Valia chien cell

To determine the permeability of the PCTE membranes, diffusion studies were conducted using a custom-built amber Valia-Chien Cell with 2 mL volumes and a 5 mm orifice (Permegear, PA). The membrane was degassed in a 50% ethanol solution to remove an air bubbles blocking the pores, washed several times in degassed deionized water, and placed in the center of the diffusion cell. One side of the cell was filled with 2 mL of deionized water, while the other was filled with 2 mL of a 500 μS/cm KCl conductivity standard. A conductivity meter (eDAQ Conductivity Isopod with Miniature Dip-In Conductivity Electrode) was placed in the water-side of the diffusion cell and recorded the conductivity of the solution every second for 10 min. To ensure diffusive-dominated transport, both sides of the diffusion cell were connected to an external bath of deionized water using 20 cm of 0.5 mm ID tubing. The conductivity values were converted to concentrations using a standard curve, and the flux was calculated as the slope of the concentration vs. time plot. The normalized permeability values K (m⁻¹) was then calculated from the following equation:
$$J=K{A}_{m}D\Delta C$$
where J (mol/s) is the flux of KCl, A_m(m²) is the area of the membrane, D is the diffusivity of KCl (1.85×10⁻⁹ m²/s), and ΔC (mol/m³) is the concentration difference between the two sides of the diffusion cell.