Customized polyamide nanofiltration membranes with hyperbranched polyamide-amine-modified graphene oxide interlayer for desalination

Graphene oxide (GO) membranes with a two-dimensional layered structure have ultra-fast water permeability and are considered to be one of the most promising membrane separation materials, including nanofiltration (NF) membranes for high-performance seawater desalination. In this work, a high-performance polyamide (PA) NF membrane using GO-Hyperbranched polyamide-amine (GO-HPAMAM) composite interlayer was designed. The hydrophilic PA layer was synthesized on the membrane surface by interfacial polymerization (IP) process to improve the water permeability of the membrane. The GO-HPAMAM composite nanofiltration membranes (CNFs) exhibited a good water permeability, the rejection of Na 2 SO 4 was 96.5 %, and the order of rejection of salt ions was Na 2 SO 4  > MgSO 4  > MgCl 2  > NaCl, in accordance with the Donnan effect. Furthermore, the GO/HPAMAM CNFs demonstrated excellent antifouling properties, long-term stability, and consistent separation performance when subjected to high-pressure cross-flow conditions. The permeability and separation performance of the GO/HPAMAM CNFs illustrate that the modification of GO by HPAMAM and the formation of a PA layer on the membrane surface enable the control of interlayer channel structure and membrane surface properties. This advancement holds promise for practical applications in seawater desalination processes.