Microwave combustion method (MCM) is a direct method to synthesize NiAl2O4 nanoparticles and for the first time we report the using of Sesame (Sesame indicum L.) plant extract in the present study. Solutions of metal nitrates and plant extract as a gelling agent are subsequently combusted using microwave. The structure and morphology of NiAl2O4 nanoparticles are investigated by X-ray diffraction (XRD), Fourier transforms infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), high resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy, Brunauer-Emmett- Teller (BET) analysis and vibrating sample magnetometer (VSM). XRD pattern confirmed the formation of cubic phase NiAl2O4. The formation of NiAl2O4 is also confirmed by FT-IR. The formation of NiAl2O4 nanoparticles is confirmed by HR-SEM and HR-TEM. Furthermore, the microwave combustion leads to the formation of fine particles with uniform morphology. The magnetic properties of the synthesized NiAl2O4 nano and microstructures were investigated by vibrating sample magnetometer (VSM) and their hysteresis loops were obtained at room temperature. Further, NiAl2O4 prepared by MCM using Sesame (S. indicum L.) plant extract is tested for the catalytic activity toward the oxidation of benzyl alcohol. © 2014 Elsevier B.V.

John Kennedy L

Physics

School of Advanced Sciences

Chennai Campus

Ragupathi C

Vijaya J.J

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Materials Science and Engineering: B

In the present study, we have focused on opuntia dilenii haw mediated green synthesis of cobalt ferrite (CoFe2O4) nanoparticles through microwave combustion method (MCM) and it is further compared with the conventional combustion method (CCM). The effect on structural, morphological, optical and magnetic properties of the synthesized nanoparticles was investigated systematically. In addition, the efficiency of self heating measurements was investigated for hyperthermia applications. X-ray diffraction studies confirmed the formation of single phase crystalline nature of CoFe2O4 nanoparticles. The crystallite size of 58 nm and 49 nm is obtained for CCM and MCM respectively. The functional groups occurred at 597 cm−1, 599 cm−1, 427 cm−1 and 437 cm−1 that corresponds to Fe-O and Co-O bands at tetrahedral and octahedral sites are analyzed by FT-IR studies. Scanning electron microscopy images of the samples revealed the morphology as spherical with the average particle size range of 40–200 nm. The existence of Co, Fe, O present in the sample is confirmed by EDX analysis which shows the purity of the samples. UV–Visible diffuse reflectance spectroscopy is used to analyze the optical band gap energy of the samples estimated from Kubelka-Munk function as 2.01 eV, 1.93 eV for CCM and MCM respectively. The structural defects present in the samples are investigated by photoluminescence studies and the samples emit the light at two different wavelengths of 494 nm, and 621 nm. Vibrating sample magnetometer is carried out to analyze the magnetic properties of the samples at room temperature. The saturation magnetization of the CoFe2O4 nanoparticles is found to be 77.29 emu/g and 68.76 emu/g for MCM and CCM respectively. The results obtained in this work suggested that the value of crystallite size, particle size, band gap value, luminescence intensities, and coercivity values increases with an increase in calcination temperature in conventional combustion method. Specific absorption rate (SAR) increases with a decrease in the crystallite size and particle size in microwave combustion method. The gradual increase in SAR is due to the hysteresis loss that occurs because of the ferromagnetic nature obtained by the microwave combustion method. An overview of the present work gives a summary on the green synthesis of magnetic nanoparticles, which provides comprehensive evaluation of hyperthermia through self heating process. Finally, from our results, the SAR obtained by microwave combustion method has higher efficiency compared to the conventional combustion method. © 2017 Elsevier B.V.

Journal of Alloys and Compounds

Self heating efficiency of CoFe2O4 nanoparticles: A comparative investigation on the conventional and microwave combustion method

A comparative study of the structural, optical and catalytic properties of CoAl2O4 nanoparticles is reported. Cobalt aluminate (CoAl2O4) nano and microstructures were synthesized by both conventional and microwave methods using Sesame (Sesamum indicum, L.,) as a plant extract. The use of Sesame extract provides an alternative method for a simple and economical synthesis of cobalt aluminate. Synthesized cobalt aluminate powder were characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) studies. CoAl2O4 prepared by the microwave method was found to possess a higher surface area, and lower crystallite size than the one prepared by the conventional method, which in turn leads to the improved performance towards the selective oxidation of benzyl alcohol to benzaldehyde.

Ceramics International

Highly selective oxidation of benzyl alcohol to benzaldehyde with hydrogen peroxide by cobalt aluminate catalysis: A comparison of conventional and microwave methods

Commercial mordenite was dealuminated with hydrochloric acid by refluxing at 373 K for different durations to develop a stable catalyst for the selective oxidation of benzyl alcohol. The commercial and dealuminated mordenite samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, N2 adsorption-desorption, high resolution scanning electron microscopy (HR-SEM) and temperature programmed desorption (NH3-TPD). The results revealed that the external surface area increased with acid treatment while preserving the mordenite structure. The catalytic performance of acid-treated mordenite was evaluated in the selective oxidation of benzyl alcohol with tert-butyl hydroperoxide (TBHP) as the oxidant and acetonitrile as the solvent. The influences of the variation in catalyst amount, reaction temperature, TBHP/BzOH ratio and SiO2/Al2O3 ratio (SAR) were investigated. The sample with a SAR of 33, obtained after acid treatment for 3 h, exhibited a higher conversion than the other samples. At the optimum conditions, the benzyl alcohol conversion and benzaldehyde selectivity were about 99% and 98%, respectively, over this sample. This catalyst could be reused at least four times without any significant loss in its activity and selectivity. The selective oxidation of substituted benzyl alcohols is also reported. © 2015 Elsevier Ltd. All rights reserved.

Polyhedron

Characterization and catalytic reactivity of mordenite - Investigation of selective oxidation of benzyl alcohol

The purpose of this research work is to prepare and assess the catalytic performance of platinum (Pt) dealuminated mordenite for the of n-hexane, n-pentane and light naphtha isomerization. The Pt dealuminated mordenite was prepared by dealumination of commercial mordenite catalyst by refluxing using hydrochloric acid at 100 °C in various time durations (0.50, 1.0, and 3.0 h). The commercial as well as dealuminated mordenite catalysts were examined by X-ray diffraction analysis, X-ray fluorescence, N2 adsorption-desorption, Fourier-transform infrared spectroscopy, temperature-programmed desorption (NH3-TPD), scanning electron microscopy, and transmission electron microscopy with high resolutions XRD and BET surface area analysis. These afore mentioned studies confirm that the dealumination process exhibit an increasing the external surface area and improved the total acidity with retaining the structure of mordenite. The catalytic performance was investigated for the of n-hexane, n-pentane and light naphtha isomerization by varying factors such as, temperature, reaction pressure, hydrogen flow, hourly mass feed flow rate and catalyst mass. Among the catalysts, the dealuminated catalyst with SiO2/Al2O3 ratio of 40% exhibited highest conversion Pt–Cl–Al2O3 operate set the lowest temperature on and selectivity. The density functional theory (DFT) calculation implies that the activation free energy for isomerization of n-hexane varies with the position of interacting C–H bond with mordenite (Pt/Mordenite) cluster. Besides, the activation energy for the n-pentane isomerization is lesser than the n-hexane isomerization. © 2019

Microporous and Mesoporous Materials

Effect of acidity and porosity changes of dealuminated mordenite on n-pentane, n-hexane and light naphtha isomerization

Combustion synthesis, structure, magnetic and optical properties of cobalt aluminate spinel nanocrystals

A series of Sr(II)-added nickel aluminate nanocatalysts with different molar ratios of Ni:Sr (1.0:0.0, 0.9:0.1, 0.8:0.2, 0.7:0.3, 0.6:0.4 and 0.5:0.5) keeping the molar ratio of aluminum constant were synthesized by modified sol-gel method using ethylenediamine and sintered at 900 °C. The samples were labeled as NiSA1-900, NiSA2-900, NiSA3-900, NiSA4-900, NiSA5-900, NiSA6-900, respectively. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), nitrogen adsorption/desorption isotherms and tested for the catalytic oxidation of benzyl alcohol. Influence of the reaction parameters (molar ratio of Sr(II) added to nickel aluminate nanocatalyst, reaction time, reaction temperature and solvent effect) on the catalytic oxidation of benzyl alcohol were studied. It was observed that the addition of Sr(II) improves the performance of the nickel aluminate nanocatalysts towards the selective oxidation of benzyl alcohol and decreases the grain size. Higher activity was obtained for the conversion of benzyl alcohol to benzaldehyde for 0.3 molar percentage Sr(II) added nickel aluminate catalyst (NiSA4-900). Stability and reusability of the catalyst was also investigated. Copyright © 2013 American Scientific Publishers.

Journal of Nanoscience and Nanotechnology

Modified Sol–Gel Prepared Sr(II)-Added Nickel Aluminate Nanocatalysts for Selective Oxidation of Benzyl Alcohol

Strontium(II)-added ZnAl 2O 4 nanomaterials with spinel structure were prepared by modified sol-gel method using ethylenediamine followed by sintering at 900°C. The samples were labeled as ZnSA1-900, ZnSA2-900, ZnSA3-900, ZnSA4-900, ZnSA5-900, ZnSA6-900, respectively, where the molar ratios of Zn:Sr was 1.0:0.0, 0.9:0.1, 0.8:0.2, 0.7:0.3, 0.6:0.4 and 0.5:0.5 and aluminum molar ratio was kept constant, 900 refers to the sintering temperature. The effect of Sr addition on the structural, morphological and optical properties of zinc aluminate nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), nitrogen adsorption/desorption isotherms, diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The addition of Sr improves the performance of the zinc aluminate towards the selective oxidation of alcohols and decreases the grain size. The effect of solvent, oxidant and reaction time on the Sr(II)-added zinc aluminate nanomaterials for the oxidation of benzyl alcohol was studied. Higher activity was obtained for the conversion of benzyl alcohol to benzaldehyde for 0.3 molar percentage Sr(II)-added zinc aluminate (ZnSA4-900) which was used for the selective oxidation of other alcohols. Stability and reusability of the nanomaterials was also investigated. © 2012 Elsevier B.V.

Powder Technology

Synthesis, characterization and performance of porous Sr(II)-added ZnAl2O4 nanomaterials for optical and catalytic applications

A simple and rapid microwave-assisted combustion method was developed to synthesize CdO nanospheres (CNS). The study suggested that the application of microwave heating to produce the homogenous CNS was achieved in a few minutes. The structure and morphology of the as-prepared CNS were investigated by means of X-ray diffraction (XRD), Fourier transforms infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), Energy Dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), diffused reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The XRD confirmed the formation of face centered cubic structure of CdO. The formation of CdO phase is also confirmed by FT-IR. The formation of spherical hollow nanospheres was confirmed by HR-SEM and TEM and their possible formation mechanisms were also tentatively proposed. The optical properties were determined by DRS and PL spectra. © 2011 Elsevier B.V.

Journal	Data powered by TypesetMaterials Science and Engineering: B
Publisher	Data powered by TypesetElsevier BV
ISSN	0921-5107
Open Access	0