Fabrication of PVDF-blended ultrafiltration membranes incorporated by chiral mesoporous silica for enantioseparation

Recent developments and applications of solid membrane in chiral separation

Chirality is a fundamental property in nature, and chiral molecules are closely related to human health and the origin of life. Therefore, the exploration and preparation of optically active compounds of paramount importance. Membrane separation is a large-scale and continuous separation technique that has been developing quickly in recent years. It has many potential applications, particularly in chiral membrane separation technology, which is currently a hotspot for study. Depending on the types of membranes, chiral membranes can be divided into two categories: chiral solid membranes and chiral liquid membranes. Solid membranes outperform the others in terms of better mechanical performance and separation efficiency. This review presents in-depth summaries of chiral solid membranes made of different materials, and their applications in drug separation. It also providing insights into the potential for the future development of chiral solid membranes.

Thiol-Ene Click Reaction in Constructing Liquid Separation Membranes for Water Treatment

In the evolving landscape of water treatment, membrane technology has ascended to an instrumental role, underscored by its unmatched efficacy and ubiquity. Diverse synthesis and modification techniques are employed to fabricate state-of-the-art liquid separation membranes. Click reactions, distinguished by their rapid kinetics, minimal byproduct generation, and simple reaction condition, emerge as a potent paradigm for devising eco-functional materials. While the metal-free thiol-ene click reaction is acknowledged as a viable approach for membrane material innovation, a systematic elucidation of its applicability in liquid separation membrane development remains conspicuously absent. This review elucidates the pre-functionalization strategies of substrate materials tailored for thiol-ene reactions, notably highlighting thiolation and introducing unsaturated moieties. The consequential implications of thiol-ene reactions on membrane properties-including trade-off effect, surface wettability, and antifouling property-are discussed. The application of thiol-ene reaction in fabricating various liquid separation membranes for different water treatment processes, including wastewater treatment, oil/water separation, and ion separation, are reviewed. Finally, the prospects of thiol-ene reaction in designing novel liquid separation membrane, including pre-functionalization, products prediction, and solute-solute separation membrane, are proposed. This review endeavors to furnish invaluable insights, paving the way for expanding the horizons of thiol-ene reaction application in liquid separation membrane fabrication.

Supramolecular Interaction Modulation in Thermosensitive Composites: Enantiomeric Recognition and Chiral Site Regeneration

Herein, a novel strategy was implemented to modulate the supramolecular interaction between enantiomers and chiral recognition sites (CRSs), effectively resolving the issue of CRS saturation. Randomly methylated-β-cyclodextrin (Rm-β-CD) was used as the CRS (host molecule), and polymerized ionic liquids [poly([vbim]TFSI)] were used as the supramolecular modulator (guest molecule), which self-assembled to generate thermosensitive supramolecular host/guest complexes. The enantiomeric binding capacity and enantioselectivity of chiral separation systems centered on supramolecular host-guest complexes are characterized by a high degree of temperature dependence. Poly([vbim]TFSI) bonded to Rm-β-CD at temperatures between 17 °C ± 3 and 50 °C ± 3 °C, and the binding free energy difference (|ΔΔG|) between the (S)- and (R)-enantiomer was 0.55. Conversely, poly([vbim]TFSI detached from Rm-β-CD at temperatures >50 °C ± 3 °C or <17 °C ± 3 °C, and |ΔΔG| between (S)- and (R)-enantiomer was 0.03. The |ΔΔG| value of the (R)-enantiomer can reach 0.86 in two temperature intervals. Therefore, the binding of poly([vbim]TFSI) to Rm-β-CD afforded the favorable separation of four racemic sample mixtures: mandelic acid (e.e.% = 61.3%), ibuprofen (e.e.% = 21.6%), warfarin (e.e.% = 14.9%), and naproxen (e.e% = 18.2%). The detachment of poly([vbim]TFSI) from Rm-β-CD released the enantiomer bound to CRSs. The decomplexation of mandelic acid reached 75.1%.

Enhanced management and antifouling performance of a novel NiFe-LDH@MnO2/PVDF hybrid membrane for efficient oily wastewater treatment

Layered double hydroxides (LDHs) have gained significant recognition for their facile synthesis and super-hydrophilic two-dimensional (2D) structure to fabricate antifouling membranes for oily wastewater separation. However, conventional PVDF membranes, due to their hydrophobic nature and inert matrix, often exhibit insufficient permeance and compatibility. In this study, a novel NiFe-LDH@MnO2/PVDF membrane was synthesized using ultrasonic, redox, and microwave-hydrothermal processes. This innovative approach cultivated grass-like NiFe-LDH@MnO2 nanoparticles within an inert PVDF matrix, promoting the growth of highly hydrophilic composites. The presence of NiFe-LDH@MnO2 resulted in pronounced enhancements in surface morphology, interfacial wettability, and oil rejection for the fabricated membrane. The optimal NiFe-LDH@MnO2/PVDF-2 membrane exhibited an extremely high pure water flux (1364 L m-2•h-1), and increased oil rejection (from 81.2% to 93.5%) without sacrificing water permeation compared to the original PVDF membrane. Additionally, the NiFe-LDH@MnO2/PVDF membrane demonstrated remarkable antifouling properties, evident by an exceptional fouling resistance ratio of 96.8% following slight water rinsing. Mechanistic insights into the enhanced antifouling performance were elucidated through a comparative "semi-immersion" investigation. The facile synthesis method, coupled with the improved membrane performance, highlights the potential application prospects of this hybrid membrane in emulsified oily wastewater treatment and environmental remediation.

Enantioseparation Membranes: Research Status, Challenges, and Trends

The purity of enantiomers plays a critical role in human health and safety. Enantioseparation is an effective way and necessary process to obtain pure chiral compounds. Enantiomer membrane separation is a new chiral resolution technique, which has the potential for industrialization. This paper mainly summarizes the research status of enantioseparation membranes including membrane materials, preparation methods, factors affecting membrane properties, and separation mechanisms. In addition, the key problems and challenges to be solved in the research of enantioseparation membranes are analyzed. Last but not least, the future development trend of the chiral membrane is expected.

Super-Assembled Chiral Mesostructured Heteromembranes for Smart and Sensitive Couple-Accelerated Enantioseparation

In the context of sustainable development, chirality, especially chiral drugs, has attracted great interest in the pharmaceutical industry, yet the smart and sensitive separation of enantiomers still presents a major scientific challenge. Herein, inspired by supramolecular templating via chiral transcription nanoparticles, an artificial chiral nanochannel membrane with asymmetric structure, porosity, and abundant chiral surface is fabricated for smart and sensitive enantiomer recognition and separation. Constructed from chiral transcript mesoporous silica (CMS) super-assembled on a porous anode alumina oxide (AAO) support, the obtained heterostructured chiral membrane (CMS/AAO) exhibits enhanced enantioseparation (approximately 170% compared to the supramolecular-templated nanoparticles) among a series of amino acids with various isoelectric points (PIs). Especially for amino acids with a PI greater than 7, the couple-accelerated enantioseparation (CAE) can be achieved for the first time. Further analysis using an osmotic energy conversion test and simulations based on the Poisson-Nernst-Planck (PNP) equations confirm that the heterostructure and charge polarity are the key to achieve chiral amino acids and ion separation. We expect this work will inspire the development of multifunctional membrane systems for more sustainable and energy-efficient enantioseparation.