Search

Producing crystalline covalent organic framework (COF) films is intimately related to the elusive nucleation and growth processes, which is desirable for efficient molecular transport. Rational control over these processes and insights into the mechanisms are crucial to improve synthetic methodology and achieve COF films with regular channels. Here, we report the controllable synthesis of COF films via the temperature‐swing strategy and explore their crystallization from monomer assemblies to film formation. A detailed time‐dependent study reveals that COF crystallites preferentially coalesce at low temperature, progressing from assembled nanospheres to continuous films through lateral and vertical interactions. Moreover, appropriately elevating the synthesis temperature promotes crystal growth and eliminate the defects of weakly crystalline regions, contributing to highly crystalline and porous COF film with a surface area of 746 m2 g−1. The prepared COF composite membrane exhibits a methanol permeance of 79 L m−2 h−1 bar−1, which is 4.5 times higher than the weakly crystalline counterpart. In addition, the molecular sieving test recognize great membrane selectivity to discriminate the antibiotic mixture with a high separation factor of 15.4. This work offers a feasible way for the rational design of the synthesis environment, enabling access to highly crystalline framework materials for targeting molecular separations. [ABSTRACT FROM AUTHOR]

This study investigates the fabrication of organic solvent nanofiltration (OSN) membranes through laser‐induced graphitization of polybenzimidazole (PBI). Employing a CO2 laser, the polymer is converted into graphene, resulting in controlled submicron‐scale porous 3D structures, a feat not achievable with traditional methods such as chemical crosslinking. The effectiveness of this process hinges on precise adjustments of laser parameters, such as fluence, to attain the ideal graphitization levels. The findings indicate that partial graphitization, as opposed to excessive, is crucial for preserving the membrane's microstructure and enhancing its functional properties. The partially graphitized PBI‐LIG (Polybenzimidazole ‒ Laser‐induced Graphene) membranes achieved up to 94% rejection of Congo red from ethanol, with an ethanol permeance rate of 12.14 LMH bar−1—nearly twice that of standard PBI membranes. Additionally, these membranes showcased outstanding chemical stability and solvent resistance, maintaining over 99% structural integrity and experiencing <1% weight loss after prolonged exposure to various industrial solvents over a week. These results highlight the potential of laser‐graphitized PBI membranes for applications in harsh chemical conditions, paving the way for further optimization of high‐performance OSN membranes. This research advances membrane technology, merging laser engineering with materials science, and contributes to environmental sustainability and industrial efficiency. [ABSTRACT FROM AUTHOR]

Membrane separation technology has found widespread application in molecular sieving and water reclamation. Its use in organic solvent nanofiltration (OSN) has been limited by the modest permeation rates and stability of existing membranes. In this study, 2D clay nanolaminated membranes are engineered, derived from the stacking of exfoliated vermiculite nanosheets, as a potential solution for OSN. The as‐synthesized clay membrane displayed limited stability in both water and solvents due to rapid hydration or solvation of the nanosheets. To enhance the membrane's stability and sieving capabilities, cations of various valences (K+, Na+, Mg2+, Ca2+, Fe3+) are intercalated into the interlayer of the clay nanosheets. The resulting cation‐treated clay membranes display considerable enhancement in structural stability in both aqueous and organic media. Subsequently, the solvent transport behavior and separation performance of these clay membranes are evaluated and described by molecular dynamic simulation and experiments. It is identified that Fe‐intercalated nanolaminates demonstrate controllable stacking order, resulting in enhanced sieving performance with a rejection rate of over 95% for Methyl Orange and a methanol permeation rate of ≈165 L m−2 h−1 bar−1 [LMHB]. The findings of this work pave the way for the practical applications of 2D nanolaminated clay membranes in OSN. [ABSTRACT FROM AUTHOR]

Fabrication of crystalline, robust covalent organic framework (COF) membranes based on disorder‐to‐order strategy is promising yet highly challenging. Herein, a microwave‐assisted method for fabricating COF membranes is proposed. Initially, monomers polymerize rapidly on the surface of porous Al2O3 substrate at room temperature to form an amorphous pristine membrane. Subsequently, a microwave field is exerted to trigger fast crystallization, acquiring a crystalline COF membrane within 60 min. The amorphous pristine membrane exhibits a high dissipation factor, indicating excellent microwave absorption capability, which accelerates the dynamic reversible reactions during the microwave treatment and thus ensures a rapid transition from the amorphous to the crystalline state. Owing to the high‐crystallinity and robust structure, the COF membranes exhibit high rejection rates for solute molecules with molecular weights exceeding 700 Da (e.g., Evans blue: 98.7%) and high solvent permeance for organic solvents (e.g., ethanol: 87.8 Lm−2h−1 bar−1, n‐hexane: 222.3 Lm−2h−1 bar−1). Surprisingly, the COF membranes exhibit superior mechanical properties, with Young's modulus of 33.91 ± 3.94 GPa, outperforming previously reported polycrystalline COF membranes and are close to those for inorganic zeolite membranes. The microwave‐assisted COF crystallization method opens a new avenue to fabricating a variety of crystalline membranes for advanced separations. [ABSTRACT FROM AUTHOR]

A key challenge in efficient molecular separation is fabricating large‐scale, highly selective polymeric membranes with precise pore control at the molecular scale. Herein, a new contorted monomer 6,6′‐dihydroxy‐2,2′‐biphenyldiamine (DHBIPDA) is introduced as a building block to generate cross‐linked, ultra‐thin microporous nanofilms (sub‐10 nm) via interfacial polymerization, enabling rapid, and precise molecular nanofiltration. Using diacyl chloride (TPC) as the cross‐linker instead of trimesoyl chloride (TMC) significantly reduces the pore sizes within the membranes and achieves a narrower pore distribution due to a semi‐crystalline structure. The film structures are confirmed using comprehensive characterization techniques including wide‐angle X‐ray scattering (WAXS), X‐ray diffraction (XRD), positron annihilation lifetime spectroscopy (PALS), CO2 adsorption analysis, and molecular‐scale simulation. The DHBIPDA/TPC and DHBIPDA/TMC membranes achieve methanol permeance values of up to 16.4 and 15.1 LMH bar−1 coupled with molecular weight cutoffs (MWCOs) as low as 283 and 306 Da, respectively. The DHBIPDA/TPC membrane demonstrates both higher permeance and higher selectivity compared to its relatively disordered counterpart DHBIPDA/TMC, consistent with characterization data. The DHBIPDA‐derived membrane efficiently separates dye mixtures with similar molecular weights and enables effective recycling of organometallic homogeneous catalysts, suggesting its potential for industrial applications. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs), known for their chemical stability and porous crystalline structure, hold promises as advanced separation membranes. However, fabricating high‐quality COF membranes, particularly on industrial‐preferred hollow fiber substrates, remains challenging. This study introduces a novel vapor/vapor‐solid (V/V−S) method for growing ultrathin crystalline TpPa‐1 COF membranes on the inner lumen surface of alumina hollow fibers (TpPa‐1/Alumina). Through vapor‐phase monomer introduction onto polydopamine‐modified alumina at 170 °C and 1 atm, efficient polymerization and crystallization occur at the confined V−S interface. This enables one‐step growth within 8 h, producing 100 nm thick COF membranes with strong substrate adhesion. TpPa‐1/Alumina exhibits exceptional stability and performance over 80 h in continuous cross‐flow organic solvent nanofiltration (OSN), with methanol permeance of about 200 L m−2 h−1 bar−1 and dye rejection with molecular weight cutoff (MWCO) of approximately 700 Da. Moreover, the versatile V/V−S method synthesizes two additional COF membranes (TpPa2Cl/Alumina and TpHz/Alumina) with different pore sizes and chemical environments. Adjusting the COF membrane thickness between 100–500 nm is achievable easily by varying the growth cycle numbers. Notably, TpPa2Cl/Alumina demonstrates excellent OSN performance in separating the model active pharmaceutical ingredient glycyrrhizic acid (GA) from dimethyl sulfoxide (DMSO), highlighting the method's potential for large‐scale industrial applications. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the fabrication of organic solvent nanofiltration (OSN) membranes through laser‐induced graphitization of polybenzimidazole (PBI). Employing a CO2 laser, the polymer is converted into graphene, resulting in controlled submicron‐scale porous 3D structures, a feat not achievable with traditional methods such as chemical crosslinking. The effectiveness of this process hinges on precise adjustments of laser parameters, such as fluence, to attain the ideal graphitization levels. The findings indicate that partial graphitization, as opposed to excessive, is crucial for preserving the membrane's microstructure and enhancing its functional properties. The partially graphitized PBI‐LIG (Polybenzimidazole ‒ Laser‐induced Graphene) membranes achieved up to 94% rejection of Congo red from ethanol, with an ethanol permeance rate of 12.14 LMH bar−1—nearly twice that of standard PBI membranes. Additionally, these membranes showcased outstanding chemical stability and solvent resistance, maintaining over 99% structural integrity and experiencing

Organic solvent nanofiltration (OSN) plays important roles in pharmaceutical ingredients purification and solvent recovery. However, the low organic solvent permeance under cross‐flow operation of OSN membrane hampers their industrial applications. Herein, we report the construction of coffee‐ring structured membrane featuring high OSN permeance. A water‐insoluble crystal monomer that dissolved in EtOH/H2O mixed solvent was designed to react with trimesoyl chloride via interfacial polymerization. Owing to the diffusion of EtOH to n‐hexane, coffee‐ring nanostructure on the support membrane appeared, which served as the template for construction of coffee‐ring structured membrane. The optimal nanostructured membrane demonstrated 2.6‐fold enhancement in the effective surface area with reduced membrane thickness. Resultantly, the membrane afforded a 2.7‐fold enhancement in organic solvent permeance, e.g. ~13 LMH/bar for MeOH, without sacrificing the rejection ability. Moreover, due to the rigid monomer structure, the fabricated membrane shows distinctive running stability in active pharmaceutical ingredients purification and the ability for concentration of medicines. [ABSTRACT FROM AUTHOR]

• PDA-HKUST-1 interlayer enhances the stability of OSN membrane structure. • PA layer thickness of PA/ PDA -HKUST-1 0.6 /PEI membrane is about 14 nm. • PA/CaAlg-HKUST-1 6 /PEI membrane has good solvent resistance. Polydopamine (PDA) and metal-organic skeleton HKUST-1 were co-deposited on the base membrane of hexamethylenediamine (HDA)-crosslinked polyetherimide (PEI) ultrafiltration membrane as the interlayer, and high-throughput organic solvent nanofiltration membrane (OSN) was prepared by interfacial polymerization and solvent activation reaction. The polyamide (PA) layer surface roughness from 28.4 nm in PA/PEI to 78.3 nm in PA/PDA-HKUST-1 0.6 /PEI membrane, reduced the thickness of the separation layer from 79 to 14 nm, and significantly improved the hydrophilic, thermal and mechanical properties. The flux of the PA/PDA-HKUST-1 0.6 /PEI membrane in a 0.1 g/L Congo Red (CR) ethanol solution at 0.6 MPa test pressure reached 21.8 L/(m2·hr) and the rejection of CR was 92.8%. Solvent adsorption test, N, N-dimethylformamide (DMF) immersion experiment, and long-term operation test in ethanol showed that the membranes had high solvent tolerance. The solvent flux test demonstrated that, under the test pressure of 0.6 MPa, the flux of different solvents ranked as follows: methanol (56.9 L/(m2·hr)) > DMF (39.6 L/(m2·hr)) > ethanol (31.2 L/(m2·hr)) > IPA (4.5 L/(m2·hr)) > N - hexane (1.9 L/(m2·hr)). The ability of the membranes to retain dyes in IPA/water dyes solution was also evaluated. The flux of the membrane was 30.4 L/(m2·hr) and the rejection of CR was 91.6% when the IPA concentration reached 50%. This OSN membrane-making strategy is economical, environment-friendly and efficient, and has a great application prospect in organic solvent separation systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Phenolic compounds from a hydroalcoholic extract of wet olive pomace were purified and concentrated by an integrated membrane process in organic media. First, UF010104 (Solsep BV) and UP005 (Microdyn Nadir) membranes were tested to be implemented in the ultrafiltration stage, with the aim of purifying the extract and obtaining a permeate enriched in phenolic compounds. Despite the high flux observed with the UF010104 membrane (20.4 ± 0.7 L·h−1·m−2, at 2 bar), the UP005 membrane was selected because of a more suitable selectivity. Even though some secoiridoids were rejected, the permeate stream obtained with this membrane contained high concentrations of valuable simple phenols and phenolic acids, whereas sugars and macromolecules were retained. Then, the ultrafiltration permeate was subjected to a nanofiltration step employing an NF270 membrane (DuPont) for a further purification and fractionation of the phenolic compounds. The permeate flux was 50.2 ± 0.2 L·h−1·m−2, working at 15 bar. Hydroxytyrosol and some phenolic acids (such as vanillic acid, caffeic acid, and ferulic acid) were recovered in the permeate, which was later concentrated by reverse osmosis employing an NF90 membrane. The permeate flux obtained with this membrane was 15.3 ± 0.3 L·h−1·m−2. The concentrated phenolic mixture that was obtained may have important applications as a powerful antioxidant and for the prevention of diabetes and neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

In the pursuit of developing advanced nanofiltration membranes with high permeation flux for organic solvents, a TiO2 nanofilm was synthesized via a vapor–liquid interfacial reaction on a flat-sheet α-Al2O3 ceramic support. This process involves the reaction of glycerol, an organic precursor with a structure featuring 1,2-diol and 1,3-diol groups, with TiCl4 vapor to form organometallic hybrid films. Subsequent calcination in air at 250 °C transforms these hybrid films into carbon-doped titanium oxide nanofilms. The unique structure of glycerol plays a crucial role in determining the properties of the resulting nanopores, which exhibit high solvent permeance and effective solute rejection. The synthesized carbon-doped TiO2 nanofiltration membranes demonstrated impressive performance, achieving a pure methanol permeability as high as 90.9 L·m−2·h −1·bar−1. Moreover, these membranes exhibited a rejection rate of 93.2% for Congo Red in a methanol solution, underscoring their efficacy in separating solutes from solvents. The rigidity of the nanopores within these nanofilms, when supported on ceramic materials, confers high chemical stability even in the presence of polar solvents. This robustness makes the carbon-doped TiO2 nanofilms suitable for applications in the purification and recovery of organic solvents.

Hollow fiber (HF) organic solvent nanofiltration (OSN) membranes have recently attracted significant interest in the field of membrane technology. Their popularity stems from comparative advantages, such as high packing density, fouling resistance, and easier scalability for larger applications, unlike flat-sheet/spiral-wound OSN membranes, which may present challenges in these aspects. The combination of interfacial polymerization (IP) and HF configuration has opened up new opportunities for developing advanced membranes with enhanced separation performance that can be tailored for various OSN applications. The objective of this review is to discuss the latest advancements in developing thin film composite (TFC) HF membranes, with a focus on the IP method. Novel materials and processes are discussed in detail, emphasizing the fabrication of greener, interfacially polymerized HF OSN membranes. In addition, the commercial viability and limitations of TFC HF membranes are highlighted, providing perspectives on future research directions. [ABSTRACT FROM AUTHOR]

Membrane technology has become one of the most promising separation technologies for its energy saving, high separation efficiency, environmental friendliness, and economic feasibility. Covalent organic frameworks (COFs) with intrinsically high porosity, controllable pore size, uniform pore size distribution and long-range ordered channel structure, have emerged as next-generation materials to fabricate advanced separation membranes. This feature article summarizes some latest studies in the development of pure COF membranes in our lab, including their fabrication and applications in chemical separations. Finally, current challenges facing high-performance COF separation membranes are discussed. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration has been commonly used in the pharmaceutical and petroleum chemistry industries. As a two-dimensional (2D) nanomaterial, graphene oxide (GO) nanosheets have great potential for the fabrication of organic solvent nanofiltration membranes, while unfavorable swelling and peeling of the GO membrane have hampered their practical application. Herein, GO hybrid membranes with strong stability were designed using reduced graphene oxide (rGO) nanoflake as intercalation and poly-(vinyl alcohol) (PVA) as binder to improve the interfacial bonding force between the GO hybrid layer and nylon substrate. Benefiting from the excellent structure stability, the optimized GO hybrid membranes exhibited a high water permeance (24.49 L m–2 h–1 bar–1), an excellent solvent nanofiltration performance of 28.32 L m–2 h–1 bar–1 for methanol and 10.11 L m–2 h–1 bar–1 for ethanol, and a molecular weight cutoff (MWCO) of 320 g mol–1. Furthermore, the GO hybrid membranes exhibit good antifouling properties with a higher permeance recovery ratio after physical washing with deionized water. Overall, GO hybrid membranes with excellent permeability and antifouling properties are expected to be valuable in the field of organic solvent nanofiltration. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) is an emerging separation technology. Significant efforts have been dedicated to designing and fabricating thin film composite (TFC) membranes for OSN in recent years. The development and utilization of TFC membranes in OSN are paramount in ensuring the permeability of organic solvent and rejection of solute. Additionally, researchers have delved into optimizing preprocessing and post‐treatment procedures during preparation. The preparation process has emerged as another avenue for improving the separation performance of TFC membranes. Simultaneously, various supports have been explored to enhance the TFC membranes′ performance, including polymer substrates and inorganic substrates, as well as the interlayers between the substrate and the TFC membrane, each with unique advantages and disadvantages, and the choices of support depend on the specific requirements of the intended application. The limitations of conventional membranes could be overcome and thus achieve superior performance via an improved preparation strategy of the TFC membranes. This review presents a comprehensive overview of the preparation process for TFC membranes, including a detailed discussion of the preparation methods, the optimizing processes, and the substrates. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) featuring high porosity and well-defined pore structures are attractive candidates for organic solvent nanofiltration (OSN). However, preparing defect-free COF membrane and manipulating pore size for precise molecular separation in OSN remains a significant challenge. Herein, we address this challenge by developing composite membranes through molecular soldering a benzimidazole-linked polymer (BILP-101x) onto a continuous ACOF-1 membrane. The shared monomer of ACOF-1 and BILP-101x promotes good compatibility, allowing the amorphous BILP-101x chemically stitch the grain boundary defects of the crystalline ACOF-1 layer and create narrow, staggered pores at the interface, thereby enhancing the OSN performance. Non-equilibrium molecular dynamics simulations were employed to reproduce and explain the permeability order of the solvents and dyes, revealing a hydrogen-bond cluster permeation mode for alcohols. Furthermore, the optimized BILP-101x/ACOF-1 composite membrane exhibits excellent ethanol permeance (13.2 ​L ​m−2 ​h−1 bar−1) and outstanding rejection towards various dye molecules, together with desirable and stable OSN performance under continuous filtration operation. This work opens a new avenue for improving the separation performance of continuous COF membranes in OSN applications.

Organic solvent nanofiltration (OSN) is an emerging energy-efficient separations technology, which urgently requires easily processable OSN membranes with high selectivity and broad-spectrum organic solvent applicability to facilitate enhanced industrial applications. Herein, we describe the preparation of microporous polyesteramide (PEA) membranes through interfacial polymerization (IP) between amino-diphenol monomers and trimesoyl chloride (TMC) on a poly(ether ether ketone) (PEEK) support. The crosslinked network structures and large twisted monomers enhance the microporosity of PEA membranes, leading to a significant improvement in solvent permeance while maintaining high selectivity. The optimized PEA membrane demonstrates exceptional permeance for acetone (21.0 ​L ​m−2 ​h−1 bar−1) and methanol (14.3 ​L ​m−2 ​h−1·bar−1), with a molecular weight cut-off of 296 ​g ​mol−1. Additionally, the PEA/APH-diphenol membrane exhibits ultrafast permeance for the nonpolar solvent toluene (8.3 ​L ​m−2 ​h−1·bar−1), owing to the introduction of a large number of ester groups. Overall, PEA membranes prepared through the molecular-level structure design of IP monomers possess enormous industrial application potential owing to their high performance and broad-spectrum applications.

Covalent organic polymers (COPs) membranes have been widely investigated in recent years for the application and preparation of composite nanofiltration (NF) membranes due to the abundant pore structure. However, there are still difficulties in the easy and reliable preparation of scalable and highly permeable COPs membranes. In this work, the polyaminophenylene (PAP) layer was constructed on polysulfone (PSF) ultrafiltration membranes by diazonium-induced anchoring process (DIAP), and then used as a substrate to prepare ultra-thin and highly permeable COPs NF membranes by interfacial polymerization (IP) in only 20 ​s. The presence of PAP layer increases the aqueous phase monomer storage to promote the forward progression and limits the reaction zone of IP, thus resulting in ultrathin and highly crosslinked COPs membranes. In addition, the PAP layer covalently grafted onto the PSF molecular chain also participates in the IP reaction, thus the separation layer is connected to the substrate as a whole for better stability and can operate for long periods of time in an alcohol-based organic solvent environment. The methanol permeance of optimal NF-PAP membrane prepared based on the above strategy can reach 362-398 ​L−1m−2h−1bar−1, which almost achieves an order of magnitude enhancement relative to other reported COPs organic solvent nanofiltration (OSN) membranes. The retention rate of the COPs composite membrane for naphthol green B (Mw ​= ​878) dye was about 98.5 ​%, demonstrating good alcohol recovery ability. In conclusion, this study offers a potential strategy for the development and application of COPs OSN membranes.

Organic solvent nanofiltration (OSN) is a membrane separation method that has gained much interest due to its promising ability to offer an energy-lean alternative for traditional thermal separation methods. Industrial acceptance, however, is held back by the slow process of membrane screening based on trial and error for each solute-solvent couple to be separated. Such time-consuming screening is necessary due to the absence of predictive models, caused by a lack of fundamental understanding of the complex separation mechanism complicated by the wide variety of solute and solvent properties, and the importance of all mutual solute-solvent-membrane affinities and competing interactions. Recently, data-driven approaches have gained a lot of attention due to their unprecedented predictive power, significantly outperforming traditional mechanistic models. In this review, we give an overview of both mechanistic models and the recent advances in data-driven modeling. In addition to other reviews, we want to emphasize the coherence of all mechanistic models and discuss their relevance in an increasingly data-driven field. We reflect on the use of data in the field of OSN and its compliance with the FAIR principles, and we give an overview of the state of the art of data-driven models in OSN. The review can serve as inspiration for any further modeling activities, both mechanistic and data-driven, in the field. [ABSTRACT FROM AUTHOR]

Membranes synthesized by stacking two-dimensional graphene oxide (GO) hold great promise for applications in organic solvent nanofiltration. However, the performance of a layer-stacked GO membrane in organic solvent nanofiltration can be significantly affected by its swelling and interlayer spacing, which have not been systematically characterized. In this study, the interlayer spacing of the layer-stacked GO membrane in different organic solvents was experimentally characterized by liquid-phase ellipsometry. To understand the swelling mechanism, the solubility parameters of GO were experimentally determined and used to mathematically predict the Hansen solubility distance between GO and solvents, which is found to be a good predictor for GO swelling and interlayer spacing. Solvents with a small solubility distance (e.g., dimethylformamide, N-methyl-2-pyrrolidone) tend to cause significant GO swelling, resulting in an interlayer spacing of up to 2.7 nm. Solvents with a solubility distance larger than 9.5 (e.g., ethanol, acetone, hexane, and toluene) only cause minor swelling and are thus able to maintain an interlayer spacing of around 1 nm. Correspondingly, GO membranes in solvents with a large solubility distance exhibit good separation performance, for example, rejection of more than 90% of the small organic dye molecules (e.g., rhodamine B and methylene blue) in ethanol and acetone. Additionally, solvents with a large solubility distance result in a high slip velocity in GO channels and thus high solvent flux through the GO membrane. In summary, the GO membrane performs better in solvents that are unlike GO, i.e., solvents with large solubility distance.

Fatty acids (FAs) and FA methyl esters (FAMEs) are easily isolated from vegetable oil and are important starting materials for the chemical industry to produce commercial products that are green, biorenewable, and nontoxic. A challenge in these applications is that mixtures of five or more FAs and FAMEs are isolated from a vegetable oil source, and methods to separate these mixtures are decades old and have increasingly high costs associated with the production of high-purity single-component FAs or FAMEs. We developed a method to separate these mixtures using mixed matrix membranes containing nanometer-sized covalent organic frameworks. The 2D, crystalline COFs possessed narrow distributions of pore sizes of 1.3, 1.8, 2.3, and 3.4 nm that separated FAs and FAMEs based on their degrees of unsaturation. The COFs were synthesized, characterized, and then encapsulated at 10 or 20% by weight into a prepolymer of epoxy that was then fully cured. For all mixed matrix membranes, as the degree of unsaturation increased, the FAs or FAMEs had a slower flux. The largest difference in flux was obtained for a COF/epoxy membrane with a pore size of 1.8 nm, and methyl stearate had a 5.9× faster flux than methyl linolenate. These are the first membranes that can separate the important C18 FAs and FAMEs found in vegetable oil. [ABSTRACT FROM AUTHOR]

Nanoporous graphene is promising for the fabrication of high-performance organic solvent nanofiltration (OSN) membranes owing to the excellent chemical resistance of graphene in organic solvents. Moreover, the nanopores increase solvent permeance by providing diffusion channels. However, conventional chemical and physical etching methods are generally applicable on a laboratory-scale, and the large-scale fabrication of these structures is challenging. Herein, a large-area nanoporous multilayer graphene oxide (NMG) membrane was prepared using a combination of slot-die coating and confined thermal treatment. Graphene oxide (GO) was coated on polymeric supports using a slot-die coater, which is generally used for continuous coating in industry. Afterward, the GO membrane was treated using a hot-pressing method to activate the nanopores on the graphene surface and weld the polymeric support with the graphene layer. The interlayer and pore structure of GO were tuned by modulating the hot-pressing time, and its influence on OSN performance was systemically investigated. The optimized NMG membrane exhibited a high ethanol permeance of 300 Lm−2h−1bar−1 and a sharp molecular weight cut-off of 500 g/mol. Furthermore , the enhanced adhesion between graphene and the polymeric support enables mechanically stable membrane operation under cross-flow conditions for 30 days, which is the longest test time reported for two-dimensional material-based OSN membranes thus far. [Display omitted] [ABSTRACT FROM AUTHOR]

The widely used dyes in the pharmaceutical, chemical, and medical industries have brought about an intensive concern for the sustainable development of the environment. Membrane separation offers a versatile method for classified recycling and the reuse of residual components. In this work, polyimide membranes were synthesized via the polymerization of 4,4′-(hexafluor-isopropylidene) diphthalic anhydride and 1,4-bis (4-aminophenoxy) benzene diamine. The organic solvent nanofiltration membrane was prepared by casting onto a glass plate and precipitating in the non-solvent phase. The properties of the membranes were recorded by FTIR, 1HNMR, TGA, and GPC. The molecular simulations were carried out to analyze the affinity between the membrane and different solvents. The membrane was used in the removal of Rose Bengal, methyl blue, Victoria blue B, and crystal violet from methanol. The effects of the feed liquid concentration, operating pressure, swelling degree, organic solvent resistance, and long-term running on the membrane performance were studied. Results showed that membranes prepared in this work demonstrated high solvent permeation and dye rejection due to the sieving effect and solvent affinity. For methyl blue, the solvent performance achieved a permeability of 2.18 L∙m−2∙h−1∙bar−1 corresponding to a rejection ratio of 94.2%. Furthermore, the membrane exhibited good stability over 60 h of continued testing. These results recommend a potential strategy in the development of a suitable monomer to prepare a polyimide membrane for dye separation. [ABSTRACT FROM AUTHOR]

Herein, thin‐film composite membranes consisting of poly(m‐phenyleneisophthalamide) substrate and polyamide active layer were constructed by transition metal ion‐assisted interfacial polymerization method. As compared to the traditional polyamide membranes, a much thinner polyamide layer (33 vs. 200 nm) can be synthesized with higher permeance (3.2 vs. 0.62 L m−2 h−1 bar−1) in the organic solvent nanofiltration. Similarly, the prepared membranes maintained a high rejection (>99%) for various dyes. Optimal membranes prepared by using Co2+ exhibited strong tolerance to various organic solvents with good long‐term stability. Positron annihilation spectroscopy and other characterization methods were used to investigate the relationships between the membrane microstructures and the enhanced separation performance. Based on molecular dynamics simulation, it was found that the diffusion coefficient of polyethyleneimine monomer decreased by about 18 times after adding Co2+ to the aqueous solution (forming coordination interaction). This procedure has great potential and sustainability for practical organic solvent nanofiltration applications. [ABSTRACT FROM AUTHOR]

Experimental data, along with theoretical modelling, are combined to explore the potential for the separation of an azeotropic polar/non-polar solvent mixture through an OSN membrane. A mixture of toluene/butanol was used for the model development, and then applied to toluene/ethanol, and toluene/heptane mixtures. Experimental data was obtained at various testing conditions to validate simulation results from a non-ideal solution diffusion transport model incorporating the Flory–Huggins ternary equations. Accounting for the effects of non-ideality in the feed and permeate solutions generated a better fit to the experimental data. The system of equations was solved using parameters obtained from mono component membrane data only. The model developed can be used as a pre screening check for the separation of a potential solvent mixture that an OSN membrane can offer prior to embarking upon an extensive experimental program. • Siloxane membranes fabricated and applied to separation of azeotropic mixture of toluene/butanol. • Flory Huggins ternary equations integrated into solution diffusion model and solved to aid in understanding of membrane transport. • Separation performance went through distinct maximum, and appeared governed by non-ideality of the system. [ABSTRACT FROM AUTHOR]

[Display omitted] • Organic solvent nanofiltration membranes are reviewed. • Discussed the role of functionalization and covalent crosslinking in membrane. • Covalent incorporation of organic, inorganic, and hybrid materials is described. • New OSN membranes incorporating 2D nanomaterials are discussed. • The challenges and prospects around OSN membranes are discussed. Organic solvent nanofiltration (OSN) membranes have gained significant attention owing to their pivotal role in various industrial applications, including pharmaceuticals, fine chemicals, and manufacturing. This review provides a comprehensive overview of the recent advances in OSN membrane technology, focusing on membrane materials, fabrication techniques, and strategies for tuning the chemistry, structure, and performance of OSN membranes. Initially, the fundamental principles underlying OSN are described, highlighting the critical parameters influencing membrane selectivity, permeability, and stability in organic solvents. It also focuses on the importance of covalent crosslinking in the design and fabrication of dense polyamide membranes. Subsequently, the design and synthesis of novel membrane materials are discussed, including polymeric, inorganic, and hybrid membranes. The use of 2D nanomaterials is summarized, with an emphasis on their structural characteristics and tailored properties for solvent separation applications. We further explored the innovative fabrication strategies, such as interfacial polymerization, modification of ultrafiltration supports, and tuning of the active layer chemistry by incorporating the membrane structure with porous nanofillers. This review also discusses the inhomogeneity issues between inorganic nanofillers and organic matrices of membranes as well as the strategies to overcome these limitations through proper functionalization. Finally, we identified emerging trends and prospects in OSN membrane research, encompassing sustainability, scalability, and integration with other membrane processes, to address existing challenges and discover new opportunities for efficient solvent separation in diverse industrial sectors. [ABSTRACT FROM AUTHOR]

Microporous organic polymers (MOPs) featuring chemically rigid backbones and permanent micropores are desirable for fabricating molecular selective membranes towards organics separation. However, coordinating facile film processing with high micropore persistence remains a challenge. In this paper, a low molecular weight polymers of intrinsic microporosity was rationally designed by precisely controlling the stoichiometric equilibrium of polymerization monomer. The polymers of intrinsic microporosity oligomers combine rigid and contorted structures with the aqueous solution processability, promoting the formation of 25-nm-thick polyaramide nanofilms with enhanced microporosity via support-free interfacial polymerization (SFIP). The resulting composite membranes have superior retention of small molecular solutes and high nonpolar and polar solvent permeances. Experiment and simulation results show that their excellent separation performance is due to substantially open and interconnected microporosity formed in the polymer networks based on rigid and contorted diamines as well as reduced film thickness. This study provides a new sight for using MOPs to construct high-microporosity membranes for precise and rapid molecular sieving. [Display omitted] • A novel rigid molecule that polymers of intrinsic microporosity oligomer (APIMO) was rationally designed. • APIMO was employed as the building block for constructing thin film via support-free interfacial polymerization. • The resultant thin film composite membrane displayed superior permeances of both nonpolar and polar solvents. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN), also called solvent-resistant nanofiltration (SRNF), has emerged as a promising technology for the removal of impurities, recovery of solutes, and the regeneration of solvents in various industries, such as the pharmaceutical and the (petro)chemical industries. Despite the widespread use of OSN/SRNF, the presence of scattered, non-standardized data, and the absence of openly accessible data pose critical challenges to the development of new membrane materials and processes, their comparison to the state-of-the-art materials, and their fundamental understanding. To overcome these hurdles, data from peer-reviewed research articles and commercial datasheets were curated via a standardized procedure to obtain an extensive dataset on the membrane materials, synthesis parameters, operational conditions, physicochemical properties, and performance of OSN/SRNF membranes. Thanks to a truly impressive joint effort of the OSN/SRNF community, the dataset contains, as per April 2024, 5006 unique membrane filtrations from 294 publications for 42 solvents under several process parameters. This findable, accessible, interoperable, reproducible, and open (FAIR/O) dataset is available on both the OSN Database and the newly inaugurated Open Membrane Database for SRNF (OMD4SRNF). These databases provide multiple visualization and data exploration tools. Here, the standardized procedure applied to curate the data and the functionality of the databases are outlined, as well as the online user interface to deposit new data by external users on the OMD4SRNF. This community-led project has been supported by all the co-authors of this work. Most importantly, they additionally agreed to systematically deposit their future peer-reviewed data on OSN/SRNF into the databases. We thereby pave the road for FAIR/O data in the field of OSN/SRNF to increase transparency, enable more accurate data analysis, and foster collaboration and innovation. [Display omitted] • New dataset containing synthesis and performance metrics of OSN/SRNF membranes • A data standardization protocol is proposed, following FAIR/O data practices • Inauguration of the OMD4SRNF, including a tool for data submission by external users • Data visualization and exploration tools available on OSN Database and OMD4SRNF • Community-led commitment to share future data on the OSN Database and OMD4SRNF [ABSTRACT FROM AUTHOR]

Resource recovery and reuse are essential for sustainable development, particularly for high-value resources such as homogeneous (photo)catalysts, active pharmaceutical ingredients, and high-value natural compounds, which can offer economic benefits. Recently, organic solvent nanofiltration (OSN) for resource recovery has gained significant attention owing to its advantages including low energy consumption and seamless integration with other processes. Polymers of intrinsic microporosity (PIMs) have great potential as membrane materials for OSN, owing to their excellent pore properties and solution processability. However, swelling and dissolution of PIMs in organic solvents can impede the filtration performance of PIMs-based OSN membranes. In this study, we fabricated thin-film composite hollow fiber membranes for OSN based on PIMs with improved organic solvent stability using a semi-interpenetrating polymer network (semi-IPN) formed by cross-linking Matrimid with 1,6-hexanediamine within the PIMs through the liquid phase cross-linking method. Semi-IPNs mitigate swelling and tighten the pores of PIMs-based membranes, enabling excellent filtration and molecular separation performance. Furthermore, the fabricated PIMs with a semi-IPN membrane exhibited excellent rejection performance (>96 %) for homogeneous photocatalysts, allowing successful concentration and recovery via OSN. Therefore, PIMs-based membranes with a semi-IPN hold great promise as OSN membranes for the recovery of valuable resources. [Display omitted] • Introducing semi-IPN into PIMs-based membrane for organic solvent nanofiltration. • The semi-IPN was formed within PIMs via liquid phase cross-linking method. • The semi-IPN improved solvent stability of PIMs-based membrane. • The semi-IPN made the pore size of PIMs-based membrane tighter. • The developed membrane exhibited excellent separation performance in organic solvent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Preparation of gel membrane by bridging TA to SA. • The double network enhanced the solvent resistance of the gel membrane. • Gel membrane had higher porosity and mechanical properties. • Gel membrane had high dye anti-fouling and self-cleaning ability. It is necessary to prepare a nanofiltration membrane with high permeation flux that can be used in the field of organic solvents. Gel membranes have a high solvent permeation flux, but their chained macromolecular structure is often unstable. In this study, tannic acid-bridged sodium alginate (TA x -Ca/FeSA) organic solvent nanofiltration (OSN) membranes were prepared by the phase transition method using aqueous Ca2+ and Fe3+ solutions as cross-linking agents. TA can interact with SA through hydrogen bonding hydrophobic bonding and other interactions to form an interpenetrating three-dimensional network structure. Compared with Ca/FeSA membrane, the average pore size of TA 0.125 -Ca/FeSA membrane was reduced from 1.03 nm to 0.74 nm, and the porosity was increased from 47.62 to 59.2 %. In addition, the TA 0.125 -Ca/FeSA membrane has the characteristics of a negative charge, super hydrophilicity, and high mechanical properties, exhibits a high permeation flux of 48.97 L·m−2·h−1·bar−1 with a rejection of 96.25 % for Congo red ethanol solution, has excellent solvent resistance, stain resistance, and self-cleaning ability. The TA 0.125 -Ca/FeSA membrane was demonstrated to have great potential for application in the fields of purification and solvent recovery. [ABSTRACT FROM AUTHOR]

Semi-crystalline poly (ether ketone) (PEK) materials with intrinsic solvent resistance are ideal materials for the preparation of organic solvent nanofiltration (OSN) membranes. Although some precursor materials have been developed for soluble processing through group protection strategies, these precursors are difficult to hydrolyze, limiting their practical applications. In this work, we designed an easily hydrolyzable N-cyclohexyl-poly (ether ketone ether imide) (CYH-PEKEI) precursor that could be converted to PEK by acid treatment at 80°C within 1 h. The results showed that the prepared membrane was stable in various organic solvents, with a permeance of 1.29 L m−2 h−1 bar−1 in N, N-Dimethylformamide (DMF), a molecular weight cutoff of 320 g/mol, and good long-term operational stability. Additionally, the membrane demonstrated excellent aging resistance during variable temperature DMF operation. This work has stimulated the potential of PEK membranes for OSN applications by optimizing the precursor structure. [Display omitted] • A soluble and processable PEK precursor polymer was synthesized. • The solvent-resistant PEK membrane can be obtained through a simple and rapid acid treatment. • The PEK membrane is capable of long-term operation in DMF solvent. • The PEK membrane exhibits excellent aging resistance and thermal stability. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) membranes with precise molecular-sieving performance have become increasingly important in chemical and pharmaceutical industries, desiring superior membranes with both high permeability and selectivity. Herein, the V-shape Tröger's base (TB) structure is incorporated in the polyamide network to engineer microporosity as well as the molecular-sieving performance of the thin-film composite (TFC) polyamide membrane for organic solvent nanofiltration (OSN). The TFC membrane containing the TB structure features a rigid and contorted chain structure, which affords high and stable methanol permeability in OSN applications. Furthermore, the H-bond interaction between the H of amide groups and N in TB reinforces the interchain interaction, endowing the membrane with a precise selectivity to organic solutes. The as-prepared TFC membrane demonstrated high methanol permeance of 16.6 L m−2 h−1 bar−1 and sieving performance to organic molecules with molecular weight cut-off (MWCO) down to 349 Da. Furthermore, the membrane demonstrates shape selectivity for organic solutes, exploiting the fine microporous structure. This study may provide insights into the molecular design of TFC membranes by finely tuning the molecular features for precise solute separations. TFC membranes prepared by interfacial polymerization using TBDA as an aqueous monomer with a V-shape structure were selected for the formation of trapped nanovoids in the polymer network. [Display omitted] • The V-shape TBDA was explored as aqueous phase to incorporate contorted polymer chains in the polymer network. • The PA-TBDA TFC membranes with a fine microporous structure exhibit both size and shape selectivity for organic solutes. • The PA-TBDA TFC membranes show excellent methanol permeance of 16.6 L m−2 h −1 bar −1 with MWCO down to 349 Da. • The PA-TBDA TFC membranes demonstrate excellent long-term stability and can be operated at 10 bar for 7 days in DMF. [ABSTRACT FROM AUTHOR]

Study of membrane performance and permeation model is of great significance for the development of solvent-resistant nanofiltration membranes. In this work, filtration experiments were carried out for ten solutes in methanol and ethanol solvents with two polymeric nanofiltration membranes. The effects of solvent, solute and membrane on the separation performance were investigated. The Donnan-steric-pore nanofiltration transport model (DSPM) based on aqueous nanofiltration was modified for the non-aqueous nanofiltration. It was found that the separation performance of the membrane was dominated by membrane structure parameters, physical properties of solvent and features of solute. The modeling results revealed that the solvent had influences on the average pore radius of the membrane; solute charge, solute-solvent-membrane interactions existed in non-aqueous nanofiltration; and the modified model was suitable to predict rejections of neutral solutes rather than charged solutes in the non-aqueous system. These findings provide a novel modification strategy that could be utilized as a convenient and powerful tool for predicting membrane performance and understanding the separation disciplines of non-aqueous nanofiltration. [ABSTRACT FROM AUTHOR]

The development of polymer materials and polymer membrane fabrication techniques in recent years greatly elevates the importance and feasibility of organic solvent nanofiltration (OSN) technology, while challenges from different perspectives still hinder the wider applications of polymer based OSN membranes. This article reviews the OSN membrane research specifically from the perspective of polymer membrane materials, starting by recapping the recent progress of polymer based integrally skinned asymmetric (ISA) and thin film composite (TFC) OSN membranes. Comparing to commercially available polyimide ISA membranes and polyamide TFC membranes, multiple categories of emerging polymer materials result in membranes with much improved permselectivity for highly efficient molecular separation. In view of adopting OSN membranes for engineering applications, this review also summarizes some key challenges unique to polymer membranes including material swelling, physical aging and membrane compaction, and recent efforts to overcome them. The future research direction and application prospects of polymer OSN membranes are briefly discussed in the latter part of the article, noting that improved membrane formation control and crosslinking strategies, and the development of emerging polymer membrane materials is at high necessity to break through the application constraints of OSN in terms of permselectivity and performance stability. [ABSTRACT FROM AUTHOR]

For the sake of recovery of precious organic solvents from industrial organic solvent waste stream or alternatively for recovery of active principle ingredient (API) synthesized in pharmaceutical companies, organic solvent nanofiltration (OSN) membranes have recently been emerged. A thin film composite (TFC) membrane was fabricated by using rapid membrane fabrication technique. The PA(TEPA-TCL)@PSU/PETP membrane was fabricated by penta-amine (TEPA) impregnation of polysulfone (PSU) matrix during phase inversion which in turn was reacted with terephthaloyl chloride (TCL) through interfacial polymerization (IP). The PA(TEPA-TCL)@PSU/PETP membrane was characterized by scanning electron microscopy (SEM), water contact angle (WCA), energy dispersive X-ray (EDX) analysis, ATR-FTIR and elemental mapping. The PA(TEPA-TCL)@PSU/PETP membrane was applied for OSN by using water, methanol, ethanol and isopropanol as solvents. When methanol was used as feed, it showed a permeate flux of 28 L m−2 h−1 (LMH) at 20 bar. An inverse relationship was found between viscosity and flux of the solvents. A feed composed of methanol and dyes (dyes were used as model pollutants) was used to evaluate the OSN performance of the membrane. Apparently, size exclusion mechanism was found to be responsible for rejection of dyes as EBT was rejected up to > 92 % and Congo red (CR; M.W. = 696.6 g mol−1) rejection reached > 96% while it stayed at ≈ 88 % for Methylene blue (MB; M.W. = 319.8 g mol−1). The UV-Visible analysis of feed and permeate was conducted which confirmed the rejection of CR and MB. Hence, the PA(TEPA-TCL)@PSU/PETP membrane was found to be efficient for the purification of organic solvents contaminated with organic dyes. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of highly permeable and selective thin-film composite (TFC) membranes is essential for organic solvent nanofiltration (OSN) applications. However, overcoming the permeability–selectivity trade-off in polymer membranes remains highly challenging owing to the difficulty in controlling the thickness and nanostructures of the selective layers. In this study, TFC OSN membranes with sandwich-like structures were developed via interfacial polymerization on Cu-TCPP nanosheet-modified microporous polyvinylidene fluoride (PVDF) substrate surface. The interfacial polymerization was done by using mixed amine (polyethyleneimine and piperazine) in the aqueous phase and the 1,3,5-benzenetricarbonyl trichloride in the hydrophobic ionic liquid phase as monomers. It was found that the Cu-TCPP nanosheets of micrometer lateral dimensions and nanometer thickness (1.5 ± 0.6 nm) can be deposited on the PVDF substrate as an interlayer to facilitate the following interfacial polymerization reaction. The Cu-TCPP interlayer also can be served as a binder between the polyamide selective layer and the microporous PVDF substrate to enhance their mechanical strength. As compared with the PVDF/PA membrane, the PVDF/t-Cu-TCPP/PA membrane exhibited higher elongation (8.0 vs. 4.6%) while ensuring slightly lower tensile strength (36.0 vs. 48.6 MPa). Under optimal synthetic conditions, the TFC membranes could achieve 2.7 L m–2 h–1 bar–1, and 98.9% and 95.0% rejection to Brilliant Blue R (826 Da) and Congo red (697 Da), respectively, in ethanol. Furthermore, the membranes showed steady performance throughout the 36 h nanofiltration of the Rose bengal/ethanol mixture and exhibited good performance in the concentration of lecithin in methanol. Accordingly, this work highlights the potential of using thin metal–organic framework nanosheets as interlayers to develop high-performance TFC membranes for OSN applications. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) is an emerging membrane separation technology, which urgently requires robust, easily processed, OSN membranes possessing high permeance and small solutes‐selectivity to facilitate enhanced industrial uptake. Herein, we describe the use of two 2,2′‐biphenol (BIPOL) derivatives to fabricate hyper‐crosslinked, microporous polymer nanofilms through IP. Ultra‐thin, defect‐free polyesteramide/polyester nanofilms (≈5 nm) could be obtained readily due to the relatively large molecular size and ionized nature of the BIPOL monomers retarding the rate of the IP. The enhanced microporosity arises from the hyper‐crosslinked network structure and monomer rigidity. Specifically, the amino‐BIPOL/PAN membrane exhibits extraordinary permselectivity performances with molecular weight cut‐off as low as 233 Da and MeOH permeance of ≈13 LMH/bar. Precise separation of small dye mixtures with similar M.W. based on both their charge and molecular size are achieved. [ABSTRACT FROM AUTHOR]

Recycling of valuable solutes and recovery of organic solvents via organic solvent nanofiltration (OSN) are important for sustainable development. However, the trade-off between solvent permeability and solute rejection hampers the application of OSN membranes. To address this issue, the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) nanoparticle membrane with hierarchical pores is constructed for OSN via vacuum filtration. The small pores (the free volume of the polymer chain) charge for the solute rejection (high rejection efficiency for low molecule weight solute) and allow solvent passing while the large pores (the void between two PEDOT:PSS nanoparticles) promote the solvent transport. Owing to the lack of connectivity among the large pores, the fabricated PEDOT:PSS nanoparticle membrane enhanced solvent permeance while maintaining a high solute rejection efficiency. The optimized PEDOT:PSS membrane affords a MeOH permeance of 7.2 L m -2 h -1 bar -1 with over 90% rejection of organic dyes, food additives, and photocatalysts. Moreover, the rigidity of PEDOT endows the membrane with distinctive stability under high-pressure conditions. The membrane is used to recycle the valuable catalysts in a methanol solution for 150 h, maintaining good separation performance. Considering its high separation performance and stability, the proposed PEDOT:PSS membrane has great potential for industrial applications., (© 2024 Wiley‐VCH GmbH.)