Functionalized polyacrylonitrile nanofiber membranes with carbonic anhydrase for enhanced carbon dioxide capture and conversion: A performance study

As industrial activity rises, atmospheric carbon dioxide levels have significantly contributed to global warming and climate change. Developing effective carbon dioxide capture technologies is imperative to mitigate these effects. Carbonic anhydrase (CA) enzymes represent one of the most promising solutions due to their rapid reaction rates, environmental safety, and efficiency in facilitating CO₂ conversion. This study takes a novel approach by investigating the immobilization of CA on functionalized polyacrylonitrile (PAN) nanofiber membranes to enhance CO₂ conversion and mineralization. PAN nanofibers were fabricated via electrospinning and chemically modified to introduce carboxylic groups, resulting in NM-COOH nanofiber membranes. In addition, amine groups from chitosan (CS) were incorporated to form NM-COOH-CS nanofiber membranes. The immobilization of CA on these membranes revealed that covalent attachment through NM-COOH significantly enhances catalytic activity compared to physical attachment methods. The NM-COOH-CA membrane exhibited superior performance, achieving efficient conversion of CO₂ into HCO₃⁻ and promoting CaCO₃ mineralization. It reached a precipitation efficiency of 11.77 mg CaCO₃ per gram of membrane-active unit (WAU) and maintained 63.12 % of its initial CaCO₃ production over five cycles over five weeks. This study presents a novel, eco-friendly approach to greenhouse gas reduction, emphasizing the effectiveness of CA-immobilized nanofiber membranes. The findings mainly highlight the advantages of carboxylic functional groups in enhancing CA performance, paving the way for future research in carbon capture technologies.