Green synthesis of Europium (III) Oxide nanoparticles using Hibiscus sabdariffa flower extract
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Date
2018
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University of Zululand
Abstract
Nowadays there is a need to develop eco-friendly processes, inexpensive and nontoxic chemical use in the synthesis protocol in order to obtain biocompatible and harmless nanoparticles. Green chemistry approach is the eco-friendly process which has taken the researchers attention globally due to its advantages over conventional methods. This ecological method has potential in transforming the inorganic metal ions into metal oxides NPs via the bio-reduction of molecules present in the particular organism. This contribution reports on the synthesis, the main physical and optical properties of Europium (III) oxide (Eu2O3) nanocrystals synthesized for the first time by a completely green physical-chemistry process using Hibiscus sabdariffa (HB) natural flower extract and Europium nitrate pentahydrate (Eu(NO3)3.5H2O) salts as a precursor. The HB natural extract solution was used as a reducing agent for the production of Eu2O3 nanoparticles. The 1 g of EuN3O9.5H2O was dissolve in 100 ml of HB extract solution. The precipitate obtained was dried in the oven set at 100oC and thereafter annealed for 2 hrs at various temperature; 300oC, 500oC and 700oC using a standard furnace. The structural and optical properties of such biosynthesis nanocrystals were analyzed using High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), Electron Dispersive X-rays Spectroscopy (EDS), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Raman Spectroscopy, Ultraviolet and visible spectrometer (UV-Vis-NIR) as well as room temperature photoluminescence (PL). The HRTEM and SEM results showed the images of small NPs formed, which indicated that the Eu2O3 NPs are nano-scaled with a mixed population of crystalline particles. The TEM and XRD analysis showed grain size of nanoparticles ranging between 14 nm and 25 nm. The XRD results confirmed the characteristic body centered cubic (BCC) structure of Eu2O3 nanoparticles and the UV-Vis proved that Eu2O3 absorbs in a wide range of electromagnetic wave from ultraviolet region. The luminescence properties of such cubic were characterized by an intense red emission centered at 614.93 nm (5D0-7F2). It was observed that a biosynthesized cubic Eu2O3 nanocrystal is an efficient luminescence material due to a very good luminescent response with potential application as red phosphors. These results represent an important step forward in the investigation of Eu2O3 nanoparticles properties synthesized via green chemistry process. It is a promising cost-effective path and energy wise non-consuming with zero waste end products for highly stable and well-characterized nanoparticles. The green synthesized Eu2O3 nanoparticles would be beneficial for the development of nontoxic, clean and environmentally friendly biosynthesis procedure.
Description
A thesis submitted to the Faculty of Science and Agriculture in fulfillment of the requirements for the Degree of Master Of Science in the Department of Physics and Engineering at the University of Zululand, 2018
Keywords
green chemistry --hibiscus sabdariffa --natural extract --europium (III)oxide --nanoparticles --rare earth oxides --photoluminescence