Equipment Sonochemical reactor

In the sonochemical reactors, selection of suitable operating parameters such as the intensity and the frequency of ultrasound and the vapor pressure of the cavitating media is an essential factor as the bubble behavior and hence the yields of sonochemical transformation are significantly altered due to these parameters. It is necessary that both the frequency and intensity of irradiation should not be increased beyond an optimum value, which is also a function of the type of the application and the equipment under consideration. The liquid phase physicochemical properties should be adjusted in such a way that generation of cavitation events is eased and also large number of smaller size cavities are formed in the system. 

There are numerous different types of equipment available for use as sonochemical reactors. The initial source of ultrasound comes from transducer devices which convert alternating electrical impulses to mechanical vibrations. Generally these are constructed of either piezoelectric or magnetostrictive material (p. 5). A purely mechanical low-frequency emitter is the whistle system, not frequently used by sonochemists, but of widespread usage in food processing (p. 311). Several set-ups are used to produce low-frequency ultrasoimd, from the simple cleaning baths to much more sophisticated emitters, sometimes using two... 

The reactor used for the sonochemical work was a conventional ultrasonic bath that many readers will recognise as a piece of equipment for cleaning components. The hydrodynamic cavitation reactor was a vessel with an orifice plate in the main feed line to generate cavitation. While fully acceptable yields of 97-99% were achieved with the sonochemical reactor (and also, except for the case of peanut oil feedstock, with the hydrodynanuc cavitation reactor), the most interesting data related to the energy used. These are compared in Table 8.4. The energy efficiency is defined as the yield in kg of product per kJ of energy used in the reactor. 

Entezari MH, Petrier C, Devidal P (2003) Sonochemical degradation of phenol in water a comparison of classical equipment with a new cylindrical reactor. Ultrason Sonochem 10 103-108... 

Solutions to the problem of the scale-up of sonochemical reactions do exist but they are not so simple as the use of bigger versions of laboratory equipment. In a production situation the volumes treated vill be very much larger than those considered in the laboratory and the type of process vill govern the choice of reactor design. It could well be that some processes would be more suited to low intensity sonication (e. g. using a bath type reactor) whereas others may need higher intensity irradiation via a probe type system). 

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