Abstract: The flat sheet ultrafiltration membranes were prepared through phase inversion with polyether sulfone (PES) as a membrane material, N-methyl-2-pyrrolidone as a solvent and polyvinyl pyrrolidone (PVP) with different molecular weights (PVP K10, PVP K30, PVP K50, PVP K70) as additives, and the effects of preparation conditions on the structure and performances of the resultant membranes were investigated. The results indicated that the average water flux and average rejection ratio of the membrane reached 90.7 L/（m2·h） and 95.1 %, respectively, when 18 wt% of PES and 6 wt% of PVP K30 was added. The rejection ratios of these five types of membranes for the boving serum albumin solution (1 g/L) were measured, and their silting density index (SDI) values of the water samples obtained from a drinking tap water and a swimming pool were also measured. It was found that the SDI5 min value from the drinking tap water after five minutes filtering decreased with an increase of rejection ratio, but the SDI5 min of filtered water in swimming pool kept a stable value with the rejection ratio.

Key words: polyether sulfone;ultrafiltration membrane, rejection ratio, silting density index value