Abstract
ABSTRACTIn this work, mixed matrix membranes (MMMs) based on chitosan (CS) and different fillers (room temperature ionic liquid [emim][OAc] (IL), metallic Sn powder, layered titanosilicate AM‐4 and layered stannosilicate UZAR‐S3) were prepared by solution casting. The room temperature electrical conductivity and electrochemical response in strong alkaline medium were measured by electrochemical impedance spectroscopy and cyclic voltammetry (CV). The ionic conductivity of pure CS membranes was enhanced, from 0.070 to 0.126 mS cm−1, for the pristine CS and Sn/CS membranes, respectively, as a function of the hydrophilic nature of the membrane and the coordination state of Sn. This hydrophilic and charge nature was corroborated by water uptake measurements, where only the introduction of IL in the CS membrane led to a water uptake of 3.96 wt %, 20 or 30 times lower than the other membranes. Good thermal and chemical stability in alkaline media were observed by thermogravimetric analyses and X‐ray photoelectron spectroscopy analyses, respectively, and good interaction between CS and the fillers observed by X‐ray diffraction, scanning electron microscopy and CV. Thus, thin CS‐based MMMs (40–139 µm), resistant in high alkaline media, show higher conductivity than pure CS membranes, especially those fillers containing tin, and although the electrochemical performance is lower than commercially available anion‐exchange membranes they have potential in pervaporation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42240.
Highlights
Nowadays, ion-exchange membranes are widely used in the diffusion dialysis, water electrochemical synthesis for the production of potable and industrial water, for the treatment of industrial effluents, and for the chlorine-alkaline production, the demineralization and purification of different products, acid recovery, and energy conversion and storage in electrochemical devices 1
It can be noted from the cross sections of AM-4/CS and UZAR-S3/CS matrix membranes (MMMs) that AM-4 particles were distributed homogenously throughout the membrane thickness, while UZAR-S3 was found only on the surface of the membrane
In this work, mixed matrix membranes (MMMs) were prepared by solution casting from chitosan biopolymer, as continuous matrix, and a non-toxic ionic liquid, tin particles, layered titanosilicate AM-4 and stannosilicate UZAR-S3 particles, as fillers
Summary
Ion-exchange membranes are widely used in the diffusion dialysis, water electrochemical synthesis for the production of potable and industrial water, for the treatment of industrial effluents, and for the chlorine-alkaline production, the demineralization and purification of different products, acid recovery, and energy conversion and storage in electrochemical devices 1. Many research groups are focused on production and characterization of AEMs that allow to replace proton exchange membranes (PEMs, usually named Nafion) as electrolyte in order to obtain an improvement of performance in the storage and energy conversion in alkaline electrochemical devices 3. Commercial AEMs are emerging and being established in the market as proper options and alternatives in alkaline conditions and somewhat overcomes the problems found in based fuel cells using perfluorosulfonic polymers commercialized strong basic AEMs with good thermal and mechanical stability for long periods of time in a pH range 0-14 and 1-11, respectively, in the absence of oxidant species and under frequent regeneration thereof, being the electrolysis and electrodialysis its main applications for which are used.
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