Sustainable Usage of Microwave Energy to Extract Natural Dyes from Hypericum triquetrifolium Turra: Phytochemical Characterization and Dyeing Properties

With the need to find natural dyes, scientists were driven to search for new modern techniques to extract natural dyes from plants, animals and minerals. The present work aims to take advantage of the microwave extraction technique to extract natural dyes from Hypericum triquetrifolium Turra species. Thus, the effect of the experimental parameters namely: microwave power, pH and extraction time on the extraction performance was studied. In order to evaluate the extraction performance, the contents of total phenolic compounds, flavonoids, condensed and hydrolysable tannins were estimated at each time. Then, the dyes extracted from the aerial part of the H. triquetrifolium plant were used for dyeing wool fabrics. The calculation of the colorimetric coordinates (L*, a*, b*) as well as the colour strength (K/S) was carried out in order to evaluate the quality of the dye. The fastnesses of the dye were also evaluated. Acceptable fastnesses to washing, rubbing and light were obtained. Finally, the optimization of the dyeing process of wool fabric by the dye extracted from the Hypericum plant is done according to the response surface methodology.