Wastewater to Ecological Dyeing Process and Bioactive Compounds Resources: Case Study of Dittrichia graveolens Hydrodistillation Aqueous Residue

Abstract

The release of aqueous residues generated by the extraction process of essential oils presents a real risk of environmental pollution. This work aims to reduce this risk and produce value-added materials. The aqueous residue of Dittrichia graveolens (D. graveolens) hydrodistillation has been reused in two valorization ways: 1/in the ecological dyeing. 2/in biological field. First, a phytochemical study of the aqueous residue was carried out by determining the content of polyphenols (237\xa0mg EqAG g−1) and flavonoids (91\xa0mg EqC g−1). Second, HPLC analysis allowed the identification and evaluation of catechin (5.92\xa0mg g−1 of extract) and quercetin (4\xa0mg g−1 of extract) as two of the coloring molecules present in this aqueous residue. Third, the eco-dyeing process with the aqueous residue was performed on the polyamide fabric, the process was optimized by the surface response methodology using Minitab software. Thus, the optimum dyeing conditions were evaluated at pH, temperature and duration of 3, 80\xa0°C and 90\xa0min, respectively, giving a maximum value of K/S color yield (equal to 7.5). Fourth, the dyeing process was evaluated by measuring fastness tests for the optimal conditions. Finally, the aqueous residue was assessed for its antioxidant, antibacterial, anti-inflammatory and cytotoxic potential from where it is proven that it could be a source of the bioactive compounds.