deposition of colloidal particles on solid surfaces. This tech-The impinging jet is a well-established technique to study the nique, pioneered by Dabros and van de Ven (2), has the deposition of colloidal particles onto a solid surface (a collector) advantage that particle deposition can be observed continuunder well-defined hydrodynamic and physicochemical condiously under well-defined hydrodynamic and physico-chemitions. The presence of polymers, in solution, adsorbed onto the cal conditions. The effects of polymers on the deposition colloidal particles or onto the collector surface, can have a large kinetics has been studied in detail (3)(4)(8).
effect on the deposition kinetics of the particles. In this study we
In this study we investigated the kinetics of the competishow that it is possible to characterize polymers by using colloidal tive deposition of PEI-coated particles and PEI adsorption particles as probes. By choosing experimental conditions under on a glass surface as a function of the amount of free PEI which a competition takes place between polymer adsorption and particle deposition on the solid surface, the kinetics of particle in solution. A theory to account for the data is presented, deposition is governed by the properties of the polymers. Under based on the assumption that polymer molecules behave conditions for which particle deposition is absent when both the similarly to colloidal particles. particles and the solid surface are coated by polymer, the impingement of a mixture of polymers and polymer-coated particles will THEORY cause an initial deposition of polymer-coated particles which stops when the solid surface is coated by polymers in solution. The time Hydrodynamic Flow in the Impinging Jet at which particle deposition stops equals the time t ads at which the solid surface is coated by polymers. This time depends on therm closely resembles the one obtained by classical methods (colloid titration). The advantage of the present method is that between the plates, the radius R of the inlet tube, and the the technique can be applied for very low polymer concentrations, velocity of the fluid entering the cell. Since the flow is axitypically in the range 10 ppb to 1 ppm.