TY - JOUR
T1 - Water sorption, desorption and transport in Nafion membranes
AU - Majsztrik, Paul W.
AU - Satterfield, M. Barclay
AU - Bocarsly, Andrew Bruce
AU - Benziger, Jay Burton
N1 - Funding Information:
The authors thank the National Science Foundation (CTS-0354279 and DMR-0213707 through the Materials Research and Science Engineering Center at Princeton) for its support of this work.
PY - 2007/9/1
Y1 - 2007/9/1
N2 - Water sorption, desorption, and permeation in and through Nafion 112, 115, 1110 and 1123 membranes were measured as functions of temperature between 30 and 90 °C. Water permeation increased with temperature. Water permeation from liquid water increased with the water activity difference across the membrane. Water permeation from humidified gas into dry nitrogen went through a maximum with the water activity difference across the membrane. These results suggested that the membrane was less swollen in the presence of water vapor and that a thin skin formed on the dry side of the membrane that reduced permeability to water. Permeation was only weakly dependent on membrane thickness; results indicated that interfacial mass transport at the membrane/gas interface was the limiting resistance. The diffusivity of water in Nafion deduced from water sorption into a dry Nafion film was almost two orders of magnitude slower than the diffusivity determined from permeation experiments. The rate of water sorption did not scale with the membrane thickness as predicted by a Fickian diffusion analysis. The results indicated that water sorption was limited by the rate of swelling of the Nafion. Water desorption from a water saturated film was an order of magnitude faster than water sorption. Water desorption appeared to be limited by the rate of interfacial transport across the membrane/gas interface. The analysis of water permeation and sorption data identifies different regimes of water transport and sorption in Nafion membranes corresponding to diffusion through the membrane, interfacial transport across the membrane-gas interface and swelling of the polymer to accommodate water.
AB - Water sorption, desorption, and permeation in and through Nafion 112, 115, 1110 and 1123 membranes were measured as functions of temperature between 30 and 90 °C. Water permeation increased with temperature. Water permeation from liquid water increased with the water activity difference across the membrane. Water permeation from humidified gas into dry nitrogen went through a maximum with the water activity difference across the membrane. These results suggested that the membrane was less swollen in the presence of water vapor and that a thin skin formed on the dry side of the membrane that reduced permeability to water. Permeation was only weakly dependent on membrane thickness; results indicated that interfacial mass transport at the membrane/gas interface was the limiting resistance. The diffusivity of water in Nafion deduced from water sorption into a dry Nafion film was almost two orders of magnitude slower than the diffusivity determined from permeation experiments. The rate of water sorption did not scale with the membrane thickness as predicted by a Fickian diffusion analysis. The results indicated that water sorption was limited by the rate of swelling of the Nafion. Water desorption from a water saturated film was an order of magnitude faster than water sorption. Water desorption appeared to be limited by the rate of interfacial transport across the membrane/gas interface. The analysis of water permeation and sorption data identifies different regimes of water transport and sorption in Nafion membranes corresponding to diffusion through the membrane, interfacial transport across the membrane-gas interface and swelling of the polymer to accommodate water.
KW - Diffusion
KW - Interfacial mass transfer
KW - Nafion
KW - Water permeation
KW - Water sorption
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U2 - 10.1016/j.memsci.2007.06.022
DO - 10.1016/j.memsci.2007.06.022
M3 - Article
AN - SCOPUS:34547411431
SN - 0376-7388
VL - 301
SP - 93
EP - 106
JO - Journal of Membrane Science
JF - Journal of Membrane Science
IS - 1-2
ER -