Membranes with microscopic pores are useful for water filtration. The effect of pore size on water filtration is well-understood, as is the role of ions, charged atoms, that interact with the membrane. For the first time, researchers have successfully described the impact water molecules have on other water molecules and on ions as part of the filtration mechanism. The researchers detail a feedback system between water molecules, which opens up new design possibilities for highly selective membranes. Applications could include virus filters.

Synthetic chemistry is a field of study related to the creation and exploration of new substances and materials that do not exist in nature. Sometimes a specific property or behavior of a material is required for an application such as pharmaceutical or high-tech manufacture. Synthetic chemistry can help find, create or refine suitable materials. For example, so-called synthetic liquid crystal membranes could be used for water filtration.

When filtering water or other liquids, the aim is to separate chemical components, such as ions, from your target fluid. Use of a porous membrane can be the primary method for doing this. It’s intuitively obvious that holes in a surface will stop anything larger than the hole from passing through. But advanced membranes like synthetic liquid crystal membranes can have pores that are barely a few nanometers, billionths of a meter, across. At these scales, there’s more to membrane functionality than just the size of a pore.

“Chemistry plays a big part in what happens at these small scales,” said Professor Takashi Kato from the Department of Chemistry and Biotechnology at the University of Tokyo. “In the case of water filtration, the pores are sized to let nothing larger than water pass through. However, there are also electrostatic forces between ions and pores. If the material is engineered correctly, these forces serve as a further barrier to ions even if they’re smaller than the pores. This is fairly well-understood. But there is yet another important substance at play that can impact water filtration, and that’s actually the water molecule itself.”

Read the full story: https://www.u-tokyo.ac.jp/focus/en/press/z0508_00132.html
Source: u-tokyo.ac.jp/