COLLOIDAL PARTICLES AT SOLID-LIQUID INTERFACES - MECHANISMS OF DESORPTION-KINETICS

We study the sorption of colloids on equally charged surfaces. Our foc us is on the time scale from hours to weeks, where adsorption is not a n irreversible process but interplays with (spontaneous) desorption. U sing model calculations, we show how the desorption kinetics is influe nced by readsorption, a potential barrier, a secondary potential minim um, local variation of the potential, and bond aging. In the experimen tal part we present results of in situ observation of the sorption kin etics of polystyrene latex particles onto a glass surface. Combining t he evanescent field method with video microscopy, we were able to iden tify the particle arrival and departure times individually and therefr om determine the adhesion time distribution function. The nonexponenti ality of this function can be explained by a gamma distribution of the potential depth at the binding sites as well as by logarithmic bond a ging. (C) 1998 Academic Press.