Future growth and economic development are critically dependent on a sustainable source of clean water.  However, a vast majority of the global water supply is either sea or brackish water creating significant challenges that will intensify as demand for fresh water grows.  Desalination offers the potential to purify seawater and provide access to an abundant source of fresh water.  We present new membrane materials with enhanced water transport for desalination applications.  First, graphene has great potential to serve as a separation membrane due to its unique properties such as chemical and mechanical stability, flexibility and its single atom thickness.  Single layer, non-porous graphene synthesized by a standard chemical vapor deposition method with methane in hydrogen was exposed to an oxygen plasma to create sub-nanometer pores with pore edge functionality.  The desalination performance was evaluated for varying pore sizes.  Results show that an appropriate pore size of approximately 1nm in the graphene enabled nearly 100% salt rejection while maintaining fast water transport confirming the potential for desalination.  In addition, we show that ion transport in a three dimensional porous carbon membrane can be controlled through the application of an electric potential.  In the absence of the electric potential, both cationic and anionic molecules freely diffuse across the membrane via a concentration gradient. However, when an electrochemical potential is applied, the transport of ions through the membrane is inhibited enabling gated control of the transport of organic molecular species and ions.  These novel materials have potential for high performance water desalination and purification for future fresh water needs.<br/>

Membrane-based water desalination: From graphene to porous carbon

255th National Meeting (2018)

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