Membranes with selective laminar nanochannels of modified reduced graphene oxide for water purification

Developing graphene-based membranes is important for a wide range of applications such as in desalination, wastewater treatment, separation and purification. Herein, a novel graphene-based nanofiltration (NF) membrane was fabricated by depositing the magnesium silicate modified reduced graphene oxide (MgSi@RGO) nanosheets on a polyacrylonitrile (PAN) ultrafiltration membrane via a vacuum filtration method. The MgSi@RGO/PAN composite membrane exhibits special selectivities for separation of organic molecules. Molecule permeation through the MgSi@RGO selective skin layer was observed with the broadened nanochannels propped up by MgSi nanosheets. The rejections of different PEG molecules (PEG200, PEG400, PEG600 and PEG1000) were tested, and the experimental results and theoretical calculations showed high consistency, which means the theoretical model can be effectively used for calculating the real diameter of “pore” in NF membrane. Additionally, three dye molecules were selected to investigate the NF membrane performance, and the MgSi@RGO/PAN composite membrane showed different separation characteristics of charged molecules.