Effect of Fluid Flow, Solution Chemistry and Surface Morphology of Fibrous Material on Colloid Filtration

The goal of this paper is to focus on the effect of fluid flow, solution chemistry and surface morphology of fibrous media (in terms of roughness and charge heterogeneity) on colloid removal. A theoretical framework on the role of flow velocity on particle deposition to cylindrical substrate is presented. Existing theories related to particle attachment onto cylindrical substrates and on the effect of surface morphology on better predictability of particle adhesion have been modified. At higher flow velocities, the theory predicted the detachment of larger sized particles from the collector surface owing to the increased lift forces. Experimental studies confirmed removal of 3  particles at higher flow velocities. The effect of solution chemistry (in terms of concentration and ionic strength) on the particle adhesion has been studied. The ionic strength improved the attachment of the microspheres, despite the presence of high energy barriers as predicted by DLVO calculations. A new model incorporating the surface roughness and charge heterogeneity was developed that predicted a reduction in the energy barriers in otherwise unfavorable conditions of adhesion, and hence could explain the adhesion more accurately than DLVO alone.