Alkaline anion exchange membrane fuel cells (AAEMFC) are attracting ever-increasing attention, as they are promising electrochemical devices for energy production, presenting a viable opponent to the more researched proton exchange membrane fuel cells (PEMFCs). Consequently, great progress has been made in the area of designing and developing synthetic or naturally-derived anion exchange membrane (AEM), the properties of which have been discussed in this review, i.e. ionic conductivity, ion exchange capacity, fuel crossover, durability, stability and cell performance. Major groups of natural polymers (e.g. chitosan (CS)) and nanocellulose, together with modification/crosslinking routes, have been mentioned as more ecologically and economically viable raw materials for AEM processing compared to synthetic ones. Performances of fuel cells are also discussed, with different fuels used as anode feeds. Although the AEMFC technology is promising, the longevity challenges remain, originating from the still-limited long-term stability of hydroxide-conducting ionomers, particularly when operating at higher cell temperatures.

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Alkaline membrane fuel cells: anion exchange membranes and fuels

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

The eco-sustainable use of materials derived from agricultural and food processing waste will represent one of the most stimulating challenges shortly. Chitin and chitosan are two remarkable examples of how molecules with high added value can be extracted from food waste, such as crustaceans’ shells, fungi, mollusks, etc. This Perspective summarizes the current state of knowledge about chitin extraction, chitosan production, and hydrogel formation, highlighting the environmental critical steps in the common route (use of strong acids and basis, toxic solvents, and not eco-friendly crosslinkers). At the same time, promising green alternatives are described and analyzed. Examples are the employment of NADESs or DESs (such as choline chloride: urea or choline chloride: organic acids mixtures) for chitin extraction and dissolution, use of citric acid both in chitin extraction and hydrogel formation or utilization of natural extracts, like genipin, as green cross-linkers under mild conditions (heating at 37 °C for 12 h). In particular, this perspective aims to provide a stimulating basis for the development of processes based on the recycling and reusing of chemicals, during the different preparation steps, in line with “system chemistry” and “circular economy” principles.

https://www.mdpi.com/2673-4079/1/3/22/pdf

Green Routes for the Development of Chitin/Chitosan Sustainable Hydrogels

Preparation of PP non-woven fabric with good heavy metal adsorption performance via plasma modification and graft polymerization

Improved performance of nanocomposite polyimide membranes for pervaporation fabricated by embedding spirobisindane structure-functionalized graphene oxide

Edward S. Xiao

Papers

Using genipin as a “green” crosslinker to fabricate chitosan membranes for pervaporative dehydration of isopropanol