Solvent-antisolvent precipitation in a spinning disc reactor: Precipitation kinetics and mathematical modelling of starch nanoparticles

Abstract

Experimentally determined kinetics for the precipitation of starch nanoparticles in ethanol antisolvent are reported in a spinning disc reactor. Induction times (tind) obtained from visualisation studies are estimated to be between 13 and 144 ms, with lower tind obtained at higher shear and supersaturations. Nucleation rates are measured to be of the order of 1016 mL−1s − 1, with higher values obtained on a smooth disc at the highest shear conditions and 9:1 antisolvent/solvent ratio. The grooved texture is deemed more advantageous in the low shear regions (i.e. at low flow rate and disc speed) where the passive mixing induced by the flow disrupting grooves produces more nuclei than the smooth surface under similar conditions. Modelling of particle size distribution via population balance equations combined with an engulfment micromixing model has been validated against the experimental profiles with good agreement for most of the conditions studied, even in the presence of agglomerates.