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Aruldoss U.,CSIR - Central Leather Research Institute | Kennedy L.J.,Vellore Institute of Technology | Judith Vijaya J.,Catalysis and Nanomaterials Research Laboratory | Sekaran G.,CSIR - Central Leather Research Institute
Journal of Colloid and Interface Science | Year: 2011

Investigations were carried out to study the photocatalytic degradation of phenolic syntan (PS), a widely used environmentally polluting chemical in the leather tanning industry. Photocatalytic inactive commercial TiO2 was used as the precursor for the preparation of TiO2 impregnated activated carbon (Ti-AC) photocatalyst. Experiments were conducted by varying the concentrations of PS solution (50-1000mg/l), pH (2.5-10) and time intervals to optimize the working parameters. A 254nm UV light was used throughout the study. The effect of PS degradation using Ti-AC was also compared with direct UV photolysis. The Ti-AC was characterized using X-ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS), Scanning Electron Microscopy (SEM) and energy dispersive X-ray analysis (EDX) to determine the structural, optical, surface morphology and elemental analysis respectively. X-ray studies revealed the formation of catalytically active anatase phase in Ti-AC. Photodegradation of PS was examined by chemical oxygen demand (COD) method. PS degradation occurred at both the extreme end of acidic and alkaline pH conditions. However, the percentage degradation was comparatively higher at pH 2.5. The photodegradation followed pseudo first order kinetics. UV-Visible studies substantiated the occurrence of bathochromic and hyperchromic effects as a result of ring opening in the PS molecule. © 2010 Elsevier Inc. Source


Clament Sagaya Selvam N.,Catalysis and Nanomaterials Research Laboratory | Vijaya J.J.,Catalysis and Nanomaterials Research Laboratory | Kennedy L.J.,Vellore Institute of Technology
Industrial and Engineering Chemistry Research | Year: 2012

ZnO nanomaterials with different morphologies such as nanoflakes, spherical nanoparticles (SNPs), and nanorods have been synthesized via a simple low temperature coprecipitation method. The concentration of the capping agent is a key factor in the morphological control of ZnO nanostructures. Triton X-100 micelles were found to be single molecules at low concentration but spherical and rod-like shaped micellar aggregation at higher concentrations. The formation of different morphologies of ZnO was confirmed by HR-SEM and HR-TEM. XRD data showed the formation of single-phase ZnO with the wurtzite crystal structure. The influence of Zr contents on the structure, morphology, absorption, emission, and photocatalytic activity of ZnO SNPs was investigated systematically. The influence of the ZnO morphologies on the photocatalytic degradation (PCD) of resorcinol as a model reaction is evaluated and discussed in terms of particle size, surface area, crystal growth habits, and oxygen defects. The results indicated that the particle size is an important factor for the PCD, and thus, the 1.5 wt % Zr-doped ZnO SNPs show superior performance toward PCD of resorcinol than other samples due to the small particle size distribution. Furthermore, the effect of different photocatalytic reaction parameters on the resulting PCD efficiency of ZnO SNPs was investigated. © 2012 American Chemical Society. Source


Selvam N.C.S.,Catalysis and Nanomaterials Research Laboratory | Kumar R.T.,Catalysis and Nanomaterials Research Laboratory | Kennedy L.J.,Vellore Institute of Technology | Vijaya J.J.,Catalysis and Nanomaterials Research Laboratory
Journal of Alloys and Compounds | Year: 2011

Magnesium oxide (MgO) was synthesised by a simple microwave-assisted combustion route without using any template, catalyst or surfactant. For the purpose of comparison, it was also prepared using conventional method. The as-synthesized MgO was characterized by powder X-ray diffraction (XRD), Fourier Transform infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), Energy Dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The XRD results confirmed the formation of cubic phase MgO. FT-IR was used to investigate the adsorption of water and CO2 on MgO surface and confirm the formation of Mg-O phase. The formation of MgO micro cubes structures was confirmed by HR-SEM. The formation of MgO nanosheets was confirmed by HR-SEM and TEM and their possible formation mechanisms were also proposed. The optical absorption and photoluminescence emissions were determined by DRS and PL spectra respectively. An attempt has been made to compare the lattice parameter and the PL intensity. © 2011 Elsevier B.V. Source


Ragupathi C.,Catalysis and Nanomaterials Research Laboratory | John Kennedy L.,Vellore Institute of Technology | Judith Vijaya J.,Catalysis and Nanomaterials Research Laboratory
Advanced Powder Technology | Year: 2014

The present study reports a green chemistry approach for the biosynthesis of nano-zinc aluminate by a microwave method using high purity metal nitrates and aloe vera plant extract. Aloe vera extract simplifies the process and provides an alternative process for a simple and economical synthesis of nanocrystalline zinc aluminate. It is prepared by conventional and microwave method by with and without using the plant extract for comparison purpose. The obtained nanomaterials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (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. The XRD confirmed the formation of cubic structure of zinc aluminate. The formation of zinc aluminate phase is also confirmed by FT-IR. The change in morphology from nanorods to nanosheets from the conventional method to microwave method is clearly shown by HR-SEM. The optical properties were determined by DRS and PL spectra. © 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. Source


Clament Sagaya Selvam N.,Catalysis and Nanomaterials Research Laboratory | Judith Vijaya J.,Catalysis and Nanomaterials Research Laboratory | John Kennedy L.,Vellore Institute of Technology
Journal of Colloid and Interface Science | Year: 2013

A simple, low temperature co-precipitation method was developed to synthesize ZnO nanomaterials with different morphologies such as nanoflakes, spherical nanoparticles (SNPs), and nanorods. The concentration of the capping agent, Triton X-100, is a key factor in the morphological control of ZnO nanostructures. The formation of different morphologies of ZnO was confirmed by HR-SEM and HR-TEM. XRD data showed the formation of single-phase ZnO with the wurtzite crystal structure. The influence of La contents on the structure, morphology, absorption, emission, and photocatalytic activity of ZnO SNPs was investigated systematically. The influence of the ZnO morphologies on the photocatalytic degradation (PCD) of Bisphenol A (BPA) as a model reaction is evaluated and discussed in terms of surface area, crystal growth habits, particle size, and oxygen defects. The results indicated that the particle size is an important factor for the enhancement of PCD. Furthermore, the effect of different photocatalytic reaction parameters on the resulting PCD efficiency of ZnO SNPs was investigated. © 2013 Elsevier Inc. Source

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