Composite chitosan and quaternary ammonium modified nanofibrillar cellulose anion exchange membranes for direct ethanol fuel cell applications

Fuel cells are a promising technology for energy production, but their commercialization is hindered mainly due to high costs. Direct alkaline ethanol fuel cells (DAFC) are receiving increasing attention as they can utilize cheaper, non-precious metal catalysts. A vital component of a DAFC is the anion exchange membrane (AEM). Currently, the commercially available AEMs don’t possess satisfactory properties. This indicates a need for the development of new highly efficient, environmentally friendly, and economically viable AEMs. Synthesis of synthetic polymer AEMs is usually complex and time-consuming, as well as environmentally unfriendly. Therefore, it is highly desired that the membrane material is bio-renewable, non-toxic and environmentally benign. In this work, a series of biopolymer membranes were designed by a simple, cost-effective, dispersion-casting procedure, fully complying with green-chemistry principles. Design of experiments was used as a methodology for identifying optimal combinations of influencing factors and their relations within selected responses. The obtained chitosan-Mg(OH)2 composite membranes containing modified nanofibrillar cellulose (CNF) fillers with quaternary ammonium groups were investigated for their mechanical properties, swelling ratio, ethanol permeability and ion exchange properties. Obtained data suggest the applicability of newly prepared, biopolymeric composites as eco-friendly AEMs in DAFC technologies.

Introducing oxophilic metal and interstitial hydrogen into Pd lattice to boost electrochemical performance of alkaline ethanol oxidation

The sluggish kinetics of ethanol oxidation reaction (EOR), poor C1 selectivity and susceptibility to toxicity of CO intermediates hinder the commercialization of direct ethanol fuel cells (DEFCs). In this paper,...

Preparation and characterization of PVA thin-film composite membrane for pervaporation dehydration of ethanol solution

These days, ethanol fuel has been widely consumed worldwide to replace gasoline due to its possible environmental and long-term economic advantages. In detail, the ethanol fuel (purity ≥ 99.5 wt%) has been produced by traditional separation processes such as azeotropic distillation or molecular sieve adsorption, which excessively employs energy and capital cost. The pervaporation has already been considered as an effective alternative to conventional methods because of its high separation efficiency and low power consumption. Pervaporation separation of ethanol/water solution using hydrophilic membranes has been extensively studied owing to their superior perm-selectivity. In this present work, the polyvinyl alcohol thin-film composite membrane is prepared by casting a thin crosslinked polyvinyl alcohol (PVA) film on the polyacrylonitrile (PAN) porous substrate. The effect of PVA concentration on the pervaporation performance of the fabricated membrane is studied. The physicochemical properties of the prepared membrane are characterized using FTIR, SEM images, and contact angle measurements. The separation performance in terms of permeation flux and selectivity is simultaneously evaluated through a pervaporation dehydration of ethanol/water mixture of 80/20 wt.% at 60°C. The results show that the increase in PVA concentration leads to the decline in the hydrophilicity and the growth of the thickness and swelling degree of the membrane. Therefore, the selectivity of the membrane is found to improve significantly, while the permeation flux decreased with the PVA concentration ranging from 2.5 to 15 wt.%. Based on the results, the PVA membrane prepared from the 10 wt.% concentration is likely to provide high separation performance.