. The prepared material was thoroughly characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and vibrating-sample magnetometer (VSM) techniques. Four operating parameters, including the CV dye concentration, time, catalyst dosage, and NaBH4 amount, were evaluated by employing central composite design (CCD) based on response surface methodology (RSM) for the catalytic reduction of CV. In the catalytic reduction of CV dye, the optimum conditions were determined as 15.67 mg/L CV dye concentration, 80.24 s time, 0.341 mg/mL catalyst dosage, and 14.56 mM NaBH4 amount with CV reduction efficiency of 99.98 %. The catalytic reduction kinetic of CV was studied by applying the pseudo-first-order model, and the apparent rate constant (kapp) values were obtained under different temperature (293–323 K). It was observed that kapp values increased upon increment of temperature. From kinetic studies, the activation energy was measured as 37.18 kJ/mol. Moreover, thermodynamic results showed that the activation entropy (ΔS#) and enthalpy (ΔH#) were obtained as −179.49 J/mol K and 34.62 kJ/mol, respectively. The thermodynamic parameters suggest that the catalytic reduction of CV was favorable and endothermic in nature. Regeneration tests indicated that the activity of Co@MIL-68(Fe)@Fe3O4@CM-BC was retained after five uses. Based on all of the results, the prepared material is a good candidate for the treatment of wastewater containing dyes like CV.

Preparation and sustained-release study of Litsea cubeba essential oil inclusion complex with γ-cyclodextrin-metal–organic frameworks

BackgroundLitsea cubeba essential oil (LCEO) is a food additive that requires encapsulation to delay its release due to its irritating nature. To identify an appropriate inclusion material, gamma (γ)-cyclodextrin (CD)-metal organic frameworks (MOF) were prepared, and the sustained release of the inclusion complex (IC) was studied.ResultsThe γ-CD-MOF was formed using γ-CD, potassium hydroxide (KOH), cetyltrimethylammonium bromide (CTAB), and silane coupling agents through the vapor diffusion method. The highest encapsulated rate achieved was 26.02%, with a temperature of 50 °C, a stirring time of 2.5 h, and an LCEO to γ-CD dosage ratio of 1:8. During the adsorption test, the amount of LCEO gradually increased within the first 180 min. However, after this time, there was no significant change in the adsorption amount of LCEO, indicating that the γ-CD-MOF had reached adsorption equilibrium. The average release rate of the IC reached 9.76% at 11 h. By comparison, the average release rate of the IC with γ-CD was 9.30% at 10 min, resulting in a diffusion index of 0.349. Under ultraviolet (UV) scanning, the sustained-release solution of the IC exhibited a strong characteristic citral absorption peak at 238 nm. Moreover, under infrared spectroscopy scanning, the absorption peak intensity of the IC was 1.19 times higher than that of blank γ-CD-MOF at 1676 cm−1. The IC, as observed through a scanning electron microscope, exhibited round pellets with a diameter of 40–60 μm. Energy dispersive spectroscopy images showed uniform distribution of potassium and sulfur elements. In X-Ray diffraction, the diffraction peaks of the IC were found at 5.27°, 7.45°, 10.54°, 12.08°, 14.20°, 14.92°, 15.84°, 16.68°, 19.24°, 21.80°, and 23.69°, with no significant change in the adsorption amount of LCEO. The Brunauer–Emmett–Teller (BET) testing revealed that the surface area of γ-CD-MOF was 5.089 m2/g, and the pore diameter was 3.409 nm by the Barrett–Joyner–Halenda (BJH) method.ConclusionThese data demonstrated that the sustained effect of the γ-CD-MOF was superior to that of γ-CD. The adsorption kinetics curve followed the Quasi-primary kinetics model, while the release curve adhered to the Ritger–Peppas model. Furthermore, the release behavior was primarily governed by the Fick diffusion mechanism, which was advantageous for achieving the sustained release of LCEO. The UV spectrum, infrared spectroscopy (IR), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), X-ray diffraction (XRD), and BET techniques confirmed the successful formation of the IC of LCEO with γ-CD-MOF. This study offers a promising technical solution for delaying the release and improving the sustained-release product of LCEO.Graphical

Microwave-assisted conversion of fructose to 5-HMF using carbonaceous acidic catalysts

Recently, the catalytic conversion of fructose to 5-hydroxymethylfurfural (5-HMF) has attracted much interest. The idea of a low-cost, sustainable, energy-efficient method is critical to obtain excellent yield and selectivity for the target product 5-HMF. In this work, microwave (MW) irradiation was chosen as a heating source for the conversion of fructose to 5-HMF with the presence of various amorphous carbons containing Brønsted acid sites as catalysts in dimethyl sulfoxide (DMSO) as a solvent. The catalysts’ morphology, surface functional groups, thermal stability, and compositions of the obtained solids were examined by scanning electron microscope (SEM), elemental mapping, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), energy dispersive X-Ray spectroscopy (EDX), Raman spectroscopy and X-ray diffraction (XRD) techniques. The effect of solvent, heating technique, MW power, time, and catalytic loading on the reaction was studied thoroughly. The highest 5-HMF yield of 79.9% and 5-HMF selectivity of 79.7% were achieved with the optimal condition. 5-HMF was easily separated using a liquid-liquid extraction procedure with high purity. Moreover, the catalyst can be quickly recovered and reused. MW irradiation has proved to selectively and efficiently promote the formation of 5-HMF with high yield in a short reaction time. A mechanism for the formation 5-HMF from fructose was also proposed.

Structural and Mechanical Properties of DLC/TiN Coatings on Carbide for Wood-Cutting Applications

In this work, the diamond-like carbon and titanium nitride (DLC/TiN) multilayer coatings were prepared on a cemented tungsten carbide substrate (WC—3 wt.% Co) using the cathodic vacuum arc physical vapor deposition (Arc-PVD) method and pulsed Arc-PVD method with a graphite cathode for the deposition of TiN and carbon layers, respectively. The structural and mechanical properties of the prepared coatings were studied, and different techniques, such as scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy, and microindentation techniques investigated their microstructure, composition, and phases. The prepared coatings had a multilayer structure with distinct phases of DLC, TiN, and carbide substrate. The potentiodynamic polarization method (PDP) was performed for the DLC/TiN multilayer coatings in 3% NaCl solution to evaluate the corrosion resistance of the prepared coatings. It has been shown that the DLC layer provided the coating with a polarization resistance of 564.46 kΩ. Moreover, it has been demonstrated that the DLC/TiN coatings had a high hardness of 38.7–40.4 GPa, which can help to extend the wood-cutting tools’ life.

Ultrasonic-assisted chemical modification of a natural clinoptilolite zeolite: Enhanced ammonium adsorption rate and resistance to disturbing ions

A natural clinoptilolite zeolite was modified by ultrasonic-assisted chemicals (NaOH, FeCl3 and HCl) to improve their performance in ammonium removal from (waste) water. The obtained modified zeolites were characterized by Field Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD) and gas sorption techniques to understand the relation between physiochemical factors of the modified zeolites and ammonium adsorption. The highest elimination efficiency of ammonium by the natural zeolite modified by ultrasonic-assisted HCl treatment, HZU2, was ≥ 99%. However, ammonium removal by the raw natural zeolite was only 51.66%. The efficiencies of ammonium removal in the presence of various disturbing anions and cations by the HZU2 and raw zeolite were in the range of 79–93% and 15–30%, respectively. The HZU2 was reused five times presenting stable adsorption removal of ammonium. The theoretical calculations were performed to identify the key kinetics and thermodynamics parameters controlling the adsorption rate. The maximum adsorption capacity (qmax) of HZU2 obtained by the Langmuir model was about 142.85 (mg-ammonium/g-adsorbent) suggesting that the adsorption capacity of a monolayer and the relative content of alkali metal cations are suitable for the improvement of ammonium ion adsorption. The obtained thermodynamics parameters showed that the ammonium adsorption is a spontaneous and exothermic physisorption process. Consequently, we showed that ultrasonic-assisted chemical modification is a promising approach to control both textural properties and chemical composition of natural zeolites to enhance the ammonium removal from wastewater.

Self-healing of recycled aggregate fungi concrete using Fusarium oxysporum and Trichoderma longibrachiatum

This research is aimed to investigate the performance and crack healing phenomenon of recycled aggregate concrete (RAC) by using fungi (Fusarium oxysporum and Trichoderma longibrachiatum) as potential bio-admixtures. The microbial behavior and efficiency of the chosen fungal strains were studied on induction in the RAC by direct intrusion and after being immobilized in recycled coarse aggregate (RCA). The microbial activity in concrete was activated using calcium lactate as nutrition medium. Analysis and comparison of both fungal inoculation approaches with the reference matrix was conducted based on mechanical performance, durability tests, self-healing attributes, and the supporting forensics. Based on the results, F. oxysporum is proven as the potential strain for enhancing RAC performance when immobilized in RCA. The attained increase in compression and tension using F. oxysporum is 11.62 % and 31.18 % respectively at the age of 28 days. Further, the mentioned strain reduced the water absorption by 0.8 % and enhanced the acid resistance of concrete by 4.5 % in terms of measured mass loss. The crack size of 1.34 mm was completely sealed through bio-metabolic activity of F. oxysporum immobilized in RAC and restored 58.75 % of its compressive strength. Fungus hyphae of both the strains were identified in the respective RAC mixes through microscopic examination by Field Emission Scanning Electron Microscopy (FESEM) which proves the compatibility of RCA as the suitable carrier medium for fungi. The crack filler compound was forensically confirmed as bio-calcite through Energy Dispersive X-ray spectroscopy (EDX), Thermogravimetry Analysis (TGA), and X-ray Diffraction (XRD) technique.

Hydrogen production activity of nickel deposited graphite electrodes doped with CoW and CoIr nanoparticles

BackgroundThe need for clean and renewable energy resources is increasing day by day. One of the most important of these resources is hydrogen, known as green energy. The most environmentally friendly method among hydrogen production processes is the electrolysis, in which pure hydrogen is obtained without any separation and purification processes. Carbon emissions is zero during production. The disadvantage of this method is that the production costs are high. For this reason, this study is aimed at improving a cathode material, which play a major role in the efficiency of electrolyzers. MethodElectrochemically Ni, hydrothermally CoW and CoIr nanoparticles modified graphite electrodes are prepared as hydrogen evolution catalysts. The hydrothermally synthesized nanoparticles are impregnated on Ni-deposited graphite. The hydrogen evolution reaction activity of the prepared electrodes was investigated by electrochemical techniques. The cyclic voltammetry, linear sweep voltammetry, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques performed the electrochemical analyzes.The surface morphology and chemical composition of the synthesized nanoparticles were investigated using scanning electron microscopy, Energy-Dispersive X-ray spectroscopy and X-ray diffraction techniques. Significant FindingsThe catalytic efficiency is near for C/NiCoIr, and C/NiCoW electrodes, which has hydrogen volume of 108 and 105 mL cm−2 h−1 by electrolysis of water.

Graphene/macrocylic Yb nanocomposite as counter electrode in dye sensitized solar cell

In recent article, ligand octaaza-bis-α-diimine and its Yb complex grafted upon GO have been synthesized and characterized using scanning electron microscopy, fourier transform infrared spectroscopy, energy dispersive spectroscopy, raman spectroscopy, x-ray diffraction, and cyclic voltammetry techniques. The composites with varying ratio's GO/Yb (1:1), (1:3) and (1:10) have been investigated as counter electrode in dye sensitized solar cell. The fabricated device was analysed using current density–voltage, incident photon-to-current conversion efficiency, and electrochemical impedance spectroscopy techniques. The device fabricated with highest ratio (1:10), exhibit the highest Voc, Jsc values and it showed the maximum PCE value of 7.98%. Due to the homogeneous distribution of catalytic Yb particles on the surface of RGO, the RGO/Yb CE demonstrated effective electrocatalytic activity. According to the findings, a DSSC with RGO/Yb CE can demonstrate the efficiency highest than platinum (Pt) CE and thus can replace traditional Pt CE DSSCs to reduce the cost of solar cells.

Structural and theoretical investigations on the “coloring” scheme of γ-brass type phase Ag5Cd8

The γ-brass type phase in the binary Ag–Cd system has been synthesized by high-temperature method, and its composition and crystal structure were analyzed by energy dispersive X-ray spectroscopy and X-ray diffraction techniques. The compound Ag5Cd8 crystallizes in the I4¯3m (cI52) space group, having cell parameter of ∼9.9 ​Å, and the unit cell contains 52 atoms distributed over 4 crystallographically independent positions. Due to the weak X-ray scattering contrast between Ag and Cd, the first principle DFT calculations using the Vienna Ab Initio Simulation Package (VASP) code have been employed to address the “coloring problem” in the structure of Ag5Cd8. Like the ideal cubic γ-brass type phases, the structure can be conveniently described by 26-atom γ-cluster made of four concentric shells: inner tetrahedron (IT), outer tetrahedron (OT), octahedron (OH), and cuboctahedron (CO). Theoretical calculations guide that in Ag5Cd8, Cd prefers IT and CO sites and Ag in OT and OH sites of the γ-cluster. The electronic structure calculation for the model Ag5Cd8 shows the appearance of a pseudogap near the Fermi level, which validates the phase stability by the Hume-Rothery mechanism as a result of the Fermi surface-Brillouin zone (FS-BZ) interaction. Bonding analysis (COHP) using the LOBSTER package shows the Ag–Cd heteroatomic interaction being the highest contributor towards the overall stability of the γ-brass type Ag5Cd8.

Laser cladding of HA-TiO2 composite coating on Mg-alloy: microstructural characterisation and wettability analysis

ABSTRACT In the present work, hydroxyapatite (HA)-50 wt.% TiO2 composite coating has been developed on Mg-alloy by laser cladding process using 400 W continuous wave fibre laser. A detailed microstructural characterisation has been done by using optical profilometry, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction techniques. The wettability analysis has been done by the sessile method using hank’s solution. The average roughness is 0.5 μm for the Mg-1% Ca alloy and 1.45 μm for laser-cladded surface. The microstructure analysis shows uniform deposition with the presence of porosities, particles and few cracks on the top surface of laser-cladded surface. The composition analysis shows the uniform and homogeneous distribution of Ca, Ti, P, and O on the laser-cladded surface. The phase analysis shows the presence α, β phase in Mg-1% Ca alloy and the presence of Ca2P2O7, Ca3(PO4)2, CaTiO3 and TiO2 (rutile) phases in the laser-cladded surface. There is an improvement in wettability of the laser-cladded surface as compared to as-received Mg alloy.

Highly efficient elimination of uranium (VI) and thorium (IV) from aqueous solution using activated carbon immobilized on polystyrene

Purpose The purpose of this study is to prepare a new adsorbent activated carbon immobilized on polystyrene (ACPS) for uranium (VI) and thorium (IV) removal from an aqueous solution. Activated carbon (AC) was derived from biochar material by chemical activation to increase the active sites on its surface and enhance the adsorption capacity. Activated carbon (AC) was immobilized on polystyrene (PS) to improve the physical properties and facilitate separation from the working solution. A feasibility study for the adsorption of uranium (VI) and thorium (IV) on the new adsorbent (ACPS) has been achieved. Adsorption kinetics, isotherms, and thermodynamics models of the adsorption process were used to describe the reaction mechanism. Design/methodology/approach Activated carbon was synthesized from biochar charcoal by 2 M H2SO4. Activated carbon was immobilized on the pretreatment polystyrene by hydrothermal process forming new adsorbent (ACPS). Characterization studies were carried out by scanning electron microscope, energy-dispersive X-ray spectrometer, infrared spectroscopy and X-ray diffraction techniques. Different factors affect the adsorption process as pH, contact time, solid/liquid ratio, initial concentration and temperature. The adsorption mechanism was explained according to kinetic, isothermal and thermodynamic studies. Also, the regeneration of spent ACPS was studied. Findings The experimental results showed that pH and equilibrium time of the best adsorption were 6.0 and 60 min for U(VI), 4.0 and 90 min for Th(IV), (pHPZC = 3.4). The experimental results fit well with pseudo-second order, Freundlich and Dubinin–Radushkevich models proving the chemisorption and heterogenous adsorption reaction. Adsorption thermodynamics demonstrated that the adsorption process is exothermic and has random nature of the solid/liquid interface. In addition, the regeneration of spent ACPS research showed that the adsorbent has good chemical stability. According to the comparative study, ACPS shows higher adsorption capacities of U(VI) and Th(IV) than other previous bio-adsorbents. Originality/value This study was conducted to improve the chemical and physical properties of bio-charcoal purchased from the local market to activated carbon by hydrothermal method. Activated carbon was immobilized on polystyrene forming new adsorbent ACPS for eliminating U(VI) and Th(IV) from aqueous solutions.

Characterization of a Nb-Pb composite target

A thin Nb target on a Pb backing was fabricated using the rolling technique. In the present work, the characterization of the sample has been carried out using various techniques to study the surface morphology, crystallography, elemental analysis, thickness and electrical conductivity useful for the intended use of the target prepared. The thin Nb target was analyzed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Rutherford back-scattering spectroscopy (RBS) techniques. The uniform and smooth surface of the sample was confirmed by SEM imaging. The presence of oxygen in the EDS spectra and peaks corresponding to crystal planes of PbO2 in the XRD spectrum confirms the oxidation of Pb foil. The XRD spectrum shows clear peaks corresponding to (011), (002), (112) crystal planes of pure Nb. The thickness of the thin Nb foil measured using the RBS techniques was found to be 0.8 mg/cm2. The current(I)-voltage(V) curve (relationship between the current flowing through an electronic device and the applied voltage across its terminals) at room temperature for the Pb and Nb/Pb foils was plotted and showed linear relationship between applied voltage and current flowing through the target foil. The measured electrical conductivity indicates an enhancement of 35.9 % for Nb/Pb foil relative to the conductivity measured for the Pb foil.

Preparation of NiCrBSi-WC/Co coatings by stable magnetic field assisted supersonic plasma spraying and its wear resistance mechanism

To enhance the wear resistance resistance of Ni-based coatings, Ni-based coatings were prepared using NiCrBSi (80 wt%) and WC/Co powders (20 wt%) as raw materials with a stable magnetic field assisted supersonic plasma spraying device at four magnetic field strength gradients. The microstructures, grain orientations and sizes of the four coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) techniques. The mechanical and tribological properties of the four coatings were also investigated. The results show that the average grain size of the coating increases from 0.92 μm decreases to 0.55 μm. The composition distribution of hard phase is more uniform, and the defects such as internal pores are significantly reduced. The maximum wear loss of the coating was reduced by 66.1% after applying a stable magnetic field. The main wear mechanisms are adhesive wear and abrasive wear. This is because the steady magnetic field induces thermoelectric magnetic force (TEMF) and thermoelectric magnetic convection (TEMC) in the deposition process of the coating, resulting in uniform distribution of hard phase and fine grain. And the coating exhibits excellent wear resistance. This process provides new possibilities and methods for processing and molding of materials assisted by a steady magnetic field. • A steady magnetic field assisted supersonic plasma spraying technique was innovatively used to prepare nickel-based coatings. • The effect of magnetic field on coating properties is proved by the improvement of stable magnetic field. • The wear resistance mechanism of NiCrBSi-WC/Co coating assisted by supersonic plasma spraying with steady magnetic field was studied. • The research results not only provide new ideas for improving the defects of coatings prepared by thermal spraying technology, but also provide references for further exploration by colleagues.