Showing papers by "L. John Kennedy published in 2018"

Green synthesis of NiO nanoparticles using Aegle marmelos leaf extract for the evaluation of in-vitro cytotoxicity, antibacterial and photocatalytic properties.

Abstract: In the present study, we report the green synthesis of NiO nanoparticles using Aegle marmelos as a fuel and this method is ecofriendly and cost effective. The plant Aegle marmelos is used in the field of pharmaceuticals to cure diseases like chronic diarrhea, peptic ulcers and dysentery in India for nearly 5 centuries. The as-prepared nanoparticles were confirmed as pure face centered cubic phase and single crystalline in nature by XRD. The formation of agglomerated spherical nanoparticles was shown by HR-SEM and HR-TEM images. The particle size calculated from HR-SEM was in the range 8-10 nm and it matches with the average crystallite size calculated from the XRD pattern. NiO shows intense emission peaks at 363 and 412 nm in its PL spectra. The band gap of 3.5 eV is observed from DRS studies and the formation of pure NiO is confirmed by FT-IR spectra. The as-prepared NiO nanoparticles show super paramagnetic behavior, when magnetization studies are carried out. It is then evaluated for cytotoxic activity towards A549 cell culture, antibacterial activity and photocatalytic degradation (PCD) of 4‑chlorophenol (4‑CP), which is known as the endocrine disrupting chemical (EDC). From the results, it is found that the cell viability of A549 cells was effectively reduced and it showed better antibacterial activity towards gram positive bacterial strains. It is also proved to be an efficient and stable photocatalyst towards the degradation of 4‑CP.

Optimization of biodiesel production from waste cooking oil by magnesium oxide nanocatalyst synthesized using coprecipitation method

Abstract: Nanostructured magnesium oxide (MgO) catalysts were prepared by the coprecipitation method and employed for the transesterification of waste cooking oil using methanol. The X-ray diffraction analysis showed that nanostructured MgO phase was formed at calcination temperature of 500 °C. The mean crystallite size of MgO nanoparticles is 7.86 nm. Fourier-transformed infrared spectroscopy studies confirmed the formation of MgO phase with the characteristic vibrational mode of Mg–O. UV–Vis diffuse reflectance spectroscopy reveals that the energy band gap is around 5.84 eV. The presence of magnesium and oxygen elements was determined from energy-dispersive X-ray analysis. The effect of various parameters such as catalyst loading, methanol-to-oil molar ratio, reaction temperature, reaction time and reusability was investigated. A maximum biodiesel yield of 93.3% was achieved with 2 wt% of MgO nanocatalyst (MO5 sample), methanol/oil molar ratio of 24:1, reaction temperature about 65 °C and reaction time 1 h. The nanocatalyst (MgO) was reused at least for 5 times and thereafter resulted in a decrease in the biodiesel yield. The kinetic study of the transesterification reaction followed pseudo-first-order rate kinetics. The composition of fatty acid methyl ester was determined using gas chromatography–mass spectroscopy.

Anti-cancer activity of hierarchical ZSM-5 zeolites synthesized from rice-based waste materials

Abstract: Herein, organic template-free MFI-type ZSM-5 zeolites were successfully synthesized by the hydrothermal method using waste materials such as rice husk ash (RHA), rice hull ash (RHuA), and rice straw ash (RSA). The waste materials were locally obtained, precleaned, and properly heat-treated to produce a high-purity crystalline SiO2 that was used in the synthesis of ZSM-5 zeolites under autogenous pressure in a short reaction time (5 days). The mineralogical phases, morphology, textural and thermal properties of the synthesized products were investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy, high-resolution scanning electron microscopy (HR-SEM), N2 adsorption/desorption isotherms (BET), temperature-programmed desorption (NH3-TPD), and thermogravimetric analysis (TGA/DTA). The as-synthesized ZSM-5 zeolites showed good crystallinity, and no amorphous material existed in the framework of the ZSM-5 zeolites after calcination and ammonium exchange processes. The characterization results prove that the high crystallinity of RHA as compared to that of the other materials (RHuA and RSA) is due to the high silica content in RHA. The transformation occurs from high-crystallinity RHA into ZSM-5 zeolite and also increases the crystallinity of zeolites. In addition, we have investigated hierarchical ZSM-5 zeolites at various concentrations for their potential cytotoxicity effect against the human lung epithelial cancer A549 cells.

Co2+ substituted La2CuO4/LaCoO3 perovskite nanocomposites: synthesis, properties and heterogeneous catalytic performance

Abstract: Cobalt substituted La2CuO4/LaCoO3 perovskite nanocomposites were prepared using a microwave combustion method. X-ray diffraction analysis showed that Co2+ substitution in La2CuO4 induced the formation of a secondary LaCoO3 phase with rhombohedral structure along with the existing orthorhombic (La2CuO4) structure. The orthorhombic/rhombohedral structured nanocomposites possessed an average crystallite size in the range of 36–46 nm and 21–49 nm, respectively. The Rietveld analysis confirmed the formation of these two phases. The appearance of FT-IR bands around 682 and 512 cm−1 was correlated to the orthorhombic stretching modes while the bands around 580 and 445 cm−1 were associated with the rhombohedral stretching modes thereby confirming the two-phase perovskite system. An optical study revealed two linear regions depicting two band gaps related to the La2CuO4 and LaCoO3 phases. The band gap was found to increase with an increase in the Co2+ doping fraction. Morphological observations using scanning electron microscopy showed intragranular pores and fused grains with distinct grain boundaries. The change in the magnetic properties was associated most probably with the exchange of the A and B sites within the La2CuO4 host lattice because of Co2+ doping, as well as the important phase composition of La2CuO4/LaCoO3 obtained from the ferromagnetic-to-paramagnetic transition. The BET surface area of the pure and doped nanocomposites was found to vary considerably within the range of 12.2–43.7 m2 g−1. The as-fabricated La2CuO4/LaCoO3 perovskite nanocomposites were evaluated for the conversion of glycerol to formic acid in a liquid phase batch reactor under atmospheric conditions. This La3+ based nanocomposite behaves as an efficient bifunctional catalyst with high conversion efficiency and selectivity around 96.5% and 95.1%, respectively.

In-vitro anti-cancer activity of organic template-free hierarchical M (Cu, Ni)-modified ZSM-5 zeolites synthesized using silica source waste material.

Abstract: The present paper is focused on a simple and economical route to synthesize the organic template-free hierarchical pure and M (Cu, Ni)-modified ZSM-5 zeolites (1%, 3% and 5%) using hydrothermal treatment in the presence of silica rich rice husk ash and its application studies through the evaluation of their anti-cancer activity on A459 human lung epithelial cancer cell lines. The physical properties of the samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, high resolution scanning electron microscopy, high resolution transmission electron microscopy, N2 adsorption/desorption techniques and thermogravimetric analysis respectively. These metals modified hierarchical ZSM-5 zeolites showed considerable in-vitro anticancer efficiency towards human lung cancer (A549) cell lines through (3-(4, 5-dimethyl thiazolyl)-2, 5-diphenyl tetrazolium bromide) MTT assay. Among the all M (Cu, Ni)-modified ZSM-5 zeolites, 5% Cu-ZSM-5 zeolites showed higher potential cytotoxicity against A459 cell lines. The possible mechanism was explored from the fundamental signaling pathways of cell death by hierarchical metal modified ZSM-5 zeolites in A459 human lung epithelial cancer cell lines. Finally, our experimental results revealed that the organic template-free hierarchical pure and M (Cu, Ni)-modified ZSM-5 zeolites have significant anti-cancer mediating action by inducing oxidative stress to intercede DNA damage and can be considered as a potential applicant in the biomedical field.

Investigation on preferably oriented abnormal growth of CdSe nanorods along (0002) plane synthesized by henna leaf extract-mediated green synthesis.

Abstract: The theme of this work is to highlight the significance of green plant extracts in the synthesis of nanostructures. In asserting this statement, herein, we report our obtained results on the synthe...

Synthesis, Structural, Optical and Dielectric Properties of Nanostructured 0-3 PZT/PVDF Composite Films.

Abstract: Nanostructured PbZr0.52Ti0.48O3 (PZT) powder was synthesized at 500 °C-800 °C using sol-gel route. X-ray diffraction and Rietveld analysis confirmed the formation of perovskite structure. The sample heat treated at 800 °C alone showed the formation of morphotropic phase boundary with coexistence of tetragonal and rhombohedral phase. The PZT powder and PVDF were used in 0-3 connectivity to form the PZT/PVDF composite film using solvent casting method. The composite films containing 10%, 50%, 70% and 80% volume fraction of PZT in PVDF were fabricated. The XRD spectra validated that the PZT structure remains unaltered in the composites and was not affected by the presence of PVDF. The scanning electron microscopy images show good degree of dispersion of PZT in PVDF matrix and the formation of pores at higher PZT loading. The quantitative analysis of elements and their composition were confirmed from energy dispersive X-ray analysis. The optical band gap of the PVDF film is 3.3 eV and the band gap decreased with increase in volume fraction of PZT fillers. The FTIR spectra showed the bands corresponding to different phases of PVDF (α, β, γ) and perovskite phase of PZT. The thermogravimetric analysis showed that PZT/PVDF composite films showed better thermal stability than the pure PVDF film and hydrophobicity. The dielectric constant was measured at frequency ranging from 1 Hz to 6 MHz and for temperature ranging from room temperature to 150 °C. The composite with 50% PZT filler loading shows the maximum dielectric constant at the studied frequency and temperature range with flexibility.

Liquid Phase Catalytic Oxidation of Toluene Over Rich Silica and Alumina Composition of Hierarchical Ordered ZSM-5 Zeolites Prepared Without Organic Templates.

Abstract: Hierarchical ordered ZSM-5 zeolites were successfully synthesized by a template-free hydrothermal treatment using rice joints ash as the source of silica. The formation of hierarchical ordered ZSM-5 zeolites and its physicochemical properties were investigated systematically. The mineralogical phases, morphology, surface area and porosity, acidity and thermal stability of the synthesized hierarchical materials were investigated using XRD, FT-IR, HR-SEM, N2 adsorption-desorption (BET) analysis, NH3-TPD and TGA/DTA analysis. The excellent catalytic activity of hierarchical ordered ZSM-5 zeolites (150 °C) was revealed in the selective oxidation of toluene to the corresponding benzaldehyde with 82% conversion and 94% selectivity. The material was evaluated for the oxidation of toluene in the presence of H2O2 as the oxidizing agent and 1,4-dioxane solvent. The obtained results noted that the material was highly active, stable and can be recycled at least four times without a loss of catalytic efficiency. The crystallization was carried out in an autoclave for 5 days maintained at a temperature of 150 °C for the transformation of RJA into hierarchical ZSM-5 zeolite structure as well as to achieve high crystallinity.