Intensified Nanoparticle Synthesis Using Hybrid Microwave and Ultrasound Treatments: Consecutive and Concurrent Modes

Abstract

Bubble formation around nucleated particle is inevitable when quick heating of microwave is employed in nanoparticle synthesis. Since these bubbles may cause bumping behavior, the bubble growth must be possibly suppressed to ensure stable microwave‐assisted operation. In this study, sequential and simultaneous ultrasound treatment and microwave irradiations on nanoparticle synthesis are proposed and investigated to assess the benefit of ultrasound in preventing superheating behavior and producing finer particles. Experimental results indicate that the inclusions of ultrasound treatment result in finer particle sizes and suppression of bumping behavior. Particularly, consecutive ultrasound treatment and microwave irradiation are recommendable due to its practicality and generating smallest bubbles and final particle sizes. This technique can therefore be expected as an innovative way to enhance industrial applications of quick thermal response induced by microwave.

Prediction of Particle Number Density in Suspension by Measuring the Sizes of Bubbles Generated During Microwave Irradiation

“…Microwave technology has been attractive for nanoparticle synthesis because finer particle can be obtained due to nucleation promotion by the quick thermal response. [ 1–9 ] Higher particle number density obtained by microwave effect is advantageous to prevent excessive heat generation within the particle due to microwave absorbance. This prevention is possible because at high particle density microwave energy is distributed to more particle in suspension.…”