Zeta Potential Determination from Molecular Simulations

ζ-Potential (ZP) is among key physical properties characterizing the behavior of nanoparticles in colloidal solutions. Despite many attempts to calculate and neatly interpret the ZP, a full understanding of various factors influencing its values has not been achieved yet, even for standard metal oxides, particularly when considering high ionic concentrations and the effect of temperature. This contribution extends our recent work [Předota, M. Langmuir 2016, 32, 10189−10198], where we suggested a direct approach to calculate the ZP from nonequilibrium molecular dynamics (NEMD) simulations. Here, we investigate NaCl, RbCl, CaCl2, SrCl2, and Na2C2O4 aqueous solutions interacting with TiO2 and SiO2 surfaces and show contrasting ZP behaviors of these metal oxides, elucidated by theoretical insights gained by molecular simulations. We show that both surface-specific and ion-specific properties play a key role in the observed electrokinetics. Additionally, we explore the concentration and temperature influence on the ZP of selected systems and discuss the measurement of the ZP of systems with surfaces and ions modeled using scaled partial charges. Our results agree well with available experimental data and capture all key ZP features predicted by theory or revealed by experiments and advance the microscopic description of solid/liquid interfaces, promoting further applications of the suggested NEMD approach.