Site Selectivity in the Deposition and Redeposition of Polystyrene Particles to Glass.

The site selectivity in the deposition and redeposition of negatively charged, polystyrene particles to a glass collector surface was studied under flow, by first depositing particles to the collector surface and then removing them by passing of an air-liquid interface. Using an image analysis system, the coordinates of the occupied sites were memorized and subsequently the probability of redeposition on these sites relative to deposition on other collector surface areas was determined. In low ionic strength buffers, 20 and 30 mM KNO3, redeposition probabilities on previously occupied sites were up to 51 times higher than for deposition elsewhere, while in high ionic strengths buffers (above 30 mM) redeposition probabilities were essentially similar as for deposition on other collector surface sites. It is suggested that high affinity sites for particle deposition exist on glass, on which preferential (re)deposition is mediated through attractive electrostatic interactions. Although such a suggestion is not new, this is the first time supporting evidence has been collected through redeposition experiments as described here. Copyright 1998 Academic Press.