Sonochemical reactions, when, where and how: Experimental approach

The sonochemical reactions proceed with the cavitation bubble implosion that results in unique chemical and physical effects from extreme conditions in localized hot–spots, which can boost reactions that need high temperature, pressure, and long reaction time. The sites where sonochemical reactions take place include the gas phase, the interfacial region surrounding collapsing bubble, and the bulk solution. The mechanisms can be categorized as chemical pathways of pyrolysis and free radical oxidation, and physical pathways caused by high–speed microjets and shockwaves. This chapter elaborates the sonochemical reactions in detail, along with detection techniques for cavitation. Sonochemical degradation of organic pollutants are chosen as examples to illustrate the application of sonochemical reactions.