Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

The stationary permeate flux during ultrafiltration of colloidal suspensions reaches a limiting value, J_l, at high pressure differences. According to the gel polarization model employed here, the existence of this limiting flux is a consequence of gelation of the solution at the membrane-solution interface. The limiting permeate flux, J_l, can easily be determined from experimental data by plotting ∆p/J_s against ∆p. Furthermore, the membrane resistance at zero pressure difference, R_m⁰, and the pressure difference necessary to reach 95 per cent of the limiting flux, i.e. the threshold pressure, ∆p_t, may be calculated, too. The agreement between the model and experimental data is satisfactory. The laboratory-made silica sol consisting of uniform spherical particles with a surface average diameter of 18 nm was selected as a working fluid throughout this study.

Keywords: Ultrafiltration; Limiting flux; Membrane resistance; Silica sol; Threshold pressure.