Surface modification of PES hollow fiber membranes using iron oxide particles for water treatment: does particle size really matter?

Abstract

Factors such as particle type and its loading have been previously studied in tailoring the efficiency of particles-modified polymeric membranes for water treatment. However, the role of particle sizes in membrane modification is often overlooked. Thus, in this work, two commercial iron oxide (Fe3O4) particles (i.e., 50-100 nm and <5 μm) were separately incorporated into 20 wt% polyethersulfone (PES) dope solution via blending method followed by dry/wet spinning process to produce hollow fiber membranes. Subsequently, a series of analytical instruments and filtration assessment to study the impacts of Fe3O4 particle size on membrane properties. Results revealed that the addition of smaller Fe3O4 particles into PES solution produced membrane with better hydrophilicity (contact angle: 75.77°) and consequently higher pure water flux (PWF) (110.42 L/m2.h.bar) compared to the pristine PES membrane (82.60 L/m2.h.bar) and the membrane with larger Fe3O4 particles (91.54 L/m2.h.bar). This is due to the better dispersion of smaller particles in the solvent, which led to improved particle distribution on the PES membrane surface. Most importantly, the membrane modified by smaller particles displayed the best separation performance by rejecting 80.43% bovine serum albumin (BSA), and exhibited the highest antifouling properties by recovering 86.03% of its flux after tested with foulant-contained solution. As a comparison, the PES membrane with larger particles only showed 77.65% BSA rejection and 75.23% flux recovery rate.