Enhancement of the knowledge on the ultrasonic reactor behaviour by an interdisciplinary approach.

Our work is a step to a better understanding of high frequency ultrasonic reactors behaviour. Using finite elements calculations, it was demonstrated that localization of chemical and physical effects can be well correlated with mechanical behaviour of ultrasound emitter. This complementary approach enables us to propose a full interpretation of the sonochemical reactor behaviour. A major reason of scientific interest on ultrasound is the well-known enhancement of chemical or physical phenomena. This is so important that "Enhancement" is probably the most used word in the title of related publications. To fully understand experimental results, present work demonstrates that ultrasound needs also to significantly enhance a very difficult knowledge transfer operation that might be named interdisciplinary co-working. Hence, ultrasound is now used and studied in many different fields of science such as acoustic, chemistry, medical imaging, disease treatment (lithotripsy), non-destructive testing. Each one has his own vocabulary, approach, and method to describe the phenomenon. In this work four different methodologies were involved to study of the same effect but using a chemical, chemical engineering, physical and mechanical approach respectively. All these viewpoints were then brought together in order to explain new original results.

Degradation of pentachlorophenol aqueous solutions using a continuous flow ultrasonic reactor: experimental performance and modelling.

The degradation of aqueous solutions of pentachlorophenol (PCP) in a three-stage sonochemical reactor operating in the continuous flow mode has been investigated. The experimental reactor may be considered as a series of three high-frequency ultrasonic units. The influence of several parameters such as ultrasonic power, reactor volume and volumetric feed flow rate on the reactor performance is reported. Application of classical basic chemical engineering principles leads to a model that enables us to predict the PCP concentration within the reactor. In steady state, experimental conversion rates are shown to be in good agreement with model predictions.

Experimental study of the hydrodynamic behaviour of a high frequency ultrasonic reactor.

In relation to design and modeling of sonochemical reactors, the hydrodynamic behaviour of a high-frequency ultrasonic reactor has been investigated. Residence time distribution (RTD) measurements have been performed by means of a tracer method. The influence of ultrasound on the response to an inlet pulse was evidenced. It was shown that the reactor behaves like a completely stirred tank reactor (CSTR) as soon as ultrasonic irradiation operates. Preliminary observations on acoustic streaming occurring within the reactor will also be presented.