Ultrasound-assisted sustainable and energy efficient pre-treatments, dyeing, and finishing of textiles – A comprehensive review

Traditional pre-treatments, dyeing, and finishing of textiles have high environmental impacts because of the high usage of energy, water, and chemicals, and the production of effluent containing leftover harmful dyes and chemicals. In this comprehensive review article, the advances in applications of ultrasound in the sustainable pre-treatments, dyeing, and finishing of various types of textiles to reduce their environmental impacts are discussed and the advantages/disadvantages of such processes are outlined. The enhancement of pre-treatment, dyeing, and finishing performances along with a reduction in processing time, temperatures, and chemical usage by applying sonication has been summarized. The effect of sonication on dye adsorption isotherms, adsorption kinetics, and dye adsorption mechanisms of various fibers dyed with different dyes are also discussed. Moreover, challenges and prospects for ultrasound in the chemical processing of textiles are projected. The application of ultrasound considerably reduces processing time, temperature, and chemical usage and also enables low-liquor ratio dyeing of textiles. However, the lack of availability of convincing data on savings of energy, water, and chemical usage of using ultrasound in actual industrial production machinery is one of the key reasons that the textile industry is slow in adopting sonochemical processes.