Sonochemistry

TLDR

Ultrasound induces high‑energy chemistry that is applied to both homogeneous liquid reactions and heterogeneous liquid‑solid systems. The high‑energy effects arise from acoustic cavitation, where bubble collapse generates intense heating, shock waves, and high‑velocity collisions that can melt metals. These cavitation hot spots reach ~5000 °C and 500 atm, enabling metal surface cleaning, melting, and the initiation or enhancement of catalytic reactions.

Abstract

Ultrasound causes high-energy chemistry. It does so through the process of acoustic cavitation: the formation, growth and implosive collapse of bubbles in a liquid. During cavitational collapse, intense heating of the bubbles occurs. These localized hot spots have temperatures of roughly 5000°C, pressures of about 500 atmospheres, and lifetimes of a few microseconds. Shock waves from cavitation in liquid-solid slurries produce high-velocity interparticle collisions, the impact of which is sufficient to melt most metals. Applications to chemical reactions exist in both homogeneous liquids and in liquid-solid systems. Of special synthetic use is the ability of ultrasound to create clean, highly reactive surfaces on metals. Ultrasound has also found important uses for initiation or enhancement of catalytic reactions, in both homogeneous and heterogeneous cases.