(351d) Comonomer Effects on Co-Permeation of Methanol and Acetate in Cation Exchange Membranes | AIChE

(351d) Comonomer Effects on Co-Permeation of Methanol and Acetate in Cation Exchange Membranes

Authors 

Kim, J. M. - Presenter, Auburn University
Beckingham, B., Auburn University
Co-permeation in a hydrated dense membrane is crucial in many applications from energy conversion (i.e. photoelectrochemical CO2 reduction cells) to liquid separation (i.e. pervaporation cells). One of the major challenges of CO2 reduction cells is to design an ion exchange membrane that minimize the permeation of CO2 reduction products (i.e. methanol and acetate). Previously, the transport behavior of Nafion® 117 and crosslinked PEGDA-AMPS cation exchange membranes to methanol and sodium acetate was investigated and distinct changes in permeabilities of membranes to sodium acetate was observed in co-permeation with methanol. To further investigate this co-permeation behavior, we modified PEGDA-AMPS structure by varying negatively-charged AMPS content with three different charge-neutral comonomers, acrylic acid (AA, n = 0), 2-hydroxylethyl methacrylate (HEMA, n = 1), and poly(ethylene glycol) methacrylate (PEGMA, n = 5). While the permeability to sodium acetate in co-permeation with methanol was increased for membranes with shorter comonomers, PEGDA-AA-AMPS and PEGDA-HEMA-AMPS, it was consistent for PEGDA-PEGMA-AMPS membranes. From these experiments, we deduce that charge-neutral molecules, both moving (e.g. methanol) and membrane-bound (e.g. ethylene glycol), can interfere with the electrostatic repulsion during ionic transport in ion exchange membranes and this shielding of electrostatic repulsion leads to variance in transport behavior.