What Is Sonochemistry?

Sonochemistry is an area of chemistry that studies the effect that sonic waves have on chemical systems. The sonochemistry effects derives from a phenomenon known as acoustic cavitation, that is the formation, growth, and the implosion of bubbles in a liquid. Initial studies on sonochemistry started in 1927. However, the science of sonochemistry went unnoticed until the 80s when technological advances on materials and engineering made it possible to find analytical and industrial applications

The whole body of knowledge of sonochemistry and all its applications is based on a single process known as cavitation. In chemistry, cavitation refers to the formation, growth, and implosion of tiny small bubbles. This process is induced by the sound waves irradiated on the sample.

The collapse (implosion) of bubbles is very fast. Experimental studies have demonstrated that these tiny bubbles formed during sonication (irradiation with sound) have very high temperatures (near 5000 Kelvin degrees) and very high pressures (around 1000 atmospheres). This cavitation process creates extreme physical and chemical conditions in cold liquids although the extremeconditions are very localized.

Basically, there are 3 types of sonochemical process: homogeneous sonochemistry of liquids, heterogeneous sonochemistry of liquid-liquid or solid-liquid systems, and, some type that represents a mix of both homogeneous and heterogeneous sonochemistry.

There are many applications of sonochemistry both in industrial and laboratory settings. Sound can be successfully used to process of a variety of organic and inorganic materials in a wide range of volumes, typically between 50µL to 2 liters in a laboratory environment. For example, ultrasound homogenizers can be used to help prepare (disintegrate tissues and cells, homogenize, disperse and disaggregate) samples for biological and or chemical analysis. Also, the acceleration of chemical reactions is possible with sound waves.At the industrial level, sonochemistry also has its share of accomplishments. At these levels, processing by sound can be in batch or in continuous form. And processing volumes can range from half a liter to 2000L per batch.Among the applications of sonochemistry in industry it can be mentioned the following: dispersion and milling of pigments for paint or ink manufacturing, formulation of high nano coatings (coating surface with nanomaterials), biodiesel production, and even food or beverage pasteurization.

Bar, R. 1987. Ultrasound Enhanced Bioprocesses. Biotech and Eng, Number 32, Pages 655-663

Suslick, K. S. 1990. Sonochemistry. Science. Number 247, pages: 1439-1445

Suslick, K.S. 1998. Kirk-Othmer Encyclopedia of Chemical Technology. Wiley & Sons: New York, Number 26, Pages 517-541