TY - JOUR
T1 - When Salt-Rejecting Polymers Meet Protons
T2 - An Electrochemical Impedance Spectroscopy Investigation
AU - Fridman-Bishop, Noga
AU - Freger, Viatcheslav
N1 - Funding Information:
This project was funded by the Israel Science Foundation grant (#1152/11). N.F.-B. acknowledges the President of Israel Scholarship for Outstanding Ph.D. Students.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/2/14
Y1 - 2017/2/14
N2 - Polymeric membranes are widely used for salt removal, but mechanism of ion permeation is still insufficiently understood. Here we analyze ion transport in polymers relevant to desalination, dense aromatic polyamide Nomex and cellulose acetate (CA), using impedance spectroscopy, focusing on the effects of the salt type, concentration and pH. The results highlight the role of proton uptake in ion permeation. For Nomex the exceptionally high affinity to proton results in a power-low scaling of conductivity with salt concentrations with an unusual exponent 1/2. The results for CA suggest dominance of pore transport, with pore charge increasing with decreasing pH, which contradicts previous view of CA as a weakly acidic polymer and points to proton uptake as possible pore-charging mechanism. The observed effects may have far-reaching consequences in desalination, as even at neutral pH they may both enhance and suppress salt permeation and affect pH changes.
AB - Polymeric membranes are widely used for salt removal, but mechanism of ion permeation is still insufficiently understood. Here we analyze ion transport in polymers relevant to desalination, dense aromatic polyamide Nomex and cellulose acetate (CA), using impedance spectroscopy, focusing on the effects of the salt type, concentration and pH. The results highlight the role of proton uptake in ion permeation. For Nomex the exceptionally high affinity to proton results in a power-low scaling of conductivity with salt concentrations with an unusual exponent 1/2. The results for CA suggest dominance of pore transport, with pore charge increasing with decreasing pH, which contradicts previous view of CA as a weakly acidic polymer and points to proton uptake as possible pore-charging mechanism. The observed effects may have far-reaching consequences in desalination, as even at neutral pH they may both enhance and suppress salt permeation and affect pH changes.
UR - http://www.scopus.com/inward/record.url?scp=85012934007&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.6b04263
DO - 10.1021/acs.langmuir.6b04263
M3 - Article
C2 - 28103044
AN - SCOPUS:85012934007
VL - 33
SP - 1391
EP - 1397
JO - Langmuir
JF - Langmuir
SN - 0743-7463
IS - 6
ER -