A critical analysis of extracts of okra seeds and amla offering green chemistry for synthesis of zinc oxide nanoparticles and their promising role in reducing crude oil viscosity

Abstract

To produce zinc oxide (ZnO) nanoparticles, aqueous solution growth offers cost and energy advantages over gas phase methods making the process green, but the quality of the ZnO nanoparticles could be compromised. It is often exaggerated that plant extracts can make the solution growth process even more ‘green’, but its overall impact requires careful evaluation. In this study, the effectiveness of plant extracts obtained from okra seeds and amla and their impact on ZnO nanoparticle production are investigated. Results showed that certain chemicals like phenolic compounds from amla can exhibit significant antioxidant activity. Extraction in water at room temperature is advantageous for the green synthesis, but may require greater amount of plant part or longer extraction time. Characterization techniques including FT-IR spectroscopy, UV–vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) are employed. There are possibilities of some impurity caused by remnants of precursor for ZnO, indicating requirement for additional purification stages. SEM analysis reveals distinct morphologies influenced by plant extracts, with particle sizes ranging from sub-100 nm to several microns. Elemental composition of synthesized ZnO are consistent with that of commercial ones. Apart from synthesizing ZnO nanoparticles, their impact on the viscosity of Arab Medium Crude Oil is also investigated. Dispersion of the ZnO particles in the oil reveals up to 70% reduction in viscosity.