Dyeing potential of polyamide fibers using eucalyptus leaf extract

Abstract

Textile substrates are commonly dyed with synthetic dyes, which are not always easily removed from effluents using conventional treatments. Due to this limitation, natural dyes have been investigated more extensively in recent years. This study evaluated the use of aqueous extracts from different eucalyptus leaves in dyeing polyamide knitwear, employing two biomordants: soy milk and lemon juice. The extracts were obtained from fresh and mature eucalyptus leaves, dried both naturally and in an oven, through water-based extraction. Dyeing was carried out using an exhaust process in infrared-heated cup equipment at 98 °C for 30 minutes. The results were assessed through analyses of color intensity and color fastness, as well as by scanning electron microscopy and Fourier transform infrared spectroscopy. Findings indicated that mature leaves exhibited greater dyeing capacity than fresh leaves, producing intense brown shades. The soy milk biomordant combined with mature leaf extract also proved effective, yielding a K/S value of 108.55 and a wash fastness rating of 4/5 for both alteration and transfer. These results demonstrate that eucalyptus leaf extract can be applied as a sustainable alternative in textile dyeing.