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The determination of effective diffusion coefficient from the electrochemical impedance spectra of composite poly (vinyl alcohol) membranes
Author(s) -
Tomas Martin,
Remis Tomas,
Gholami Fatemeh
Publication year - 2019
Publication title -
environmental progress and sustainable energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.495
H-Index - 66
eISSN - 1944-7450
pISSN - 1944-7442
DOI - 10.1002/ep.13195
Subject(s) - vinyl alcohol , membrane , dielectric spectroscopy , swelling , diffusion , materials science , chemical engineering , nafion , ionic conductivity , conductivity , polymer chemistry , electrochemistry , analytical chemistry (journal) , chemistry , composite material , organic chemistry , polymer , electrolyte , electrode , thermodynamics , biochemistry , physics , engineering
This study presents the effect of swelling on effective diffusion coefficient of the composite poly(vinyl alcohol) (PVA) membranes through electrochemical impedance spectroscopy. The PVA based membranes were cross‐linked by sulfosuccinic acid (SSA) or tetraethylorthosilicate (TEOS) to improve the ionic conductivity and suppress the swelling. The impedance spectra of the synthesized membranes were recorded and then fitted using Randles circuit. The values of the Warburg element were analyzed and the effective diffusion coefficient was calculated for membranes in dry or wet state. Obtained values were compared with those of the Nafion NR 212 and pure PVA. A significant dependency of effective diffusion coefficient on dimension change caused by swelling was measured. In case of SSA cross‐linking, an improvement of ionic conductivity by chemical modification was observed. However, the highly hydrophilic behavior of PVA SSA samples is limiting further utilization of membrane in applications such as methanol fuel cells. To improve the stability of membrane in the wet environment, the composite PVA SSA TEOS membrane was prepared. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019