Measurement of particle/membrane interactions by a hydrodynamic method

A fundamental study of particle detachment of micron-sized glass particles from a model membrane surface is made. The model membrane surface consisted of a cellulose diacetate film which is the polymeric constituent of the hollow fibre membranes used in industrial water treatment. This experimental study aims to analyse the factors leading to the retention of particles on these membranes. We used a hydrodynamic method in which the release of deposited particles was measured under the action of fluid flow. The hydrodynamic force is calculated under well defined hydrodynamic conditions and related to the total adhesive force acting on the particle. We studied the influence of several factors such as, pH, solution salinity, and the effects of adsorbed polymer or non-ionic surfactant on the particles. In the absence of organic solutes adsorbed on the particles, the magnitude of the particle-membrane interaction depended on the pH and the salinity of the aqueous medium, as predicted by the DLVO theory. When adsorbed polymer layers an coated on the surface of the particles, the adhesive force between the particles and the surface was found to be significantly greater than that for bare particles. This contrasted to the decrease in adhesion force observed for particle coated with non-ionic surfactant.