Multicomponent transport of alcohols in an anion exchange membrane measured by in-situ ATR FTIR spectroscopy

Multicomponent transport through membranes is encountered in many applications, including photoelectrochemical CO2 reduction devices that convert CO2 into alcohols. We report the use of in-situ ATR FTIR spectroscopy to quantify the permeability of Selemion AMV, a commonly used anion exchange membrane, to mixtures of alcohols. An in-situ ATR FTIR spectrophotometer probe inserted into a standard diffusion cell enabled straightforward measurement of membrane permeability in multicomponent transport experiments without the need to periodically remove aliquots from the diffusion cell. The solubilities of alcohols in Selemion AMV were measured using a standard sorption/desorption technique. The solution-diffusion model was used to calculate alcohol diffusivities in Selemion AMV from measured permeabilities and solubilities. The relative contributions of alcohol solubility and diffusivity to overall permeability are discussed, and changes in permeability, solubility, and diffusivity with changing composition in binary and ternary alcohol mixtures are described.