The textile industry is currently grappling with severe environmental crises caused by synthetic dyes, which contribute to approximately 20% of global industrial water pollution and introduce carcinogenic and mutagenic risks through azo compounds. This study addresses these sustainability challenges by investigating the valorization of Tropical Almond (Terminalia catappa) fruit peels, an abundant agricultural waste rich in tannins and flavonoids, as a renewable bio-colorant source. To optimize pigment recovery, three green extraction methodologies, including aqueous, ultrasonic assisted, and acidic extraction, were systematically evaluated using dark purple ripe fruit peels, which were subsequently applied to cotton fabric with an alum mordant. The study utilized CIELAB colorimetric analysis and UV-visible spectrometry to quantify the extraction efficiency and color properties. The experimental results revealed that ultrasonic assisted extraction is the most efficient methodology, achieving high color intensity at lower temperatures (60 ± 5 °C) and shorter durations by utilizing high-frequency waves to disrupt plant cell walls. In contrast, acidic extraction yielded the most saturated and stronger reddish-brown shades, exhibiting exceptional and prominent absorbance peaks in the 500-520 nm region. Although aqueous extraction remains the most environmentally friendly and safe approach, it requires higher thermal energy (90 ± 5 °C) to achieve significant dye solubility. Ultimately, this study provides a comprehensive framework for utilizing organic waste to produce non-toxic, biodegradable dyes, offering a viable pathway toward a circular economy and reducing the toxicological footprint of the textile coloration industry.
Publication Date: 2026-05-27