Green Synthesis of Cation Exchange Membranes: A Review

Abstract

Cation exchange membranes (CEMs) play a significant role in the transition to a more sustainable/green society. They are important components for applications such as water electrolysis, artificial photosynthesis, electrodialysis and fuel cells. Their synthesis, however, is far from being sustainable, affecting safety, health and the environment. This review discusses and evaluates the possibilities of synthesizing CEMs that are more sustainable and green. First, the concepts of green and sustainable chemistry are discussed. Subsequently, this review discusses the fabrication of conventional perfluorinated CEMs and how they violate the green/sustainability principles, eventually leading to environmental and health incidents. Furthermore, the synthesis of green CEMs is presented by dividing the synthesis into three parts: sulfonation, material selection and solvent selection. Innovations in using gaseous SO3 or gas–liquid interfacial plasma technology can make the sulfonation process more sustainable. Regarding the selection of polymers, chitosan, cellulose, polylactic acid, alginate, carrageenan and cellulose are promising alternatives to fossil fuel-based polymers. Finally, water is the most sustainable solvent and many biopolymers are soluble in it. For other polymers, there are a limited number of studies using green solvents. Promising solvents are found back in other membrane, such as dimethyl sulfoxide, Cyrene™, Rhodiasolv® PolarClean, TamiSolve NxG and γ-valerolactone.

Advancing Sustainable Peptide Synthesis by Solvent Quality Control: Understanding and Mitigating Hydroperoxide in 1-Butyl-2-pyrrolidinone (NBP)

“…Specifically, as GC/GC–MS techniques are routinely used in QC for solvent analysis, we opted to use GC–MS to complement our LC-HRMS results. As from a sustainability standpoint the use of NMP is not tenable and should be phased out, we focused on GC–MS evaluation of NBP, which is deemed as one of the next-generation green solvents − , and has shown great promise as a solvent for sustainable peptide synthesis. ,,,,,,,, To this end, the three NBP batches were evaluated by GC–MS, and in these analyses, these samples exhibited higher purities (97.79–99.98%, Figure a) than purities observed in the corresponding LC-HRMS analyses (94.18–99.76%, Figure ). Nevertheless, while the higher GC–MS purities indicated that some of the impurities observed by LC-HRMS were either not resolved and/or degraded during the conditions of the analysis, we did observe a back-eluting NBS impurity (Figure b), which was present to a similar extent (n.d.1.97%, Figure a) to which NBP-OOH was observed by LC-HRMS (n.d.2.20%, Figure ).…”

Overcoming the Trade-Off between Methanol Rejection and Proton Conductivity via Facile Synthesis of Crosslinked Sulfonated PEEK Proton Exchange Membranes

“…The main drawbacks are its high methanol permeability [6,9,10] and high production cost [9][10][11][12]. In addition, it contributes to global PFAS pollution, endangering human health and the environment [13][14][15][16].…”