Colloidal Particles at Water-Glass Interface: Deposition Kinetics and Surface Heterogeneity

Area of Science:

• Colloid and Surface Science
• Materials Science
• Physical Chemistry

Background:

• Colloidal particle sorption is crucial in various applications.
• Understanding surface heterogeneity is key to controlling sorption.
• Previous studies often assumed homogeneous surfaces.

Purpose of the Study:

• To investigate the sorption behavior of colloidal particles on a glass surface under flow.
• To elucidate the mechanisms behind observed sorption patterns.
• To challenge the assumption of surface homogeneity in sorption studies.

Main Methods:

• Videomicroscopy combined with evanescent field illumination.
• Experiments conducted in a parallel plate channel with colloidal particle suspension.
• Analysis of particle sorption dynamics in the presence of electrostatic barriers.

Main Results:

• Glass surfaces exhibit non-uniform sorption, with particles binding to preferred sites.
• These sorption sites are dynamic, appearing and disappearing randomly.
• A dissociation rate constant (kd) of 1.3 x 10^-5 s^-1 was determined for site disappearance.

Conclusions:

• The observed dynamic sorption sites are explained by slow glass surface dissolution.
• Dissolution exposes transient adsorbers from the bulk glass.
• These transient sites are subsequently removed by the buffer flow, leading to dynamic sorption behavior.