2.5.3. Current–voltage curves
The details of the method used to obtain the current–voltage (I–V)
characteristic curves of the membranes are described in our previous
paper. 28 Briefly, first, the membranes were
equilibrated in the test solution for 24 h. All membranes were
characterized using 0.5 M NaCl and 0.3 M
Na2SO4 solutions as the test and
electrode rinsing solutions, respectively. The test cell was connected
to a HSPY-120-01 (Hanshengpuyuan Technology Co. Ltd., China) DC power
supply via two Ti-coated ruthenium oxide electrodes. The current
was incrementally increased and the changes in trans-membrane potential
were recorded periodically (every 30-40 s) using a multimeter connected
to Ag/AgCl electrodes.