Heterogeneous sonochemistry liquid-solid reactions

Sonochemistry can be roughly divided into categories based on the nature of the cavitation event homogeneous sonochemistry of liquids, heterogeneous sonochemistry of liquid—liquid or liquid—solid systems, and sonocatalysis (which ovedaps the first two) (12—15). In some cases, ultrasonic irradiation can increase reactivity by neady a million-fold (16). Because cavitation can only occur in liquids, chemical reactions are not generally seen in the ultrasonic irradiation of solids or solid-gas systems. 

Heterogeneous Sonochemistry Reactions of Solids with Liquids 737... 

One of the most important aspects inherent in sonochemistry concerns synthesis and treatment of organic and inorganic materials. Effects of ultrasound on chemical transformations were studied in three directions sonochemistry in homogeneous liquid system, sonochemistry in heterogeneous liquid-liquid or liquid-solid several times as well as sonocatalysis. Thus, the cavitation concentrates sound energy to affect the synthesis from soluble precursors. Chemical reactions are usually not observed in sonicated solid-solid and solid or gas systems. 

Ultrasonic cavitation has particularly important effects on biphasic systems, emulsification of immiscible liquid-liquids, particle breakage and dispersion, and surface cleaning in liquid-solid mixtures. These mechanical effects, even if sometimes oversimplified, appear to be understandable and predictable by nonexperts in the field, who exploited them in a variety of heterogeneous reactions. Sonochemistry of biphasic systems then developed rapidly, and synthetic applications were reviewed in recent articles. In many cases, the presence of a phase transfer catalyst becomes unnecessary, and sonication can be considered as a "physical substitute to PTC", according to the expression of Ando. a... 

Heterogeneous sonochemistry The use of high-intensity sound or ultrasound to alter chemical reactions in a two-phase system, usually a liquid and a solid. 

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