ADSORPTION OF DEXTRANS AND PULLULANS AT THE SILICA-WATER INTERFACE - HYDRODYNAMIC LAYER THICKNESS MEASUREMENTS - ROLE IN THE FOULING OF ULTRAFILTRATION MEMBRANES

We studied the adsorption of a series of dextrans and pullulans at the silica-water interface. The system of dextran-precipitated silica was chosen as a model of solutes and mineral particles present in water to investigate the influence of the interactions between these two components on the fouling of membranes used for water treatment. Therefore, adsorption isotherms and hydrodynamic layer thicknesses were determined. Results show the importance of adsorption phenomena of polysaccharides on silica particles, particularly that of the high adsorbed layer thickness (δh), 4 < δh < 16 nm, which depends on molecular weight, 104 < Mw < 106. Thus, we suggest that a suspension covered by polymer must play a major role in the fouling process. © 1990.