Synthesis of Nanoparticles with Novel Technology: High-Gravity Reactive Precipitation

On the basis of the analysis of key engineering factors predominating in a reactive precipitation process, a new method called high-gravity reactive precipitation (HGRP), which means that reactive precipitation takes place in high-gravity conditions, is presented here for the massive production of nanoparticles. A rotating packed-bed reactor was designed to generate acceleration higher than the gravitational acceleration on Earth. The syntheses of nanoparticles of CaCO3, aluminum hydroxide, and SrCO3 were employed to demonstrate the advantages and industrial potentials of this technology, where the typical gas−liquid−solid, gas−liquid, and liquid−liquid multiphase reaction systems were involved. Experimental results show that the mean size of CaCO3 particles can be controlled and adjusted in the range of 17−36 nm through the change of operation conditions such as high-gravity levels, fluid flow rates, and reactant concentrations. Nanofibrils of aluminum hydroxide of 1−10 nm in diameter and 50−300 nm in length as well as nanoparticles of SrCO3 with a mean size of 40 nm were synthesized. The crystal structures of these compounds synthesized in high-gravity conditions were the same as those in gravitational conditions. HGRP technology is believed to be capable of the preparation of nanoparticles with low-cost and high-volume production and therefore to have potential applications in industry.