This work shows that incorporating highly compatible polyrhodanine nanoparticles (PRh-NPs) into a polyamide (PA) active layer allows for fabricating forward osmosis (FO) thin-film composite (TFC)-PRh membranes that have simultaneously improved antimicrobial, antifouling, and transport properties. To the best of our knowledge, this is the first reported study of its kind to this date. The presence of the PRh-NPs on the surface of the TFC-PRh membranes active layers is evaluated using FT-IR spectroscopy, SEM, and XPS. The microscopic interactions and their impact on the compatibility of the PRh-NPs with the PA chains were studied using molecular dynamics simulations. When tested in forward osmosis, the TFC-PRh-0.01 membrane (with 0.01 wt % PRh) shows significantly improved permeability and selectivity because of the small size and the high compatibility of the PRh-NPs with PA chains. For example, the TFC-PRh-0.01 membrane exhibits a FO water flux of 41 l/(m·h), higher than a water flux of 34 l/(m·h) for the pristine TFC membrane, when 1.5 molar NaCl was used as draw solution in the active-layer feed-solution mode. Moreover, the reverse solute flux of the TFC-PRh-0.01 membrane decreases to about 115 mmol/(m·h) representing a 52% improvement in the reverse solute flux of this membrane in comparison to the pristine TFC membrane. The surfaces of the TFC-PRh membranes were found to be smoother and more hydrophilic than those of the pristine TFC membrane, providing improved antifouling properties confirmed by a flux decline of about 38% for the TFC-PRh-0.01 membranes against a flux decline of about 50% for the pristine TFC membrane when evaluated with a sodium alginate solution. The antimicrobial traits of the TFC-PRh-0.01 membrane evaluated using colony-forming units and fluorescence imaging indicate that the PRh-NPs hinder cell deposition on the TFC-PRh-0.01 membrane surface effectively, limiting biofilm formation.

Sustainable and energy-efficient molecular separation requires membranes with high gas permeability and selectivity. This work reports excellent CO 2 separation performance of self-standing and thin-film mixed matrix membranes (MMMs) fabricated by embedding 2D Ti 3 C 2 T x MXene nanosheets in Pebax-1657. The CO 2 /N 2 and CO 2 /H 2 separation performances of the free-standing membranes are above Robeson's upper bounds, and the performances of the thin-film composite (TFC) membranes are in the target area for cost-efficient CO 2 capture. Characterization and molecular dynamics simulation results suggest that the superior performances of the Pebax−Ti 3 C 2 T x membranes are due to the formation of hydrogen bonds between Ti 3 C 2 T x and Pebax chains, leading to the creation of the wellformed galleries of Ti 3 C 2 T x nanosheets in the hard segments of the Pebax. The interfacial interactions and selective Ti 3 C 2 T x nanochannels enable fast and selective CO 2 transport. Enhancement of the transport properties of Pebax-2533 and polyurethane when embedded with Ti 3 C 2 T x further supports these findings. The ease of fabrication and high separation performance of the new TFC membranes point to their great potential for energy-efficient CO 2 separation with the low cost of $29/ton separated CO 2 .

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The synthesis of nanostructures with tunable antibacterial properties using green solvents at room temperature is of environmental interest, and antibacterial nanomaterials are used in the fabrication of biofouling-resistant membranes for water purification and wastewater treatment. In this study, we investigate the effect of organic ligands on the antibacterial and structural properties of silver-based metal−azolate frameworks (Ag-MAFs). Three new Ag-MAFs were synthesized with silver, as the metal center, and imidazole-based linkers having different chemistries via a facile and environmentally friendly method conducted at room temperature. The coordination of silver ions with the linkers resulted in the formation of Ag-imidazole, Ag-2 methylimidazole, and Ag-benzimidazole complexes with octahedral, hexagonal nanosheet, and nanoribbon morphologies, respectively. The Ag-MAFs exhibited excellent antibacterial activity (up to 95% die-off of bacteria at a short exposure time of 3 h) in colloidal forms against both Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) because of synergetic effects of silver and the imidazole-based linkers. Ag-2 methylimidazole showed the highest antibacterial activity, owing to its high silver concentration and special nanocrystal structure that provides better contact with bacteria. This work indicates that the antibacterial activity of Ag-MAF nanostructures can be tailored by changing the organic linker, allowing for creating nanostructures with desired biocidal properties.

Incorporating metal–organic frameworks (MOFs) into the thin layer of thin-film composite (TFC) membranes is an effective way of improving the CO2/CH4 separation performance. In this study, porous polyethersulfone (PES) membranes were surface-coated with a novel CO2-permeable layer consisting of CO2-philic Pebax and nickel-based MOF particles. The MOF particles were synthesized using nickel­(II) acetate tetrahydrate as a metal source and 2-amino-1,4-dicarboxybenzene (NH2-BDC) as an organic linker. The properties and performance of the MOFs and synthesized membranes were assessed using analytical techniques including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and dynamic light scattering (DLS). DLS analysis showed that the MOF particle size range was in a range of 350–650 nm. Moreover, cross-sectional FE-SEM images depicted that a uniform and dense Pebax layer was shaped on top of the PES substrate. Well dispersion of the particles was demonstrated by surface FE-SEM imaging. DSC analysis showed that embedding Ni-NH2-BDC MOF particles into the Pebax-1657 film increased the crystallinity degree and the glass-transition temperature (T g) of resulted membranes. To evaluate the membrane’s separation performance, permeation experiments were performed with CO2, CH4, and CO2/CH4 mixtures at ambient temperature. Embedding 5 wt % Ni-based MOF particles improved the CO2 permeability and CO2/CH4 selectivity from 19.05 Barrer and 32.2 to 31.55 Barrer and 94, respectively, compared to MOF-free membranes. Loading MOF particles into the Pebax matrix also improved the real gas separation factor. The obtained results demonstrate the great potential of the fabricated TFC membranes for gas separation.