Green Mediated Synthesis of Zinc Oxide Nanoparticles using Tamarind Bark Extract and their Applications in Textile Dye Degradation and Antimicrobial Studies

Abstract

ZnO nanoparticles were synthesized using tamarind bark extract as a green reducing agent in alkaline medium. The tamarind bark solution acts both as a stabilizing and a reducing agent which regulates the size and the shape of the green synthesized zinc oxide nanoparticles. The progressive growth of ZnO nanoparticles was monitored by using UV-visible spectral studies. A sharp peak at 349 nm indicates the formation of spherical shaped zinc oxide nanoparticles. The size and shape of the ZnO nanoparticles were observed using scanning electron microscopy (SEM). The catalytic behaviour of a ZnO nanoparticle was studied for the degradation of textile dyes like methylene blue and Congo red and observed that the degradation reaction follows pseudo first-order kinetics with a rate constant k =0.0331 min-1, 0.0283 min-1 and 0.1175 min-1, 0.1167 min-1, respectively for ZnO nanoparticles at 50 µg and 100 µg. The antimicrobial activity of ZnO nanoparticles was also tested for various Gram-positive, Gram-negative bacteria and fungi in which higher zone of inhibition was observed for Gram-negative microorganism.