EFFECTS OF POLYELECTROLYTES ON FLOW-INDUCED DEPOSITION OF TITANIUM-DIOXIDE PARTICLES ONTO A CELLOPHANE SURFACE

The rate of depositon of titanium dioxide particles onto a cellophane surface in the presence of cationic polyelectrolytes was studied in a stagnation point flow. The initial deposition rates were found to agree with predictions of the mass transport equation, which takes all colloidal and hydrodynamic interactions into account, for both low and high electrolyte concentrations. For intermediate values the observed rate was larger, possibly due to the contraction of polyelectrolytes with increasing salt concentration, thus increasing the amount of polyelectrolyte on the surface. It was also found that the deposition rate decreased with time, due to the adsorption of excess polymers on the collector surface. The initial rate, however, was independent of the amount of excess polymer, in agreement with theoretical predictions. © 1990.