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Item EFFICIENT REMOVAL OF DYES FROM AQUEOUS SOLUTION USING POLYMER FUNCTIONALIZED GRAPHENE OXIDE - METAL OXIDE NANOCOMP(SRM IST, Chennai., 2019-01-28) J, Balavijayalakhshmi; P, ReeshmaA versatile type of reduced graphene oxide / β-Cyclodextrin /MnO2 nanocomposites is synthesized via chemical reduction method. In this present work, graphene oxide is prepared from natural graphite flakes by modified hummers method and then into reduced graphene oxide using hydrazine hydrate and ammonia. The structural and morphological properties of the prepared nanocomposites are investigated by X-Ray diffraction analysis and Field emission scanning electron microscopy (FE-SEM). The crystallite size is found to be 18 nm and found to increase with increase in the concentration of manganese oxide. The presence of the functional groups in the synthesized nanocomposites is studied by Fourier Transform Infrared Spectroscopy (FT-IR) and band at 513 cm-1 is assigned to the Mn - O stretching vibrations of MnO2 nanoparticles and the depth increases with increase in the concentration of manganese oxide. The Energy dispersive X-Ray Analysis (EDAX) is used to identify elemental composition of materials. The adsorption properties of graphene oxide / β-Cyclodextrin /MnO2 towards industrial dyes are investigated. The resulting adsorption isotherm is analyzed systematically. The adsorption capacity of reduced Graphene oxide/ β – cyclodextrin /MnO2 nanocomposites are higher than that of Graphene oxide / MnO2 nanocomposites. These nanocomposites are found to be more efficient adsorbent for the removal of anionic industrial dyes.Item SYNTHESIS OF MOLYBDENUM DISULFIDE DOPED ZINC OXIDE NANOCOMPOSITES BY MICROWAVE ASSISTED METHOD(SRM IST, Chennai., 2019-01-28) Krithika S; Balavijayalakshmi JMolybdenum disulfide (MoS2 ) is a layered transition metal dichalcogenides (TMDs) and is anistropic in nature. It has remarkable physio-chemical properties such as large surface-to-volume ratio, distinctive electronic characteristic, tunable band gap, high carrier mobility, friction, catalytic and optical properties. Zinc oxide is one of the most versatile materials due to its excellent inherent properties of wide band gap, large exciton binding energy and high chemical stability. Molybdenum disulfide doped zinc oxide nanocomposites exhibited high stability, good repeatability and high sensitivity. These nanocomposites are synthesized by Microwave assisted method. The prepared nanocomposites are characterized by Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction Analysis (XRD) and Fourier- Transform Infrared (FT-IR) spectral analysis for its morphological, structural and spectral studies. These nanocomposites are one of the prominent materials with prospective application in the field of energy storage.Item IMPACT OF ENCAPSULATED METAL NANOPARTICLES ON POLYMER FUNCTIONALIZED GRAPHENE NANOCOMPOSITES FOR ITS SENSING APPLICATIONS(Centre for NanoScience and Technology, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Hyderabad, 2018-10-04) Balavijayalakshmi J; Ramalakshmi VThe present work describes the synthesis of beta cyclodextrin functionalized silver nanoparticles encapsulated graphene oxide nanocomposite for the sensitive electrochemical detection of nitrophenol (NP) isomers. The functionalization and encapsulation of graphene oxide surface using beta cyclodextrin and silver nanoparticles are done by using chemical reduction of graphene oxide, beta cyclodextrin and silver nitrate chemical reagents. The physico-chemical properties of synthesized GO-CD-Ag nanocomposites are investigated using XRD, SEM, TEM and RAMAN analytical techniques [1]. The SEM and TEM morphological analysis confirms that the beta cyclodextrin molecules are effectively covered on the surface of graphene oxide nanosheets and also the silver nanoparticles are uniformly encapsulated on the surface of beta cyclodextrin functionalized graphene oxide nanosheets. The synthesized GO-CD-Ag nanocomposite modified GCE is employed for the sensitive detection of nitrophenol isomer such as para-nitrophenol (p-NP) and meta-nitrophenol (m-NP). The cyclic voltammetry studies show that the GO-CD-Ag nanocomposite modified GCE exhibits a good electrochemical behaviour for the reduction of p-NP and m-NP isomers in PBS solution [2]. The enhancement in the electrochemical behaviour of graphene oxide may be due to the host guest recognition properties of beta cyclodextrin and electronic properties of silver nanoparticles. The synthesized GO-CD-Ag nanocomposite modified electrochemical sensor exhibits the linear detection limits of 25 mm and 15 mm for p-NP and m-NP, respectively.Item POLYMER FUNCTIONALIZED REDUCED GRAPHENE OXIDE BASED NICKEL NANOPARTICLES AS HIGHLY EFFICIENT DYE CATALYST FOR WATER REMEDIATION(International and Interuniversity Centre for Nanoscience and Nanotechnology (IIUCNN), Mahatma Gandhi University, Kottayam, Kerala, 2018-05-11) Ramalakshmi V; Balavijayalakshmi JThe present work describes the synthesis and characterization of reduced graphene oxide based nickel nanoparticles containing beta cyclodextrin composite and its application for removal of textile dye from aqueous medium. For this purpose graphene oxide is produced by modified Hummer’s method, then after, GO-CD and GO-CD-Ni nanocomposites are synthesized via wet chemical method. The synthesized adsorbents (GO, GO-CD and GO-CD-Ni) are characterized using different characterization techniques such as FT-IR, XRD, FE-SEM. Also, the various parameters affecting dye removal like pH, contact time, amount of adsorbents and initial dye concentrations are investigated. The synthesized adsorbents exhibits excellent adsorption performance for the removal of textile dyes. The adsorption process is pH dependent and the adsorption capacity is increased with the increase in contact time and with that of adsorbent dosage.Item ELECTROCHEMICAL BEHAVIOUR OF PREPARED REDUCED GRAPHENE OXIDE/ CHITOSAN NANOCOMPOSITES(Sastra University, Thanjavur., 2017-02-27) Yuvashree S; Balavijayalakshmi JRecently, efforts have been made to develop technologically feasible graphene-based devices. The development of composite materials based on graphene and natural polymers provides an ideal material in the biomedical field. However, the lack of good mechanical and thermal properties limits its applications. This drawback could be overcome by the reduction of graphene oxide into reduced graphene oxide (RGO). The RGO combined with the polymer helps to increase the conductivity of nanocomposites which thereby enhances the properties of the material to suit commercial applications. This present work is based on the investigation of the electrochemical behaviour of reduced graphene oxide/Chitosan nanocomposite synthesized by chemical reduction method. The synthesized rGO/CS nanocomposites are characterized using ultraviolet–visible (UV-Vis) spectral analysis, Fourier transform infrared (FT-IR) spectral analysis, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis. The surface charge as well as stability of the nanocomposites is examined by electrochemical characterization using cyclic voltammetry technique. The analytical responses and the redox mechanisms are evaluated which shows high current response for RGO/Chitosan nanocomposites compared to pure RGO nanosheets. This suggests that RGO/Chitosan nanocomposites have excellent electrochemical behaviour and is further applied for bio sensing applications.Item A FACILE SYNTHESIS OF REDUCED GRAPHENE OXIDE/CHITOSAN/AG NANOCOMPOSITES(Vizhi Chudar Pathippagam / Anna University, Chennai., 2017-01-06) Yuvashree S; Balavijayalakshmi JGraphene is a monolayer of carbon atoms, which is densely packed in a honeycomb lattice. Owing to its two-dimensional (2D) nanostructure, it has attracted enormous attention in the field of nanotechnology. Due to its unique catalytic, magnetic, optoelectronic and biological properties, Graphene and its derivatives has exhibited extensive and potential applications in electrode modifying materials, sensors, biomedical, bioengineering, drug delivery, gene delivery and semiconductors [1]. Chitosan (CS) is a natural bio polysaccharide and the most abundant polymer which is biocompatible and can be degraded by enzymes in human body. It has attracted considerable interest due to its biodegradability, biocompatibility, non-toxicity, good water permeability, high mechanical strength, adhesion and antibacterial properties, which leads to tremendous applications in agriculture, biopesticide, wine making, polyurethane coating, medicine etc., [2]. In addition to these, metal nanoparticles have been widely used for the fabrication of nanocomposites. Silver (Ag) nanoparticles, a well known and most popular, have also been used for long time in research areas because of its excellent chemical and physical properties. It has been applied in antimicrobial coatings, textiles, keyboards, wound dressings, and biomedical applications such as drug delivery, antibacterial etc. These biomedical devices now contain silver nanoparticles that continuously release a low level of silver ions to provide protection against bacteria. In this present work, reduced graphene oxide/Chitosan/Ag nanocomposites have been synthesized by chemical reduction method. Graphene Oxide (GO) is obtained from natural graphite powder according to a modified Hummers method, in which graphite is treated with a mixture of very strong oxidizers such as sulphuric acid, sodium nitrate and potassium permanganate. The carbon atoms in GO loses the electrical conductivity nature of graphene and it can be restored by reduction of GO into reduced graphene oxide (rGO). This is then followed by synthesizing rGO/CS, rGO/CS/Ag nanocomposties [3]. Thus the prepared GO, rGO, rGO/CS, rGO/CS/Ag nanocomposites is further characterized using ultraviolet–visible (UV-Vis) spectral analysis, Fourier transform infrared (FT-IR) spectral analysis, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis. It is observed from UV-Vis spectral analysis that the absorption spectra for GO has two characteristic peaks around 230 nm and 301nm due to π-π* transition of aromatic C=C bonds and n-π* transition of C=O bonds respectively. On further reducing GO, the peak gets shifted around 265 nm and the peak around 301nm gets disappeared, which confirms the reduction of GO into rGO [4]. A new peak formed around 430 nm indicates the formation of rGO/CS/Ag nanocomposites. FT-IR spectral analysis confirms the functional groups of the as-obtained GO, rGO, rGO/CS/Ag nanocomposites. The FT-IR spectra is observed in the region of 4000 to 400 cm-1.The absorption band around 3500 cm-1 attributes to O-H stretching vibrations due to hydroxyl groups in GO. The band around 1720 cm-1 indicates the –COOH vibrations, which shows the reduction of GO into rGO and the C-H stretching vibrations are assumed to be around 2854 cm-1. The band around 1680 cm-1 indicates the presence of acetyl amino groups and C=C stretching vibration is observed around 1387 cm-1[5]. The crystalline structure of the prepared GO, rGO, rGO/CS/Ag nanocomposites is confirmed by X-ray diffraction (XRD) analysis. The diffracted peak formed corresponds to the (002) plane of GO which exhibits inter-planner spacing of 0.80±3nm. On further adding CS and Ag nanoparticles, the diffraction peak of GO reduces and simultaneously the diffraction peak of Ag increases. RGO/CS/Ag nanocomposites shows diffraction peak for rGO, CS and Ag. The morphological studies have been carried out using Scanning Electron Microscope [6]. It indicates that CS/Ag nanocomposites are uniformly dispersed on to the rGO nanosheets. Thus the prepared rGO/Chitosan/Ag nanocomposites can be tested for biomedical applications [7].