Synthesis and characterization of polyethersulfone-magnetic nanoparticle nanocomposite membrane for membrane defouling

Abstract

A major factor limiting the use of membrane in water treatment process is the membrane fouling by natural organic matter such as humic acid (HA). In this study, polyethersulfone (PES)-magnetic nanoparticle (Fe3O4) nanocomposite membranes were prepared by a phase inversion technique; they were characterized and evaluated for fouling resistant applications with humic acid. The synthesized PES-Fe3O4 nanocomposite membranes with different Fe3O4 loadings were characterized with scanning electron microscopy (SEM), contact angle, porosity and pore size measurement respectively. Filtration of humic acid demonstrated that the PES-Fe3O4 nanocomposite membrane displayed a better antifouling performance than the neat PES membrane. This is because the incorporation of Fe3O4 nanoparticles to PES membrane offers hydrophilicity and induces negative surface charge on the membrane that lead to a condition that negatively charged foulants (humic acid) would be repelled, which subsequently reduced the rate of fouling. The nanocomposite membrane with 1.0 wt% of Fe3O4 nanoparticles possessed the greatest permeation flux after 2 hours of filtration time due to its highest hydrophilicity and the lowest relative flux reduction of 41.91% with a HA rejection of 70.12%. The fouling behaviour of 1 wt% PES-Fe3O4 nanocomposite membrane was then analyzed by using single fouling mechanism models and the model obtained was standard pore blocking model.