A Novel Stable GO/PDA/CNT Double-Layer Low-Pressure Membrane for Humic Acid Removal

Based on the interface bonding function of polydopamine (PDA) coating, GO/PDA/CNT double-layer low-pressure membrane with stable mechanical properties was successfully loaded on the PES membrane by vacuum filtration method. From the perspective of the structure-performance relationship, the upper carbon nanotube (CNT) layer can play the role of pre-filtration and pre-adsorption, which possess an antifouling function. The lower layer contains a lot of narrow nanochannels formed by stacking graphene oxide (GO) nanosheets, which further reject the pollutants. The filtration experiments with humic acid (HA), a significant component of natural organic matter (NOM), showed that the GO/PDA/CNT double-layer membrane demonstrated better HA removal (88.5%) and better antifouling performance. In addition, the GO/PDA/CNT membrane can be restored entirely after simply rinsing with pure water. Compared with the GO membrane, the GO/PDA/CNT double-layer membrane flux is more stable and higher than the single-layer GO membrane in the whole filtration process, which solves the compaction problem of the GO membrane in the pressure-driven filtration process.