Adsorption of neutral polysaccharides at the silica-water interface role in the formation of a fouling cake at the filtration membrane surfaces used in water treatment

Abstract

Membrane fouling is the main drawback of the ultrafiltration process used in water treatment, especially when mineral solids and polymer solutes are both present in the medium to be filtered. We are concerned with the role of the molecular interactions particles/solutes on the formation of a fouling cake. We used model components representative of natural system particles/macromolecular solutes. We worked with two polysaccharides (dextran and pullulan) and with spherical particles of silica. We simulated the fouling deposit accumulated at the membrane surface with a packed bed of silica particles and showed how the adsorption of the polysaccharides at the silica-water interface could induce a great increase of pressure through the bed. The pressure drop after adsorption makes it possible to obtain a hydrodynamic layer thickness of the macromolecules adsorbed on the silica. We compared these calculated values with the viscometric thicknesses determined in a previous study.