Valorization of natural dye extracted from date palm pits (Phoenix dactylifera) for dyeing of cotton fabric. Part 1: Optimization of extraction process using Taguchi design

Nowadays, clothes dyed with synthetic dyes contain a large variety of harmful products for health and environment. These substances are potentially carcinogenic, especially when they mix with sweat. That is why great efforts were carried out to promote natural dyeing while valuing plants considered as a waste. In this study, aqueous solution extracted from date pits powder is characterized and valorized. Experiments were carried out using Taguchi experimental design to be able to analyze the main effects of each parameter and to deduce optimum conditions for extraction process. Obtained results indicate that the most suitable solvent is acetone with an optimal percentage of 10% of the volume of the solution used fort extraction, the optimal temperature is found at 80 °C and the optimal duration is 90 min. After the extraction under optimum conditions, the stability and the storage conditions of the extracted solution were evaluated using the factorial experimental design. The parameters analyzed are those influencing the dyeing process, namely: the pH of the solution, the temperature and the duration. The analyzed responses are the polyphenol content and the absorbance of the aqueous extract. Obtained results proved that the extracted solution can be conserved in the darkness more than 15 days in 3 °C.