Scanning Electron Microscopy-energy Dispersive X-ray Research Articles

Bio-fabrication and Characterization of Green Synthesized Nanoparticles from Commercial Honey

Green approaches to nanoparticle synthesis offer sustainable and environmentally friendly alternatives, avoiding hazardous chemicals typical in traditional methods. This study characterizes nanoparticles (NPs) synthesized from silver nitrate (AgNO3) and iron oxide (Fe2O3) using commercial honey as a reducing and capping agent. Characterization revealed significant disparities between silver NPs (AgNPs) and iron NPs (FeNPs). AgNPs had a larger particle size (Z-average: 3115.67 nm) compared to FeNPs (Z-average: 1813 nm). AgNPs showed a monodisperse population, while FeNPs had a slightly broader size distribution. Additionally, AgNPs had a higher particle concentration (mean count rate: 505.17 kcps) than FeNPs (mean count rate: 296.65 kcps). Both AgNPs and FeNPs displayed negative surface charges, at -6.499 mV and -1.652 mV, respectively, where FeNPs exhibit a slightly higher value. Elemental composition analysis by scanning electron microscope – energy dispersive X-ray (SEM-EDX) revealed that AgNPs are primarily composed of silver, carbon, and oxygen, whereas FeNPs consisted mainly of iron, oxygen, and carbon. These findings provide insights into the physical and chemical properties of AgNPs and FeNPs synthesized using commercial honey. Understanding these properties is essential for optimizing synthesis processes and exploring applications in medicine, catalysis, and environmental remediation. The eco-friendly synthesis approach using honey underscores the potential for sustainable nanomaterial production. Further research can explore specific applications and benefits of AgNPs and FeNPs synthesized through this green method, offering an efficient and economical alternative for nanoparticle synthesis.

Catalytic upgrading of Naomaohu coal pyrolysis volatiles over NiAl and NiLiAl oxides

Catalytic upgrading of volatiles is an essential technology to improve the product distribution of pyrolysis for the clean and efficient utilization of low-rank coals. In this work, novel acid-base bifunctional catalysts composed of Ni/Li/Al oxides were designed and prepared using LDH precursors with tunable chemical composition and structural properties. The catalysts were systematically characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), physisorption, NH3-temperature programmed desorption (NH3-TPD), CO2-temperature programmed desorption (CO2-TPD), H2-temperature programmed reduction (H2-TPR), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). A two-stage fixed bed reactor was employed to evaluate the performance of the catalysts. Characterization results suggest that the crystal size of NiO and the surface area of the catalyst decreased with increasing Li content and decreasing Ni content in the catalyst, while the pore volume and pore diameter were positively correlated with Li content. Moreover, the addition of Li reduced the amount of weak acid sites and raised the amount of total basic sites. Consequently, the bifunctional catalysts boosted the yield of light tar and the contents of aromatics and phenols in tar. Specifically, with the highest total acid sites (569 μmol/g) promoting the cracking of heavy pitch components, Ni2.5Li0.5Al1 decreased the content of pitch in tar to 23.8wt.%, representing a 42.7% drop from the corresponding non-catalytic pyrolysis. Accordingly, it improved the light tar yield to 7.2wt.%, which was 18% higher than non-catalytic pyrolysis. 450°C is identified as a suitable temperature for the catalytic upgrading of volatiles from Naomaohu coal; higher catalysis temperatures at 500°C and 550°C led to lower tar yield and lower phenols content, along with higher gas yield and more carbon deposition.

Preparation, characterization and photocatalytic studies of defect pyrochlore, KMn0.33Te1.67O6 and its composite with g-C3N4

Skeletal materials belonging to the defect pyrochlore family have been the subject of considerable interest due to their remarkable properties. In this work, a highly efficient, stable and visible light active composite photocatalytic system consisting of defect pyrochlore of composition KMn0.33Te1.67O6 (KMnTeO) and g-C3N4 (g-CN) has been successfully prepared by simple physical mixing of pre-prepared KMnTeO and g-CN components synthesized in solid state and thermal treatment of low-cost melamine, respectively. Structural, morphological and optical properties of as-prepared catalysts were deduced from powder X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), Raman, Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (FESEM-EDX), Transmission Electron Microscopy-High Resolution Transmission Electron Microscopy (TEM-HRTEM), Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS), X-ray Photoelectron Spectroscopy (XPS) and Photoluminescence (PL) measurements. The lattice parameter “a” of parent KMnTeO was obtained from Rietveld refinement of its powder XRD pattern. The FTIR and Raman spectra of KMnTeO gave characteristic bands belonging to the defect pyrochlore structure. The photocatalytic activities of KMnTeO and composite KMnTeO-g-CN were evaluated by the degradation of methylene blue (MB). Scavenger experiments were carried out to identify the reactive species responsible for the degradation of MB. Furthermore, the reusability and stability of the photocatalysts were explored. The probable photocatalytic mechanism for MB degradation over the composite KMnTeO-g-CN was surmised according to the scavenger experiments. The work provides a new approach for the development of novel defect pyrochlore based composite photocatalysts to treat industrial wastewater containing organic pollutants.

Co-gasification of lignite and spent tea waste for the generation of hydrogen-rich syngas in a fluidized bed gasifier

The co-gasification of high moisture and high volatile content low-rank lignite (LG) coal and a common waste generated from the brewed tea leaves was studied in a fluidized bed gasification unit. Multiple experiments were conducted at different temperatures, ranging from 800 °C to 900 °C, at fixed operating parameters to elucidate the catalytic thermo-chemical impact on the gasifier performance parameters. The catalytic effect of alkali and alkaline earth metals (AAEMs), especially CaO, K2O, and Na2O present in the spent tea waste (STW) sample, on the product gas composition and performance parameters during the co-gasification experiments with LG was demonstrated. Mixed blends of LG and STW showed enhancement in the overall reactivity of the steam gasification runs, compared to the LG-only feed, primarily due to the change in the surface morphology, textures, and pore structures of the solid product ash samples, as identified with the electron spectroscopy analysis. Liquid and product samples were analyzed using characterization techniques such as Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) analytical techniques, along with the proximate, ultimate, and X-ray fluorescence (XRF) analysis of the gasification feed samples. An optimized blend ratio of 20 wt % of STW with LG sample enhanced the volumetric gas composition of H2 and CH4 gases from 52.03 % to 61.32 % and 3.98 %–5.45 % (on a dry-N2-free basis) with a relatively constant CO gas composition. It showed a reduced CO2 composition from 28.64 % to 18.25 % (on a dry-N2-free basis) for the gasification temperature of 900 °C. Even at the lower gasification temperatures of 800 °C and 850 °C with LG + STW feed, steam gasification experiments showed relatively comparable or superior performance to gasification experiments at 900 °C with LG-only feed. The present study indicated a holistic way to utilize the spent tea waste generated from millions of homes and commercial establishments in various parts of the world with potential application towards synergistic gasification process with other conventional carbon-source materials.

Effect of ZrO2 on the phase relations for CaO-SiO2-TiO2 system related to efficient extraction of titanium from titania-bearing slag

The selective crystallization and phase separation process has been regarded as a promising process for the recycling of titanium from titania-bearing furnace slag, however, the composition modification mechanism still remains unclear due to the lack of fundamental thermodynamic data. In the present work, the influence of ZrO2 addition on the equilibrium phase relations and the 1400 °C isotherm for CaO-SiO2-TiO2 system were experimentally determined by using the high temperature equilibration-quenching technique, and Scanning Electron Microscopy-Energy Dispersive X-ray Spectrometry, and X-ray diffraction analysis. The equilibrium solid phases of rutile (TiO2), perovskite (CaTiO3), and tridymite (SiO2) are determined to be coexisting with the liquid phase. In addition, comparisons of present results with thermodynamic calculation by FactSage show significant discrepancies. The present work is important for enriching the thermodynamic database of titania-bearing slag oxide systems as well as optimizing the selective crystallization and phase separation process.

Enhancing methyl orange discoloration with TiO2/Fe2O3/AC composites: synergistic adsorption-photocatalysis

Fe2O3/TiO2/AC nanocomposites were successfully synthesized via a sol–gel method, and their efficacy in decomposing methyl orange via adsorption-photocatalytic processes was reported for the first time in this study. Systematic exploration of the physicochemical properties impacting photocatalytic activity was conducted through x-ray diffraction, scanning electron microscopy—energy-dispersive x-ray spectroscopy, and Fourier transform infrared spectroscopy (FTIR) characterizations. The study revealed that the discoloration of methyl orange resulted from a synergistic interplay between adsorption and photocatalysis. The incorporation of Fe2O3 nanoparticles significantly elevated photocatalytic activity by 70%, with additional enhancement observed upon the introduction of activated carbon (AC) particles. The synergistic effects of AC adsorption and TiO2/Fe2O3 photocatalysis exhibited remarkable efficiency in degrading methyl orange under visible light irradiation. The trial functioning of Fe2O3 and AC in the TiO2/Fe2O3/AC composite, which serves as an adsorbent, an electron trap, and a co-catalyst providing active sites, significantly improved photocatalytic activity. These findings not only contribute to understanding the crucial role of composite TiO2 in conjunction with metal and carbon-based co-catalysts but also hold valuable implications for advancing research in the development of adsorption-photocatalytic systems for wastewater treatment.

Analytical Study of Polychrome Clay Sculptures in the Five-Dragon Taoist Palace of Wudang, China

During the Ming Dynasty, the Five-Dragon Palace functioned as a royal Taoist temple set atop one of China’s holiest Taoist mountains, Wudang Mountain. Two tower polychrome sculptures with exquisite craftsmanship have remained over the centuries. In this study, the painting materials and the techniques used to construct these sculptures were analyzed through multiple characterization methods, including optical microscope (OM) observations, micro-Raman spectroscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), X-ray diffraction (XRD), micro-Fourier-transform infrared spectroscopy (μ−FTIR), and pyrolysis–gas chromatography/mass spectrometry (Py−GC/MS). The results revealed that the pigments used in these sculptures included red pigments, which were composed of mercury (II) sulfide (cinnabar or vermillion), minium (Pb3O4), and hematite (Fe2O3); green pigments, which included atacamite and botallackite (Cu2Cl(OH)3), and blue pigments, which comprised smalt (CoO·nSiO2) and azurite (Cu3(CO3)2(OH)2). The white base layer was composed of quartz and mica minerals combined with gypsum or plant fiber, and the gold foil was adhered to the surface using heated tung oil. In addition, a special multi−layer technique was applied, with red under the golden gilding, white under the blue layer, and gray and black under the green layer. Drying oil was used as a binder for lead-containing pigments. This study offers substantial proof of reliable techniques to use in the continuing conservation of these sculptures, and it also serves as a foundation to determine if they can be dated to the late Ming or early Qing Dynasty (17th century).

Copper oxide nanoparticles (CuO-NPs) as a key player in the production of oil-based paint against biofilm and other activities

Copper oxide nanoparticles are among the metal nanoparticles gaining popularity in many biotechnological fields, particularly in marine environments. Their antimicrobial and antibiofilm activities make them appealing to many researchers. Among the various methods of producing nanoparticles, biosynthesis is crucial. Thus, a large number of reports have been made about the microbiological manufacture of these nanoparticles by bacteria. Nevertheless, bio-production by means of the cell-free supernatant of marine bacteria is still in its primary phase. This is landmark research to look at how bacteria make a lot (14 g/L) of copper oxide nanoparticles (CuO-NPs) via the cell-free supernatant of Bacillus siamensis HS, their characterization, and their environmental and medical approaches. The biosynthesized nanoparticles were characterized using a UV–visible spectrum range that provides two maximum absorption peaks, one obtained at 400 nm and the other around 550–600 nm. Diffraction of X-rays (XRD) clarifies that the size of the NPs obtained was estimated to be 18 nm using Debye-Scherrer's equation. Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) displays 91.93 % copper oxide purity. The Transmission Electron Microscope (TEM) image proves that the particles have a spherical form and an average diameter of 6.54–8.60 nm. At the environmental level, nanoparticles incorporated into oil-based paint can be used as antibiofilm tools to diminish the biofilm formed on the submerged surface in the marine environment. In disease management, NPs can be used as a wound healing agent to reduce the wound gap size as well as an anti-tumour agent to control liver cancer cells (hepatoma cells (HepG2)).

Post-fire curing and autogenous self-healing in alkali-activated slag: Microstructures and healing mechanisms

Among various ways to counter the effects of cracking and damage induced by exposure to elevated temperatures, self-healing appears to be a promising technique for maintaining construction materials' structural integrity and longevity. This research investigates the effectiveness and potential of autogenous self-healing for alkali-activated concrete performance recovery after exposure to elevated temperatures up to 800 °C. Two post-fire curing methods were examined: exposure to ambient air and immersion in sodium hydroxide (NaOH), to assess their effectiveness in promoting self-healing in AAS. To achieve better understanding of the mechanisms behind post-fire AAS's self-healing, a comprehensive evaluation of crack healing, microstructural changes, and the durability of the treated materials was conducted through a combination of visual inspection, ultrasonic pulse velocity, water sorptivity, rapid chloride permeability tests, scanning electron microscopy-energy dispersive X-ray, and X-ray diffraction. Findings reveal that NaOH immersion significantly enhances self-healing, evidenced by reduced crack widths and improved material properties. Changes in the amount of hydration products and various shapes of self-healing product crystals, such as trigonal, cubical, and rectangular, were detected. However, the dominant healing product was calcium carbonate (CaCO3), which precipitates through a combination of hydration reactions and carbonation processes, crucially contributing to the closure of microcracks and the restoration of the material's integrity. This process underscores the critical role of chemical reactions in AAS's self-healing mechanism, offering insights into its potential for enhancing the durability and resilience of construction materials. This emphasized the potential for leveraging AAS properties by self-healing and mitigating fire damage, thus extending the lifespan of structures and reducing maintenance costs.

Simple distance-based thread analytical device integrated with ion imprinted polymer for Zn2+ quantification in human urine samples.

This article presents the development of a distance-based thread analytical device (dTAD) integrated with an ion-imprinted polymer (IIP) for quantitative monitoring of zinc ions (Zn2+) in human urine samples. The IIP was easily chemically modified onto the thread channel using dithizone (DTZ) as a ligand to bind to Zn2+ with methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as well as 2,2-azobisisobutyronitrile (AIBN) as cross-linking agents to enhance the selectivity for Zn2+ detection. The imprinted polymer was characterized using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS). Under optimization, the linear detection range was from 1.0 to 20.0 mg L-1 (R2 = 0.9992) with a limit of detection (LOD) of 1.0 mg L-1. Other potentially interfering metal ions and molecules did not interfere with this approach, leading to high selectivity. Furthermore, our technique exhibits a remarkable recovery ranging from 100.48% to 103.16%, with the highest relative standard deviation (% RSD) of 5.44% for monitoring Zn2+ in human control urine samples, indicating high accuracy and precision. Similarly, there is no significant statistical difference between the results obtained using our method and standards on zinc supplement sample labels. The proposed method offers several advantages in detecting trace Zn2+ for point-of-care (POC) medical diagnostics and environmental sample analysis, such as ease of use, instrument-free readout, and cost efficiency. Overall, our developed dTAD-based IIP method holds potential for simple, affordable, and rapid detection of Zn2+ levels and can be applied to other metal ions' analysis.

Sustainable production of heavy metal-binding levan by a subarctic permafrost thaw lake Pseudomonas strain 2ASCA

Pseudomonas strain 2ASCA isolated in subarctic Québec, Canada, produced a cell membrane bound levan-type exopolymer (yield 1.17 g/L), after incubation in growth media containing 6 % sucrose (w/v) at temperature of 15 °C for 96 h. The objective of this study was to optimize levan production by varying the growth parameters. Moreover, the polymer's chemical characterization has been studied with the aim of increasing knowledge and leading to future applications in many fields, including heavy metal remediation. Higher levan yields (7.37 g/L) were reached by setting up microbial fermentation conditions based on the re-use of the molasses obtained from sugar beet processing. Spectroscopy analyses confirmed the levan-type nature of the exopolymer released by strain 2ASCA, consisting of a β-(2,6)-linked fructose repeating unit. Gel permeation chromatography revealed that the polymer has a molecular weight of 13 MDa. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) showed that the levan sequestered with a strong affinity Cr(III), which has never been previously reported, highlighting an interesting biosorption potential. In addition, SEM analysis revealed the formation of nanoparticles in acidified water solution.

Synthesis and characterization of chitosan-based pH-sensitive biofilm: An experimental design approach for release of vitamin B12

Hydrogels because of their unique potentials, such as highwater content and hydrophilicity, are of interest for the controlled release of drug molecules. In the present study, a biofilm was produced using chitosan, a natural polymer. Characterization analyses of the synthesized biofilm were performed using Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis-differential thermal analysis, x-ray diffraction, and scanning electron microscopy-energy dispersive x-ray spectrometry. The analysis results of the film before loading were compared to the analysis made after adding vitamin B12 to the film. The release percentage of vitamin B12 was investigated by using ultraviolet-visible spectrophotometery. The FT-IR bands of vitamin B12 were in the range of 2,800-3,500 cm-1 and 1,000 cm-1-1,750 cm-1. When pH increased from 3 to 7, release of vitamin B12 from the biopolymer increased up to pH 5. While examining the release potential, parameters, such as pH, initial concentration of vitamin B12, release time, and solution volume, were optimized by using response surface methodology. It was determined that with the increase in release time and the initial concentration, pH contributed positively to the release of vitamin B12. The following conditions were determined for release of vitamin B12 from the biofilm: pH: 4.2, initial concentration of vitamin B12: 54.0 mg L-1, the release time: 117 min, and volume of solution: 2.1 mL. The analysis of variance results showed that the determination coefficients for the use of synthesized biofilm in vitamin B12 release were high and R2 =0.9704.

Broad-spectrum pH functional chitosan-phosphatase beads for the generation of plant-available phosphorus: utilizing the insoluble P pool.

Utilization of organic phosphates and insoluble phosphates for the gradual generation of plant-available phosphorus (P) is the only sustainable solution for P fertilization. Enzymatic conversions are one of the best sustainable routes for releasing P to soil. Phosphatase enzyme aids in solubilizing organic and insoluble phosphates to plant-available P. We herein report the preparation of highly functional chitosan beads co-immobilized with acid phosphatase and alkaline phosphatase enzymes via a glutaraldehyde linkage. The dual enzyme co-immobilized chitosan beads were characterized using Fourier-transform infrared (FTIR), thermogravimetric (TGA), and scanning electron microscopy-energy dispersive x-ray (SEM-EDX) analyses to confirm the immobilization. The co-immobilized system was found to be active for a broader pH range of ∼4-10 than the individually bound enzymes and mixed soluble enzymes. The bound matrix exhibited pH optima at 6 and 9, respectively, for acid and alkaline phosphatase and a temperature optimum at 50°C. The phosphate-solubilizing abilities of the chitosan-enzyme derivatives were examined using insoluble tri-calcium phosphate (TCP) for wide pH conditions of 5.5, 7, and 8.5 up to 25 days. The liberation of phosphate was highest (27.20mg/mL) at pH 5.5 after the defined period. The residual soil phosphatase activity was also monitored after 7days of incubation with CBE for three different soils of pH ∼5.5, 7, and 8.5. The residual phosphatase activity increased for all the soils after applying the CBE. The germination index of the Oryza sativa (rice) plant was studied using different pH buffer media upon the application of the CBE in the presence of tri-calcium phosphate as a phosphate source. Overall, the dual-enzyme co-immobilized chitosan beads were highly effective over a wide pH range for generating plant-available phosphates from insoluble phosphates. The chitosan-enzyme derivative holds the potential to be used for sustainable phosphorus fertilization with different insoluble and organic phosphorus sources.

Fabrication and Optimization of Primary Batteries Using Ni/Graphene Nanosheet Electrodes

This study aims to investigate the impact of varying the mass ratio of Ni to Graphene Nano Sheets (GNS) and how incorporating GNS affects the performance of a primary battery prototype (Ni/GNS//electrolyte//GNS). The primary battery prototype was developed using both impregnation and alloy methods. Different mass ratios of Ni/GNS to electrolyte to GNS were tested, including ratios of 1:2:1 (A), 2:2:1 (B), 1:2:2 (C), 2:1:2 (D), and 1:1:2 (E). The characterization of GNS, Ni/GNS, and the primary battery prototype involved using X-Ray Diffraction (XRD) and Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX) instruments. A multimeter was employed to measure electrical conductivity, energy density, and power density. A potentiostat/galvanostat was used to measure cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). XRD analysis showed a broad and weak peak at 2θ= 24.32° for GNS, confirming its successful synthesis. Additionally, a peak at 2θ = 43.5° indicated effective deposition of Ni on the GNS surface in Ni/GNS. The SEM-EDX results supported the XRD findings, showing regularly spaced pores and a thin surface layer in GNS. Notably, white spots on the graphene surface in Ni/GNS indicated successful Ni deposition. In terms of electrical conductivity, the highest value was observed in the primary battery prototype for sample D (2:1:2), which measured 1.11 S/cm2. These results were also supported by measurements of energy density and power density in sample D, which achieved the highest values among all samples, with 144,788 Wh/kg and 252,500 W/kg, respectively. Moreover, the CV and EIS measurements remained stable at 0.30 kΩ and 0.88 kΩ, suggesting that GNS could potentially conduct electrons owing to its electrical conductivity.

Electrical Characterization of Epoxy Nanocomposite under High DC Voltage.

This work studies the direct current breakdown characteristics of unfilled epoxy and epoxy nonconductive nanocomposites (SiO2,MgO and Al2O3). It also examines the variation of electrical properties in epoxy nanocomposites. The novel aspect of this study is that the samples of Epoxy nanocomposite were exposed to high voltages of up to six kilo volts for three hours using field electron microscopy under high vacuum conditions (10-5 mbar). The current emitted from these samples was measured at three different intervals of time. In addition, the influence of high voltage on the permittivity, loss factor (tan(δ)), and conductivity of the epoxy nanocomposite was studied. This evaluation was conducted before and after applying the voltage at room temperature, The frequency range extends from 10-2-10-7 Hz using the Novo Control Alpha-A analyzer. Current-voltage characterization was performed through field electron microscopy. The samples were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy and Fourier Transform Infrared Spectroscopy. The unfilled epoxy exhibited structural degradation, resulting in the formation of holes when exposed to high voltages of up to six kilo volts, leading to a reduction in electrical properties. Nevertheless, the addition of nanoparticles shows a significant increase in the operational lifetime of the epoxy nanocomposite. The degree of increase in the lifetime of epoxy composite varied depending on several factors such as the type of NPs introduced and their respective sizes. The epoxy/Al2O3 nanocomposite comparing with epoxy/MgO and epoxy/SiO2 nanocomposite showed elevated resistance to direct current breakdown strength and maintaining its dielectric.

High Valency of Charge Compensator (Mo6+) to Substitute Ti Site in REE Doped Zirconolite (REE=Nd, Sm, Gd, Ho and Yb): Solid Solubility, Phase Evolution and Structural Analysis

Zirconolite ceramics have been proven to be a promising matrix for high-level waste immobilization, especially for minor actinides. In this study, a series of CaZr1-2xREE2xTi2-xMoxO7 (REE = Nd, Sm, Gd, Ho, Yb) samples were prepared to investigate the formation of zirconolite REE as surrogates of minor actinides and Mo6+ as charge compensator. Synchrotron and in-house powder X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) were used to study their solid solubility, phase evolution, and structural details. XRD results show that the formation of zirconolite-2M can be up to x=0.15 in the CaZr1-2xNd2xTi2-xMoxO7 samples when co-existence of 2M and 4M was observed at x=0.20 and 0.25. The “yellow phase” appears when x exceeds 0.4. The phase evolutions of CaZr1-2xSm2xTi2-xMoxO7, CaZr1-2xGd2xTi2-xMoxO7, CaZr1-2xHo2xTi2-xMoxO7 and CaZr1-2xYb2xTi2-xMoxO7 solid solutions are similar to each other: (1) zirconolite-2M in x=0.05 and 0.10; (2) co-existence of 2M and 4M and then formation of 4M phase from x=0.15 to 0.25; (3) formation of “yellow phase” and pyrochlore when x≥0.30. Interestingly, perovskite exits in all the ceramic samples, and its lattice parameters slightly change when increasing the dopants. Rietveld refinement results reveal that Sm/Ho mainly incorporates into 8f (Wyckoff position) Zr-sites while Mo replaces the 8f (Wyckoff position) Ti-sites. XANES results further confirm the occupation of Mo in TiO5 coordination environments. Furthermore, there is a considerable amount of Sm/Ho incorporated into 8f Ca-sites, demonstrating a different substitution mechanism from the preliminary design.

Adsorptive removal of anthraquinone dye from wastewater using silica-nitrogen reformed eucalyptus bark biochar: Parametric optimization, isotherm and kinetic studies

BackgroundDye sequestration from textile wastewater is required prior to discharge because of environmental concerns and the potential risk posed by colored contaminants. MethodsHerein, a novel composite adsorbent of biochar derived from eucalyptus bark and 3-aminopropyl triethoxysilane (TESPA, as source of silica) and diethylene triamine (DIEN, as source of nitrogen) was synthesized via impregnation method. The prepared adsorbents were characterized by scanning electron microscopy-energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, N2 adsorption-desorption and pH at point of zero charge (pHpzc) analyses. The optimal TESPA: DIEN molar ratio for the silica-nitrogen doped eucalyptus bark biochar (Si-N@EBB) composite to adsorb acid blue 25 (AB25) dye was 2:1. The independent process parameters (contact duration, adsorbent dosage, pH and initial AB25 concentration) influencing the AB25 adsorption by Si-N@EBB2:1 were optimized by Box-Behnken design in response surface methodology at temperature of 26± 2 °C. The obtained experimental data were analyzed by the Langmuir, Freundlich and Temkin isotherms. Kinetic data obtained at various AB25 concentrations were evaluated using pseudo-first-order (PFO), pseudo-second-order (PSO) and intraparticle diffusion equations. Significant FindingsPredicted values of removal efficiency were found to be in agreement with the experimental values obtained (R2 = 0.9823; Adj − R2 = 0.9646). Optimization findings revealed that maximum removal efficiency of 96.03± 2.57 % was achieved at the optimum conditions of 21.01 mg L−1 initial AB25 concentration, 3.91 dye solution pH, 0.913 g L−1 adsorbent dosage and 117.2 min contact duration. The equilibrium adsorption data fitted well to the Langmuir isotherm with a monolayer uptake capacity found to be 197.4 mg g−1. PSO model suited the kinetic data well, indicating the dominance of chemisorption mechanism.

Characterization of novel solar based nitrogen doped titanium dioxide photocatalytic membrane for wastewater treatment

The increasing presence of microbial and emerging organic contaminants pose detrimental effects on the environment and ecosystem such as diseases, pandemics and toxicity. Most of these synthetic pollutants are biorecalcitrant and therefore persist in the environment. Conventional water treatment methods are not effective thereby necessitating the development of advanced techniques such as photocatalysis and membrane processes. In this study, visible light-driven photocatalytic membrane was synthesized through the immobilization of nitrogen-doped nanoparticles onto the polyvinylidene fluoride (PVDF) membrane and performance evaluated with E.coli microbial contaminant removal. Characterization was done using Fourier transform infrared spectra, X-ray diffraction (XRD), water contact angle, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The Nitrogen-doping of titanium dioxide red-shifted the light absorption to a visible range of 440 nm from 400 nm. Nitrogen dopant was detected at 1420 cm−1and 1170 cm−1 for nitrogen doped nanoparticles and 1346-1417 cm−1 for nitrogen doped titanium dioxide PVDF membrane. SEM-EDX confirmed presences of nitrogen in nitrogen doped titanium dioxide nanoparticles on membrane surface with nitrogen elemental composition of 0.01 % wt. The water contact angle reduced by 81.39o from 120.14o to 38.75o because of PVA immobilization of nitrogen-doped titanium dioxide and glutaraldehyde crosslinking. Nitrogen doping resulted in visible light active photocatalytic membranes with better hydrophilicity and fouling resistance. 8.42 E.coli log removal and a relative flux of 0.35 was obtained within 75 min. The developed photocatalytic membrane enables the use of sunlight hence a less costly method for decontamination of wastewater.

Development of suitable magnetite–diatomite nanocomposite for Cd (II) adsorptive removal from wastewater

A magnetite-diatomite nanocomposite (MDM) adsorbent was synthesized using the co-precipitation method, wherein a magnetite precursor was intercalated into diatomite clay minerals sourced from the Ethiopian Rift Valley. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy energy dispersive X-ray (SEM-EDX), Brunauer-Emmet-Teller (BET) and magnetometry measurements were used to look into the structure and magnetic properties of the adsorbent. Batch experiments were conducted to study the remarkable Cd (II) adsorption capacity of MDM and the ease of separating the used adsorbent with a bar magnet. The most important adsorption parameters, namely, initial pH, adsorbent dose (g), initial (Cd (II) concentration (mg), and contact time (min), were optimized using Box-Behnken design (BBD). The MDM has shown exceptional Cd (II) removal under optimum conditions, with a maximum adsorption capacity of 31.4 mg/g from aqueous solution. According to the isotherm and kinetic studies, the Temkin and pseudo-second-order models respectively, offered the best fit for adsorption equilibrium when compared to the other models. The thermodynamic studies, under standard conditions revealed that, Cd (II) uptake is exothermic and spontaneous. The finding of this study confirms that the MDM adsorbent is easily reusable, extractable from the solution using an external magnet, and capable of recovering around 80 % of Cd (II) when HNO3 is used as a desorbing agent. The study demonstrates a cost-effective and environmentally friendly approach to remediate Cd (II) pollution in wastewater. Furthermore, the superior Cd (II) adsorption capacity, combined with the ease of separating using a bar magnet and high reusability, highlights the potential of this novel adsorbent as a sustainable and efficient solution for addressing Cd (II) contamination in various wastewater treatment applications.Thereby contributing significantly to advancements in the field of heavy metal removal from aqueous solutions.

Performance of pulsed plasma thruster at low discharge energy

As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster (PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at 2 J or more of discharge energy. In this work, the performance of a PPT with a side-fed, tongue-flared electrode configuration operated within a lower discharge energy range of 0.5‒2.5 J has been investigated. Ablation and charring of the polytetrafluoroethylene propellant surface were analyzed through field-effect scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy. When the discharge energy fell below 2 J, inconsistencies occurred in the specific impulse and the thrust efficiency due to the measurement of the low mass bit. At energy 2 J, the performance parameters are compared with other PPT systems of similar configuration and discussed in depth.