Dyeing of textiles with natural dyes extracted from Terminalia arjuna and Thespesia populnea fruits

•Natural dyes are always superior to synthetic dyes in terms of eco-friendliness.•Ultrasonic dyeing is more energy efficient compared to conventional dyeing.•Reusing the dye bath is sustainable.•Researchers try to explore novel sources for natural dye extraction. Natural dyes are eco-friendly, non-hazardous and sustainable. But the use of metal mordants such as copper, chromium, tin and zinc could make the application of natural dyes unsustainable since they are heavy metals. Hence, sustainable natural dyeing could be achieved with natural mordanting assistant such as myrobalan, metal mordants like alum and ferrous sulphate which have lesser environmental impacts compared to other metal mordants. The current study aims at extracting natural dyes from the fruits of Terminalia arjuna and Thespesia populnea and their application on textiles such as silk, cotton and nylon. Ultrasonic bath dyeing, an energy-efficient method, has been adopted for the study and the process has been compared with conventional water bath dyeing. It has been observed that ultrasonic dyeing is better both in terms of dye exhaustion and energy conservation compared to water bath dyeing.