A set of experiments was carried out for the aqueous solutions of sodium bicarbonate, and also for those of both sodium bicarbonate and sodium arsenite to explain the mechanism of facilitated transport.
It was confirmed that the permeation of carbon dioxide is facilitated by the presence of sodium bicarbonate and sodium arsenite.
Sodium arsenite, which is well known to be the catalyst for the hydration of carbon dioxide, plays a significant role in the facilitation as expected.
The liquid membranes used in the experiment was made by soaking the Millipore filters in the solutions of sodium bicarbonate and/or sodium arsenite with known concentration.
A boundary layer approximation was used to solve the nonlinear governing equations numerically, and the results are fairly in good correlation with experimental data over the whole but low range of sodium bicarbonate concentration.
It can be concluded from the numerical simulation that the increased facilitation by sodium arsenite is due to its buffering action, preventing upstream side of the liquid membrane from being more acidic (i.e., having a lower value of pH).