Improving the dyeing affinity of natural dyes for cotton fabrics using nanotechnology : a comparative evaluation of nanoparticles

Abstract

The growing demand for eco-friendly textile dyeing has renewed interest in natural dyes due to their biodegradability, non-toxicity, and sustainable source. However, their low affinity for cotton fibres and poor colourfastness properties remain major limitations. These challenges are typically addressed using metallic mordants, which increase significant environmental and health concerns. Therefore, the present study aims to enhance the dyeing affinity and fastness properties of natural dyes on cotton fabrics through a nanotechnology-based approach. The objectives of this study are to synthesise and isolate nanoparticles, extraction of natural dyes from selected plant sources, apply nanoparticles as pre-treatments to cotton fabrics, and evaluate their effect on dye performance. Cellulose nanocrystals (CNCs), chitosan nanocrystals (ChsNCs), and iron nanoparticles (FeNPs) were either synthesized or isolated and subsequently characterized using analytical techniques. Natural dye extracts were obtained from the four selected plant leaves of Mangifera indica, Tectona grandis, Lannea coromandelica and Bridelia retusa using aqueous extraction methods, and characterized using analytical techniques. The nanoparticles were used as pre- treatment agents for cotton fabrics prior to dyeing with the natural extracts. The dyed fabrics were assessed for colour properties to evaluate dye uptake and performance. Furthermore, the morphology and interactions among dye molecules, nanoparticles, and cotton fibres were analyzed using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The nanoparticle-treated fabrics showed significantly improved dye performance compared to the untreated sample. Among the nanoparticle treatments, CNCs and ChsNCs exhibited more effective interactions with dye molecules and cotton fibres compared to FeNPs. This study confirms that functionalized nanoparticles offer an efficient, environmentally benign approach to improving the performance of natural dyes on cotton fabrics, thereby enhancing sustainable textile processing and reducing reliance on hazardous mordants and synthetic dyes