Mechanism of mass-transfer enhancement in textiles by ultrasound

The intensification of wet textile processes, such as cleaning and dyeing, by application of ultrasound is well known. In these processes, mass transfer in the interyarn and intrayarn pores of the textile is the basic physical phenomenon. The results of experiments on textile cleaning, based on basic principles of acoustics and cavitation, coupled with analysis of the surface and cross section of the ultrasound-treated textile and high-speed imaging of the cleaning process, are reported. It is revealed that transient cavitation in the vicinity of the textile surface, and not the ultrasound wave itself, is the physical mechanism responsible for the enhanced cleaning effect. Intense microconvection due to the transient bubble motion driven by ultrasound enhances fluid flow and, thus, mass transfer through the textile.