Synthesis and characterization of chitosan/zinc oxide nanocomposite for antibacterial activity onto cotton fabrics and dye degradation applications

Abstract

The present study reports an eco-friendly synthesis of chitosan/zinc oxide (CS/ZnO) nanocomposite using S. lycopersicum leaf extract by a bio-inspired method. The synthesized CS/ZnO nanocomposite was characterized by using UV-visible spectroscopy, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR) techniques. The XRD analysis revealed wurtzite crystalline structure of CS/ZnO nanocomposite. Electron microscopy images showed agglomeration of CS/ZnO nanocomposite having spherical shaped structure with an average size of 21-47 nm. The observed bands around 400-500 cm^-1 in the IR spectrum indicated the presence of metal‑oxygen bond, whereas bands at 1512 and 1745 cm^-1 indicated the presence of amine groups (-NH₂) which confirms the presence of CS in the CS/ZnO nanocomposite. The synthesized nanocomposite showed potential antibacterial activity against skin infection causing S. aureus and the mechanism of bactericidal activity was confirmed by using FE-SEM. The CS/ZnO nanocomposite incorporated cotton fabrics also exhibited antibacterial activity against S. aureus, B. subtilis and E. coli. Furthermore, CS/ZnO nanocomposite acted as photocatalyst for the degradation of Congo red under sunlight irradiation. In conclusion, as-synthesized CS/ZnO nanocomposite can be used as bactericidal agent in textile industries and also as photocatalyst for dye degradation.

Keywords: Antibacterial activity; Chitosan; Photocatalyst; Zinc oxide nanocomposite.