Chinese scientists have made significant strides in seawater desalination by developing a portable device that resembles a thermos in both shape and size, weighing less than one kilogram. This innovative technology can provide fresh water for over a week to individuals stranded at sea. The project, led by Professor Fang Haiping from the School of Physics at East China University of Science and Technology, was awarded the First Prize in Natural Science at the 2023 Shanghai Science and Technology Awards for its practical applications, including the desalination device.
The principle behind this desalination device utilizes a specialized graphene oxide membrane, which effectively filters and blocks salt ions while allowing water molecules to pass through. Graphene, a carbon-based material characterized by its honeycomb-like planar membrane and unique two-dimensional structure, holds immense potential for applications in energy and materials. This has sparked global interest in leveraging graphene’s properties to create high-performance separation membranes, particularly for seawater desalination and wastewater treatment.
However, achieving optimal performance requires precise control of the interlayer spacing of graphene, down to one-tenth of a nanometer. Professor Fang, who has been focused on water research since 2008, recognized the importance of ion-π interactions within graphene's structure, which can interact strongly with cations like sodium ions. While this interaction has often been overlooked in aqueous solutions due to the presence of hydrated ions, Fang's team applied statistical physics theory to highlight its significance.
Utilizing quantum mechanics calculations, the researchers developed computational software to propose a method for using ions to accurately control the interlayer spacing of graphene membranes, facilitating effective ion sieving for seawater desalination. Their theoretical framework was successfully validated through experimental results, culminating in a publication in Nature.
Building on this foundational research, the team created a graphene composite seawater desalination membrane that boasts a water flux approximately 15 times greater than that of Dow's seawater desalination membrane, positioning it among the most advanced practical desalination membranes available today. Additionally, the portable seawater desalination device has been recognized in the Shanghai Green Technology Directory, highlighting its potential impact in addressing water scarcity challenges.
