Naar een groene synthese van verknoopte gesulfoneerde PEEK kation uitwisseling membranen voor gecombineerde CO2-remediëring en afwaterbehandeling

The transition toward sustainable technologies demands greener materials and processes. Cation exchange membranes (CEMs) are crucial in applications such as CO2 electrolysis, artificial photosynthesis, and fuel cells. However, conventional CEMs often rely on perfluorinated polymers and toxic solvents, compromising environmental goals. This PhD work focuses on the development of high-performance CEMs using non-fluorinated materials and green solvents. Membranes based on sulfonated polyether ether ketone (sPEEK) were crosslinked with α,α'-dichloro-p-xylene (DCX) via a Friedel-Crafts reaction. By tuning the sulfonation and crosslinking degree, a balance between methanol rejection and proton conductivity was achieved, outperforming Nafion 117 in both parameters. The combination of a high sulfonation degree and low membrane thickness contributed significantly to the high conductivity and reduced methanol crossover. A greener membrane fabrication route was explored using seven candidate solvents. Tamisolve NxG and DMSO were identified as suitable options. It was observed that the use of DMSO caued the formation of a semi-cristalline membrane morphology, enhancing the resistance and lowering the methanol permeation. In addtion, by blending DMSO and Tamisolve NxG, an optimized membrane (sPEEK/DCX-10/90%) was obtained, with superior performance compared to Nafion 117. Finally, a novel green solvent blend, ASTROBIO™NS6, was tested and also obtained a low resistance and low methanol permeability. Two promising membranes, sPEEK-DMSO and sPEEK/DCX-NS6, were evaluated in a hybrid CO2 electrolyzer and electrodialysis. While gas crossover limited CO2 reduction to gaseous products, energy consumption decreased. In electrodialysis, sPEEK/DCX-NS6 matched commercial benchmarks in performance. This work demonstrates that sustainable CEMs with excellent performance can be fabricated without fluorinated components, using green solvents, and shows their promise in applications such as electrodialysis and organic wastewater treatment.