Nanostructured Materials Synthesis Using Ultrasound

Abstract

Recent applications of ultrasound to the production of nanostructured materials are reviewed. Sonochemistry permits the production of novel materials or provides a route to known materials without the need for high bulk temperatures, pressures, or long reaction times. Both chemical and physical phenomena associated with high-intensity ultrasound are responsible for the production or modification of nanomaterials. Most notable are the consequences of acoustic cavitation: the formation, growth, and implosive collapse of bubbles, and can be categorized as primary sonochemistry (gas-phase chemistry occurring inside collapsing bubbles), secondary sonochemistry (solution-phase chemistry occurring outside the bubbles), and physical modifications (caused by high-speed jets, shockwaves, or inter-particle collisions in slurries).

Synthesis and Characterization of Amorphous Iron Oxide Nanoparticles by the Sonochemical Method and Their Application for the Remediation of Heavy Metals from Wastewater

“…The formation of IONPs by the sonochemical method is due to acoustic cavitation, which involves three basic sequential steps; formation of bubbles followed by growth and implosive collapse that result in high pressure as well as temperature followed by the high cooling rate [32]. The chemical reactions which are involved in the sonochemical method are reported to be driven by intense ultrasonic waves that are strong enough to produce cavitation are oxidation, reduction, dissolution, decomposition, and hydrolysis [47]. Initially, there is a formation of a minute bubble that gradually grows in size due to the fusion of several small particles and once the size of the bubbles reaches to its maximum i.e., threshold than the bubble could not sustain the pressure difference, and consequently, the bubble implosively collapses and generates a localized hotspot through adiabatic compression or shock wave formation within the gas phase of the collapsing bubble [48].…”

The Effects of Ultrasound on Crystals: Sonocrystallization and Sonofragmentation

“…Another application of sonocrystallization is for the generation of nanocrystals and nanostructures [104][105][106][107][108][109][110]. Qian et al reported ultrasonic irradiation as a new method for generating zinc oxide nanocrystals [111].…”

General and Prospective Views on Oxidation Reactions in Heterogeneous Catalysis

“…Ultrasound and microwave irradiations, ball milling and sonophotodeposition, to name a few strategies, represent innovative technologies to the conventional solid-state, wet chemistry and gas phase synthesis procedures. Many review articles are available in the literature, offering a comprehensive discussion on this subject [57][58][59][60][61]. Here, through a few selected examples, we wish to highlight the advantages of using ultrasound, ball milling, sonophotodeposition and sonoelectrodeposition in the synthesis of solid catalysts (and photocatalysts) for the selective oxidation of alcohols to the corresponding aldehydes or carboxylic acids.…”