Assessment of the Extension of Water Boundary Layers at the Particle Surfaces of Monodisperse Silica Sol in a 0.15 M NaCl Solution at Different pH Values

Abstract

The coagulation kinetics of a monodisperse sol of Monosphere 250 silica in a 1.5 × 10^–1 М NaCl solution has been studied within a pH range of 2.0–6.2. The obtained results have been used to estimate the radius of action of the structural forces for interacting SiO₂ particles. It has been shown that, depending on the pH of a medium, the extension of boundary layers varies over a range of 4–8 nm, with the thickest boundary layers being observed near the point of zero charge of the particles.