REVERSE ELECTRODIALYSIS USING BIPOLAR ION-EXCHANGE MEMBRANES AS A SOURCE OF ELECTRIC ENERGY

It is established that, in the regime of the H+ and OH- ions recombination, voltage on the bipolar membranes and the efficiency of the latter, as a transformer of chemical energy into electric, increases in the series of ionogen groups contained in the bipolar contact region, namely, -SO3-/-N(CH3)3, -N(CH3)2 < -PO3-H/-N+(CH3)3, -N(CH3)2 < -PO3-H/=N, =N+CH3. This is due to an increase in the recombination rate constants in the bipolar contact in the above series for the H+ and OH- ions. As the sodium and chlorine ions penetrate the bipolar transition region, they sharply decrease the membrane potential and the voltage drop on the bipolar membranes, because die ionogen groups tum into salt form, which is catalytically inactive in the H+ and OH- ions recombination reaction. It is shown that the source of current, containing the MB-24 (bipolar), MF-4sk (cation-exchange), and AMV (anion-exchange) ion-exchange membranes, has a specific power of 0.11 W/dm2 (calculated in terms of one bipolar membrane) and efficiency of 29% for 0.5 M solution of hydrochloric acid and sodium hydroxide, and 0.5 A/dm2 current density.