Chemical Engineering Science, Vol.199, 100-112, 2019
Population balance Monte Carlo simulation of self-assembly of core (micro-Al2O3)-shell (nano-TiO2) structure in aqueous suspensions
This study aimed to employ population balance Monte Carlo (PBMC) method to guide the tailor-making of core-shell microarchitecture of particles in aqueous suspensions. Larger micro-Al2O3 (mu m-Al2O3) particles were coated with smaller nano-TiO2 (nm-TiO2) particles by self-assembly technique, under the consideration of complex colloidal particle dynamics. For a desired core-shell structure, hetero-aggregation (TiO2-Al2O3) with a higher priority than homo-aggregation (Al2O3-Al2O3, TiO2-TiO2) can be achieved by adjusting Derjaguin-Landau-Verwey-Overbeek (DLVO) forces through the process parameters pH and ionic strength (IS). To simulate such multicomponent aggregation, PBMC was adopted to directly track the competition of various aggregations and the change of particle variables, based on Brownian motion and extended-DLVO theory. For better understanding the competition kinetics, attachment efficiency was calculated to reveal quantitatively the combined effect of van der Waals attraction, electric double layer repulsion/attraction, and hydration repulsion. A charge balance model was developed to view the change of particle surface electrostatic potential issued from the aggregation of various charged particles. A dynamic light scattering measurement was conducted to validate the PBMC simulation. This PBM method was implemented to explore the effects of pH and IS, then to obtain the optimized coverage efficiency of the final core-shell composite particles. These findings look promising for understanding inherent particle dynamics and rationalizing self-assembly process of core-shell microarchitectures. (C) 2019 Elsevier Ltd. All rights reserved.