Extraction of Natural Dyes from Delonix regia Flowers for Cotton Fibres

Abstract

Textile colouration is among the major industry that pollutes the environment with effluents rich in dye chemicals. Most of the dyes used are synthetics which possess health and environmental impacts. Potentially, the use of bio-based dyes and other chemicals can lessen the environmental challenges of the textile effluents. This study reports on sustainable extraction and dyeing of cotton fabric using extract of Delonix regia flowers. The extraction process was done using acidified water as a solvent and the dyeing process was free from hazardous auxiliary chemicals. To improve the dyeing performance, banana sap was used as an affordable and eco-friendly bio-mordant. To optimise energy consumption, dyeing experiments were done between room temperature and 90 °C. The dyeing performance was assessed through wash fastness, rub fastness and colour strength tests. The cotton fabric was successively dyed with the Delonix regia flowers extract rich in anthocyanin pigments in the presence of banana sap bio-mordant. The optimum dye performance was obtained at a dyeing temperature of up to 60 °C, above which the performance was negatively affected.