Enhancing the performance of thin-film nanocomposite nanofiltration membranes using MAH-modified GO nanosheets

In this work, novel thin-film nanocomposite (TFN) nanofiltration (NF) membranes were developed through modification with maleic anhydride functionalized graphene oxide (MAH-GO) via interfacial polymerization (IP). First, MAH-GO was synthesized by linking MAH molecules to the electrophilic groups (C–OH) of GO nanosheets. The resulting materials were characterized in depth by FT-IR, TEM, SEM, AFM, XPS and Raman spectroscopy. Subsequently, the MAH-GO and GO nanosheets were individually introduced into the polypiperazine-amide (PPA) active layer of TFN NF membranes via IP between piperazine (PIP) and trimesoyl chloride (TMC). The influence of the MAH-GO or GO concentrations on the morphology and performance of TFN NF membranes was systematically investigated. Compared with TFC-blank, the TFN-MG-60 and TFN-GO-80 membranes demonstrated significantly enhanced separation performance without reduction of the salt rejection. Particularly, the water flux of TFN-MG-60 and TFN-GO-80 was found to be 49.3 L m−2 h−1 and 42.0 L m−2 h−1, respectively, corresponding to 176.7% and 150.5% of TFC-blank. Moreover, TFN-MG-60 demonstrated superior water permeability, antifouling capability and chlorine resistance to TFN-GO-80, which was attributed to the incorporation of MAH-GO nanosheets having more hydrophilic carboxyl groups. Meanwhile, TFN-MG-60 retained a high salt rejection rate of 97.6% to Na2SO4, comparable to that of TFC-blank. The MAH-GO nanosheets show great potential in developing high-performance TFN NF membranes to overcome the trade-off effect of conventional thin-film composite membranes.