Optimization of the process parameters for dyeing silk fabric with a fungal pigment using RSM

This study explores the extraction and application of a sustainable dye derived from Talaromyces purpurogenus fungi for dyeing silk fabric. The fungal dye imparted a vibrant red shade to silk, offering a promising alternative to synthetic dyes. The dyeing process was optimized using the Box and Behnken Design of RSM software, focusing on dye pH, dyeing temperature, and dyeing time. Silk fabric was dyed using an HTHP dyeing machine, and its performance was assessed in terms of colour strength, percent absorption, light fastness, rubbing fastness, and washing fastness. SEM imaging and FT-IR spectroscopy were employed to investigate the interaction between the dye and silk fabric. The optimized dyeing process resulted in silk fabric with a satisfactory red shade, demonstrating favorable fastness ratings at pH 5. The optimal dyeing conditions included a dye pH of 5, dyeing temperature of 82 °C, and dyeing time of 55 minutes, with an optical density of 10 and MLR of 1:30. Silk fabric exhibited maximum dye absorption capacity at pH 5, while maintaining excellent washing and rubbing fastness properties. However, the light fastness of the dyed silk fabric was relatively poor. Microscopic examination revealed a rough surface texture. Overall, this study highlights the potential of T. purpurogenus fungal dye as a sustainable alternative for silk fabric dyeing, while emphasizing the importance of addressing challenges such as improving light fastness through surface treatment and further exploring dyeing techniques. [Display omitted] •Extraction of a fungal dye from Talaromyces purpurogenus fungi for dyeing silk fabric.•Fungal dye exhibits a bright red and rose hue on silk fabric.•Based on dye pH, temperature, and time, BBD was used to optimize the dyeing process.•Dyeing at pH 5 enhanced silk fabric's colour strength and absorption.•Silk fabric showed excellent washing and rubbing fastness.