Low temperature biosynthesis of crystalline zinc oxide nanoparticles from Musa acuminata peel extract for visible-light degradation of methylene blue

Abstract

The aim of this work is to optimize the synthesis parameters involved in the green synthesis of zinc oxide (ZnO) nanoparticles using banana peel (BP) extract as reducing and capping agents. The UV–vis spectra of biosynthesized ZnO exhibited a strong absorption peak at 344 nm with a band gap of 2.95–3.14 eV. FTIR analysis revealed the presence of biomolecules on the synthesized ZnO nanoparticles. XRD results proved that the purity of the prepared ZnO nanoparticles was pH dependent with size of 30−80 nm when determined by the Debye–Scherrer equation. SEM images also revealed different ZnO morphologies were formed depending on the pH of the synthesis conditions. The samples exhibited red photoluminescence emission in the visible region. According to the results, the best conditions for the synthesis of ZnO nanoparticles were pH = 12, 1 mL BP extract, 0.02 M zinc acetate dihydrate, 3 h synthesis time, and 60 °C temperature. The synthesized ZnO nanoparticles displayed good visible-light photocatalytic activity for the reduction of methylene blue (MB). The optimized biosynthesized ZnO showed reusability for 4 catalytic cycles.