Synthesis of ZnO and ZnO/PVA nanocomposite using aqueous Moringa Oleifeira leaf extract template: antibacterial and electrochemical activities

Abstract

The application of flexible polymer nanocomposites for food packaging to inactivate microorganisms associated with foods is the demand of the present-day food industry to assure quality throughout the packaging operation. The utilization of polyvinyl alcohol (PVA) assisted zinc oxide nanocomposite for food stuff packaging has been very attractive in the recent past. Nanostructured ZnO was synthesized at optimized pH (10.5) from different ratios of zinc acetate and Moringa oleifeira leaf extract (1:7, 1:3, 1:1 and 3:1). ZnO coated polyvinyl alcohol (ZnO/PVA) nanocomposites were prepared from 5, 9, 13 and 16% by wt of ZnO and PVA using solution casting method. The thermal stability of ZnO synthesized with 1:1 ratio at pH 10.5 was investigated with TGA/DTA. The analytical techniques such as X-ray diffraction (XRD), ultra-violate visible analysis (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) were used for the characterization of the synthesized ZnO and ZnO/PVA nanocomposites (NCs). The antibacterial activity of the synthesized ZnO and ZnO/PVA NCs were evaluated against gram negative E. coli and gram positive S. aureus bacteria. The electrochemical stability of ZnO/PVA NCs was also investigated by cyclic voltammetric (CV) method. The thermogram of ZnO indicated that the oxide was found to be stable even beyond 500°C. The SEM analysis revealed rod shaped morphology for synthesized ZnO from 1:1 ratio at pH 10.5. But the nanocomposite prepared with 5% of ZnO of (1:1) at the same pH exhibited uniformly dispersed rod-shaped particle on the surface as well as in matrix of polyvinyl alcohol film. According to XRD result, ZnO synthesized with more percentage of plant extract resulted in the small size crystallites while that with low percentage of plant extract resulted in the larger crystallite size. The antibacterial inhibition efficiency of ZnO/PVA NCs was better and found to increase with increase in the amount of ZnO.

Novel Green In Situ Synthesis of ZnO Nanoparticles on Cotton Using Pomegranate Peel Extract

“…Similar results were obtained with our samples, with the peaks around 31°, 34°, 36°, and 39°. The weak ZnO band signals were found to be in cases of lower concentrations of ZnO and higher precursor to natural extract ratios, and they also depend on the type of the natural extract and the crystalline structure of the final ZnO product [ 85 , 91 , 92 ]. The precursor type and the treatment process also lead to different nano-structured and nano-porous forms of ZnO with different coordinated networks, which exhibit different peak intensities (some very weak) in the XRD spectrum [ 93 , 94 , 95 , 96 , 97 ].…”

UV Blocking and Oxygen Barrier Coatings Based on Polyvinyl Alcohol and Zinc Oxide Nanoparticles for Packaging Applications

“…Polymeric food packaging films seem to be the most frequent solution, and they work well [10]. Polymeric food packaging may preserve food from microbial damage and possesses features including elasticity, toughness, tensile, and an atmospheric and humidity barrier [11,12]. Polyvinyl alcohol (PVA) is an emerging polymer used for packaging; it is a biodegradable and water-soluble polymer that is ecologically beneficial [13,14].…”

ZnO Nanoparticle/Poly(vinyl alcohol) Nanocomposites via Microwave-Assisted Sol–Gel Synthesis for Structural Materials, UV Shielding, and Antimicrobial Activity

“…aureus, which showed a zone of inhibition larger than 10 mm using all films containing ZnO. Most likely, the enhancement of antibacterial activity is sensitive to the ZnO ratio, as described by Dejen and co-workers and Amin and co-workers. , Both groups reported inhibition zones 13–16 mm in diameter for Gram-negative bacteria (E. coli) and 14–26 mm for Gram-positive bacteria (S.…”