Electron Microscopy Study of Green Synthesized Zero Valent Iron Nanoparticle Vijayshree Sharma*and Dr. Jyoti Sharma Department of Chemistry, Govt. R.R.(PG) Autonomous College, Alwar (Raj.) ABSTRACT Nanotechnology is gaining tremendous impulsion in the present century due to its capability of modulating metals into their nanosize. They exhibit a high surface/volume ratio leading to different properties far different from those of bulk material. Biomolecules present in plant extracts can be used to reduce metal ions to nanoparticles in a single step green synthesis process. The biogenic reduction of metal ion to base metal is quite rapid, readily conducted at room temperature and easily scaled up. In this work, a novel green and cost-efficient method is used for the synthesis of zerovalent iron nanoparticles with an average diameter of 50-100 nm. Characterization of nzvi was performed systematically by using ph analysis, SEM, TEM studies. Keywords: zero valent iron nanoparticles, green synthesis, ph, SEM, TEM. 1. INTRODUCTION In recent years, nonmaterials have been focusing on nanoscience and nanotechnology which is a growing multidisciplinary field of study and application due to their unique surfaces, Structural and bulk properties attracted tremendous interests, investments and efforts in research and development around the world 1-5. Nano-sized particles have been present on earth for millions of years and have been used by mankind for thousands of years. A nanoparticle can be defined as a microscopic particle that has atleast one dimension less than 100 nm in size 6. The physical and chemical properties of nanoparticles are mainly determined by its size, shape, composition, crystallinity and structure 7-8. Nanotechnology is a growing field in which theunderstanding and control of matter in the nanometer scale is used to develop new solutions. Unique physical properties of molecule at 1-100 nanometer scale make novel application possible. Nanoparticle show completely new or improved properties, such as size, distribution and morphology of the particles etc. Novel applications of nanoparticles and nanomaterials are emerging rapidly on various fields 9. Nanotechnology is a reliable and enabling environment friendly process for the synthesis of nanoscale particles. In fact, nanoparticles display completely unique properties in comparison with their large-size counterparts 10. For environmental applications, nanotechnology the potential of novel functional materials, processes and devices with unique activity toward recalcitrant contaminants, enhanced mobility in environmental media and desired application flexibility 11, 12. These tiny products also have a large surface area to volume ratio, which is their most important feature responsible for the widespread use of nanomaterials in mechanics, optics, electronics, biotechnology, microbiology, environmental remediation, medicine, numerous engineering fields and material science 13. Different protocols have been designed for the production of metallic nanoparticles.physical and chemical methods are being used extensively for production of metal nanoparticles. However, this production requires the use of very reactive and toxic reducing agents which cause undesired detrimental impacts on the environment, plant and animal life it supports. Use of biological organisms such as microorganisms, plant extractor plant biomass could be an alternative to chemical and physical methods for the production of nanoparticles in an ecofriendly manner 14-16. Plant mediated biological synthesis of nanoparticles has gained importance only in the recent years 17. 654 Vijayshree Sharma and Dr. Jyoti Sharma
The need for environmental non-toxic synthetic protocols for nanoparticles synthesis leads to the developing interest in biological approaches which are free from the use of toxic chemicals as byproducts. Thus, there is an increasing demand for green nanotechnology 18. Many biological approaches for both extracellular and intracellular nanoparticles synthesis have been reported till date using microorganisms including bacteria, fungi and plants 19, 20. Green synthesis provide advancement over chemical and physical method as it is cost effective, environment friendly, easily scaled up for large scale synthesis and in this method there is no need to use high pressure, energy, temperature and toxic chemicals 1. The biological molecules undergo highly controlled assembly for making them suitable for the metal nanoparticle synthesis which was found to be reliable and eco friendly 21. Iron nanoparticles (nzvi) have been mostly synthesized using different plant extracts. Plant extract act as low-cost reducing and stabilizing agents. Plant extract reduce the metal ions in a shorter time as compared to microbes. In the present study we have performed the synthesis of green iron nanoparticles using tea leaves extract. Aqueous ferric chloride solution, after reacting with tea leave extract, led to rapid formation of highly stable, crystalline iron nanoparticles. The rate of nanoparticle synthesis was very high, which justifies use of plant over microorganisms in the biosynthesis of metal nanoparticle through greener and safer methods. 2. MATERIALS AND METHODS 2.1 Reagents and chemicals 1. 0.01M FeCl 3 solution 2. Distilled water 3. Tea leaves 2.2 Green method of synthesis of zerovalent iron nanoparticle(nzvi) The synthesis of nzvi utilizing tea leaves extract containing a range of polyphenols. Without the addition of any surfactant or polymer, the stable nanoparticles were obtained at room temperature. Polyphenols in plant act as both reducing agent and a capping agent, resulting in stable green nanoscale zero valent iron nanoparticles with unique properties. Iron nanoparticles are prepared by adding 0.1M FeCl 3 solution to the tea extract (prepared from 200 mg of tea leaves) in 1:2 volume ratio. The mixture was hand shaken and allowed to stand at room temperature for 1 hr. the colour of the solution changes from pale yellow to black indicating the formation of iron nanoparticles. Figure below illustrates general mechanism forsynthesis of nanoparticles using plant extracts. 655 Vijayshree Sharma and Dr. Jyoti Sharma
2.3 ph ANALYSIS The ph was determined by using Digital phmeter Systronics. The ph of the reduced solution with Nanoparticle synthesized was found to be 2.17. Plant Extract ph Change UV Change Tea leaves Before After 5.42 2.17 216-268 nm T a b l e I : Change in ph during Iron Nanoparticle Synthesis. 3. RESULTS AND DISCUSSION In this experiment tea Leaves extract is used to produce Iron Nanoparticles. Fe +3 ions were reduced into Fe 0 nanoparticles. After the reduction an immediate change in color from Light yellow to Black and change in ph of the solution is observed. It is known that Ferric Chloride exhibit bright yellowish color in distilled water. On mixing the plant extract with the aqueous FeCl 3 solution it changed the color of the solution immediately and reducing the ph, which is an indication of formation iron nanoparticles. 3.1 Transmission Electron Microscopy (Tem) Analysis Morphology and size of synthesized nano-particles are determined by investigation of transmission electron microscopy (TEM). From the TEM micrograph, the biologically synthesized nanoparticlesare granular in nature, mostly spherical in shape and exist as chain-like aggregates. TEM images of biologically synthesized iron nanoparticles are shown in figure 1. 656 Vijayshree Sharma and Dr. Jyoti Sharma
3.2 Scanning Electron Microscopy (SEM) Analysis The surface morphology of nano ZVI was revealed by SEM image (Figure 2). The surface of iron nanoparticles was smooth and the shape looked like aggregated round shape. It can be observed that iron nanospheres are mostly spherical in shape and exist as chain-like aggregates. 4. CONCLUSION A green single-step synthesis of iron nanoparticles using tea polyphenols is described that uses no additional surfactants/polymers as capping or reducing agents. The expedient reaction between polyphenols and ferric chloride occurs within a few minutes at room temperature and is indicated by color changes from pale yellow to dark black in the formation of iron nanoparticles. The synthesized iron nanoparticles were characterized using Transmission electron microscopy (TEM), Scanning electron microscopy (SEM). Thus, the green synthesis using Tea leave extracts can be economic and effective method for the synthesis of zero-valent iron nanoparticle. 5. ACKNOWLEDGEMENT: The authors are thankful to the Head of the Department of Chemistry, University of Rajasthan, Jaipur, for providing laboratory facilities. 6. REFERENCES 1. Lu.G.Q. and Zhao.X.S., (2004). Nanoporous Materials: Science and Engineering: Nano porous materials-an overview, Series on Chemical engineering vol 4, Emprecial College Press. 2. Kong.J, Franklin.R.N., Zhou. C.W., Chapline,.G.M., Peng.S., Cho.K., Dai.H.J., 2000. Nanotube molecular wires as chemical sensors. Science 287 (5453), 622 625. 3. Kra lik. M., Biffis.A, 2001. Catalysis by metal nanoparticles supported on functional organic polymers. J. Mol. Catal. A: Chem. 177 (1), 113 138. 4. Long.Q.R, Yang.R.T, 2001. Carbon nanotubes as superior sorbent for dioxin removal. Journal of the American Chemical Society 123, 2058 2059. 5. Kipp.J.E, 2004. The role of solid nanoparticle technology in the pteral delivery of poorly water-soluble drugs. Int. J. Pharm. 284, 109 122. 6. Thakkar.K.N, Mhatre.S.S and Parikh. R.Y, Biological synthesis of metallic nanoparticles, Nanomedicine, vol.6,no. 2, pp. 257-262, 2010. 7. Addadi, L. and S. Weiner, 1992. Control and design principles in biological mineralization.angewandtechemie International Edition in English, 31(2): 153-169.Bazylinski, D.A., R.B. Frankel and 657 Vijayshree Sharma and Dr. Jyoti Sharma
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