Multicomponent transport of methanol and acetate in a series of crosslinked PEGDA-AMPS cation exchange membranes

Multicomponent transport through hydrated dense membranes is utilized in many applications, including photoelectrochemical CO2 reduction cells. One of the main challenges in these devices is to design an ion exchange membrane that minimizes crossover of CO2 reduction products, such as methanol and acetate, while maintaining sufficient ionic conductivity. Previously, the transport behavior of a sulfonated cation exchange membrane, Nafion® 117, to methanol and sodium acetate was investigated and an increase in permeability to sodium acetate was noticed in co-permeation with methanol. To further investigate this transport behavior, a charge-neutral membrane (PEGDA) and a series of sulfonated cation exchange membranes (PEGDA-AMPS) were prepared by varying the poly(ethylene glycol) diacrylate to 2-acrylamido-2-methylpropanesulfonic acid ratio. A distinct increase in permeability to sodium acetate in co-permeation with methanol is observed in co-permeation experiments compared to single solute permeation experiments. We attribute this transport behavior to the shielding of electrostatic repulsion, in which methanol interferes with electrostatic repulsion between acetate and membrane-bound sulfonate anions.