Extraction of natural dye from waste wine industry: Optimization survey based on a central composite design method

The wine industry rejected large amounts of pressed grape pomace containing huge reserves of natural dyes that could be exploited in textile dyeing. The present paper aims to develop and optimize an extraction method of natural dye from grape pomace in order to dye wool fabrics. The influence of the main extraction conditions (grape pomace amount, sodium hydroxide concentration, extraction temperature and duration) on the dyeing performances of wool fabrics was studied. These performances were appreciated by measuring the color yield (K/S) of dyed wool fabrics. A central composite design method made with MINITAB 15 software was used for the optimization of the extraction method. The optimum conditions were found to be: concentration of sodium hydroxide of about 0.13 M, amount of grape pomace of about 69.56 g/l, extraction temperature of about 80 °C and extraction duration of about 70 min.