Preparation of stable and superior flux GO/LDH/PDA-based nanofiltration membranes through electrostatic self-assembly for dye purification

Graphene oxide (GO) has triggered significant attention as a new type of self-assembly membrane material. However, the low filtration flux and unstable performance of GO membrane limit its practical application. Hence, in this work, layered double hydroxides (LDHs), as a 2D material with double-layer channel structure and positive electricity, were self-assembled with GO at weight ratio of 7:3 by electrostatic interaction. Then, the GO/LDH hybrids combined with polydopamine (PDA) to obtain stable and high-flux GO-based membranes through vacuum filtration and the structure and morphology of as-prepared samples were characterized by FT-IR, XRD, XPS, and SEM. Furthermore, the separation performance and surface electronegativity of membranes were tested via pure water flux, rejection efficiency, recycle experiments, and zeta potential. Results revealed that the stability and flux of composite membrane were enhanced significantly compared with neat GO-based membrane. Further, the dye rejection rate of methylene blue (MB) is higher than Congo red (CR) and rhodamine B (Rh B) and reached to 99.8%.