Buvaneswari G

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Aswathy V

Rajakumari R.

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

Dyes and Pigments

In the current investigation, a new series of Ce doped gahnites of the formula ZnAl2-xCexO4 (x = 0–0.04), Fe doped gahnites of the formula ZnAl2-yFeyO4 (y = 0–0.5) and Ce and Fe co-doped gahnites of the formula ZnAl2-x-yCexFeyO4 (x = 0–0.04; y = 0–0.5) with high near infrared (NIR) reflectance were fabricated to mitigate the heat island effect. All the designed pigments were characterized by powder X-ray diffraction (PXRD), Fourier transformed infra red spectroscopy (FT-IR), Ultraviolet-Diffuse reflectance spectroscopy (UV-DRS). Scanning Electron Microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM) and CIE-L*a*b* colour values. Band gap of the white gahnite of the formula ZnAl2O4 (Eg = 3.8 eV) shifted to 2.70 eV and 2.15 eV for the pigments ZnAl1.96Ce0.04O4 and ZnAl1.5Fe0.5O4 respectively. Ce doped gahnites broadened the absorption centre from 250 nm to 350 nm in the UV spectrum and resulted in yellow colour. Whereas Fe doping introduced additional electronic transition between 440 nm and 490 nm and exhibited reddish yellow colour. NIR reflectance of ZnAl1.96Ce0.04O4, ZnAl1.5Fe0.5O4 and ZnAl1.78Fe0.2Ce0.02O4 was found to be 86%, 65%, 80% respectively between 700 and 2500 nm regions. Good thermal and chemical stability along with high NIR reflectance made the prepared pigments as a potential candidate to design cool roofing materials. © 2019 Elsevier B.V.

Journal of Alloys and Compounds

Ce and Fe doped gahnite: Cost effective solar reflective pigment for cool coating applications

Chinese Journal of Chemical Engineering

Copper doped nickel aluminate: Synthesis, characterisation, optical and colour properties

In this study, bismuth doped copper aluminate (CuAl2-xBixO4 x = 0, 0.01, 0.03, 0.05 and 0.10) nanoparticles were prepared via the solution combustion method and characterized by numerous procedures like powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance spectroscopy (DRS), scanning electron microscopy equipped with energy dispersive X-ray analysis (SEM-EDAX) and vibrating sample magnetometer (VSM). UV–Vis spectra exhibit low band gap energy ranging from 1.77 to 1.88 eV for the synthesized semiconductor oxide nanoparticles. The photocatalytic activity of copper aluminate and bismuth doped copper aluminate nanoparticles was studied by performing the decomposition of organic pollutants such as Methylene blue and Rhodamine-B under UV-light and visible light. It has been noticed from the results that the highest degradation was observed for Methylene blue dye with the bismuth doped copper aluminate (CAB03) nanoparticles compared to Rhodamine B. 99.71% degradation of Methylene blue was obtained within 60 min under UV-light irradiation and 99.90% within 60 min under visible light (H2O2) with 25 mg of catalyst. © 2017 Elsevier B.V.

Materials Chemistry and Physics

Structural, optical, magnetic and photocatalytic properties of bismuth doped copper aluminate nanoparticles

Nanostructured Co1-xZnxFe2O4 (0≤x≤0.5) catalyst synthesized by the microwave combustion method was employed for the photocatalytic degradation of rhodamine B (RhB) under visible light. Doping of Zn2+ ions in the cobalt ferrite matrices were confirmed by the diffraction peak-shift towards lower angles. The Williamson-Hall method was used to calculate the crystallite size considering the strain components. The conduction band (CB) and valence band (VB) edges of all the samples were calculated using optical studies. Photoluminescence analysis performed at an excitation wavelength of 330 nm disclosed the rate of recombination of electron-hole pairs and the defects present. Photocatalytic degradation of RhB with pure cobalt ferrite system was performed at pH 2.0 by varying the time, initial concentration and addition of hydrogen peroxide to behave like a Fenton like process. However the effective photodegradation of all zinc doped cobalt ferrite were done at optimal RhB concentration of 6 mg/l at identical operational conditions. Among all the samples Co0.6Zn0.4Fe2O4 exhibited an enhanced degradation efficiency of 99.9% at visible light exposure time of 210 min. The degradation pathway followed first order rate rather than the second order rate kinetics. Based on the values of CB and VB edges in the Co0.6Zn0.4Fe2O4 system, possible routes for the degradation of RhB are suggested. © 2016 Elsevier Ltd and Techna Group S.r.l.

Ceramics International

Photocatalytic degradation of rhodamine B under visible light using nanostructured zinc doped cobalt ferrite: Kinetics and mechanism

In this paper, a simple and economic route for the preparation of CuAl2O4 is proposed. The method was developed with the objective of obtaining a material with greater surface area, when compared to the spinel prepared by conventional combustion method (CCM). The catalytic properties of CuAl2O4 spinel prepared by CCM are compared with the one prepared microwave combustion method (MCM). Nano-sized CuAl2O4 were synthesized by both CCM and MCM using Opuntia dillenii haw as the plant extract, and were characterized by X-ray diffraction analysis (XRD), high resolution scanning electron microscopy (HR-SEM), N2 adsorption/desorption isotherms, and diffuse reflectance spectroscopy (DRS). Oxidation to their corresponding carbonyl compounds, high selectivity, and inexpensive precursors make this catalytic system a useful oxidation method for benzyl alcohol. The XRD results confirmed the formation of a cubic CuAl2O4. The formation of CuAl2O4 nanorices and nanorods structures were confirmed by HR-SEM. Through MCM method, CuAl2O4 (sample B) with a high specific surface area of was obtained. The band gap values of the (2.30 and 2.35 eV) for the obtained oxides are due to the nanometric dimensions of the nanostructures. The effect of the solvent, temperature, and oxidant on the oxidation of benzyl alcohol is reported. © 2014 Elsevier B.V. All rights reserved.

Journal of Molecular Structure

Selective liquid phase oxidation of benzyl alcohol catalyzed by copper aluminate nanostructures

The effect of ethylenediamine addition in the sol-gel method for the preparation of nano CuAl 2O 4 spinel for the enhancement in their structural, electrical, optical and catalytic properties was investigated. The samples were prepared by two different methods: sol-gel and modified sol-gel technique using ethylenediamine. X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), high resolution-transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), nitrogen adsorption/desorption isotherms, temperature dependent conductance measurements, thermoelectric power (TEP) measurements and UV-visible diffuse reflectance (UV-vis-DRS) spectra were used to characterize the samples prepared. CuAl 2O 4 prepared by modified sol-gel technique was found to possess a higher surface area, lower crystallite size, lower activation energy and high porosity than the one prepared by sol-gel method which in turn lead to the improved performance of it towards the selective oxidation of benzyl alcohol to benzaldehyde. Effect of solvent on the catalytic oxidation of benzyl alcohol by the nano CuAl 2O 4 prepared by modified sol-gel technique was also investigated. © 2012 Elsevier B.V. All rights reserved.

Comparative study of nano copper aluminate spinel prepared by sol–gel and modified sol–gel techniques: Structural, electrical, optical and catalytic studies

Highly dispersed (Cr, Sb)-co-doped rutile pigments of cool color with high near-infrared reflectance

Novel and environmentally friendly (Bi,Ca,Zn)VO4 yellow pigments

New purple-blue ceramic pigments based on CoZr4(PO4)6

Comparison of color and optical absorbance properties of divalent ion substituted Cu and Zn aluminate spinel oxides synthesized by combustion method towards pigment application

Journal	Data powered by TypesetDyes and Pigments
Publisher	Data powered by TypesetElsevier BV
ISSN	0143-7208
Open Access	0