Filtering on the Nanoscale

 


When making coffee, water and aromatic substances can pass through the filter, unchecked, while the finer coffee powders get stuck to the filter.

Scientists realized that filtering only by size is not effective for cleaning or separating chemical substances. Some of these chemical substances can include colorant in water, or even various charged atoms, called ions. Different techniques are needed to separate different ions of similar size.

In biology, cell membranes are capable of the separation. They allow additional processes to take place in the thin “pores” of the sieve. Creating these sieves is still difficult. 

New research was published by the Max Planck Society in the journal Advanced Materials. Scientists Christopher Synatschke and Tanja Weil from the department of “Synthesis of Macromolecules,” have created a new filter. 

This filter contains a membrane that is 20 nm thick. It is able to separate different types of ions or even a mixture of different dyes. 

Scientists were inspired by the ocean, as the membrane is very close to one created by mussels. It is called polydopamine and it uses an electro polymerization process. The membrane can be used in such a way that it contains sub nanometer size channels. This is referred to as sieve pores. 

Sieve pores are noted for having a special surface chemistry.  This opens the door for new possibilities. It is now possible to separate monovalent ions and divalent ions, despite their similar size. 

Synatschke reports, “ Such easily producible membranes are of great interest in applications. This makes it possible, for example, to produce more efficient filters for water, eg. for industrial waste.”

Researchers claim that the filter is more efficient than any other to date. They hope more polydopamine filter membranes will be used in the future!  

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