Effect of the mass ratio of Fe 3 O 4 /PAA on separation properties and the extractive amount of Fe 3 O 4 during the formation of Fe 3 O 4 ‐PES ultrafiltration membranes

A series of Fe 3 O 4 ‐PES ultrafiltration membranes with different mass ratios of Fe 3 O 4 and PAA were prepared from suspensions, using the phase inversion process. The suspensions consisted of polyether sulfone (PES), dimethyl formamide, polyacrylic acid (PAA), and ferrosoferric oxide (Fe 3 O 4 ). The separation properties of ultrafiltration membranes with different Fe 3 O 4 /PAA mass ratio were investigated by a cross‐flow experimental system. The Fe 3 O 4 /PAA mass ratio had little effect on the rejection of membranes to BSA. However, the pure water flux had a slight decline and then rised rapidly with the increase of Fe 3 O 4 /PAA mass ratio. An interesting phenomenon observed was that the Fe 3 O 4 particles could diffuse into the nonsolvent bath during the formation of membrane, and the amount of Fe 3 O 4 extracted into the nonsolvent bath nearly kept a constant mass ratio to PAA, even if the Fe 3 O 4 /PAA proportion was changed. The reasons of this interesting phenomenon were investigated. This result indicates that modified inorganic fillers may be used as the pore‐forming agent to prepare the porous membranes like the template leaching method. At the same time, this method does not use any strong acid or base. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013