Chemically enhanced electrodialysis (ceed): a universal platform for selective ion removal

A method for recovering target metal ions from a fluid stream using a chemically enhanced electrodialysis membrane, the method comprising:

• (a) selecting a cation-exchange membrane comprising a surface, wherein the cation-exchange membrane:
• (i) carries a fixed charge,
• (ii) permits the permeation of cations, and
• (iii) obstructs the passage of anions;
• (b) synthesizing an ion sequestrant, wherein the ion sequestrant is capable of binding the target metal ions;
• (c) grafting the ion sequestrant onto the cation-exchange membrane, wherein:
• (i) the grafting results in a thin layer of the ion sequestrant being affixed to the surface of the cation-exchange membrane,
• (ii) the thin layer of the ion sequestrant is continuous, and
• (iii) the thin layer being affixed to the surface creates an ion-gating mechanism;
• (d) placing the cation-exchange membrane in an electrodialysis unit, wherein the electrodialysis unit comprises an anode, a cathode, and a diluate chamber;
• (e) passing a diluate stream through the diluate chamber, wherein the diluate stream comprises the target metal ions;
• (f) as a result of passing the diluate stream through the diluate chamber, passing the diluate stream through the thin layer of the ion sequestrant affixed to the surface of the cation-exchange membrane;
• and
• (g) as a result of passing the diluate stream through the thin layer of the ion sequestrant, binding the target metal ions to the cathode-exchange membrane.