Photofading of Natural Indigo Dye in Cotton Coated with Zinc Oxide Nanoparticles Synthesized by Precipitation Method

Abstract

Blue dye (indigo) from Indigofera tinctoria leaves is a popular natural dye used worldwide. The lower light fastness of natural indigo dyes compared to that of synthetic blue dyes is one of the drawbacks of the former, limiting its utilization in the textile industry. In this study, zinc oxide nanoparticles (ZnONPs) were synthesized and characterized, and their effect on the photofading of cotton fabric dyed with natural indigo was investigated. ZnO was produced by simple precipitation. Fourier transform infrared spectroscopy (FTIR), X-ray powder diffractometry (XRD), and Brunauer–Emmett–Teller analysis were employed to characterize the composition, shape, crystallinity, size, and surface area of the resulting NPs. The optical characteristics and bandgap energy of the ZnONPs were also determined using a UV-Vis spectrophotometer. XRD and scanning electron microscopy (SEM) confirmed the synthesis of ZnONPs. The ZnONPs were applied to cotton fabrics via the dip-coating method. The transmittance of cotton coated with ZnONPs was lower than that of the uncoated sample. Photofading tests with UV-A irradiation were conducted, and the fading rate of natural indigo dye in cotton showed first-order kinetics. Overall, the synthesized ZnONPs provided excellent UV protection to reduce the photofading of cotton dyed with natural indigo.

Keywords

• indigofera tinctoria
• natural dye
• photofading
• uv-protection
• zinc oxide nanoparticle