Abstract
Mixed matrix membranes (MMM) based on chitosan (CS) and poly (vinyl) alcohol (PVA) with a 50:50 w/w ratio doped with graphene oxide (GO) are prepared by solution casting and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water uptake, alcohol permeability, ion exchange capacity (IEC) and OH− conductivity measurements. The SEM analysis revealed a dense MMM where the GO nanosheets were well dispersed over the entire polymer matrix. The incorporation of GO increased considerably the thermal stability of the CS:PVA membrane. The GO-based MMM exhibited a low conductivity of 0.19 mS·cm−1 in part because the GO sheets did not change the crystallinity of the CS:PVA matrix. The reinforced structure created by the hydrogen bonds between the GO filler and the CS:PVA matrix resulted to be a good physical barrier for alcohol permeability, achieving a coefficient of diffusion of 3.38 × 10−7 and 2.43 × 10−7 cm2·s−1 after 60 and 120 min, respectively, thus avoiding additional alcohol crossover. Finally, the electrochemical performance of the GO-based MMM in the electrooxidation of propargyl alcohol was investigated in a Polymer Electrolyte Membrane Electrochemical Reactor (PEMER) under alkaline conditions, through the polarization curve and the electrolysis reactions, showing a performance comparable to anion-exchange commercial membranes.
Highlights
The development of membrane technology and its versatility in terms of structure and properties has led to the existence of a large number of membranes in multiple applications
The performance of graphene oxide (GO)/CS:poly (vinyl) alcohol (PVA) membrane was explored through the electrooxidation of a model primary alcohol like propargyl alcohol (PGA) in alkaline medium using a Polymer ElectrolyteMembrane (PEM) electrochemical reactor configuration
We have practically found the eV reveals GO layers in the membrane structure attributed to –CO
Summary
The development of membrane technology and its versatility in terms of structure and properties has led to the existence of a large number of membranes in multiple applications. To the best of our knowledge, only Yang et al developed a novel anion-exchange membrane based on CS and PVA in 1 to 9 (w/w) ratio incorporating sG and G for the manufacture of alkaline solid electrolyte membrane for direct alcohol fuel cells applications [51] These authors achieved a maximum tensile strength of. 62.2 Nmm using a 0.1 w/w loading of sG added, with a decrement of crystallinity and increasing conductivities, whose values range between 24 and 47 mScm with sG and G content, versus very slight improvements in terms of thermal stability and alcohol permeability Their membranes did not exhibit a good dispersion over the entire polymer matrix, probably due mainly to low amount of CS blended with PVA polymer. The performance of GO/CS:PVA membrane was explored through the electrooxidation of a model primary alcohol like propargyl alcohol (PGA) in alkaline medium using a PEM electrochemical reactor configuration
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