Acalypha indica–mediated green synthesis of ZnO nanostructures under differential thermal treatment: Effect on textile coating, hydrophobicity, UV resistance, and antibacterial activity

Abstract

In this study, ZnO nanoparticles were green-synthesized from Acalypha indica leaf extract using zinc acetate as a precursor. The prepared ZnO nanoparticles were calcined at three different temperatures, namely 100, 300, and 600 °C. The structure/morphology of the green-synthesized ZnO nanoparticles was ascertained through X-ray diffraction, particle size analysis, scanning electron microscopy, transmission electron microscopy, and surface area analysis techniques. It was observed from the physico-chemical and biological characterization studies that ZnO nanoparticles calcined at high temperature (600 °C) exhibit high surface area (230 m2 g−1) and small particle size (20 nm) with good antibacterial activity against Escherichia coli (22.89 ± 0.06 mm) and Staphylococcus aureus (24.62 ± 0.08 mm). In addition, cotton fabrics coated with these nanoparticles showed higher UV-protection (87.8 UPF), hydrophobicity (155°), and maximum zone of bacterial inhibition against E. coli and S. aureus (25.13 ± 0.05 mm and 30.17 ± 0.03 mm) than those coated with particles calcined at 100 °C and 300 °C. High temperature calcination has a vital role in the crystallization of the particles towards nanoscale with increased resistivity to UV exposure, washing treatments, and microbial infection in fabrics. Thus, the cost-effective ZnO nanoparticles obtained through green synthesis method proves their potential applications in the field of biomedical, textile, and cosmetic applications.