RESISTANCE TO THE PERMEATE FLUX IN UNSTIRRED ULTRA-FILTRATION OF DISSOLVED MACROMOLECULAR SOLUTIONS

The flux decline during the unstirred ultrafiltration of dissolved macromolecular solutions such as polyethylene glycol and dextran solutions was measured at different pressures from 1 to 4 multiplied by 10**5 Pa and different bulk concentrations from 0. 1 to 0. 55 kg/m**3 with three types of polysulfone membranes. On the basis of the concept that a concentrated solution layer (not a gel layer) is formed on the membrane surface, the hydraulic resistance of the boundary layer was defined with the help of solvent permeability of dissolved macromolecules. The cake filtration theory was employed to analyze the flux decline behaviour. This simple theory worked well.