Hydrophobic Surfaces Reduce Salt Solubility In Water

Hydrophobic or water-repelling surfaces can influence the solubility of salts in water, a finding which could inform the design of drugs and self-cleaning surfaces.

AsianScientist (Jun. 17, 2015) – Researchers at the University of Tokyo have demonstrated that water near a water-repelling surface has significantly less capability to dissolve salts. Their results have been published in Science.

Surface pollution is a common problem in everyday life, from dirty clothes to shellfish that grow on ship hulls. Since the initial step of pollution starts from adhesion of a pollutant onto a surface, designing antipollution surfaces require an in-depth understanding of surface adhesion at the nanoscale. However, scientific understanding of surface adhesion is still very limited.

The research group of Dr. Yoshimitsu Itoh and Dr. Takuzo Aida at the University of Tokyo, Graduate School of Engineering, Department of Chemistry and Biotechnology discovered that water near a water-repelling surface has significantly less capability to dissolve salts.

They utilized a plate where they could place a salt at a defined distance from a water-repelling surface and measured the solubility of salt in water. They found is that when the distance from the water-repelling surface decreases, the salt becomes less soluble. This phenomenon is pronounced at distances of less than one nanometer. One nanometer is the distance at which a substance sticks to a surface.

This unique understanding will force a revision of the common sense regarding salt dissolution. This could pave the way not only for designing novel anti-pollution surfaces, but also for designing drugs, which also requires a precise understanding of interactions between water-attracting and water-repelling parts of molecules.

The article can be found at: Chen et al. (2015) Subnanoscale Hydrophobic Modulation Of Salt Bridges In Aqueous Media.


Source: The University of Tokyo.
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