High-efficiency water-transport channels using the synergistic effect of superhydrophilic PA layer and robust BU cross-linked GO laminates

Graphene oxide (GO) membranes show immense promise in nanofiltration separation for water purification and recycling of water resources. However, pristine GO membranes often suffer from insufficient membrane stability due to swelling and low water permeance under high operation pressure, which severely limits the real-world utilization of GO membranes. Herein, a strategy involving surface modification of GO membrane with superhydrophilic polyamide (PA) layer combined with cross-linking with biurea (BU) amine, is proposed to fabricate highly permeable and robust GO membranes for dye removal from aqueous solution. The PA layer is prepared onto BU cross-linked GO membrane by in-situ interfacial polymerization, which results in superhydrophilic and negative-charged membrane surface. Moreover, the low reactivity of 2,5-diaminobenzenesulfonic acid (DBS) monomer contributes to low cross-linking degree and loose network of PA layer. The BU cross-linked GO laminates possess multi-level interlayer spacings and sufficient covalent interaction between GO interlayer due to crosslinking with BU, which offer large and robust transport channels for water molecules. PA@BU/GO hybrid membrane shows the optimum pure water permeability of 140.2 L·m−2·h−1·bar−1, with water permeance and TB rejection rate of 67.4 L·m−2·h−1·bar−1 and 99.9 %, respectively. Moreover, the membrane exhibits impressive dye/salt selectivity (the dye/NaCl separation factor is up to 873), long-term operation stability and good anti-fouling property, which makes it a potential candidate for the fractionation of dye/salts in textile wastewater. This work provides a promising idea for the development of high-performance 2D membranes with high-efficiency water transport channels using the synergistic effect of superhydrophilic PA Layer and robust BU cross-linked GO laminates.