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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]

Thin film nanocomposite (TFNi) membranes interlayered with 2D nanomaterials are promising for organic solvent nanofiltration (OSN) applications. However, swelling and drying problems can arise due to the instability of the 2D nanomaterial interlayer in different solvents and humidity conditions. To address this issue, covalently modified molybdenum disulfide (MoS 2) nanosheets (MoS 2 –COOH and MoS 2 –CONH 2) were used as interlayers in the fabrication of TFNi membranes. The covalent groups acted as spacers to stabilize the interlayer spacing of the MoS 2 interlayer and regulate its structural stability in diverse solvents and drying conditions. The TFNi membranes interlayered with MoS 2 –COOH and MoS 2 –CONH 2 nanosheets demonstrated excellent structural stability and maintained their high permeance even after exposure to various solvents and drying conditions. The TFNi-MoS 2 -CONH 2 membrane exhibited the highest permeance of 8.60 ± 0.23 L m−2 h−1 bar−1 for MeOH, with a high rejection of 87.1 ± 1.3 % for Evans Blue (EB). Furthermore, the TFNi membranes exhibited sustained separation performance throughout the 72 h test, demonstrating their structural stability. This study highlights the potential of TFNi membranes interlayered with covalently modified MoS 2 nanosheets for OSN applications, providing high permeance and structural stability in diverse solvents and drying conditions. [Display omitted] • Novel thin-film nanocomposite (TFNi) membranes interlayered with covalent modified MoS 2 nanosheets were fabricated. • The covalent modified MoS 2 interlayered TFNi membranes showed significantly improved solvent permeances. • The improved separation performance was attributed to the steric effect of the covalent groups. • The covalent modified MoS 2 interlayered TFNi membranes showed excellent anti-swelling and anti-drying abilities. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simultaneous Cu2+ crosslinking of polyimide substrate and polyamide layer. • Integrally-crosslinked membrane has a superior solvent resistance and performance. • The integrally-crosslinked membrane has a defect-free layer. • Slower MPD diffusion from Cu2+ crosslinked substrate of partially-crosslinked one. Thin film composite (TFC) membranes are commonly used for organic solvent nanofiltration (OSN) application. However, these membranes normally suffer from the layer delamination under harsh conditions. Chemically integral crosslinking is a common method to address this problem, but the resultant tightened polymeric chains and denser microstructure will inevitably bring the reduced solvent permeance. In this work, a facile metal integral crosslinking strategy, which has minimal adverse effect on the solvent permeance, was developed to improve the tolerance to the majority of organic solvents as well as enhance the adhesions of upper selective layers and underlying substrates simultaneously for the first time. The as-developed Cu2+ integrally-crosslinked membranes demonstrated a high permeance for organic solvents and a high rejection towards rose bengal. In comparison to the Cu2+ partially-crosslinked membranes (with substrate crosslinked only), the integrally-crosslinked ones exhibited superior solvent resistance and OSN performance. This improvement was attributed to the enhanced interactions and a defect-free PA layer. Additionally, the effects of solvent activation, crosslinking solution concentration as well as crosslinking time were also studied. It is believed that metal integral crosslinking strategy will offer a novel approach to develop promising TFC membranes with satisfactory OSN performance for practical applications. [ABSTRACT FROM AUTHOR]

• Organic solvent NF membranes were prepared using 4,4′-diaminodiphenylmethane. • Hydrophobic-modified NF membrane had the optimal performance in THF. • The permeances of organic solvents are related to the specific solvent properties. A kind of thin film composite polyamide nanofiltration (NF) membrane was synthesized via the interfacial polymerization between a new diamine monomer of 4,4′-diaminodiphenylmethane and trimesoyl chloride on the surface of cross-linked polyetherimide, and evaluated in some organic solvents including ACN, MeOH, EtOH, THF, etc. The optimal organic solvent NF membrane was selected to prepare respectively the hydrophilic membrane (Phi-NF) via grafting of Tris and the hydrophobic membrane (Pho-NF) via grafting of 2,2,2-trifluoroethylamine, combining with the characterization of ATR-FTIR, XPS, SEM, 13C NMR, AFM, etc. The permeance values of Phi-NF and Pho-NF membranes change greatly with organic solvents. Pho-NF-2 possesses the highest permeance of 66.4 L m−2 h−1 MPa−1 in THF with the erythrosin B (EB) rejection of 99.5%. Through analyzing the physiochemical properties of the organic solvents and calculating the surface energy, the correlations are deduced for the synthesized membranes, illustrating that the permeances of organic solvents are roughly proportional to the specific solvent properties for Phi-NF-2 and Pho-NF-2. The results suggest one promising method to enhance the separation performance of organic solvent NF membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A thin film nanocomposite membrane with interlayered CCN nanosheets was synthesized. • The introduction of CCN nanosheets enhanced the permeance of the TFNi membrane. • A strong chemical bonding was formed between the CCN interlayer and the PA layer. • The CCN-TFNi membrane demonstrated robust anti-swelling ability when exposed to DMF. • The CCN-TFNi-DMF membrane showed exceptional permeability and remarkable stability. The integration of a nanomaterial interlayer within a thin-film composite membrane can markedly enhance its performance in organic solvent nanofiltration (OSN). However, this enhancement often comes at the expense of membrane integrity due to differential swelling behaviors in diverse solvents. In this study, we present an interlayered thin film nanocomposite (TFNi) membrane that demonstrates both high permeance and robust stability, utilizing green, porous, and reactive crystalline carbon nitride (CCN) nanosheets as the functional interlayer. The results revealed that ascribed to the presence of the CCN interlayer, the membranes retained their rejection towards organic dyes even after 10 h of DMF exposure, while the organic solvent permeance was significantly improved by the DMF treatment. The methanol permeance of the CCN-TFNi-DMF membrane reached an impressive 8.77 L m−2 h−1 bar−1, sustaining stable performance throughout a 72 h test period under a pressure of 10 bar. We attributed this performance enhancement to the extra nanochannels introduced by the CCN nanosheets that bolstered the permeance of the TFNi membrane, as well as the formation of a stable polyamide film resulting from the reaction between the amino groups on the CCN nanosheet surface and trimesoyl chloride during the interfacial polymerization process. This work provides valuable insights into the development of structurally reinforced TFNi membranes with exceptional performance for OSN separation applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • TFC membranes with PEEK support and biphenyl polyamides active layer were fabricated for the first time. • Biphenyl polyamide nanofilms exhibited enhanced nano-mechanical strength, high solvent stability and regulated morphology. • The optimized membrane exhibited a high permeability for acetonitrile of 21.6 L m-2 h-1 bar-1. • MWCOs of the membranes can be customized between 170 to 370 g·mol−1 by employing appropriate biphenyl acyl chlorides. Developing polymeric separation membranes that combine excellent solvent stability, high permeability, and customizable molecular weight interception remains a challenge. Herein, thin-film composite (TFC) polyamide (PA) membranes with poly(ether ether ketone) (PEEK) support and biphenyl-centered polyamides active layer were fabricated through interfacial polymerization technique for the first time. Enhanced solvent stability was exhibited by the fabricated membranes due to the intrinsic resistance to organic solvents possessed by PEEK and biphenyl polyamides. The separation performance of the obtained membranes was systematically studied by relating to the properties of PA nanofilms in terms of nano-mechanical strength, morphologies, and microporosity. The organic solvent nanofiltration (OSN) performance of the resultant membranes in terms of permeability and molecular weight cut-off (MWCO) could be regulated. The optimized membrane exhibited a pure solvent permeability as high as 21.6 L m−2 h−1 bar−1 for acetonitrile and 14.0 L m−2 h−1 bar−1 for methanol. It also showed excellent long-term durability with almost unchanged permeability as well as solute retention remained above 97.8 % after a cumulative OSN operation of N, N -Dimethylformamide (DMF) based feed for 240 h. In particular, OSN membrane with targeted MWCOs covering the range of 170–370 g·mol−1 could be fabricated by selecting appropriate biphenyl acyl chlorides as building blocks. This approach offers a scalable and versatile platform for the development of solvent-stable, highly permeable, and customizable MWCO membranes for process-oriented OSN. [ABSTRACT FROM AUTHOR]

Here, we report a novel and facile technique to fabricate solvent resistant thin film composite (TFC) membranes for organic solvent nanofiltration (OSN). It consists of two steps: (1) chemically crosslinking a polybenzimidazole (PBI) membrane with dibromo-p-xylene (DBX) and (2) exposing its top surface to polyethylenimine (PEI) and forming an ultrathin and robust PEI-DBX selective layer on top of the PBI substrate. Different from the conventional interfacial polymerization, the proposed method results in the DBX crosslinked PBI substrates with great porosity and rigidity and TFC membranes with high free volume. It also eliminates the usage of hexane and trimesoyl chloride (TMC) so that the fabrication process becomes greener, faster and more efficient. Besides, it improves the adhesion of the selective layer to the support layer significantly. The resulting membranes not only display good chemical stability in DMAc at 50 °C but also possess a molecular weight cut off (MWCO) of ~350 g mol −1 with pure ethanol, acetone, tetrahydrofuran and toluene permeances of 4.5, 14, 4 and 1 L m −2 h −1 bar −1 , respectively. Given the ease of fabrication, outstanding stability and separation performance of the resultant membranes, the newly developed technique may be applicable to design next-generation OSN membranes for chemical and pharmaceutical industries involving the separation of organic solvents at elevated temperatures. [ABSTRACT FROM AUTHOR]

Thin film composite (TFC) polymer membranes are ubiquitous in membrane-based liquid separation processes, especially in reverse osmosis (RO). While the ultrathin polyamide separating layer employed in TFC membranes has exhibited excellent performance in many liquid separation processes, the polymer support has been identified as a bottleneck to practical applications. In this work, we report a highly porous, thermally and chemically robust support comprising a thermally rearranged polymer which is combined with a polyamide active layer to form a thermally rearranged, thin film composite (TR-TFC) polymer membrane for general use in liquid separation, and for environmentally-friendly power generation. The precursor polymer has good processability for scale-up of synthesis and membrane fabrication. After thermal rearrangement, the developed TR-TFC membranes containing polybenzoxazole- co -imide can be utilized in separations in any organic liquids, including under harsh environments such as dimethyl formamide even at elevated temperatures, with a remarkable performance. Moreover, the membrane achieves 40 W m −2 of power density through pressure retarded osmosis using a concentrated brine, similar to those obtained from RO plants. These results points to the possibilities for next-generation TFC polymer membranes for general use in liquid separation and power generation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanofiltration composite membrane shows excellent permeability and solvent resistance was prepared on PI/Noria composite ultrafiltration membrane. • Noria in PI solution can migrate to composite ultrafiltration membrane surface during non-solvent-induced phase separation and act as an interlayer, which can regulate the following interfacial polymerization. • This process omits the preparation process of the interlayer, making the preparation process simpler. • Due to the special composite surface structure, the interlayer is removed, which avoids the disadvantage of weak bonding force between the separation layer and the support layer caused by the existence of the interlayer. Organic solvent nanofiltration (OSN) membrane, a type of thin film composite (TFC) membrane, is widely used in separating organic solvents, but the low permeability of organic solvents is currently challenging to solve. This experiment used cross-linked polyimide (PI) as raw material and Noria as a nanoparticle additive to prepare a composite ultrafiltration membrane through non-solvent-induced phase separation (NIPS). Noria migrated to the composite ultrafiltration membrane surface during NIPS and acted as an interlayer, which can regulate the following interfacial polymerization. Then, the nanofiltration membrane was prepared by interfacial polymerization method using the modified PI membrane as the support layer. The experimental results showed that the hydrophilicity of the PI/Noria composite ultrafiltration membrane was significantly enhanced, in addition to a significant increase in pure water flux to 239 L m-2h-1bar−1. The methanol flux of the prepared composite nanofiltration membrane could be up to 5.472 L m-2h-1bar−1, which was twice as high as that of the unmodified composite membrane, and the G250 dye retention rate remained at over 99.6%. The nanofiltration performance is excellent and has good prospects for application in OSN. [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine learning was used to form prediction models for TFN-OSN membrane performance evaluation. • 20 references including 9252 data points were collected to form four different models: linear, SVM, BT, and ANN. • BT exhibited optimal prediction accuracy for membrane RP and RS performance prediction. • Partial dependence analysis provided the optimal conditions for TFN-OSN membrane fabrication. • Membrane with super-hydrophilic or super-hydrophobic surface property exhibited higher RP performance based on different feed solvent types. In this study, machine learning was used to form prediction models for thin film nanocomposite (TFN) organic solvent nanofiltration (OSN) membrane performance evaluation in terms of relative permeability (RP) and relative selectivity (RS). Twenty references including 9252 data points were collected to form four different models: linear, support vector machine (SVM), boosted tree (BT), and artificial neural network (ANN). Among the four models, BT exhibited optimal prediction accuracy in terms of root mean square error (RMSE) and coefficient of determination (R2) values for membrane RP (RMSE: 0.295, R2: 0.918) and RS (RMSE: 0.053, R2: 0.849) performance prediction. Parameter contribution analysis indicated that nanoparticle loading, amine concentration, chloride concentration, water contact angle, solvent viscosity, and molar volume are the main parameters influencing RP performance. For RS performance, nanoparticle loading, amine concentration, chloride concentration, and solute molecular weight play important roles. Partial dependence analysis indicated that the optimal conditions for TFN-OSN membrane fabrication are nanoparticle loading less than 5 wt%, the amine concentration around 2 wt%, and the chloride concentration around 0.15 wt%. In addition, membrane with super-hydrophilic or super-hydrophobic surface property exhibited higher RP performance based on different feed solvent types. Overall, this work introduces new ways both for TFN-OSN membrane performance prediction and for higher performance membrane design and development. [ABSTRACT FROM AUTHOR]

Thin-film composite membranes based on ∼100 nm cross-linked polyamides (PAs) are state-of-the-art membranes for liquid separations such as desalination. However, the PA layer shows poor antifouling properties and instability in chlorine solutions. Herein, we show for the first time that glassy amorphous perfluoropolymers (PFPs, such as Teflon AF and Hyflon AD) can be fabricated into ultrathin film composite (uTFC) membranes with a selective layer of <20 nm for desalination. Increasing the polymer concentration in the coating solutions from 0.05 mass% to 0.3 mass% increases the selective layer thickness from 9 to 25 nm. When Teflon AF2400 was fabricated into 16-nm selective layers on various porous supports, the water permeance decreases from 0.37 LMH/bar for PES10k to 0.07 LMH/bar for PES1k, and the Na 2 SO 4 rejection increases from 86.6% to 95.2%. While the water permeance is lower than the commercial PA-based NF membranes, the rejection in these PFP-based membranes is comparable. The effect of the porous support on the water permeance can be ascribed to the geometric restriction and satisfactorily described using an empirical model. Interestingly, the membranes also exhibit good Na+/Li+ separation performance and stable performance for organic solvent nanofiltration, showcasing the versatility of the PFP-based uTFC membranes for various liquid separations. [Display omitted] • Defect-free uTFC membranes comprising perfluoropolymers of <20 nm were prepared. • Porous supports may lower water permeance via geometric restriction. • Increasing the PFP free volume increases water permeance and decreases salt rejection. • UTFC membranes show salt rejection comparable to polyamide-based membranes. • PFP-based membranes show good separation properties of Li+/Na+ and methanol/dyes. [ABSTRACT FROM AUTHOR]

In this work we report a new class of solvent stable thin-film composite (TFC) membrane fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate that exhibits superior stability compared with other solvent stable polymeric membranes reported up to now. Integrally skinned asymmetric PTSC membranes were prepared by the phase inversion process and crosslinked with an aromatic bifunctional crosslinker to improve the solvent stability. TFC membranes were obtained via interfacial polymerization using trimesoyl chloride (TMC) and diaminopiperazine (DAP) monomers. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and contact angle measurement. The membranes exhibited high fluxes toward solvents like tetrahydrofuran (THF), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) ranging around 20 L/m 2 h at 5 bar with a molecular weight cut off (MWCO) of around 1000 g/mol. The PTSC-based thin-film composite membranes are very stable toward polar aprotic solvents and they have potential applications in the petrochemical and pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Abstract: Thin-film nanocomposite (TFN) membrane containing amino-functionalized UZM-5 nanoparticles was synthesized by interfacial polymerization on polyetherimide (PEI)/modified SiO2 asymmetric substrate tailored for organic solvent nanofiltration OSN process. m-Phenylenediamine (MPD) with trimesoyl chloride (TMC) was polymerized to prepare polyamide layer. UZM-5 nanoparticles (~73nm) were synthesized and then functionalized by aminopropylediethoxymethylsilane (APDEMS) and finally incorporated into polyamide (PA) selective layer at concentrations ranging from 0 to 0.2w/v%. The as-prepared TFN membranes were characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and contact angle measurements. The performances of membranes were also evaluated through dewaxing solvents (MEK and toluene) recovery from lube oil. FESEM and SEM images clearly confirmed that the polyamide/UZM-5 nanocomposite top layer was formed on the support surface and its morphology was significantly affected by UZM-5 loading. Interaction between functional groups of modified UZM-5 nanoparticles and polyamide matrix was established by ATR-FTIR. AFM results revealed that in the range of 0–0.1w/v% zeolite loading, the surface roughness of TFN membranes decreased due to the change of polyamide structure while at 0.2w/v% of zeolite loading, an increase in surface roughness was observed. It also resulted in enhanced hydrophilicity of TFN membranes in the range of 0–0.1w/v% UZM-5 loading, proved by a decreased water contact angle. The permeation test results indicated that the existence of UZM-5 in the polyamide selective layer improved both oil rejection and permeate flux under optimal concentration (0.02% w/v of UZM-5). [Copyright &y& Elsevier]

[Display omitted] • Ultra-low concentration for both MPD and TMC used during the interfacial polymerization process. • Ultra-low content Tannic acid functionalized MoS 2 nanosheets regulate the interfacial polymerization process. • Ultra-thin, ultra-smooth (2 nm in roughness) and hydrophilic TFN OSN membrane was obtained. • The TFN OSN membrane achieves a much higher pure DMF permeance of 219 L m−2h−1 MPa−1. • The TFN OSN membrane tolerates DMF at 80 ℃ for greater than 144 h and remains greater than 98% RDB (479 Da) rejection. Organic solvent nanofiltration (OSN) membranes are the key factors for the treatment of organic solution via OSN technology. In this work, we fabricated a kind of ultra-thin and ultra-smooth thin-film nanocomposite (TFN) OSN membrane using interfacial polymerization (IP) process with ultra-low concentration for both the aqueous and the organic monomers, together with doped tannic acid (TA) functionalized Molybdenum disulfide (MoS 2) nanosheets of ultra-low content in the aqueous monomer solution, and followed by post-IP chemical crosslinking and solvent activation procedures. The results demonstrated that the incorporated TA-MoS 2 nanosheets not only help to promote the solvent permeation, but also help to increase the solvent resistance and fouling resistance of the fabricated membrane. The optimal TFN OSN membrane fabricated using 0.05 wt% aqueous m -phenylenediamine (MPD) solution doped with TA-MoS 2 nanosheets content of 50 mg L−1 and 0.0025 wt% trimesoyl chloride (TMC) / n -hexane solution has an ultra-thin barrier layer, with an average thickness of about 15 nm. This endows it a much higher pure DMF permeance of 219.1 L m−2 h−1 MPa−1, which is much superior over most of literature works. Meanwhile, the fabricated TFN OSN membrane achieves a rejection of 99.1 % for rhodamine B (RDB, 479 Dalton), which is about 10.1 % increment compared with that of the baseline thin-film composite (TFC) membrane. The TFN OSN membrane also features an ultra-smooth skin layer, with a surface roughness of merely about 2.0 nm, which is quite beneficial for its fouling resistance performance. Moreover, the TFN OSN membrane features outstanding high solvent resistance. It remained a nearly constant and extremely high rejection for Rose Begal (RB, 1017 Dalton), about 99.9 %, and a much higher DMF permeance, 101 ± 2 L m−2 h−1 MPa−1, after cross-flow filtration for more than 200 h using 100 mg L−1 RB / DMF solution as feed, which is seldomly reported in literature. Even being immersed in DMF at 80 °C for more than 144 h, it remained a rejection of higher than 98 % for Rhodamine B (479 Dalton), indicating its superior solvent resistance and promising industrial application prospect. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel n-TFC membrane was developed by IP method on PEI/modified SiO2 support. [•] The amino-functionalized silica was blended with PEI to prepare solvent resistant support. [•] Effect of modified nanosilica on chemical and physical stability of support was studied. [•] Support morphology influenced the performance of resultant n-TFC membrane. [•] n-TFC membrane has proper lube oil rejection even at high pressure for OSN process. [ABSTRACT FROM AUTHOR]

Abstract: New compositions of sulfone polymer family, namely, sulfonated poly(ether sulfide sulfone) (SPESS) based on three different diphenols such as 1,1′-Thiobis(2-naphthol) (TBN), 2,2′-thiobis(4-methyl phenol) (TBMP) and curcumin (CUR) were synthesized via aromatic nucleophilic substitution copolymerization and used for enrichment of polysulfone (PSf) support in organic solvent nanofiltration. The bulk modification of PSf support was manipulated through blending with novel copolymers. Solvent resistant thin-film composite nanofiltration (TFC-SRNF) membranes were prepared on the reinforced PSf support by in situ interfacial polymerization with poly(ethyleneimine) and iso-phthaloyl dichloride. Chemical structure, morphology and physicochemical properties of the synthesized copolymers and the resultant membranes were characterized. The solubility of SPESS copolymers as an effective factor in membrane formation via phase inversion was evaluated in highly and moderate polar solvents. Their good solubility was attributed to the presence of flexible linkages and different functional groups. Furthermore, two conceptual models were presented into two different issues: (i) the mechanism of PSf bulk modification through blending with bulky SPESS copolymers and (ii) the surface property effects of the modified PSf support on the adhesion of polyamide thin film. In order to evaluate the swelling effect and organic–organic separation performance of TFC-SRNF membranes, two dyes with identical molecular size but different charges dissolved in methanol were selected. It was found that the employing SPESS reduced swelling degree significantly and consequently improved TFC-SRNF membrane performance. [Copyright &y& Elsevier]

Abstract: High free volume polymers are characterized by much higher permeability and diffusivity for gases and vapors than commodity polymers. Polymers of intrinsic microporosity (PIMs), an important member of this class of polymers, are only soluble in a few solvents. This gives reason to expect stability in many solvents and an application in organic solvent nanofiltration (OSN) may be feasible. Thin film composite membranes of PIM-1 and PIM copolymers were developed on a polyacrylonitrile (PAN) porous support. For control of swelling, a simple, technically realizable method of cross-linking was produced by blending the PIM with polyethyleneimine, coating to give thin film composites (TFCs) and thermally or chemically cross-linking the separation layer on the supporting membrane. The TFCs were tested in OSN with the solvents n-heptane, toluene, chloroform, tetrahydrofuran, and alcohols, and compared to similarly cross-linked poly(trimethylsilyl propyne) TFCs and state of the art industrial Starmem™ 240 membranes. Better retention, a steeper retention curve and much higher fluxes were detected for the newly developed PIM TFC membranes. [Copyright &y& Elsevier]

Membranes with high permeance, excellent selectivity coupled with adequate solvent resistance are required for organic solvent nanofiltration (OSN) applications. But the "trade-off" relationship between the solvent resistance and permeance remains a critical challenge for polymeric-based thin film composite (TFC) membranes with necessary chemical crosslinking. Herein, a novel facile cyclization modification of polyacrylonitrile (PAN) nanofiber substrate is proposed by a simply thermal treatment and subsequent alkaline hydrolysis, and employed for the fabrication of TFC-OSN membrane for the first time in strong polar aprotic solvent systems. The reaction mechanism involved, solvent resistance and pore structure of PAN nanofiber substrate brought by the modification are investigated. TFC-OSN membrane supported by the modified PAN nanofiber substrate exhibits ultrahigh solvent permeance up to 13.3 L m−2 h−1 bar−1 coupled with a 99.7% rejection in rose bengal/DMF system and a good long-term stability. This study is therefore believed to provide useful guidelines for the development of next-generation OSN membranes. [Display omitted] • A facile cyclization modification of PAN with thermal and alkaline treatment is proposed. • Modified PAN nanofiber substrate shows enhanced resistance in strong polar aprotic solvents. • The substrate with high porosity shows superior pure solvent permeance. • TFC membrane exhibits superior OSN performance to most previous works. [ABSTRACT FROM AUTHOR]

Electrospun polymeric membranes are promising substrates for thin-film composite (TFC) membranes due to their unique interconnected pores and high porosity. However, it is still challenging to fabricate desirable electrospun substrates for organic solvent nanofiltration (OSN) owing to the relatively complex processing procedures and the organic operating environment. In this work, solvent-resistant electrospun polyimide (PI) nanofiber substrates were successfully fabricated through electrospinning followed by chemical cross-linking and heat-pressing. The cross-linking step improved the solvent tolerance of the membranes, while the heat-pressing step reduced the substrate pore size and surface roughness. However, it was found that heat-pressing at high temperatures (>140 °C) could degrade the cross-linking of PI, undermining their solvent-resistant property. A polyamide thin film layer was then synthesized on the solvent-resistant electrospun nanofibrous substrates via interfacial polymerization using reactant monomers m -phenylenediamine (MPD) and trimesoyl chloride (TMC). The TFC membranes exhibited excellent acetonitrile and acetone permeabilities of 31.28 ± 1.93 and 26.58 ± 1.13 L m−2 h−1 bar−1, respectively, with acid fuchsin (585 Da) and methyl orange (327 Da) rejections of 98.55 ± 1.24% and 92.42 ± 1.66%, respectively, in acetone. This study successfully demonstrated the potential use of electrospun PI nanofibers substrates for TFC membranes in OSN. [Display omitted] • Solvent resistant nanofibrous PI substrates were prepared by electrospinning followed by chemical cross-linking and heat-pressing. • Heat-pressing influenced the PI substrates' surface properties and solvent resistance, and the optimal point was 140 °C. • Polyamide thin film was synthesized on the PI substrates via interfacial polymerization for OSN application. • Acetone permeability was 26.58 L m−2 h−1 bar−1 with high rejection to acid fuchsin and methyl orange. [ABSTRACT FROM AUTHOR]

Advanced organic solvent nanofiltration (OSN) membranes with high permeance and stability are highly needed in petrochemical and pharmaceutical industries. Recently, polymers of intrinsic microporosity (PIMs) have attracted significant attention for the development of advanced membranes, because of their high porosity and solution processability. In this study, a thin film composite membrane based on an amidoxime-functionalized PIM (AOPIM-1) was prepared by spin coating followed by solvent activation. The activation approach could dramatically improve the solvent permeance of the membrane without compromising its rejection performance. The changes in porosity of the AOPIM-1 layer before and after activation were confirmed by positron annihilation Doppler spectroscopy. The optimum membrane exhibited an impressively high ethanol permeance of 15.5 L m−2 h−1 bar−1, nearly one orders of magnitude higher than that of Starmem240 (a commercial polyimide-based OSN membrane) with a comparable rejection of Rose Bengal (MW 1017 Da). In addition, the present membrane exhibited outstanding stability in polar solvents and a remarkably high rejection of active pharmaceutical ingredients (vitamin B12) from ethanol. This work could provide a new avenue for developing highly permeable OSN membranes and is expected to stimulate the use of PIM membranes in OSN applications. [Display omitted] • AOPIM-1thin film composite membrane was prepared by a facile spin-coating and solvent activation method. • Solvent activation could enhance the resultant membrane performance effectively. • The resultant membranes have better stability in polar solvents. • The resultant membrane shows ultrahigh solvent permeance and excellent rejection for Vitamin B12. [ABSTRACT FROM AUTHOR]

In this work, a new molecular layer-by-layer deposition (MLD) approach was demonstrated to tailor thin-film composite (TFC) membranes with ultrathin microporous polyamide (PA) films as separation layers used for organic solvent nanofiltration (OSN). The extrinsic and intrinsic microstructures of the crosslinked PA layers were synergistically tailored by the layer-by-layer reaction between rigid tri-amine monomer 1,3,5-tris(4-aminophenyl)benzene (TAPB) with trimesoyl chloride (TMC). The thickness of defect-free PA layers, which exhibited a homogeneous cross-sectional morphology, was decreased down to 26 nm by regulating the deposition cycles, which is advantageous to achieve high solvent permeability. Moreover, the generated PA layers displayed high microporosity (specific surface area up to 114 m2 g−1) due to the rigid polyphenyl tri-amine structure of TAPB monomer. These characteristics conferred upon the prepared TFC membranes with exceptional solvent permeabilities (5.5, 5.0, 14.6, and 39.8 L m−2 h−1 bar−1 for ethanol, dimethyl formamide, methanol, and acetonitrile, respectively) and high rejection (93.2%) towards methyl orange (327 Da of molecular weight), all of which are higher than those of the majority of state-of-the-art TFC membranes using PA or other newly porous materials (e.g., polyacrylates, polymers of intrinsic microporosity-1) as separation layers. Furthermore, the membranes showed excellent solvent and pressure resistance due to highly cross-linking network character. Given the noticeable advantages of this method, a new alternative for preparing high-performance TFC OSN membranes can be provided. [Display omitted] • Molecular layer-by-layer deposition was developed to prepare TFC OSN membranes. • A new rigid tri-amine monomer of 1,3,5-tris(4-aminophenyl)benzene was used. • Highly microporous and ultrathin polyamide film was prepared as separation layer. • TFC membranes showed superb solvent permeability and dye rejection performances. [ABSTRACT FROM AUTHOR]

In this study, a thin membrane with vertically aligned mesoporous silica nanochannels was modified with long silane group molecules (E-MSTF-LTA) supported on an anodic aluminum oxide (AAO) for organic solvent nanofiltration (OSN). The ultrathin thickness, low tortuosity, ordered vertical channels and super-organophilic surface of E-MSTF-LTA endow it with an ultrahigh ethanol permeance (110 LMH/bar) over current state-of-the-art OSN membranes and a high acetone permeance of 360 LMH/bar. Furthermore, a 99% rejection of Evans blue (EB) was demonstrated, and a cut-off of approximately 660 Da was achieved. Besides, the modified Hagen-Poiseuille (HP) equation was applied to evaluate the theoretical permeance, which is consistent with the experimental results. To explore in depth the underlying principle behind the OSN performance of the vertically aligned E-MSTF-LTA membrane, the parameters, including the solvent viscosity, total Hansen solubility, solvent diameter, and solvent polarity were introduced to evaluate their influence on the permeance, while for solute transport behavior, the impact of the size exclusion effect on the solute rejection rate was examined. The results show that the viscosity is the critical factor for determining the solvent permeation, while the size exclusion effect dominates solute rejection. These findings open up a way to design next-generation vertically aligned OSN membranes and shed light on the OSN performance, both empirically and theoretically, using this system. Vertically aligned, super-organophilic mesoporous silica membrane realized ultrahigh permeance and precise molecular sieving in organic solvent nanofiltration. [Display omitted] • An ultrathin, vertically aligned, and super-organophilic mesoporous silica membrane was synthesized. • Ultrahigh permeance and precise molecular sieving with molecular dyes were demonstrated. • The transport behavior of the solvent and solute using this system was theoretically explored. [ABSTRACT FROM AUTHOR]

A 100-piece hollow fibre thin-film composite membrane module was successfully developed for pharmaceutical concentration and solvent recovery. To increase its packing density, thinner P84 polyimide hollow fibre substrates were spun using a smaller spinneret. The substrates were subsequently cross-linked with hexamethylene diamine to achieve organic solvent resistance. An MPD-based thin-film composite was synthesized through interfacial polymerisation to increase selectivity for solutes of less than 300 Da. The thin-film composite was then solvent-activated using N , N -dimethylformamide to increase its solvent permeability. The resulting membrane exhibited excellent performance with 24.2 l m−2 h−1 bar−1 acetone permeability and 90.1% methyl red (269 Da) rejection. In addition, the solvent-activated membrane maintained its performance for prolonged period, demonstrating the scalability of the thin-film composite fabrication process and stability of solvent-activated membranes. The membrane was also able to concentrate levofloxacin (361 Da) from 500 ppm to 20,000 ppm in acetone using a batch process, showing promising results for pharmaceutical applications. Image 1 • 100-piece thin-film composite OSN membrane was successfully fabricated. • 7-day filtration test showed stable organic solvent nanofiltration (OSN) performance. • High acetone permeability of 24.2 l m−2 h−1 bar−1 and 90.1% methyl red rejection. • Active pharmaceutical ingredient was concentrated to 2 wt%. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN), also known as solvent resistant nanofiltration (SRNF), has enormous potential for industrial applications. Among the emerging high-performance membrane materials, some have proven challenging to fabricate ultrathin selective layers and at a scale large enough to be practical for industrial consideration. This work demonstrates a facile and scalable solution casting method to prepare ultrathin composite films from advanced polymeric materials and porous additives. Using this method, poly(trimethylsilylpropyne) (PTMSP) membranes could be controlled to just 250 nm thickness resulting in 2 to 30-fold higher solvent permeance than other PTMSP membranes reported to date. Two highly porous additives, poly -dichloroxylene (p- DCX) and Porous Aromatic Framework (PAF-1) were employed to fabricate ultrathin PTMSP composite membranes. Compared to the native PTMSP membrane (methanol permeance of 11.5 L m−2 h−1 bar−1), these additives enhanced membrane permeance by 75% (20.1 L m−2 h−1 bar−1) and 50% (17.2 L m−2 h−1 bar−1), respectively. Inclusion of the porous additives also enhanced membrane stability, demonstrated by 300 h of continuous OSN operation. These membranes showed improved molecular weight cut-off (MWCO) and significant potential in the separation of active pharmaceutical ingredients (APIs), including the almost complete rejection of Vitamin B12 in methanol. This work demonstrates that the facile production of ultrathin membranes using intrinsically microporous polymers is possible, enabling these exciting membrane materials to be considered for industrial applications. Image 1 • Ultrathin PTMSP films were prepared by a facile and scalable method. • The inclusion of nanoporous additives greatly enhanced membrane permeability and stability. • The interaction between PTMSP and additives were studied. • Membrane showed promising molecular sieving and utility against APIs separation. [ABSTRACT FROM AUTHOR]

• Successful functionalization of reduced graphene oxide (rGO) using octadecylamine (ODA). • rGO-ODA ensures better disperse in the organic phase of the interfacial polymerization. • Polyamide based Thin Film nanocomposites membranes prepared using rGO-ODA as a filler. • rGO-ODA filler enhances ethanol permeance with respect to unmodified polyamide membrane. This work deals with the use of octadecylamine (ODA)-functionalized reduced graphene oxide (rGO) for thin film nanocomposite (TFN) membranes. The functionalization of rGO with ODA leads to graphene-based nanofillers, more hydrophobic than GO, and thus to the easier dispersion in the organic phase of the interfacial polymerization (IP) reaction carried out to produce polyamide (PA) TFN membranes. The performance of the new TFN membranes is evaluated by organic solvent nanofiltration (OSN) of alcoholic solutions containing dyes Acridine Orange (AO, MW 265 g·mol−1), Sunset Yellow (SY, MW 452 g·mol−1) and Rose Bengal (RB, MW 974 g·mol−1). The functionalized nature of the nanoparticles introduced into the hydrophilic PA layer allows an increase of the ethanol permeance from 2.8, 3.4 and 3.7 L·m−2·h−1·bar−1 for AO, SY and RB, respectively, corresponding to the bare thin film composite membrane (without rGO-ODA particles), to 4.3, 4.6 and 6.0 L·m−2·h−1·bar−1 for AO, SY and RB, respectively, for the rGO-ODA based TFN membrane. In fact, we hypothesize that the increase of the ethanol flux achieved with the use of rGO-ODA as a filler in TFN membranes is owing to a combination of the simultaneous presence of polar and non-polar groups from rGO-ODA nanosheets and the creation of still selective narrow gaps between these particles and the polyamide (PA). [ABSTRACT FROM AUTHOR]

• Polyamide TFC membranes were formed onto ceramic supports for testing in OSN. • Membranes were found to have irreversible changes in performance after exposure to solvents. • Membranes exhibited different selectivity in different solvents. • Charged dyes exhibited higher rejection than uncharged dyes. The polyamide thin film composite (TFC) has been the standard platform for reverse osmosis and nanofiltration membranes for aqueous separations for decades. It combines the properties of high permeance and unmatched selectivity for desalination applications. The highly cross-linked structure of polyamides may enable its use in organic solvent separations with several studies showing promising results. The field lacks, however, a complete understanding of how polyamides may be impacted by solvent exposure. To investigate the impacts of solvent on polyamide, we formed polyamide selective layers through interfacial polymerization onto ceramic UF supports. We quantified the permeability and selectivity changes after polyamides were exposed to an alcohol (methanol), and a ketone (acetone), and a polar aprotic solvent (DMF). We used aqueous testing before and after exposure to quantify permanent changes in membrane performance. Our results show that not only are the polyamide properties altered by the exposure to solvents, but they also show that different solvents have very different impacts on polyamide performance. The results indicate that polyamides may not be robust enough to perform nanofiltration separations in solvent environments with predictable permeability and selectivity. [ABSTRACT FROM AUTHOR]

Herein, a novel thin film composite (TFC) membrane pore-filled with polymer of intrinsic microporosity, PIM-1, has been developed for organic solvent nanofiltration (OSN). The TFC membranes were facilely prepared by dip-coating of PIM-1/chloroform solution onto polyacrylonitrile support membranes followed by a solvent vapor annealing (SVA) process. The relationship between preparation conditions, selective layer morphologies and OSN performances of the prepared TFC membranes were studied systematically. It was found PIM-1 was evidently filled into the near surface pores of support membranes due to the infiltration of PIM-1 solution. With the elongation of SVA time, the thickness of the PIM-1 layer decreased and the PIM-1/PAN interface gradually disappeared, which is advantageous to enhance the interfacial bonding. The prepared TFC membranes were used to reject organic molecules in organic solvents and exhibited tunable solvent permeability and solute rejection. Especially, the membranes were suitable for the removal of neutral molecules and anionic dyes from ethanol. The typical membrane demonstrated an ethanol permeance of 4.3 L m−2 h−1 bar−1 with a rejection of 93.7% towards Methyl Orange (327 Da). By comparing the permeance of various solvents, it is found that the closer the Hansen solubility parameter of solvent is to that of PIM-1, the higher the solvent permeance. This indicates the affinity between solvent and membrane plays an important role in solvent permeability. This work offers a novel and convenient strategy to prepare highly permeable membranes with controllable microstructures and tunable permselectivity to meet the diverse demands of molecular separation in organic solvents. Image 1 • A PIM-1 pore-filled TFC membrane was developed. • The TFC membranes were prepared through dip-coating followed by a SVA process. • The PIM-1 TFC membranes exhibited high solvent permeance. • The TFC membranes had tunable organic solvent nanofiltration performance. [ABSTRACT FROM AUTHOR]