Transport Properties of Novel Hybrid Cation-Exchange Membranes on the Base of MF-4SC and Halloysite Nanotubes

Abstract

The diffusion permeability through new hybrid materials based on a Nafion-type membrane (MF-4SC) and nanotubes of halloysite is investigated using the Nernst-Planck approach. A method of quantitative evaluation of physicochemical parameters (averaged and individual diffusion coefficients and averaged distribution coefficients of ion pairs in the membrane) of system "electrolyte solution-ion-exchange membrane-water", which was proposed earlier, is further developed. The parameters of hybrid membranes on the base of MF-4SC and nanotubes of halloysite (5% wt and 8% wt) are obtained from experimental data on diffusion permeability of NaCl solutions using theoretical calculations. New model of three-layer membrane system can be used for refining calculated results with taking into account both diffusive layers. It is shown that adding of halloysite nanotubes into the membrane volume noticeably affects exchange capacity as well as structural and transport characteristics of original perfluorinated membranes. Hybrid membranes on the base of MF-4SC and halloysite nanotubes can be used in fuel cells and catalysis.

Modelling of Ion Transport in Electromembrane Systems: Impacts of Membrane Bulk and Surface Heterogeneity

“…Similar assumptions are accepted in some recent models of ion sorption and transfer in charged membranes regarded as homogeneous medium [114][115][116][117][118][119]. Filippov et al [114][115][116][117] use the so-called fine-pore model, which allows description of some special cases, for example, when an organic IEM contains inorganic nanoparticles. Fila and Bouzek [118,119] use the same assumption as the TMS model but apply the extended Nernst-Planck equation, which contains the convective term.…”

“…Quantitative description of the effect of nanoparticles on the transport properties of IEMs is a rather complicated problem. Filippov et al [115][116][117] developed a fine-pore model of ion transfer in an IEM with immobilized nanoparticles. The membrane is considered as quasi-homogeneous medium as in the TMS theory and applies the approach known as the "fine porous membrane" model suggested by Starov, Churaev and Martynov [173].…”

“…The simulation was compared with experimental data on diffusion permeability of a hybrid MF-4SK membrane containing silica nanoparticles. This comparison allowed to the authors [115][116][117] to find in what extent the ion effective diffusion coefficients change in the membrane due to incorporation of silica. By applying the "fine porous membrane" model, the main membrane physicochemical parameters can be determined.…”

Transport Asymmetry of Novel Bi-Layer Hybrid Perfluorinated Membranes on the Base of MF-4SC Modified by Halloysite Nanotubes with Platinum

“…The content of the modifying metal was 2 wt % of the nanotubes’ mass. Such percentage of platinum was chosen based on previous research [ 18 ]. We conducted additional studies of the mechanical properties of synthesized hybrid membranes depending on the percentage of halloysite that confirmed the optimal value of halloysite nanotubes is equal to 4 weight percent (see Section 2.4 ).…”

Membrane electrolysis—History, current status and perspective

“…For the latter type, not only an increase in conductivity, but also in selectivity could be achieved. An increase in the exchange capacity of a Nafion-type membrane modified by halloysite (aluminosilicate) nanotubes was reported in [251].…”