Natural colourants from <i>Sargassum polycystum</i> C.Agardh (Phaeophyceae) for fabric dyeing: an eco-friendly method for textile colouring by response surface methodology

Natural dyes have promising potential in the textile industry as a sustainable and eco-friendly alternative to synthetic dyes. In this study, a natural dye was extracted from the brown alga S. polycystum using a microwave-assisted extraction method under various extraction parameters. Response surface methodology (RSM), which combines transformational models and sequential technologies, was used in this study to improve the procedure. Response surface models were developed to correlate the extraction yield with four parameters, namely, algal concentration, pH of extraction medium, extraction time and temperature. Dyed and undyed wool fabrics were characterized by scanning electron microscope (SEM). The results demonstrated that the colour strength (K/S) of dyed wool increases by decreasing the pH, increasing the dyeing temperature, dye concentration and time of dyeing process. The optimal level of pH, dye concentration, dyeing temperature and time for obtaining the highest K/S was 2.3 g 50 ml‒1, 120°C and 15 min, respectively. Dyeing of wool fabric processed under the optimal conditions showed strong anti-bacterial and anti-fungal activity and good colour-fastness properties.