AFM investigation of the surface properties of silica particles dispersed by bead milling

In the present study, atomic force microscopy (AFM) was used to determine the mechanism by which bead milling enhances particle surface potential. The force curves between silica particles and a mica surface were measured in water, and AFM was used to examine the surfaces of the particles. AFM was performed in contact mode with a colloid probe and was used to measure the interaction forces between silica particles and a mica surface in water and to investigate the influence of friction between the silica particles and the glass beads on the zeta potential of the silica particles. The zeta potential was enhanced by an increasing number of friction cycles. Friction between the tested silica particles and the glass beads during bead milling contributed to the enhanced zeta potential of the tested silica particles. AFM performed in imaging mode was employed to investigate the influence of friction between the tested silica particles and the glass beads on particle surface morphology. The surface roughness of both the tested silica particles and the glass beads was decreased slightly by friction. It is possible that friction between particles by the loading force of 10 nN slightly abrades the particle surface, thereby removing contaminations and impurities from the surface, increasing the hydrophilicity enhancing the surface potential.