EFFECTS OF PROTONATION ON THE TRANSPORT OF HYDROPHOBIC NITROGEN-HETEROCYCLES THROUGH PERFLUOROSULFONATE IONOMER MEMBRANES

Rates of transport for a series of nitrogen heterocycles across cast, perfluorosulfonate ion exchange (PFSA) membranes in the H+- and Na+-forms are reported. Concentrations of the heterocycles present in the hydrated membranes that have been equilibrated with the feed solutions from the transport experiments were also determined. Several trends relating to the transport and membrane concentration data were observed. The concentrations of the heterocycles found in the membranes increased with their hydrophobicity and concentrations were substantially higher when the membranes were in the H+- form. Transport rates were higher for the H+- form membranes than for the Na+- forms by as much as a factor of 230. In general, heterocycles with fewer fused rings displayed more enhancement in transport rate in the acidic membranes.