Development of Chiral Membranes for Enantioselective Separations

Chiral separation remains a critical challenge in industries where enantiomers exhibit differing biological or sensory effects, such as pharmaceuticals, agrochemicals, and food additives. Membrane-based enantiomer separation is a promising technique, yet real-world application remains limited by poor separation efficiency or productivity and complex fabrication of enantioselective membranes. This thesis explores two scalable approaches for preparing enantioselective membranes. The first involves functionalizing commercial anion-exchange membranes with polyanionic sulfobutylether-β-cyclodextrin utilizing ionic interactions to create stable, selective membranes in a single-step process. These membranes are tested in concentration driven process under various experimental conditions including temperature, feed concentration and solvent composition within separation of N-boc-D,L-tryptophan. The enantioselective transport is enabled by selective complexation within the cyclodextrin cavities, resulting in sorption driven process. Further enhancement is demonstrated through the synthesis of crosslinked polyelectrolytic cyclodextrin networks, offering a modular layer-by-layer strategy. The second strategy investigates ion-exchange mixed matrix membranes (MMMs) incorporating quinidine-functionalized silica particles, a proven chiral chromatographic material, into poly(vinylidene fluoride) and poly(ethylene-co­-vinylalcohol) matrices. Techniques like vapor-induced and non-solvent induced phase separation enables high filler loadings up to 55 %. These membranes show strong selectivity and flux, particularly for PVDF-based membranes, with efficient separation of N-(3,5-dinitrobenzoyl)-R,S-leucine. Their porous structure promotes preferential sorption-based separation, and their fast regenerability enables cyclic, near-complete enantiomer resolution over five stages in concentration-driven process and approximately twenty stages in dead-end pressure-driven process. Overall, the research provides promising modular membrane platforms with potential for practical, scalable enantiomer separation, paving the way for further optimization toward large-scale operation.