Eco-dyeing of wool with Rubia cordifolia root extract: Assessment of the effect of Acacia catechu as biomordant on color and fastness properties

In the present study, anthraquinone colorants were extracted from powdered Rubia cordifolia roots and applied on wool fiber. Acacia catechu is used as a biomordant, a replacement to metallic mordants, for wool dyeing, and the effect on color characteristics and fastness properties was assessed. Shades on wool of red tones with good to excellent color fastness properties were obtained. Pre-mordanting with A. catechu improved the overall color and fastness parameters, due to the maximum dye uptake. Auxochromic groups responsible for interaction of dye and wool were studied by Fourier transform infrared (FTIR) analysis of R. cordifolia extract. The surface morphology of dyed wool fiber was investigated by scanning electron microscopy (SEM) for any changes on fiber after dyeing.