Energy Dispersive Absorption Spectroscopy Research Articles

Dynamic photocatalytic degradation of organic pollutants employing co-doped ZnS nanoparticles synthesized via solid state reaction method

Because of their excellent optical and catalytic capabilities, ZnS with different co-doped proportions of metals has numerous applications. Their practical uses are limited due to their low photon efficiency and significant photo corrosion. Constructing heterojunctions and advanced structures with appropriate transition metal ions doping are active ways of improving semiconductor characteristics. The Pure and different dopant concentrations of Ni and Cd doped ZnS NPs were effectively synthesized via the solid-state reaction method. The influence of Ni and Cd doping concentration on the microstructure, morphology, and optical properties of pure and Ni-doped ZnS nanocrystals was characterized by X-ray diffraction, Scanning Electron Microscopy, ultraviolet-visible absorption spectroscopy, Energy Dispersive Absorption Spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectra, and the Photocatalytic studies. X-ray diffraction studies show that the average crystallite size increased to 3.30 nm from 2.64 nm upon integrating Ni ion, then decreased to 3.01 nm for Ni0.05Cd0.01 dopant level. SEM analysis reveals that a significant number of nanoparticles have a larger surface area and seem to be spherical. The active vibration frequencies of the Zn–S interaction were observed between 600cm–1 and 500cm–1 in the cubic structure of ZnS Metal oxide. The (ZnS1–0.05Ni0.05Cd0.01) sample shows Excellent photocatalytic degradation activity on the organic pollutants of the wastewater sample, about 96.67% for Methylene Blue. The reported findings demonstrate the dynamic degradation of organic dyes for minimal doping concentrations.

Dual Synthesis of Silver and Iron Oxide Nanoparticles from Edible Green Amaranthus Viridis and their In vitro Antioxidant Activity and Antimicrobial Studies

Background: There is an increasing commercial demand for nanoparticles due to their wide applicability in various areas, such as chemistry, catalysis, energy and medicine. Metallic nanoparticles are traditionally synthesized by wet chemical techniques where the chemicals used are quite often toxic and flammable. Objective: In the present study, we have described a simple, cost-effective and environmentally- friendly technique for green synthesis of silver and iron nanoparticles by using the aqueous extract of leafy vegetable Amaranthus viridis as a reducing agent. Methods: The silver and iron nanoparticles (Av-AgNPs, Av-IONPs) were characterized by different spectral methods. The surface plasmon resonance spectrums of Av-AgNPs, Av-IONPs were recorded at 422nm and 261nm. The scanning electron microscopy (SEM) analysis reveals that the Av-AgNPs and Av-IONPs are roughly spherical in shape. Energy dispersive absorption spectroscopy (EDAX) of biosynthesized Av-AgNPs and Av-IONPs indicates the reduction of silver ions to elemental silver and iron ions to elemental iron. Results: The particle size analysis of Av-AgNPs and Av-IONPs was carried out by the dynamic light scattering (DLS) method; the results reveal both Av-AgNPs and Av-IONPs to be polydispersed in nature. The average particle size of Av-AgNPs is 55.8 nm with a polydispersed index (PI) of 0.297; similarly, the average particle size of Av-IONPs is 80.6 nm with a polydispersed index (PI) of 0.469. Zeta-potential of Av-AgNPs was detected at -24.6 mV and Av-IONPs were detected at 28.8 mV; the result reveals that their high stability may be due their high negative charge and positive charge, respectively. The dual synthesized Av-AgNPs and Av-IONPs exhibited excellent antioxidant activity by DPPH, H2O2 and NO methods. DPPH was proven to be the best when compared with the other two methods. The biosynthesized Av-AgNPs and Av-IONPs proved to have very good antimicrobial activity against gram +ve and gram –ve bacteria. Conclusion: Compared with the standard antibiotic, there are several reports on the green synthesis of metal nanoparticles using various plant parts, but here, edible leafy vegetable Amaranthus viridis was used for biosynthesis of both Av-AgNPs and Av-IONPs.

Synthesis and evaluation of the antimicrobial potentials of cobalt doped- and magnesium ferrite spinel nanoparticles

The high incidence of infectious disease and increase in the incidence of antibiotic resistance has led to the exploitation of inorganic nanoparticles as novel antimicrobial agents owing to their unique physical and chemical properties. This study reports the synthesis and antibacterial activity of magnesium ferrite (MgFe 2 O 4 ) and cobalt doped magnesium ferrite (Co 0.8 Mg 0.2 Fe 2 O 4 )spinel nanoparticles (NPs). The NPs were synthesized using the low temperature combustion synthesis. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive absorption spectroscopy (EDAX) were used to characterize the synthesized NPs. The synthesized NPs exhibited good antibacterial properties against Pseudomonas aeruginosa , Escherichia coli , Staphylococcus aureus and Serratia marcescens . None of the nanoparticles induced any microbial inhibition against Micrococcus varians , Aspergillus flavus , Bacillus substilis and Candida. albicans. Co 0.8 Mg 0.2 Fe 2 O 4 NPs gave better antibacterial activity with a zone of inhibition of >20 mm against Staphylococcus aureus and Escherichia coli compared to MgFe 2 O 4 NPs. The minimum inhibitory concentration of Co 0.8 Mg 0.2 Fe 2 O 4 NPs against Escherichia coli and Staphylococcus aureus was 2500 µg/mL and 1250 µg/mL, respectively. The relatively high antibacterial effect exhibited by Co 0.8 Mg 0.2 Fe 2 O 4 nanoparticles on Escherichia coli and Staphylococcus aureus suggests its potentials in the treatment of infections commonly associated with these microorganisms. KEY WORDS : Magnesium ferrite, Nanoparticles, Antibacterial activity, Combustion synthesis, Infectious disease Bull. Chem. Soc. Ethiop. 2018 , 32(3), 451-458. DOI: https://dx.doi.org/10.4314/bcse.v32i3.4

Evaluation of cell toxicity and DNA and protein binding of green synthesized silver nanoparticles

Silver nanoparticles (AgNPs) were prepared by GREEN chemistry relying on the reduction of AgNO3 by phytochemicals present in black tea extract. AgNPs were fully characterized by transmission electron microscopy (TEM), ultraviolet-visible spectroscopy ((UV–vis)), X-ray diffraction (XRD) and energy dispersive absorption spectroscopy (EDS). The synthesized AgNPs induced a decrease of the cell viability in a dose-dependent manner with a low IC50 (0.5 ± 0.1 μM) for an ovarian carcinoma cell line (A2780) compared to primary human fibroblasts (IC50 5.0 ± 0.1 μM). The DNA binding capability of CT (calf thymus) DNA was investigated using electronic absorption and fluorescence spectroscopies, circular dichroism and viscosity titration methods. Additionally, the AgNPs strongly quench the intrinsic fluorescence of BSA, as determined by synchronous fluorescence spectra.

Synthesis and antibacterial characterization of sustainable nanosilver using naturally-derived macromolecules

Greener nanosynthesis utilizes fewer amounts of materials, water, and energy; while reducing or replacing the need for organic solvents. A novel approach is presented using naturally-derived flavonoids including Quercetin pentaphosphate (QPP), Quercetin sulfonic acid (QSA) and Apigenin Triphosphate (ATRP). These water soluble, phosphorylated flavonoids were utilized both as reducing agent and stabilizer. The synthesis was achieved at room temperature using water as a solvent and it requires no capping agents. The efficiency of the resulting silver nanoparticle synthesis was compared with naturally-occurring flavonoid such as Quercetin (QCR). Results show that QCR reduced Ag+ faster followed by QPP, QSA and ATRP respectively. This is the first evidence of direct utilization of QCR for synthesis of silver nanoparticles (AgNPs) in water. The percentage conversion of Ag+ to Ag0 was determined to be 96% after 35min. The synthesized nanoparticles were characterized using Transmission electron microscopy (TEM), Energy dispersive absorption spectroscopy (EDS), UV–vis spectroscopy, High resolution TEM (HR-TEM) with selected area electron diffraction (SAED). The particle sizes ranged from 2 to 80nm with an average size of 22nm and in the case of ATRP, the nanoparticle shapes varied from spherical to hexagonal with dispersed particle size ranging from 2 to 30nm. Crystallinity was confirmed by XRD and the SAED of (111), (200), and the fringes observed in HRTEM images. Results were in agreement with the UV resonance peaks of 369–440nm. The particles also exhibit excellent antibacterial activity against Staphylococcus epidermidis, Escherichia coli and Citrobacter freundii in water.

Effect of epitaxial strain on the magneto-electric coupling of YMnO3 thin films

We report synthesis of phase pure multiferroic YMnO3 thin films on sapphire (0001) with conducting ZnGaO buffer contact layer. Films were prepared by using pulsed laser deposition technique and characterized using x-ray diffraction, scanning electron microscopy, energy dispersive absorption spectroscopy, and magnetic field dependent dielectric measurement techniques. Structural characterizations indicated phase purity and epitaxial nature of the films. The dielectric response indicated an anomaly in dielectric constant ε and tan δ in the vicinity of 30 K, well below the bulk Néel temperature ∼70 K. This anomaly in ε and tan δ and its magnetic field dependence is explained as an influence of strain due to lattice mismatch between the substrate and YMnO3 film. A substantial enhancement in magnetocapacitance was also observed for magnetic field applied parallel to ab plane of the film. Our results show that it is possible to tune the multiferroic property of YMnO3 via changes in ferroelastic route.