Combined Microwaves/Ultrasound, a Hybrid Technology.

The combination of microwave heating and ultrasound irradiation has been successfully exploited in applied chemistry. Besides saving energy, these green techniques promote faster and more selective transformations. The aim of this review is to provide a practical overview of the complimentary and synergistic effects generated by the combination of microwaves and either ultrasound or hydrodynamic cavitation. This will begin with a brief history, as we outline pioneering achievements, and will also update the reader on recent developments. Such hyphenated techniques are able to offer reliable and efficient protocols for basic chemistry, organic and inorganic synthesis as well as processing. The development of dedicated hybrid reactors has helped scientists to find solutions to new synthetic challenges in the preparation of nanomaterials and new green catalysts. This research topic falls within the confines of process intensification as it facilitates the design of substantially cleaner, safer and more energy efficient technologies and chemical processes.