Sonochemistry: a practical approach to the synthesis of nano-structured materials- A short review

Sonochemistry is the application of ultrasound to chemical reactions and processes. Ultrasound is the part of the sonic spectrum which ranges from about 20 kHz to 10 MHz. Sonochemistry arises from acoustic cavitation: the generation, subsequent growth and collapse of the bubble cavities releasing large magnitudes of energy over a very small location resulting invery high energy densities. The implosive collapse of a bubble generates a localized hot spot; a temperature of ~ 5000 K and pressure of ~ 1800 atm, with cooling rates that exceed 109 K/s. Using these extreme conditions, a new synthetic technique (ultrasonication) has been recently developed for the synthesis of nano-structured inorganic materials through the reduction of corresponding metallic ions. These nano particles have been used in various fields such as catalysis, microelectronics, waste water treatment and medicine. Using the metal oxide supports (alumina or silica) or polymeric ligands, these sonochemically produced nano-structured solids can be trapped as supported catalysts or metal-polymer nanocomposites respectively. In case of catalysis, the former are active heterogeneous catalysts for hydrocarbon reforming and CO hydrogenation reactions.

Keywords:

Sonochemistry , Ultrasound , Cavitation , TEM , Nano composite