Effect of Dispersity of a Sulfonated Cation-Exchanger on the Current–Voltage Characteristics of Heterogeneous Membranes Ralex CM Pes

Resumo

The influence of the electrical and geometrical heterogeneity of the surface of heterogeneous sulfonated cation-exchange membranes on their current–voltage characteristic (CVC) has been experimentally studied. The objects of the study have been experimental samples of Ralex CM Pes membranes manufactured by MEGA a.s. (Czech Republic). A series of experimental membranes Ralex has been produced by hot rolling using an ion-exchanger with different particle sizes. The particle size of the ion-exchanger was controlled by its milling time from 5 to 80 min. It has been found that in the swollen state of the membranes, the ratio of conducting (ion-exchanger particles) and inert (polyethylene) areas on the membrane surface remains constant regardless of the milling time of the sulfonated cation-exchanger. At the same time, the dimensions of the conductive areas and the distance between them decreased and the surface microrelief became smoother. The influence of changes in the membrane surface properties on the CVC parameters has been revealed. With an increase in the ion-exchanger milling time corresponding to a decrease in the spacing of electrical heterogeneity of the surface, a reduction in the length of limiting-current plateau and a decrease in the resistance of the second and third regions on the current–voltage curve were observed. It has been assumed that the main cause of changes in the current–voltage characteristics is an increase in the intensity of heteroelectroconvection.