Micro-Hydrodynamic Interaction Mechanisms in TiO2 NanoColloidal Suspensions with Different Particle Size Distributions: The Effects of Electrostatic and Steric Stabilization

Micro-hydrodynamic interaction mechanisms of colloidal particles have important effects on the intrinsic properties and behavior of nano-colloidal suspensions, which in turn affect their different potential applications. Particle stability and size distribution are among the important parameters that influence the micro-hydrodynamic interaction mechanisms. The aim of this research is to investigate, both experimentally and theoretically, the effect of stabilization methods on the micro-hydrodynamic interaction mechanisms in TiO2 nano-colloidal suspensions considering the different particle size distributions. The effect of the two stability methods (electrostatic and steric) on the distribution of particle size are experimentally investigated. The effect of different particle size distributions on the motion and net forces (Brownian, gravitational, lift, and drag) acting on colloidal particles is theoretically estimated based on the correlation formula. The interactions between the particle-fluid molecules and colloidal particles themselves are considered in the calculations. The results show that the stability of colloidal particles has a significant effect on the micro-hydrodynamic interaction mechanisms in nano-colloidal suspensions, where different particle size and size distribution can be obtained. Low particle sedimentation is observed in the case of steric stabilization and with low particle concentration, which enhances the particle diffusion coefficient. The laminar motion of the TiO2 particles can be achieved in the case of high stability nano-colloidal suspension. In this case, the flow of particles occurs in the Stock’s regime. The investigation of the micro-hydrodynamic interaction mechanisms in nano-colloidal suspensions in different conditions gives clear information on the possibility of their usage in different applications.