Preparation of Zinc Oxide Nanoparticles and its Characterization ...

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ScienceDirect Procedia Technology 24 (2016) 761 – 766

International Conference on Emerging Trends in Engineering, Science and Technology (ICETEST - 2015)

Preparation of Zinc Oxide Nanoparticles and its Characterization Using Scanning Electron Microscopy (SEM) and X-Ray Diffraction(XRD) Ananthu C Mohana, Renjanadevi Bb* b

a Department of Chemical Engineering, Govt Engineering College Trichur, Thrissur, India Associate proffessor, Department of Chemical Engineering, Govt Engineering College Trichur, Thrissur, India

Abstract Zinc oxide can be called a multifunctional material thanks to its unique physical and chemical properties. The main objective of this paper is the preparation of zinc oxide nanoparticles using conventional methods and the preparation using surfactant. The first part of this paper presents the different methods of preparation of Zinc oxide nanoparticles using different precursors and its surface modification using Poly Vinyl Alcohol (PVA). The next part of this paper deals with characterization of the prepared zinc oxide using Scanning Electron Microscopy (SEM) and X-Ray Diffraction in order to determine which method is more feasible in terms of particle agglomeration, particle size, particle separation.

© 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). © 2016 The Authors.Published by Elsevier Ltd. Peer-review underresponsibility responsibilityofofthethe organizing committee of ICETEST – 2015 Peer-review under organizing committee of ICETEST – 2015. Keywords: zinc oxide;preparation; surfactant

* Corresponding author. Tel.: +0-000-000-0000 ; fax: +0-000-000-0000 . E-mail address:[email protected]

2212-0173 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICETEST – 2015 doi:10.1016/j.protcy.2016.05.078

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1. Introduction The concept of nanotechnology was introduced by Richard Feynman in 1959, when he gave a talk called “there is plenty of room at the bottom”. In his talk he never explicitly mentioned about nanotechnology, he suggested that it will eventually be possible to manipulate atoms and molecules precisely. The invention of the Scanning Tunneling Microscope in 1981 and the discovery of fullerenes in 1985 are considered as the convergence of experimental advances which leads to the emergence of nanotechnology in 1980’s. nanoscience and nanotechnology are widely cited to be the defining technology for 21st century and nanotechnology is defined as the control and manipulation of matter at nano dimensions. The introduction of nanotechnology resulted in development of Nano powders that can be used for wide range of applications. Research has been made for nano-size materials in recent years because of their unique character differing from those in the bulk state. One of the great promises that nanoparticles of metal oxides hold in chemical applications is their remarkable ability to chemically absorb a wide variety of molecules, especially organic molecules that are concern as environmental hazards. In recent years zinc oxide has promoted itself as a interesting metal oxide material because of its unique physical and chemical properties such as high chemical and mechanical stability , broad range of radiation absorption, high catalysis activity, electro chemical coupling coefficient, non toxic nature etc. In materials science, zinc oxide is considered as a semiconductor in group II-VI, with a broad energy band of 3.37 eV and high band energy of 60meV. Because of its distinct properties its widely used in many fields such as rubber industry, pharmaceutical and cosmetic industries, textile industries, electronics and electro technology industries etc . Nanometri zinc oxide can occur in variety of structures. It can occur in one dimensional (1D), two dimensional (2D) and three dimensional (3D) structures. One dimensional structures make up the largest group including needles, helixes, nanorods, ribbons, belts, wires and combs. Zinc oxide can occur in two dimensional structures such as nanopellets, nanosheet/nanoplate.[1] Examples of three dimensional structures of Zinc oxide include snowflakes, dandelion, flower etc.In this paper the method of synthesis, characterization, surface modification is discussed. Zinc oxide can be synthesized using many different methods including micro emulsion synthesis, spray drying, sol-gel method, pyrolysis, controlled precipitation , RF plasma synthesis, vapour transport process etc. controlled precipitation method was used here for the synthesis of zinc oxide nanoparticles 2. Experimental 2.1. Materials For the preparation of zinc oxide nano particles two different precursors were used. First one is zinc sulphate heptahydrate (M=287.49g/mol ,Sigma Aldrich), and zinc acetate (M=219.5g/mol, Merk), Poly Vinyl Alcohol (PVA) (Sigma Aldrich)was used as the surface modificant, distilled water was used as the solvent 2.2. Sample preparation a) Preparation using zinc sulphate as the starting material To the aqueous solution of zinc sulphate heptahydrate sodium hydroxide was added drop wise in a molar ratio of 1:2, under vigorous stirring, and the stirring action is continued for almost 18 hours and large amount of white precipitate was formed, this precipitate was filtered and washed with distilled water and dried using a muffle furnace at a temperature of 100 ƕC and it is ground to fine powders and finally the powder obtained was calcined at different temperatures such as 500ƕC,700ƕC,900 ƕC. Here the particles are calcined at different temperatures in order to obtain just an idea about the relation connecting yield and temperature, as the calcination temperature increases the yield decreases

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b) Preparation using zinc acetate as the starting material Initially 1M zinc acetate solution was stirred vigorously, and to this vigorously stirred zinc acetate, 2M sodium hydroxide solution was added drop wise, large amount of white slurry’s were formed, and this white slurry were continuously stirred for 18 hours, a white precipitate was formed, which was filtered and washed with distilled water and dried using muffle furnace and it is ground to fine powders and finally calcined at 400 °C. If the temperature is more than 400°C then the particles starts to thermally degradates and We can observe a noticeable colour change from white to a dark ash colour c)

Preparation using Poly Vinyl Alcohol (PVA) as surfactant

To prepare zinc oxide nanoparticles 0.01% PVA solution prepared initially and 2ml PVA was added to 1M zinc sulphate heptahydrate solution and 2M sodium hydroxide was added to it drop wise very slowly the resulting solution is stirred for almost 18 hours. One thing should keep in mind that if the concentration of PVA is high then it will leads to a situation in which plenty of foam will form instead of the precipitate. After 18 hours large amount of white precipitate was formed which was filtered and washed with distilled water and dried in a muffle furnace at a temperature of 100°C for 2 hours then it was ground to fine powders and finally calcined at 450°C 2.3. Measurements Scanning Electron Microscopy (SEM) images of the zinc oxide nanoparticles and the epoxy nanocomposites were obtained using a JSM-JEOL 6390 Scanning Electron Microscope. The JSM-6390 is a high performance, low cost scanning electron microscope with a high resolution of 3nm. The customizable graphical user interface allows the instrument to be intuitively operated. It is equipped with an auto coater for coating the samples and the coating time is automatically adjusted by the coater and it varies according to the nature of the sample. 3. Results and Discussions 3.1. Scanning Electron Microscopy(SEM)

Fig. 1 SEM image of zinc oxide prepared using zinc sulphate as the starting material

Fig.2. SEM image of zinc oxide prepared using zinc sulphate as the starting material

Figure 1. Shows the Scanning Electron Microscope (SEM) image of the zinc oxide nanoparticles under lower

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magnification and it shows that the particles are agglomerated and complete separation is not occurred. Fig 2 shows its SEM image at higher magnification and we can see that the particles are held together because of weak physical forces. Here particles were formed with size in the micron range, we want particles with size in the region of at least 100nm so it concludes that zinc oxide prepared using zinc sulphate as the staring material does not produce particles with size in the nanometre range and also the particle separation is not good and this method of preparation was highly affected by particle agglomeration

Fig.3 SEM image of zinc of prepared using zinc acetate as the Starting material

Fig.4 SEM image of zinc oxide prepared using zinc acetate as the starting material

Fig 3. Shows the Scanning Electron Microscope (SEM) image of zinc oxide prepared using zinc acetate as the starting material under lower magnification. Here the particles are marginally agglomerated but the particle separation is not good enough here also we can see that the particles are held together because of weak physical force .Fig 4. shows the SEM images of zinc oxide under higher magnification it clearly suggests that particle separation is not good enough and also particles with size in micron range was formed so it concludes that zinc oxide prepared using zinc acetate as the starting material does not produce particles with size in the nanometre range and the particle agglomeration is marginal compared to the previous method

Fig.5 SEM image zinc oxide prepared using PVA as surfactant

Fig.6 SEM image of zinc oxide prepared using PVA as surfactant

Fig 5.shows the Scanning Electron Microscope image of zinc oxide prepared using zinc sulphate as the starting

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material and Poly Vinyl Alcohol as the surfactant. Here the negative impact of particle agglomeration and particle separation was sorted out to an extend due to the introduction of Poly Vinyl Alcohol as surfactant. Here the particle agglomeration is very less compared to the previous methods. Fig 6. Shows the SEM images at higher magnification and we can see that particles with size less than 100nm were formed also it gave clear idea about the particle separation, we can see that the particles are separated smoothly and not highly affected by agglomeration

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3.2. X-Ray Diffraction(XRD) ϵϬϬ ϴϬϬ ϳϬϬ ϲϬϬ ϱϬϬ ϰϬϬ ϯϬϬ ϮϬϬ ϭϬϬ Ϭ Ϭ

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Figure 7. XRD spectrum of Nano zinc oxide prepared using PVA as surfactant

The XRD of the synthesized zinc oxide shows broad peaks at values of 31.9, 34.5, 36.3, 56.7, and 62.9 which are typical for the zinc oxide structure. Notable line broadening of the diffraction peaks is an indication that the synthesized materials are in nanometre range. The average particle size has been determined from full width at half maximum (FWHM) of the diffraction peaks using Scherrer’s equation. Which is given as t = 0.9 Ȝ/(B cos ș) where Ȝ is the wavelength of x-ray and B is the full width at half maximum. The average particle size of zinc oxide nanoparticles has been found to be 25nm 4. Conclusions Zinc oxide nanoparticles were successfully prepared with and without using surfactant. Poly Vinyl Alcohol (PVA) was used as the surfactant and the prepared Nano powder was characterized using Scanning Electron Microscopy (SEM) And X-Ray Diffraction (XRD). According to the characterization results it’s clear that the conventional method of preparation i.e. without any surfactant highly affected by particle agglomeration and also the particle separation is not good enough. But when prepared using a surfactant the particle agglomeration is very less and also the particle separation is good. And the most important thing is that the particle size of zinc oxide prepared using PVA is in the nanometre range whereas in conventional method of preparation particle size in the micron range. According to the XRD characterization the average particle size of zinc oxide prepared using PVA as surfactant has been determined using scherrer’s equation. The average particle size of zinc oxide nanoparticles has been found to be 25nm References [1] Agnieszka Kołodziejczak-Radzimska and Teofil Jesionowski(2014) “ Zinc Oxide—From Synthesis to Application: A Review” materials 2833-2881

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Ananthu C. Mohan and B. Renjanadevi / Procedia Technology 24 (2016) 761 – 766 [2] AbdulazizBagabas, Ahmad Alshammari, Mohamed FA Aboud and Hendrik Kosslick(2013) ”Room-temperature synthesis of zinc oxide nanoparticles in different media and their application in cyanide photo degradation” Nanoscale research letters [3] Hong, R.; Pan, T.; Qian, J.; Li, H.(2006) “Synthesis and surface modification of ZnO nanoparticles”. Chem. Eng. J. ,119, 71–81. [4] Ristiü, M.; Musiü, S.; Ivanda, M.; Popoviü,S (2005) . “Sol–gel synthesis and characterization of nanocrystallineZnO powders”. J. Alloy. Compd., 39, L1–L4. [5] Ismail, A.A.; El-Midany, A.; Abdel-Aal, E.A.; El-Shall, H. (2005) “Application of statistical design to optimize the preparation of ZnO nanoparticles via hydrothermal technique”. Mater. Lett. 59, 1924௅1928. [6] Singhal, M.; Chhabra, V.; Kang, P.; Shah, D.O.(1997). “Synthesis of ZnO nanoparticles for varistor application using Zn-substituted Aerosol OT microemulsion”. Mater. Res. Bull., 32, 239௅247. [7] A.Matei, I. Cernica1, O. Cadar, C. Roman, V. Schiopu1. “Synthesis and characterization of ZnO – polymer nanocomposites”

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