Unlocking intrafacial networks: molecular cages enable record ethanol permeance in polymeric membranes

By Elizaveta Maltseva

Abstract

Although ethanol is the preferred green solvent for sustainable industrial separations, particularly in pharmaceutical purification, realizing high-performance organic solvent nanofiltration (OSN) in this medium remains a critical challenge due to its low permeance. Here, we present a green, universal aqueous intrafacial assembly strategy in which cationic organic cages are electrostatically confined within a dynamic anionic biopolymer template to construct a supramolecular membrane featuring interconnected solvent transport pathways. The resulting membrane exhibits ethanol permeance substantially exceeding the typical values reported for ethanol-based OSN membranes, indicating the formation of low-resistance solvent transport pathways. Simultaneously, the membrane maintains sharp selectivity with > 99% rejection for solutes at the molecular-weight cut-off range, consistent with molecular sieving dominated by the cage cavities. The membrane further demonstrates stable long-term operation and straightforward scalability. This work establishes a sustainable platform for biopolymer-based OSN membranes with strong potential for pharmaceutical purification and energy-efficient chemical processing.

Biography 

Elizaveta Maltseva is a current Ph.D. student under the supervision of Prof. Niveen Khashab at King Abdullah University of Science and Technology (KAUST). Elizaveta obtained her Master’s degree of Chemistry of Applied Materials (2022) from the ITMO University, Saint Petersburg, Russia, under the supervision of Dr. Elena Krivoshapkina. Elizaveta's research interests focus on the design of functional materials, supramolecular chemistry, bio-derived and synthetic polymer matrices for advanced separation and smart material applications.

Supramolecular silica nanosieves: selective separation of aromatic and aliphatic hydrocarbons via pocket recognition

By Viktoria Zheltova

Abstract

Separating aromatic compounds from complex hydrocarbon mixtures remains a critical challenge in the petrochemical industry, primarily due to the energy intensity and limited selectivity of traditional distillation. A promising alternative involves exploiting non-covalent interactions within supramolecular materials, yet pure macrocyclic crystals typically lack the stability and scalability required for industrial implementation. To address this, we developed supramolecular silica nanosieves (Δ-SiNx) that synergize the intrinsic host-guest selectivity of macrocycles with the structural robustness of inorganic matrices. The synthesis involved preparing a hexasila-ureido-trianglamine (Δ-Si₆) precursor, characterized by NMR and ESI mass spectrometry, followed by its integration via sol-gel co-condensation. While comprehensive characterization (FTIR, TGA, EDX, XPS, solid-state NMR) validated successful incorporation, BET analysis indicated that macrocycle integration significantly reduced surface area due to pore blockage. Remarkably, despite this reduced porosity, vapor sorption studies revealed that the materials completely reject cyclic aliphatic hydrocarbons while exhibiting exceptional aromatic uptake (up to 9.4 mmol/g for benzene). Dynamic column breakthrough experiments, supported by GC-MS measurements, confirmed efficient benzene/cyclohexane separation. Furthermore, metadynamics simulations attribute this high selectivity to host-guest-driven confinement within the Δ-Si₆ pockets. These supramolecular nanosieves demonstrate benchmark performance, offering a scalable, energy-efficient alternative for industrial hydrocarbon purification.

Biography

Viktoriia Zheltova is a current Ph.D. student under the supervision of Prof. Niveen Khashab at King Abdullah University of Science and Technology (KAUST). She obtained her Bachelor (2021) and Master of Chemistry degree (2023) from Saint Petersburg State University under the supervision of Dr. Olga Osmolovskaya. Viktoriia’s research interests are focused on synthesis of hybrid inorganic nanomaterials and their application in separation technologies.