Dual path biphasic column for highly selective and ultrafast organic solvent membrane extraction

Despite significant advances in membrane technology, achieving efficient separation in organic solvent nanofiltration (OSN) remains a major challenge in the chemical and pharmaceutical industries, particularly when dealing with multicomponent molecular mixtures. To address this, in this study, we develop a biphasic column for organic solvent membrane extraction, which consists of closely packed micron-sized water droplets covered by sub-nanometer-thick ion-ligand complexes that serve as size-exclusive membranes. Molecular mixtures dissolved in an organic solvent can be selectively extracted into the droplets through the interfacial complexes based on their sizes, while the solvent flows through the micron-scale interstices between the droplets. This solute-solvent dual pathway design minimizes resistance in solvent convection, resulting in high productivity, while simultaneously achieving a high separation factor through the monodisperse nanopores of the interfacial complexes. Using aluminum ion-carboxylate terminated polydimethylsiloxane complexes as a representative, the column demonstrates a controllable, high separation factor of 600 with a productivity of 1100 L·m^-²·hour^-1·bar^-1 in cyclohexane, significantly outperforming conventional membrane OSN.