Green products such as plant pigments are gaining fame globally due to their excellent ayurvedic and biological characteristics. In this study, microwave (M.W.) has been employed to isolate colourant from black pepper (Piper nigrum L.), and bio-mordants have been included to obtain colourfast shades. Central Composite design (CCD) was formulated under response surface methodology (RSM) to optimize dyeing variables statistically. The results obtained after a series of experiments show that using 35 mL of irradiated acidic extract (RE = 6 min.) of (pH4) in the presence of 1 g/100 mL of table salt as an exhausting agent at 65 °C for 55 min has demonstrated excellent colour depth (K/S) onto microwave-treated silk fabric (RS = 6 min). By applying bio-mordants, it has been found that walnut extract (1.5%), pinenut hull extract (1%), and orange peel extract (1.5%) are there before dyeing. In contrast, walnut extract (1.5%), pinenut hull extract (1.5%), and orange peel extracts (1.5%) after dyeing have shown colourfast shades of high strength. Comparatively, salts of Al+3 (1.5%), salts of Fe+2 (1.5%), and T.A. (tannic acid = 1.5%) before dyeing, while salts of Al+3 (0.5%) and salts of Fe+2 (2%) and T.A. (Tannic acid = 1%) after dyeing, have given good results. It has been observed that the use of M.W. radiation has not only improved the yield of dyes extracted from leaves when applied to silk fabric but also the inclusion of the optimum amount of bio and chemical mordants have resulted in moderate to good and excellent colour fastness ratings.

The purpose of this research is to evaluate the colouring performance of Amba Haldi–based natural extracted yellowish colour for the dyeing of wool fabric using ultrasonic (US) treatments. Before and after the US treatment, the colourant was separated in aqueous and acidic solutions for up to 60 min. Scanning electron microscopy and Fourier-transform infrared spectroscopy were used to investigate the surface morphology and chemical changes in the cloth before and after radiation. On the wool fabric that was ultrasonically treated at 75°C for 45 min, an acidic extract of Amba Haldi powder after US treatment for 20 min showed good colour depth (K/S). Acacia extract (2%), pomegranate extract (1.5%) and pistachio extract (1%), when used as pre-biomordants, were shown to have excellent colour strength. Acacia (1.5%) extract, pomegranate (2%) extract and pistachio (1.5%) extract were also used as post-biomordants. As pre-chemical mordants, Al salts (1%), Fe salts (1.5%) and tannic acid salts (2%), whereas Al salts (2%), Fe salts (1%) and tannic acid salts (2%), have produced successful results as post-chemical mordants. Overall, it was discovered that pomegranate extract (2%), used as a post-bio-mordant, and salt of Fe (1.5%), used as a post-chemical mordant, both exhibit exceptional colour strength. Ultrasonic treatment, a procedure that is harmless for the environment, has only served to increase the colour strength of dye on wool fabric, and the addition of bio-mordants has made the process more sustainable.

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