ABSTRACT
Power ultrasound (US) and microwave (MW) dielectric heating are among the most simple, inexpensive, and effective tools in applied chemistry. These green techniques dramatically enhance heat and mass transfer, inducing faster and more selective chemical transformations. Sonochemistry has a longer history than microwave chemistry; however, in the last two decades, the latter has found a growing number of relevant applications. While popular wisdom just associates MW with superior heating and US with ef›cient agitation, these techniques are capable of doing much more and this potential provides additional impulse to their expansion in synthesis and processing. The reproducibility of these techniques, however, still requires further attention, especially since some design parameters are sometimes overlooked. Surprisingly, the additive and even synergic effects that have been observed in combined US/MW irradiations have overcome all expectations (Cravotto and Cintas, 2007). Maeda and Amemiya ›rst described the surprising synergic effects in sono-and chemiluminescence experiments carried out under simultaneous US/MW irradiations (Maeda and Amemiya, 1995). Although sequential or simultaneous irradiation with US and MW sources entails technical and safety considerations, their coupling can easily be performed on a lab scale. It is hoped that such equipment will be commercially available in the near future at a reasonable price.
