| 초록 |
The electrochemical properties of homogeneous and heterogeneous cation-exchangemembranes(CMX and Het-C, respectively) such as water content(W), ion-exchangecapacity(AR), transport number(TN), specific resistance(ρ), fraction of ion permeable area were compared. The water content of Het-C was about twice as high as that of CMX and ion-exchange capacity of Het-C was about a half as low as that of CMX. The TN was 0.93 and 0.97 for Het-C and CMX, respectively. For small molecular size ions, ρ value of Het-C is higher than that of CMX due to the difference in the ion-exchange capacity of the two membranes. However, as the radius of hydrated ions increases, the effect of AR on the resistance decreases. Instead, the effect of the pore size of the membrane increases. Because a heterogeneous membrane has relatively large pores compared to a homogeneous membrane due to the cavity, the specific resistance to transport of larger ions in the heterogeneous membrane is lower than that in the homogeneous membrane even with the low AR. To determine an effective permeable area of each membrane, a chronopotentiometric method was used. It was observed that the Het-C has the larger non-conducting region than the CMX membrane, indicated by the transition time measured. |
