Chapter 6 - Sonochemical Engineering Processes

Abstract

Sonochemical engineering processes refer specifically to “processes using ultrasound” and include all processes involving ultrasonic energy as well as cavitation bubbles. Some representative examples, from solid–liquid (cleaning, extraction, separation, aggregation, and dispersion), liquid–liquid (emulsification), gas–liquid (atomization), and reaction processes (polymerization), are introduced. Mention is made of issues to do with scale-up and operational high-efficiency of reactors. For processes dealing with extraction, separation, and dispersion, ultrasound of frequencies below 100kHz are used. On the other hand, for aggregation and atomization processes, frequencies greater than 100kHz are used. Ultrasonication of liquid systems results in the formation of nanometer sized droplets. Atomization draws attention to a method for the synthesis of porous nanoparticles and for separation of alcohol from aqueous solutions. Sonochemical efficiency in a process is strongly related to the liquid height in the reactor. Sonochemical reactions are enhanced by liquid flow and/or superposition of ultrasonic fields. It is explained that advances in design for scale-up and control of reactors with high efficiency are required for industrial usage.