Evapoporometry

Evapoporometry is a method used to determine pore-size in synthetic membranes. Based on the kelvin equation, this technique is most accurate for detection of pore diameters between 4 nm to 150 nm.

Evapoporometry uses modified forms of the kelvin equation to relate the evaporation of a wetting liquid (usually 2-propanol) from a membrane to the average diameter of the pores in that membrane. The primary equation used in this technique is:

${\displaystyle d=-{4yV \over RT*ln(W_{A}/W_{A}^{\circ })}}$

Where ${\displaystyle d}$ is the pore diameter, ${\displaystyle y}$ is the surface tension, ${\displaystyle V_{\text{A}}}$ is the vapor molar volume, ${\displaystyle R}$ is the gas constant, ${\displaystyle T}$ is the absolute temperature, ${\displaystyle W_{A}}$ is the instantaneous evaporation rate in ${\displaystyle mol/s}$, and ${\displaystyle W_{A}^{\circ }}$ is the average evaporation rate of the free-standing liquid layer in ${\displaystyle mol/s}$.

...
Wikipedia