Filtration Coefficient and Hydraulic Permeability of Nafion 125 Membranes in Metal Alkali Solutions

Abstract

Membranes based on Nation (trademark of E. I. du pont de Nemours & Company), a copolymer of tetrafluorethylene and a vinylsulfonic acid, have received to date a great deal of experimental work (1-6) because of their very interesting characteristics for use in electrolysis (7, 8), fuel cells (9), and batteries (10, 11). Experimental results on mechanical (2), structural (4), chemical (6, 10), and transport properties (5, 8) of Nation membranes demonstrate that their peculiarity depends mainly on the ion sequestering structure (clusters) and swelling properties. The water content and salt up-take of the membrane exposed to electrolyte solutions are of fundamerital importance for the membrane transport properties (7, 12). Among the transport coefficients, the hydraulic permeability and filtration coefficient have been less extensively studied despite the useful correlations which can be stated between them and the electroosmotic permeability, pore diameter, and solvation (13). In this paper experimental results on the hydraulic and filtration coefficients of Nation 125, an homogeneous 5 mils thick membrane of 1200 equivalent weight, are presented. The dependence of these parameters on the applied pressure difference, salt concentration, and counterion nature is discussed.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 157.182.150.22 Downloaded on 2015-03-10 to IP

Transport in Polymer-Electrolyte Membranes

“…The viscosity is that of pure water at the operating temperature, and thus any changes in viscosity due to the charge or hydrophobicity of the walls or due to the confined geometry are ignored. 13,[100][101][102] The value of k sat varies widely in the literature. The absolute permeability is a function of the medium geometry ͑which is a constant for a given structured medium͒.…”

“…13,56 However, there is one study by Meier et al, 99 that states that the permeability changes slightly with temperature, but in that study they also had a change in the membrane water content, and their values are suspect since they were much lower than those from other sources. 13,[100][101][102] The value of k sat varies widely in the literature. The values that seem consistent, are used in other models, and agree with each other for pure water in Nafion, are those of Yeo, 101 Bernardi and Verbrugge, 13 and Verbrugge and Hill.…”

Phenomenological Theory of Electro‐osmotic Effect and Water Management in Polymer Electrolyte Proton‐Conducting Membranes

“…16 and 17 lead to a closed form result. With the functions [22] [16] and H(a) = -rcjr[*) -Or]®(r -1)p(T) [23] T Ja u (Ofrflr2 [17] and the parameter = lie-+ iih(p) [24] [ 18] we get…”