Hierarchically Assembled Graphene Oxide Composite Membrane with Self-Healing and High-Efficiency Water Purification Performance

Graphene oxide (GO) with a two-dimensional lamellar structure and single-atom thickness has exhibited advantages in water purification by stacking to a continuous membrane. However, a proper method to further increase the separation property of the GO membrane is still urgently needed. Besides, damage to the membrane during the full-scale application processes and the resulted consequential loss are prevalent problems need to be solved. Here, a hierarchically assembled GO composite membrane was developed that can achieve high-efficiency water purification performance and self-healing property via the synergistic effect of the metal-organic framework (MOF) and the coated hydrophilic layer of chitosan. The intercalated MOF effectively expanded the channel space of GO and endowed the channels with molecular-sieving property. Meanwhile, the coated chitosan layer can selectively adsorb water and achieve self-healing through the cross-linking reaction. The prepared GO composite membrane shows largely improved water flux (14.62 L m^-2 h^-1 bar^-1), increased 344% than the water flux of the GO membrane, high rejection ratio (>99% for dyes), and good antifouling performance. In addition, the damaged GO composite membrane can recover its water flux (95%) and rejection ratio (96%) through a facile self-healing process.