The effect of silver ions and nanoparticles on the properties of ion-exchange materials

Abstract

The effect of silver ions and nanoparticles on the electrochemical properties of KU-2-8 sulfocationite, MF-4SK homogeneous sulfocationite membrane, and MA-40 heterogeneous anion-exchange membrane is studied. Using scanning electron microscopy, the particle distribution throughout the cationexchanger thickness is studied. The method of IR spectroscopy is used for studying the interaction of silver nanoparticles and ions and also of Cu2+ and Ni2+ ions with secondary and tertiary amino groups. It is shown that the mobilities of sodium and silver ions are close in sulfocationites, which suggests that silver ions are quickly washed out of such materials. In the anion-exchange membrane, silver ions are bound into complexes with ionogenic groups and induce an increase in the water dissociate rate in the membrane. The reduction of silver ions contained in cation-exchangers in a molar fraction of 80% with sodium borohydride affords a conducting metal silver film on their surfaces. The introduction of silver nanoparticles into the MA-40 anionexchange membrane is accompanied by the increase in both the limiting electrodiffusion current and the water dissociation rate in the membrane, which is apparently due to the partial oxidation of metal silver particles to afford silver oxide in the near-surface membrane layer. The latter oxide exhibits weak catalytic activity with respect to water dissociation reaction in the membrane, which results in an insignificant increase in the effective transport numbers of hydroxide ions through the membrane.