According to reports, graphene and other two-dimensional materials with only one atomic thickness are ideal materials for constructing ultra-thin nanofiltration membranes, but single-layer graphene films will be affected by problems such as cracking, so there has always been a problem of how to achieve excellent mechanical strength and large-area crack-free preparation.
Yolanda team of Wuhan University in China cooperated with Duan Xianfeng team of UCLA, using carbon nanotube film with excellent mechanical properties and porous structure as the mechanical support layer of graphene film, thus dividing the graphene film into a plurality of micro-regions, forming a structure similar to the surface of a building "water cube", leaves or insect wings.
The research shows that the pore size of this material called "graphene nano-screen/carbon nanotube composite film" is about 0.6 nm, which is larger than that of water molecules (about 0.3 nm), but smaller than that of some metal salt ions (about 0.7 nm for hydrated sodium ions). So as to effectively separate water molecules and salt ions, and the rejection rate of metal salt ions such as sodium, potassium, magnesium and the like can reach more than 85%, thereby eliminating organic pollutants in the aqueous solution.
This membrane has high permeability, and the 1 cm 2 membrane can produce pure water 1 ml per minute under a certain pressure, which is 0/0 times to 0/00 times that of some traditional similar membranes. Its mechanical properties are also very good, and it can still maintain structural integrity and water permeability under bending deformation.
Yang, the first author of the paper and a researcher at Wuhan University, said that the study overcame the limitations of the practical application of two-dimensional materials in the field of separation and opened a door to efficient selective separation.