Transform Electron Microscopy Research Articles

Synthesis of Silver Nanoparticles and Forced Convective Heat Transfer Coefficient Measurement of Silver-Water Nanofluids at Laminar Flow

Heat management in industries and other areas is a major issue currently worldwide. Conventional heat transfer fluids like water and ethylene glycol are not very effective. Nanofluids (NFs), composed of nanoparticles (NPs) dispersed throughout a base fluid (BF), have recently been identified as promising heat management agents for various industrial and other applications. Heat transmission is one of the many uses for AgNPs–water NFs (silver NPs (AgNPs) dispersed in water). The goal of this work was to determine the AgNPs–water NFs' forced convective heat transfer coefficient (HTC) in laminar flow. Due to this, we present the results of the HTC study of AgNPs–water NFs in laminar flow in this paper. First, using AgNO3 as a precursor, a chemical reduction approach was used for facile synthesis of AgNPs in one pot at ambient temperature. Synthesized NPs were examined using ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), and transform electron microscopy (TEM) techniques. The average particle size obtained from TEM is 25 nm. The required quantity of AgNPs was added to the water to produce 0.5 and 1.0 vol% of AgNPs–water NFs. Next, zeta potential and dynamic light scattering (DLS), in addition to time-lapse observation and captured picture comparison, were used to assess the stability of the formulated NFs. To calculate the forced convective HTC of prepared NFs in laminar flow, a vertical shell and tube heat transfer apparatus and computer-based data recorder were used. According to the results, in comparison to BF, the HTC of 0.5 and 1.0 vol% NFs was 3.3 and 5 times greater, respectively which encourages the use of AgNPs–water NFs in industry and other heat management. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 13−22

Nanosorbent based on coprecipitation of ZnO in goethite for competitive sorption of Cd(II)-Pb(II) and Cd(II)-Pb(II)-Ni(II) systems.

Amongst the various water pollutants, heavy metal ions require special attention because of their toxic nature and effects on humans and the environment. Preserving natural resources will have positive impacts on living conditions by reducing diseases and water treatment by nanotechnology is effective in solving this problem owing to the properties of nanomaterials. In this study, a goethite nanoparticle was prepared by hydrothermal method, while ZnO/goethite nanocomposite by co-precipitation was developed. The nanoparticles were characterized using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transform Electron Microscopy (TEM), Thermogravimetric Differential Thermal Analysis (TGA-DTA), Dynamic Light Scattering (DLS), and Breunner-Emmet-Teller (BET) surface area analysis. The adsorption of Cd(II)-Pb(II) and Cd(II)-Pb(II)-Ni(II) ions systems on ZnO/goethite nanocomposite was investigated in a batch mode. The findings of the study showed that nanoparticles ZnO/goethite composite were mixed of spherical and rod-like shapes. The BET results revealed average particle sizes of 41.11nm for nanoparticles for ZnO/goethite while TGA/DTA confirmed the stability of the adsorbents. The optimum adsorption capacities of the nanocomposite for Pb(II), Cd(II), and Ni(II) ions from the Pb-Cd-Ni ternary system were 415.5, 195.3, and 87.13mgg-1, respectively. The adsorption isotherm data fitted well with the Langmuir isotherm model. The study concluded that the nanoparticle adsorbents are efficient for the remediation of toxic pollutants and are, therefore, recommended for wastewater treatment.

Magnetic properties of gadolinium and/or dysprosium substituted Sm–Co nanocomposite ribbons

The present study reported the influence of heavy rare-earth elements (Gd and/or Dy) on Sm-Co-based melt-spun ribbons. Microstructure and magnetic properties of Sm-Co-based (Sm1–xRExCo5) ternary and quaternary systems were investigated. The X-ray diffraction, Auger spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses reveal the presence of the 1:5H and 2:17R phases in the as-spun ribbons. A high-temperature magnetic measurement reports a Curie temperature (TC) at ∼825 and ∼869 K in Sm0.6Gd0.4Co5 (ribbon A) and Sm0.6Gd0.3Dy0.1Co5 (ribbon B), respectively. A low-temperature magnetic measurement on Sm0.6Gd0.3Dy0.1Co5 ribbons exhibits a type-2 SR (spin reorientation) behaviour at ∼72 K, which arises due to the presence of the DyCo5 phase. Room temperature magnetic measurements reveal that overall magnetic measurement (OMP) is about 24 and 29.9 for ribbons A and B, respectively. Consequently, the comparative investigations profess that ribbon B shows better magnetic performance due to Dy addition with reduced grain size. This observation indicates that the Gd and Dy substituted Sm–Co magnet can be a potential magnet for high-temperature applications.

Synthesis and CO gas adsorption properties of GO/ZnFe2O4 nanocomposites

In this work, ZnFe2O4 nanoparticles were synthesized by hydrothermal method while the hummer method was used to synthesize GO nanosheet. GO/ZnFe2O4 nanocomposites (GO/ZFO) were prepared by mixing of GO with ZnFe2O4 in mass ratio of 1:99, respectively. The structure, morphology, and physical – chemical characteristics were determined by Raman spectroscopy, Transform Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FT-IR). The CO gas adsorption properties of GO/ZFO were investigated in the range of 25 – 200 ppm at room temperature using quartz crystal microbalance (QCM). GO/ZFO nanocomposites show great adsorption – desorption capacity, high repeatability, and the largest adsorption performance of 1.21‰ (0.098 µg.cm-2 at 200 ppm). The results show that this new approach is promising of spinel structure materials for CO adsorption at room temperature.

Synthesis and CO gas adsorption properties of GO/ZnFe2O4 nanocomposites

In this work, ZnFe2O4 nanoparticles were synthesized by hydrothermal method while the hummer method was used to synthesize GO nanosheet. GO/ZnFe2O4 nanocomposites (GO/ZFO) were prepared by mixing of GO with ZnFe2O4 in mass ratio of 1:99, respectively. The structure, morphology, and physical – chemical characteristics were determined by Raman spectroscopy, Transform Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FT-IR). The CO gas adsorption properties of GO/ZFO were investigated in the range of 25 – 200 ppm at room temperature using quartz crystal microbalance (QCM). GO/ZFO nanocomposites show great adsorption – desorption capacity, high repeatability, and the largest adsorption performance of 1.21‰ (0.098 µg.cm-2 at 200 ppm). The results show that this new approach is promising of spinel structure materials for CO adsorption at room temperature.

Synthesis and CO gas adsorption properties of GO/ZnFe2O4 nanocomposites

In this work, ZnFe2O4 nanoparticles were synthesized by hydrothermal method while the hummer method was used to synthesize GO nanosheet. GO/ZnFe2O4 nanocomposites (GO/ZFO) were prepared by mixing of GO with ZnFe2O4 in mass ratio of 1:99, respectively. The structure, morphology, and physical – chemical characteristics were determined by Raman spectroscopy, Transform Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FT-IR). The CO gas adsorption properties of GO/ZFO were investigated in the range of 25 – 200 ppm at room temperature using quartz crystal microbalance (QCM). GO/ZFO nanocomposites show great adsorption – desorption capacity, high repeatability, and the largest adsorption performance of 1.21‰ (0.098 µg.cm-2 at 200 ppm). The results show that this new approach is promising of spinel structure materials for CO adsorption at room temperature.

Effect of CeO2 on carbon deposition resistance of Ni/CeO2 catalyst supported on SiC porous ceramic for ethanol steam reforming

Ni/CeO2 catalysts (nCeO2:nNi = 0, 1, 4, 7, 10) supported on SiC porous ceramics for ethanol steam reforming (ESR) were investigated with respect to hydrogen production performance and growth of carbon deposition. The oxygen released from CeO2 enables the oxidation of CHx species to serve as carbon precursors, thus providing Ni/CeO2 catalysts with stronger resistance to carbon deposition compared with Ni catalysts. The Ni/CeO2 catalysts prepared by inverse microemulsion and impregnation methods exhibit regular semicircular spherical shape on SiC porous ceramics. Under 500 °C for 25 h of ESR reaction, the ethanol conversion rate over Ni/CeO2 catalysts (nCeO2:nNi = 7) is sustained up to 100% and H2 selectivity is essentially kept at 74%. The by-product selectivity declines stepwise with increasing content of CeO2, which is attributed to the adsorption and oxidation of CO and of CHx species as CH4 precursor from CeO2. The scanning electron microscopy (SEM) and transform electron microscopy (TEM) results reveal that further loading of CeO2 on the surface of Ni catalysts can alleviate both migration and sintering of Ni particles. Furthermore, carbon deposition on Ni/CeO2 catalysts preferentially outgrow filamentous rather than amorphous carbon, with a tendency for the latter to be more deactivated.

CO oxidation and 4-nitrophenol reduction over ceria-promoted platinum nanoparticles impregnated with ZSM-5 zeolite

Active new ceria-promoted platinum supported on ZSM-5 catalysts were prepared and characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), transform electron microscopy (TEM), temperature programmed desorption (TPD), and FTIR of CO adsorption. The samples were prepared by the incipient wetness impregnation method and calcined at 500 °C. The XRD patterns and FTIR spectra prove that the zeolite framework is kept unaltered after metal loadings. TEM images prove the presence of Pt nanoparticles with particle size starting from 14 to 27 nm. The FTIR data suggest the formation of Pt–O–Ce linkage. In-situ FTIR of CO adsorption over reduced samples proves the presence of Pt0 only, and no Ptn+–CO species are detected. The prepared catalysts were tested in both oxidation reaction (CO oxidation) in the gas phase and in reduction reaction (4-nitrophenol reduction) in the aqueous medium. Firstly, CO oxidation by O2 results in the formation of a CO2 peak at 2347 cm−1 as the only CO oxidation product in the studied frequency range. The intensity of the CO2 peak increases after the addition of Ce, and it is 4 times higher in Pt1Ce0.5ZSM-5 than that in the Ce-free sample. According to the FTIR data and previous reports, the increase in the catalytic activity may be due to the formation of Pt–O–Ce linkage. Secondly, Ce-promoted Pt1ZSM5 also exhibits enhanced catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol by NaBH4 in the aqueous medium. The first-order rate constant of the reduction increases ≈13 times after incorporating equal ratios of Pt and Ce (Pt1Ce1ZSM-5), and the activation energy (Ea) decreases to 40% of that in the reaction over Pt1ZSM-5.

Green synthesis of Ag@AgCl/Elaeagnus angustifolia seed nanocomposite using Elaeagnus angustifolia leaves: an amazing nanophotocatalyst with highly photocatalytic activity under sunlight irradiation.

In this investigation, Ag@AgCl nanoparticles were synthesized by a green and inexpensive method using Elaeagnus angustifolia leaves, as a reducing and stabilizing agent without using any toxic solvent, external halide source, harsh chemicals, or capping agents. In this protocol, the nanophotocatalyst was synthesized via immobilization of Ag@AgCl NPs on the surface of biowaste Elaeagnus angustifolia seed (EAS) as a green support, which prevents the agglomeration Ag@AgCl NPs and improves the catalytic activity. The biosynthesized nanophotocatalyst were characterized by UV-Vis spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE SEM), energy dispersive X-ray spectroscopy (EDS), and transform electron microscopy (TEM) and inductively couple plasma mass spectrometry (ICP). In order to investigate the photocatalytic activity of the biosynthesized nanophotocatalyst, it was used in the degradation of methylene blue (MB) under sunlight. The results showed that nanophotocatalyst had an excellent photo activity without any agglomeration. In addition, the nanophotocatalyst can be easily be recycled and reused several times without losing its activity. Graphical abstract.

Green synthesis of Pd nanoparticles supported on modified Nonpareil almond shell using almond hull extract: a beneficial nanocatalyst for convenient reduction of organic dyes

In this investigation, palladium nanoparticles were synthesized by green and inexpensive method using Nonpareil almond hull, as a reducing and stabilizing agent without using any toxic solvent or capping agents. In this protocol, two separate methods were used to immobilize Pd NPs on the surface of green-waste Nonpareil almond shell (NAS) and modified Nonpareil almond shell was obtained as an environmentally benign support. The green synthesized nanocatalysts were characterized by UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET), and transform electron microscopy (TEM). TEM images revealed that the Pd NPs immobilized on modified Nonpareil almond shell are spherical particles with average size of less than 20 nm without any agglomeration. In order to investigate the catalytic activity of green synthesized Nanocatalyst, it was used in the reduction of Methylene Blue (MB), Rhodamine 6G (R6G) and Methyl Orange (MO) at room temperature. The results showed that the modified nanocatalyst had a high catalytic activity in the reduction of these organic dyes. In addition, the nanocatalyst can be easily recycled and reused several times without losing its activity.

Green fabrication of Cu/pistachio shell nanocomposite using Pistacia Vera L. hull: An efficient catalyst for expedient reduction of 4-nitrophenol and organic dyes

Abstract A facile and rapid biosynthesis of copper nanoparticles (CuNPs) is presented here. This protocol also delivers the CuNPs immobilized on the surface of waste pistachio shell (PS), as an environmentally benign support, using pistachio hull extract (PHE), as a reducing and stabilizing agent. The biosynthesis was realized through a very simple and inexpensive one-pot procedure without employing any toxic reductants or capping agents. The biosynthesized CuNPs and copper/pistachio shell nanocomposite (Cu/PS NC) were characterized by UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and transform electron microscopy (TEM). The CuNPs and Cu/PS NC were successfully employed as efficient catalysts in the reduction of 4-nitrophenol (4-NP), methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) at ambient temperature. Cu/PS NC has shown to be a highly effective and easily recyclable catalyst, as it can be reused repeatedly without appreciable decrease in its catalytic activity. In view of these properties, Cu/PS NC was employed as the packing material of a flow reactor for running the reduction of 4-NP into 4-AP expediently in a continuous flow manner. The flow reactor was successfully tested for simultaneous reductive degradation of the dyes contaminated the real waste-water samples collected from the drains of different local textile and drug industries. The methods presented here are environmentally friendly processes and highly beneficial to address the industrial requirements.

Biosynthesis of gold nanoparticles using Capsicum annuum var. grossum pulp extract and its catalytic activity

Biological synthesis approach has been regarded as a green, eco-friendly and cost effective method for nanoparticles preparation without any toxic solvents and hazardous bi-products during the process. This present study reported a facile and rapid biosynthesis method for gold nanoparticles (GNPs) from Capsicum annuum var. grossum pulp extract in a single-pot process. The aqueous pulp extract was used as biotic reducing agent for gold nanoparticle growing. Various shapes (triangle, hexagonal, and quasi-spherical shapes) were observed within range of 6–37nm. The UV–Vis spectra showed surface plasmon resonance (SPR) peak for the formed GNPs at 560nm after 10min incubation at room temperature. The possible influences of extract amount, gold ion concentration, incubation time, reaction temperature and solution pH were evaluated to obtain the optimized synthesis conditions. The effects of the experimental factors on NPs synthesis process were also discussed. The produced gold nanoparticles were characterized by transform electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDS) and Fourier Transform infrared spectroscopy (FTIR). The results demonstrated that the as-obtained GNPs were well dispersed and stable with good catalytic activity. Biomolecules in the aqueous extract were responsible for the capping and stabilization of GNPs.

Influence of monovalent alkaline metal cations on binder-free nano-zeolite X in para-xylene separation

The adsorption process was studied for separating para-xylene from xylene mixture on modified nano-zeolite X in a breakthrough system. Nano-zeolitic adsorbent with different ratios of SiO2/Al2O3 was synthesized through hydrothermal process and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The product was characterized by X-ray diffraction, scanning electron microscopy (SEM), nitrogen adsorption, transform electron microscopy (TEM) and in situ Fourier transform infrared (FTIR) spectroscopy. The influence of nano-zeolite water content and desorbent type on the selectivity of para-xylene toward other C8 aromatic isomers was studied. The optimization of adsorption process was also investigated under variable operation conditions. The isotherm for each isomer of C8 aromatics and the desorbents possess the adsorption characteristics of Langmuir type. The selectivity factor of para-xylene relative to each of meta-xylene, ortho-xylene and ethylbenzene under the optimum conditions obtained to be 5.36, 2.43 and 3.22, in the order given.

Preparation of Nanosized Spinel Lithium Manganate by an Integrated Technique of High-Gravity Technology and Microwave Technology

A novel synthesis of nanosized spinel LiMn2O4cathode has been developed by a combination of high-gravity technology and microwave technology. Spinel lithium manganate precursor were prepared by co-precipitation method in a rotating bed with helix channels (RBHC). Calcination of the precursor in the microwave field produces uniformly sized, nanoparticles of spinel LiMn2O4as the final product. The phase structures and morphologies were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM), transform electron microscopy (TEM). The results show that nanosized spinel LiMn2O4powders with high crystallinity, uniform particle size, and the average size of about 60 nm can be synthesized by the integration of high-gravity technology and microwave technology.