Enhancing sustainable silk Textiles: Optimization of teak leaf extract dyeing and antibacterial efficacy

Abstract

This study introduces an environmentally friendly method for dyeing silk using pigments extracted from young teak leaves (Tectona grandis L.), offering a sustainable solution to reduce pollution from synthetic dyes while repurposing agricultural waste. Ethanol (95 %) extraction of teak leaves showed a rich in polyphenols and quinonoid compounds, which yielded a reddish-brown pigment suitable for dyeing. Key dyeing conditions, including temperature (30–100 °C), duration (10–60 min), and pH (3–11), were optimized to maximize color absorption and uniformity. Color performance was evaluated through spectrophotometry (L∗, a∗, b∗ values) and K/S measurements. Three mordants including alum (aluminum potassium sulfate), ferrous sulfate, and stannous chloride were tested using pre-, meta-, and post-mordanting techniques. Pre-mordanting with ferrous sulfate delivered the darkest shades and highest color intensity, along with excellent wash and light fastness (rated ≥4 on the Grey scale). FTIR spectroscopy revealed stable dye-mordant complexes formed through molecular coordination. The dyed silk exhibited mild antibacterial properties against Staphylococcus aureus and Escherichia coli in agar well diffusion tests, though inhibition zones were modest (<0.20 cm), likely due to residual bioactive compounds. These results position teak leaf extract as a multifunctional natural dye, combining aesthetic, ecological, and hygienic advantages. By aligning with circular economy principles, this approach presents a viable pathway for sustainable textile production. Nonetheless, future research should focus on optimizing extraction methods, boosting antimicrobial efficacy, and scaling the process for industrial applications.