Ion exchange membranes

A method for forming a membrane, the method comprising:

• mixing a solvent, sulfonated polyethersulfone, and humic acid to form a first mixture;
• adding a 2-1 layered aluminosilicate to the first mixture to form a second mixture, the 2-1 layered aluminosilicate including a layered structure with an octahedral sheet between two tetrahedral sheets;
• casting the second mixture;
• and
• evaporating the solvent to form a product membrane.

A reverse electrodialysis system, the reverse electrodialysis system comprising:

• an anode;
• a cathode;
• one or more anion exchange membranes;
• and
• one or more cation exchange membranes, the one or more cation exchange membranes including a plurality of sulfonated polymers, humic acid, and montmorillonite, wherein a weight ratio of humic acid to the plurality of sulfonated polymers in the one or more cation exchange membranes ranges from about 20:100 to about 30:100.