Apparent diffusivity of sulfuric acid in anion-exchange membrane Neosepta-AMH

The transport of sulfuric acid through an anion-exchange membrane Neosepta-AMH (Tokuyama Soda, Co., Inc.) has been studied. For that purpose, a two-compartment batch cell with stirrers has been used. The experiments have been carried out at various initial acid concentrations and intensity of mixing in both the compartments, the temperature being kept at a constant value of 20 degrees C. The time dependences of the acid concentration, which have been recorded, have enabled the calculation of apparent diffusivity of sulfuric acid. The dependence of apparent diffusivity upon its concentration has been approximated by the second degree polynomial whose coefficients have been determined with the help of the model based on the Fick's law. Using all the experimental data obtained, it has been shown that apparent diffusivity of sulfuric acid in the membrane is strongly concentration-dependent. Moreover, it has been found that diffusivity of sulfuric acid in a Neosepta-AMH membrane is much lower than that in a Neosepta-AFN membrane.