PhD defense of Kunyu WANG

Ion adsorption at solid-liquid interfaces is of long-term interest in various industrial applications. Especially the charged silica surface with localized punctual adsorbing sites shows high potential in water decontamination. The charged surfaces are mostly described by the electrical double layer (EDL) model within the Stern-Gouy-Chapman (SGC) formalism. Though the experimental methods can probe many macroscopic properties, accurate atomistic descriptions are only given by theoretical models or simulations. The molecular simulations are irreplaceable in liking the microscopic (atomistic) and macroscopic descriptions. This thesis explored the ion-specific adsorption in EDL driven by pair formation in the case of alkaline-earth metal chlorides (MCl₂). We describe the adsorption mechanism in the Stern layer by a series of molecular dynamics (MD) simulations, which are analyzed in the McMillan-Mayer framework. The results show that the adsorption is collective, which gives a complex speciation.

Keywords: Silica; Adsorption; Ions; Simulation

^{Credit: K. Wang / UM}