Scientists from Shinshu University and PSL University, France, theoretically proved concerted motion of the nanowindow-rim to selectively allow molecules to pass, in an energy-efficiently and fast way. This brings up new possibilities to create an advanced molecular separation membrane technology.
The mechanism of separation by nanowindows is that the atomic vibration of the nanowindow-rim changes the effective nanowidow size. When the rim of one side is deviated and the other is deviated to the opposite direction, the effective nanowindow size becomes larger than when the rim does not move. This effect is very predominant for molecules of oxygen, nitrogen, and argon, inducing an efficient separation of oxygen from air.
Study - Separation - Components - Air - Oxygen
The study considered separation of the main components of air: oxygen, nitrogen and argon. They have high industrial needs; innovative air separation technology has been highly demanded. The molecular sizes of oxygen, nitrogen, and argon are 0.299, 0.305, and 0.363 nanometers (nm). The researchers compare the permeation of these molecules on 6 differently-sized nanowindows (of 0.257 nm, 0.273 nm, 0.297 nm, 0.330 nm, 0.370 nm, and 0.378 nm).
Nanowindows were prepared by oxidation treatment. Thus their rims are passivated with hydrogen and oxygen atoms, which have essential role for selective permeation.
Molecules - Nanowindows - Nanowindow - Size - Target
Surprisingly, the molecules permeate through nanowindows even when the rigid nanowindow size is smaller than the target molecular size. For example, O2 permeates faster through 0.29nm nanowindows than 0.33nm nanowindows. The difference in permeation rate is associated with the interaction of the molecule with the nanowidow...
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