High Performance of Alkaline Anion-Exchange Membranes Based on Chitosan/Poly (vinyl) Alcohol Doped with Graphene Oxide for the Electrooxidation of Primary Alcohols

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 OHć onductivity 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 3.38ˆ10´7 and 2.43ˆ10´7 cm 2¨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.

Graphene-Based Membranes for CO2/CH4 Separation: Key Challenges and Perspectives

“…Here, it is noteworthy to highlight that the optimal loading of GO nanosheets is polymer-and application-specific. There is no strong indication to suggest a ubiquitously optimal filler loading as evidenced by mixed-matrix membranes of graphene-based or other 2D-layered materials for a variety of applications [60][61][62]. However, one thing for sure is that as the loading of GO nanosheets gets higher, there runs a higher risk of defective membrane formation as a result of increased difficulties in dispersing the GO nanosheets.…”

Preclinical assessment of chitosan–polyvinyl alcohol–graphene oxide nanocomposite scaffolds as a wound dressing

“…15,21,22 Moreover, with the increase of the GO, the surface tends to become more rough, and this can be ascribed to the greater interaction between GO and polymer. 23,24 Thermal behavior of scaffolds TGA is well-known as the most significant method to investigate the thermal stability of polymers. 25 As presented in Figure 4, when GO is loaded into the 50CS-50PVA scaffold, the degradation stages are shifted toward higher temperatures.…”

Prospects and challenges of graphene based fuel cells

“…Ineista and coworkers used mixed matrix membrane for anion exchange, formed by chitosan(CS)/PVA hetero-structures doped with graphene oxide [220] . The uniform dispersion of GO over the CS:PVA polymer matrix exhibited increased thermal stability.…”