The cation exchange membrane used in the cell of this invention may contain any of {HEAD ~ sulfonic, carboxylic and phosphoric acid groups} as {TAIL ~ an ion exchange group} 
as
The cation exchange membrane used in the cell of this invention may contain any of { HEAD ~ sulfonic , carboxylic and phosphoric acid groups } as { TAIL ~ an ion exchange group }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL