Effect of Electrolytes on Gas Oversolubility and Liquid Outflow from Hydrophobic Nanochannels.

We have experimentally studied the effect of electrolytes on gas oversolubility and liquid outflow from hydrophobic nanochannels. By immersing nanoporous material with the same porous structure and surface properties into four different aqueous electrolyte solutions with the same surface tension, the excessive solid-liquid interfacial tension of the resulted liquid nanofoam (LN) systems has been set as a constant. Upon unloading, partial liquid outflow has been observed and quantified. As the four LN systems show different degrees of recoverability, it suggests that the degree of liquid outflow is highly sensitive to the ion species. In addition, different from bulk phase scenario, the anions have a more profound effect than cations on gas oversolubility. Lower bulk gas solubility and larger gas oversolubility factor lead to higher degree of liquid outflow and recoverability of the LN systems. This fundamental understanding on the mechanism of liquid outflow enables the development of nanofluidics-based system into reusable energy absorbers.