In situ preparation of hydrophobic CaCO3 nanoparticles in a gas-liquid microdispersion process

This study presents a novel process of in situ surface modification of CaCO3 nanoparticles using a multiple-orifice dispersion microreactor. CO2/Ca(OH)(2) precipitation reaction was employed to prepare CaCO3 nanoparticles with sodium stearate surfactant. Synthesized CaCO3 products were characterized by thermogravimetric analysis (TGA), infra-red (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmet-Teller analysis (BET). The effect of various operation parameters on nanopartides and the dosage of sodium stearate were determined. The results showed that the preparation process could be precisely controlled with efficient mass transfer process. The particles were highly hydrophobic with a contact angle of 117 degrees and monodisperse with an average size of 30 nm. The adsorptions of sodium stearate and calcium ion on solid particles during the in situ surface modification process were investigated. (C) 2013 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.