Green synthesised ZnO nanoparticles from Plectranthus amboinicus plant extract: removal of Safranin- O and Malachite green dyes & anti-bacterial activity

The synthesis of Zinc oxide nanoparticles using a plant-mediated approach is presented in this paper. The nanoparticles were successfully synthesised using the sulphate derivative of Zinc and plant extract of the indigenous medicinal plant Plectranthus amboinicus. The XRD analysis confirms the hexagonal close-Packed lattice of the synthesised ZnO nanoparticle. In the UV visible spectrometer (UV - Vis) absorption peak was observed at 314 nm, which is specific for Zinc oxide nanoparticles. Field Emission Scanning Electron Microscope (FESEM) reveals the presence of Zinc oxide nanoparticles in its nanoflakes form. Energy Dispersive Spectrum (EDX) results show strong energy signals of 71.60% and 18.40% for Zinc and Oxygen, respectively. The absorption peak of Zn - O bonding between 404 cm(-1) is confirmed by FT- IR spectra. The ZnO nanoparticles degrade 85.29% of Safranin-O dye and 81.57% of Malachite green dye within 90 minutes of time. Antibacterial studies with Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria have given more than 90% results.