This paper presents a detailed investigation of fouling mechanisms for ultrafiltration membranes with polysaccharides obtained by studying
membrane–solute (static adsorption) and membrane–solute–solute interactions (ultrafiltration (UF)). Two polyethersulfone (PES) membranes
and one stabilized cellulose (cellulosic) membrane with a nominal cut-off of 10 kg/mol and dextrans with average molar mass (M) of 4,
10 and 15 kg/mol were used. The membranes before and after static adsorption of dextran were characterized by captive bubble contact
angle and tangential streaming potential measurements as well as ultrafiltration sieving curves for polyethylene glycols. Significant water
flux reductions (4–15%), which also correlated with dextran molar mass, and changes of the other membrane characteristics occurred after
static dextran adsorption for the PES membranes. An empirical model to describe the correlation between the relative water flux reduction
and the concentration of solute had also been proposed. In contrast, no significant changes could be detected for the cellulosic membrane.
Significant membrane–solute interactions had also been confirmed in the ultrafiltration experiments with dextrans where irreversible fouling
had been observed for the PES but not for the cellulosic membranes. The results provide fundamental information for a better understanding
of fouling by polysaccharides. In particular, it had been confirmed that hydrophilic and neutral dextrans can significantly foul PES membranes
via adsorption to the surface of the membrane polymer. On this basis, methods for control of this fouling can be properly developed
