Filtering molecules from the water or air with nanomembranes

If used to filter water, the carbon nanomembranes allow

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only water molecules to pass while blocking other molecules. If used to filter air, the membranes could, for example, remove carbon dioxide from vehicle exhaust emissions. 'However, we still know very little about what happens when a molecule passes through such a sieve,' says Gölzhäuser. 'This is why we are studying, for example, whether it touches the membrane, remains stuck to it, or flies directly through its pores.'

Drawing on the results of this research, the scientists can modify the production of the nanomembranes to fit each specific purpose - for every use, the appropriate nanomembrane. 'We can adapt the porosity of the membranes for different materials and also modify their conductivity, elasticity, density, and thickness.'

The manufacturing process has been developed by members of Gölzhäuser's research group: the researchers immerse a solid - such as a gold surface - in a liquid containing organic molecules. The molecules settle on the solid in a thin layer that is then irradiated with electrons. This leads them to trigger a controlled chemical reaction: a cross-linking - the molecules link together and form the nanomembrane. However, the most difficult step is yet to come: they have to be separated from the supporting layer. 'We do this by introducing what we call a transfer layer with which we can separate the carbon nanomembrane,' says Gölzhäuser.

Read more at: https://phys.org/news/2017-09-filtering-molecules-air-nanomembranes.html#jCp