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.

天然染料是环保，无害且可持续的。但是，使用诸如铜，铬，锡和锌等金属媒染剂可能会使天然染料的使用不可持续，因为它们是重金属。因此，可以使用天然的媒染助剂（如myrobalan），金属媒染剂（如明矾和硫酸亚铁）实现可持续的天然染色，与其他金属媒染剂相比，它们对环境的影响较小。目前的研究旨在从榄仁和色参的果实中提取天然染料及其在丝绸，棉花和尼龙等纺织品上的应用。超声波浴染色是一种节能的方法，已被用于研究，并且将该过程与常规水浴染色进行了比较。已经观察到，与水浴染色相比，超声染色在染料消耗和能量节省方面都更好。