Researchers from China and the United States published a paper in the new issue of "Science" magazine, introducing an ultra-thin, high-strength thin film developed using graphene and other materials, which can efficiently separate salt ions and organic pollutants in water It is expected to be used in the fields of water purification, chemical raw material separation and purification. According to reports, two-dimensional materials such as graphene with only one layer of atoms thick are ideal materials for the construction of ultra-thin nanofiltration membranes, but individual graphene films will be affected by problems such as cracking, so there has always been how to achieve excellence in related research. Problems with mechanical strength and large-area crack-free preparation. The team of Yuan Quan from Wuhan University in China and the team of Duan Feng from the University of California, Los Angeles, used carbon nanotube film with excellent mechanical properties and porous structure as the mechanical support layer of graphene film, thus dividing the graphene film into multiple micro The area forms a structure similar to the "water cube" surface of the building, leaves or insect wings. Yuan Quan, the corresponding author of the paper, told Xinhua News Agency that when there are defects, cracks or external damage to the graphene film, the carbon nanotube network structure can hinder the extension and expansion of the defect and limit the defect to a small range. Studies have shown that this material, called "graphene nanosieve / carbon nanotube composite film", has a pore size of about 0.6 nanometers, which is larger than the size of water molecules (about 0.3 nanometers), but smaller than the size of some metal salt ions (hydration) Sodium ion size is about 0.7 nanometers), so water molecules and salt ions can be effectively separated, and the rejection rate of metal salt ions such as sodium, potassium and magnesium can reach more than 85%, and the rejection rate of organic pollutant molecules in aqueous solutions is as high as 99 %. The permeability of this kind of film is high. 1 square centimeter film can produce 1 milliliter of purified water per minute under a certain pressure, which is 10 to 100 times that of some traditional similar films. Its mechanical properties are also very good, and it can maintain structural integrity and water permeability under bending deformation. Yang Yanbing, the first author of the paper and a researcher at Wuhan University, said that the study overcomes the limitations of the practical application of two-dimensional materials in the field of separation and opens a door to efficient selective separation.
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