PUMPING EFFECTS IN WATER-MOVEMENT ACCOMPANYING CATION-TRANSPORT ACROSS NAFION-117 MEMBRANES

Streaming potential study showed that the water transference coefficie nts of Nafion 117 equilibrated with solutions of aliphatic ammonium ch lorides which have both hydrophilic and hydrophobic parts increased wi th the increase in the size of aliphatic ammonium cations, which was d efinitely opposite to the trends observed in the case of alkali and al kaline earth metal cations. The result revealed the fact that the pump ing effect of the cations indeed exists and would be the dominant cont ribution in the case of hydrophobic cations. In the case of hydrophili c cations, cations together with strongly hydrated water molecules pum p loosely-bound or peripheral water molecules. Copyright (C) 1996 Else vier Science Ltd.