Covalent synthesis of three-dimensional graphene oxide framework (GOF) membrane for seawater desalination

• Covalent modification strategy is developed to prepare graphene oxide framework.
• Tubular GOF membrane was prepared through vacuum filtration of GOF suspensions.
• GOF membranes on PDI-modified α-Al2O3 tube display high desalination performances.

In the present work, we reported the preparation of graphene oxide framework (GOF) membrane through vacuum filtration of GOF suspension for seawater desalination. Firstly, 1, 4-phenylene diisocyanate (PDI) was selected as cross-linking for covalent modification of GO nanosheets to prepare three-dimensional GOF. Secondly, micron-thickness GOF membrane was prepared on the PDI-modified α-Al2O3 tube through vacuum filtration of GOF suspension. The developed GOF membrane was evaluated for seawater desalination by pervaporation. Attributing to a three-dimensional structure, the resistance of the mass transferring through GOF membrane can be reduced, thus the water flux of the GOF membranes can be increased significantly. For an 18 μm thickness of GOF membrane at 90 °C, the water flux is 11.4 kg·m− 2·h− 1 and ion rejection is over 99.9% for desalination of 3.5 wt.% seawater. Further, the GOF membrane also displays high stability for seawater desalination. This high separation performance combined with high stability and facile fabrication road of the GOF membrane suggests that the developed GOF membrane is a promising candidate for desalination of seawater and brackish water.

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