Green Synthesis of Zinc Oxide Nanoparticles using Neem (Azadirachta indica) Plant Extract Dr. H. Narayan Assoc Professor (Physics) & Head Department of Physics & Electronics National University of Lesotho E-mail:
[email protected] January 24, 2018: 4.30 PM ’Manthabiseng National Convention Centre
National University of Lesotho International Science, Technology & Innovation Conference and Expo January 23-25, 2018 MASERU, LESOTHO Southern Africa
Collaborators • Himanshu Narayan Department of Physics and Electronics, National University of Lesotho, Roma, Lesotho
• Amrita Singh, Brijesh Gaud, and Sandesh Jaybhaye Nanotech Research Lab, Department of Chemistry, Birla College, Kalyan, India
• Rinkesh Kurkure Terna College of Engineering, Nerul, Mumbai, India
Motivation • ZnO nanoparticles have received considerable attention due to their unique and remarkable chemical and physical properties • Various methods have been adopted for the preparation of nano-sized ZnO crystallites, which include sol–gel method, evaporative decomposition of solutions, gas-phase reaction, wet chemical synthesis and hydrothermal discharging gas method. • Biological methods for nanoparticle synthesis using microorganisms, enzymes, and plants or plant extracts have been suggested as possible eco-friendly alternatives.
• In this work, synthesis of ZnO NPs by Bio-Reduction of Zinc Nitrate in plant extract has been reported.
Zinc Oxide Nanoparticles • Synthesis ZnO nanostructures synthesised by bio-reduction of Zinc nitrate heptahydrate in neem (Azadirachta indica) plant extract. Hibiscus (Rosa sinensis) and Tulsi (Ocimum sanctum) plant extracts were also investigated, but the yield was maximum with neem extract
• Characterization Characterization done by X-ray diffraction (XRD), FT-IR spectroscopy, UV-visible spectroscopy, Scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM).
Sample preparation
Next slide: XRD Results
XRD & Particle size
XRD data analysis: - Hexagonal wurtzite phase of ZnO x= 0.1 Nd3+ doped TiO2 [JCPDS file 00-0790206] - unit-cell parameters:
Crystallite size from XRD:
a = b = 3.249 Å, c = 5.206 Å.
Debye-Scherrer formula,
Crystallite size: where, d = size; = wavelength = 1.5406 Å; = FWHM of a peak; and = mean-position of that peak.
Next slide: FT-IR Results
16 nm
Results: FT-IR
FT-IR Spectra measurements of Plant Extract.
FT-IR Spectra measurements of ZnO NPs.
The peak at 513 cm-1 [bottom] is the characteristic absorption of ZnO bond and the broad peak at 3444 cm-1 can be attributed to the characteristic absorption of hydroxyl group. Other prominent bands [top & bottom] are observed due to the organic matter that acts both as reducing and stabilizing agents and capping agent, as well as prevents aggregation of NPs in solution required for the stability of ZnO NPs
Results: UV-Vis
Normal spectra of ZnONPs in range of 200 -600 NM
Zoom image of ZnONPs at range of 331 – 392 nm
Results: SEM
SEM images show:
Spherical shape with smooth surface, and size of NPs:
10 - 40 nm
.
Results: AFM
Shape of the NPs was determined from AFM images and line scans.
20–36 nm and their shape was found to be approximately spherical. The tip-corrected size of NPs measured around
Conclusion • A simple, efficient and green route for synthesis of ZnO NPs using neem plant extract is reported. • ZnO NPs were obtained through a homogeneous phase reaction between zinc nitrate and plant extract solution having pH 5 at varying concentrations, with constant sonication time and temperature. • FTIR shows characteristic absorption of zinc oxide bond at 533 cm−1, which confirms formation of ZnO NPs. • X-ray diffraction confirms hexagonal wurtzite phase of ZnO which is the most stable form of zinc oxide at ambient conditions. Unit-cell parameters were determined to be: a = b = 3.249 Å, c = 5.206 Å. • The average crystallite size through Debye–Scherrer method was estimated around 16 nm. AFM picture showed that the NPs are spherical in shape with size about 20–36 nm. SEM images confirmed that most of the NPs are spherical in shape formed within diameter range of 10 – 40 nm. • The synthesized NPs have shown good anti-bactrial activity. Other potential applications are being investigated.
All my publications can be downloaded from my Research Gate page: https://www.researchgate.net/profile/Himanshu_Narayan
“It is better to light one small candle than to curse the darkness.” – Confucius (BC 551-479, Chinese thinker and social philosopher)
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