Ultrasound assistance to liquid–liquid extraction: A debatable analytical tool

A review of the effects of ultrasound (US) on liquid–liquid extraction is here presented. The phenomena produced by US, particularly cavitation, influence in different ways mass transfer between two immiscible liquids. The nature of the donor and acceptor phases and the presence of a chemical reaction dramatically affect mass transfer. Discrete and continuous approaches for the development of US-assisted liquid–liquid extraction as well as their advantages and limitations are discussed as a function of the system under study. In depth research in this field is needed in order to establish the liquid–liquid systems which can benefit by application of this type of energy.