The Effect of Divalent Ions on Reverse Electrodialysis Power Generation System

Abstract

Reverse electrodialysis（RED）systems are an emerging technology that can generate electric power from seawater and river water using ion exchange membranes. However, recent literature suggested that when a salty solution includes divalent ions in addition to monovalent ions, resulting RED performance dramatically decreases^1）. In this study, in order to investigate the degree of performance reduction in the RED due to divalent ions, we have evaluated the membrane potential（OCV）and the membrane resistance（R_m）using a mixed solution of NaCl and MgSO₄ with commercial ion exchange membranes（AMX/CMX）. Consequently, about 6 ％ of OCV of both AMX and CMX decreased, and R_m of only CMX increased twice when the molar fraction of MgSO₄ was 10 ％. Because these combinational effects will influence the resulting RED performance, the obtained knowledge is useful for practical RED applications using natural feed water.