Sonochemical effect on size reduction of CaCO3 nanoparticles derived from waste eggshells.

A novel combination of mechanochemical and sonochemical techniques was developed to produce high-surface-area, bio-based calcium carbonate (CaCO3) nanoparticles from eggshells. Size reduction of eggshell achieved via mechanochemical and followed by sonochemical method. First, eggshells were cleaned and ground, then ball milled in wet condition using polypropylene glycol for ten hours to produce fine particles. The ball milled eggshell particles were then irradiated with a high intensity ultrasonic horn (Ti-horn, 20 kHz, and 100 W/cm(2)) in the presence of N,N-dimethylformamide (DMF); decahydronaphthalene (Decalin); or tetrahydrofuran (THF). The ultrasonic irradiation times varied from 1 to 5 h. Transmission electron microscopic (TEM) studies showed that the resultant particle shapes and sizes were different from each solvent. The sonochemical effect of DMF is more pronounced and the particles were irregular platelets of ~10 nm. The BET surface area (43.687 m(2)/g) of these nanoparticles is much higher than that of other nanoparticles derived from eggshells.

Sonochemical synthesis and rheological properties of shear thickening silica dispersions.

A sonochemical method has been developed to synthesize shear thickening fluid. This shear thickening fluid (STF) is composed of hard silicon dioxide nanoparticles and polyethylene glycol (PEG) liquid polymer. The combination of flow-able and hard components at a particular composition, results a material with remarkable rheological properties that is suitable for liquid body armor applications. In the present study nine types of STF's have been synthesized with two different types of silica nanoparticles (15 nm and 200 nm) and polyethylene glycol at various weight fractions using a high intensity ultrasonic irradiation. The resultant STF samples were tested for their rheological and thermal properties. The advantages and disadvantages of this process have been discussed.