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

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.