Zwitterion functionalized graphene oxide/polyamide thin film nanocomposite membrane: Towards improved anti-fouling performance for reverse osmosis

Foulants adhesion on the surface of polyamide (PA) thin film composite (TFC) membrane is a big operational challenges in water treatment processes; therefore, there is a significant need for introducing new approaches with the aim of achieving high membrane anti-fouling performance. Herein, we developed an effective method for introducing zwitterionic polymers into the thin layer of TFC membranes using poly(2-(Methacryloyloxy)ethyl dimethyl-(3-sulfopropyl)ammonium hydroxide) (PMSA)-grafted GO (PMSA-g-GO) as an anti-fouling additive. The first zwitterionic functionalized GO (ZGO) was synthesized and then characterized by TEM, TGA and EDX analyses. Thin film nanocomposite (TFN) membranes were then made by incorporation of ZGO nanosheets into the PA thin layer. The ZGO/TFN membranes were characterized and evaluated in comparison with not only bare TFC membrane but also GO/TFN membranes by the SEM, AFM, contact angle, EDX, permeation measurements, salt rejection tests and anti-fouling parameters. As compared to bare TFC membrane, the undesired fouling caused by the hydrophobic foulants on the 0.02ZGO/TFN membrane significantly suppressed (FRR = 90.5%) and water flux also greatly improved (73%), while salt rejection remained high and showed slight increase (1%). The results also proved that fouling layers of ZGO/TFN membranes were more reversible due to the remarkable anti-fouling properties of ZGO.