Organic Solvent Nanofiltration Membranes Research Articles

Fabrication of Coffee‐ring Nanostructured Membranes for Organic Solvent Nanofiltration

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.

Fabrication of Coffee-ring Nanostructured Membranes for Organic Solvent Nanofiltration.

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.

Combined effect of polyelectrolyte assisted interfacial polymerization and tannic acid protective surface modification to boost organic solvent nanofiltration performance

Organic solvent nanofiltration (OSN) is an effective technology for separating solute with molecular weight of 200–1000 Da (Da) from organic solvents. However, as the core of this technology, most of OSN membranes exhibit a low solvent permeance. Herein, a highly permeable OSN membrane was prepared via a poly (sodium 4-styrenesulfonate) (PSSNa)-assisted interfacial polymerization reaction using ultra-low content of aqueous monomer solution, followed by a protective modification using tannic acid (TA) grafting onto the nascent polyamide surface, and a post chemical crosslinking treatment as well as an activation treatment. PSSNa manipulates the diffusion and distribution of the m-Phenylenediamine monomers, leading to a looser and thinner polyamide layer. TA molecules successfully reacted with the remaining acyl chloride groups on the nascent polyamide layer surface and formed ester, thus preventing the surface from subsequent crosslinking reaction and also making the selective layer looser, which is beneficial for solvent permeation. Moreover, the TA modification makes the surface more hydrophilic, thus further helps to improve the solvent permeance of OSN membrane. The optimal membrane possesses an excellent ethanol permeance of 71.5 L m−2 h−1 MPa−1, an increment of 41.6 % as compared with the baseline OSN membrane, while keeping a rejection of 98.2 % for rhodamine B (RDB). Meanwhile, the surface of optimal membrane is ultra-smooth, with an average roughness of 4.4 nm, which is much beneficial for antifouling. Moreover, the OSN membrane possesses a brilliant durability performance, with only a 1.5 % decrease of the RDB rejection after being immersed in N, N-Dimethylformamide (DMF) at room temperature for 115 d, and only a further 0.3 % decrease of the RDB rejection after being further immersed in DMF at 80 °C for another 11 d, indicating its superior solvent resistance, which makes it a promising candidate for treating organic solutions from pharmaceutical and textile industries.

Polyamide thin-film composite membranes with enhanced interfacial stability for durable organic solvent nanofiltration

Polyamide thin-film composite (TFC) membranes present a promising option for organic solvent nanofiltration (OSN) due to their superior advantages in facile fabrication and high separation efficiency. However, existing TFC-based OSN membranes are heavily limited by their weak interfacial stability in organic solvents, because many solvent-resistant porous supports are hydrophobic and have poor interfacial compatibility to polyamide. Herein, we report a polyamide TFC membrane with enhanced interfacial stability and durable OSN performance, by multifunctional surface modification and in-situ interfacial polymerization on a hydrophobic and solvent-resistant polypropylene substrate. Distinct from nascent ones, the polypropylene substrates modified by tannic acid/aminopropyltriethoxysilane coating possess excellent hydrophilicity and more functional groups, in which the former allows for the in-situ synthesis of integral polyamide layers via interfacial polymerization and the latter greatly enhances the binding strength between the polyamide layer and PP substrate by 30 times. With this method, the TFC membranes exhibit excellent thermal stability in 80 °C dimethylformamide solution. Meanwhile, the TFC membranes display high ethanol permeance (9.2 L m−2 h−1 bar−1) and acid fuchsin rejection (98.5 %), outperforming the performance of most OSN membranes reported. This straightforward method, robust structural stability, and extraordinary performance make the TFC membranes a step closer to commercial OSN membranes.

Ca2+, Fe3+ co-crosslinked tannic acid-bridged sodium alginate gel membrane for organic solvent nanofiltration

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 (TAx-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 TA0.125-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 TA0.125-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 TA0.125-Ca/FeSA membrane was demonstrated to have great potential for application in the fields of purification and solvent recovery.

In-situ construction of covalent organic frameworks membrane via interfacial polymerization and crosslinking modification using trimesoyl chloride for organic solvent nanofiltration

Organic solvent nanofiltration (OSN) is a modern technology for separating and purifying organic solvents. It has the advantages of both low energy consumption and low environmental pollution. In this work, we utilized an oligomer triggered interfacial polymerization (OT-IP) method and followed by a post-IP modification using trimesoyl chloride (TMC) to synthesize a kind of covalent organic frameworks (COFs)/TMC membrane. This process involves pre-mixing both COFs monomers in a same organic solvent to form oligomers, followed by conducting an IP reaction at the interface between the organic solvent phase and an aqueous phase solution containing acetic acid as a catalyst. Subsequently, a surface modification is conducted using TMC n-hexane solution, which effectively manipulates the surface hydrophilicity, average size, solute rejection, solvent permeance and solvent resistance of the membrane. Afterward, crosslinking and solvent activation are performed to improve its solvent resistance and separation permeance. The optimized OSN membrane exhibits an ethanol permeance of 72.5 L m−2h−1 MPa−1 with an RDB rejection of 98.4 %. Its surface roughness is as low as 3.4 nm. Furthermore, it has high permeance for both polar solvents (MeOH permeance of 176.7 L m−2h−1 MPa−1) and weakly polar solvents (EtOAc permeance of 183.0 L m−2h−1 MPa−1). Moreover, the optimized OSN membrane demonstrates excellent solvent resistance and excellent catalyst recovery performance. Therefore, this work presents a promising avenue for the application of COFs in OSN membranes.

Microporous and functional group Co-designed polyesteramide membranes for efficient and broad-spectrum organic solvent nanofiltration

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.

Scalable, Interfacially Synthesized, Covalent-Organic Framework (COF)-Based Thin-Film Composite (TFC) Hollow Fiber Membranes for Organic Solvent Nanofiltration (OSN).

Covalent organic frameworks have great potential for energy-efficient molecular sieving-based separation. However, it remains challenging to implement COFs as an alternative membrane material due to the lack of a scalable and cost-effective fabrication mechanism. This work depicts a new method for fabricating a scalable in situ COF hollow fiber (HF) membrane by an interfacial polymerization (IP) approach at room temperature. The 2D COF film was constructed on a polyacrylonitrile HF substrate using aldehyde (1,3,5-trimethylphloroglucinol, Tp) and amine (4,4'-azodianiline (Azo) and 4,4',4″-(1,3,5-triazine- 2,4,6-triyl) trianiline (Tta)) as precursors. The COF membrane on the PAN substrate showed 99% rejection of Direct red-80 with remarkable solvent permeance. The rejection analysis revealed that the structural aspects of the solute molecule play a major role in rejection rather than the molecular weight. We further optimized the precursor concentrations to improve the permeation performance of the resulting membrane. The durability study reveals excellent stability of the membrane toward organic solvents. This study also demonstrated the easy scalability of the membrane fabrication approach. The approach was further extrapolated to fabricate a cation-based COF membrane. These charged membranes exhibited an enhanced rejection performance. Finally, this approach can facilitate industrially challenging molecular sieving applications using COF-based membranes.

Lamellar structured GO-Melamine nanocomposite membranes with varying d-spacing for efficient organic solvent nanofiltration (OSN)

There is a lot of research being done on GO lamellar 2D membranes for separating organic solvents and dyes. These membranes are highly sought-after due to their exceptional characteristics. However, existing challenges include inadequate solvent permeability and limited dye rejection capacity due to swelling of membranes. In this study, we proposed a novel technique that employs low-pressure assisted filtration to fabricate nanocomposite membranes using GO and melamine. Remarkably, these composite membranes exhibited outstanding separation performance for dyes (≥99.06 %) in organic solvents, regardless of their positive or negative charges or when present in mixtures. The optimum GO-M0.02 nanocomposite membrane exhibits impressive organic solvent flux (J), attaining a value as high as 50.8 L/m2h (acetone), which is 6.57 times greater than that of the pure GO membrane. Furthermore, these GO-Melamine nanocomposite membranes showed excellent durability against both common and harsh organic solvents, and the flux of solvents through the GO-M0.02 nanocomposite membrane remained almost unchanged even after being immersed in methanol for up to one week. Additionally, the membrane exhibited consistent solvent flux and rejection rates for methyl green during continuous filtration. These results highlight the exceptional stability and immense potential of GO-melamine nanocomposite membranes for real organic solvent nanofiltration.

Preparation of highly efficient nanofiltration membranes resistant to organic solvents by adjusting zinc oxide nanoparticle-loaded attapulgite

Zinc oxide nanoparticle-loaded attapulgite was successfully added to the polyamide layer for the preparation of high-efficiency organic solvent nanofiltration membranes. The addition of zinc oxide nanoparticle-loaded attapulgite to the aqueous monomer regulates the diffusion rate of interfacial polymerization, generating a thin and loosely packed polyamide layer. In addition, the abundant hydrophilicity of the nanoparticles lays the foundation for increased polar solvent permeation. The organic solvent nanofiltration membrane with the best performance exhibited an optimum methanol permeability of 13.19 L m−2h−1 bar−1, which was 1.54 times higher than that of the unadded membrane. Meanwhile, the optimum membrane consistently rejected more than 99.40 % of Evans blue dye, and the rejection rates of different dyes were consistent with the size-sieving effect. Furthermore, the permeation capacities of the membranes were evaluated using organic solvents with different polarities, viscosities, and molecular diameters, and the permeability of acetonitrile reached 16.98 L m−2h−1 bar−1. In addition, the optimum membranes retained excellent rejection capacity after soaking in the strongly polar solvent N, N-dimethylformamide (DMF) for 10 days at room temperature.

Construction of ultrathin and microporous polyesteramide nanofilms for efficient organic solvent nanofiltration (OSN) using diacyl chloride

The integration of high permeability and exceptional selectivity, thereby overcoming the conventional “trade-off” effect, remains a persistent challenge for the practical implementation of organic solvent nanofiltration (OSN) membranes. Herein, at the molecular level of design, we utilized the 5,5′-diamino-2,2′-biphenol (amino-BIPOL) and diacyl chloride as IP monomers to prepare OSN membranes with high perm-selectivity. The amino-BIPOL, a contorted biphenol molecule with four reactive sites, serves as a molecular-level unit to hinder efficient packing of polymer chains and induce the formation of interconnected micropores in the resulting polyesteramide layers. By employing diacyl chloride terephthaloyl dichloride (TPC) and isophthaloyl dichloride (IPC) as the oil-phase cross-linker, two kinds of TFC membranes were prepared. The resulting membranes both present smooth surface morphology, with ultrathin and high microporous selective layer allowing for efficient mass transfer. Specifically, the methanol permeance of amino-BIPOL/TPC and amino-BIPOL/IPC membrane reaches up to 15.1 and 15.6 LMH/bar, while maintaining a molecular weight cut-off (MWCO) value of 300 and 373 Da, respectively. Overall, this work illustrates the different oil-phase cross-linkers will result in diverse nanofilm microstructure and thus with distinct perm-selectivity properties, offering new insights for the design and modification of advanced OSN membranes.

Simulation insights into the spirobifluorene aryl diamine (SBAD-1)/porous organic cage mixed-matrix membranes for organic solvent nanofiltration

Mixed-matrix membranes (MMMs) have emerged as promising materials for organic solvent nanofiltration (OSN) applications due to their potential to synergize polymer and porous nanomaterials. Theoretically understanding the role of nanofillers within MMMs in determining the OSN performance is crucial for the development of new MMMs. In this work, the molecular simulations are performed to investigate the swelling process and OSN performance of the spirobifluorene aryl diamine (SBAD-1)/porous organic cage (POC) MMMs. Three POCs (i.e., CC3, CC5, and CC17) and three organic solvents (i.e., methanol, acetonitrile, and acetone) are studied. The pure SBAD-1 and pure POC membranes are also constructed for comparison. Results show that the attractive interactions between SBAD-1 and POC can restrict the flexibility of polymer chains, and thereby decrease the dilation of polymer matrix and also the porosity of swollen MMM. Based on this, the solvent resistant property and dye rejection would be well enhanced. Moreover, compared with pure SBAD-1 and pure POC membranes, the solvent permeabilities through swollen MMMs are found to drop due to the blockage of POC pores by SBAD-1 chains and the smaller porosity in membrane. This work reveals the pivotal role of interaction between SBAD-1 and POC in the swelling and OSN performance of SBAD-1/POC MMMs, and would provide theoretical support for the development of MMMs for OSN applications.

Spiral-wound organic solvent membrane modules for dewaxing solvent recovery

The petrochemical industry is typically energy-intensive, involving frequent and intricate separation processes. SINOPEC is a globally recognized lubricant manufacturer and distributor, with a substantial production capacity exceeding 1.7 million tonnes in 2022. The dewaxing solvent recovery process in lubricant production necessitates a multi-stage flash and distillation treatment, resulting in substantial energy consumption and high costs. Utilizing organic solvent nanofiltration (OSN) membranes offers a feasible alternative approach to address this issue. A series of thin film composite OSN membranes with varying molecule weight cut-offs were prepared through precise adjustment of the chemical composition and proportion of the organic co-monomers. The application potential of the optimized membranes in the lubricant dewaxing solvent recovery was evaluated using lubricant base oil derived from the actual production line, specifically light deasphalted oil and vacuum cut2. The membrane exhibited a rejection of 99.3 % for light deasphalted oil and 95.6 % for vacuum cut2, with corresponding fluxes of 16.8 and 13.4 LMH under 2 MPa, respectively. Based on this, spiral-wound membrane modules (1.8″ × 12″) were fabricated and their suitability for dewaxing solvent recovery was further validated. The fabrication of spiral-wound membrane modules (8″ × 40″) is in progress, with intentions to conduct a pilot plant trial on the lubricant oil manufacturing line.

Organic mixture fractionation enabled by carbon nanotube/graphene nanoribbon organic solvent nanofiltration membrane

We developed a hybrid membrane composed of carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) by controlling the degree of unzipping in multi-walled CNTs through oxidation. The CNT/GNR hybrid hydrogel was applied onto a porous polymer filter by large-scale coating using slot-die coating, which was then subjected to hot-pressing at 150 °C and 20 bar. The resulting CNT/GNR hybrid membrane exhibited outstanding performance in organic solvent nano-filtration (OSN), with ultrafast permeance of 60–200 LMH/bar for alcohol solvents and a molecular weight cut-off of 961 Da, surpassing the upper bound of polymer-based OSN membranes. The rapid solvent permeance can be attributed to the increased interlayer spacing due to CNT intercalation and the elimination of oxygen functionalities through an additional reduction process. Meanwhile, the stacked nanoribbon structure effectively separated organic molecules based on interlayer spacing size. Notably, this membrane demonstrated exceptional stability under practical separation conditions, with consistent performance even after 1315 h of cross-flow operation. This operational lifespan is a record for graphene-based membranes and can be attributed to the enhanced adhesion between the polymer substrate and the carbon layer as a result of the welding effect. Finally, the membrane was used to separate a concentrated binary dye mixture solution made of nanometer-sized components, showing precise separation ability with a separation factor of 740 and nearly 100 % purity of permeate and retentate solution after the filtration-based separation process. The membrane has the potential for a wide range of applications in the separation and purification of organic compounds dissolved in organic solvents.

Controllable preparation of novel homogenous reinforcement poly(p-phenylene terephthamide) hollow fiber nanofiltration membrane with nanoscale ordered structures for organic solvent nanofiltration

Organic solvent nanofiltration (OSN) is a green, energy-saving, and highly efficient emerging membrane separation technology, and there is an urgent need for robust, easy-to-process OSN membranes with high permeance and small solute selectivity for industrial applications. Herein, we propose a new strategy for accurately designing novel OSN membranes. Specifically, a polyamide (PA) interlayer was synthesized in-situ on the surface of homogeneous reinforced poly(p-phenylene terephthamide) (PPTA) hollow fiber membrane by interfacial polymerization (IP) using both ultra-low concentrations piperazine (PIP, 0.05 wt%) and trimesoyl chloride (TMC, 0.005 wt%), and then a defect-free and dense PPy layer was deposited on top of the hydrophilic PA interlayer by chemical vapor deposition (CVD) process to prepare PA/PPy composite membranes with spherical cluster or strip cluster “Turing-like” structure. The resulting PA/PPy composite membranes presented an excellent high selective permeability, the dimethylacetamide (DMAc) permeability was 21.1 L·m−2·h−1·MPa−1, and the molecular weight cut-off (MWCO) was as low as 185 Da. A 30-hour OSN test at elevated temperatures (80 °C) and in organic solvent (DMAc), as well as a one-month immersion test in ethanol and DMAc at room temperature, demonstrated superior separation performance and structural stability of the membranes, indicating their application potential in harsh solvent systems. Our novel method for developing nanoscale ordered structured PA/PPy composite membranes offers great potential for the development of multilevel structural designs in the preparation of high-performance OSN membranes with potential industrial applications.

SWCNTs-channeled MOF nanosheet membrane for high-efficient organic solvent nanofiltration

Organic solvent nanofiltration (OSN) has become increasingly important in petrochemical and pharmaceutical industries, demanding superior and robust membranes. 2D MOF nanosheets hold great promise in the preparation of OSN membrane. Nevertheless, the fabrication of defect-free 2D MOF membranes with robust mechanical strength is hampered due to the weak interlamellar interactions between MOF nanosheets. Herein, 2D MOF composite membrane for high-performance OSN application is fabricated through the assembly of copper 1,4-benzene dicarboxylate (CuBDC) nanosheets and NH2-SWCNTs. Within this composite configuration, NH2-SWCNTs can shelter the defects between the adjacent CuBDC nanosheets, rendering CuBDC/CNTs composite membranes precise molecular sieving ability. Meanwhile, the nanochannels created by NH2-SWCNTs with low frictional coefficients on the internal surface promote the permeation of organic solvents. Moreover, the multiple interactions between CuBDC and NH2-SWCNTs improve the mechanical strength of composite membranes. Accordingly, the composite membranes display excellent rejections of dye molecules on the basis of size-sieving mechanism with superior methanol permeance of 1260 L m−2h−1 bar−1, as well as steady congo red rejection at high trans-membrane pressure of 5 bar, demonstrating good pressure resistance of composite membranes. Moreover, the composite membranes exhibit outstanding stability against high-concentration feeds and long-term operation for 50 h, confirming excellent practicality in the purification of dyes from organic solvents. The design approach in this work may inspire the fabrication of other nanosheet-based membranes for high-efficient OSN.

Effects of polyacrylonitrile carboxylation on pore structure and performance of thermally crosslinked organic solvent nanofiltration membrane

In this work, polyacrylonitrile (PAN) membranes were hydrolyzed with NaOH solution, and then hydrolyzed PAN (HPAN) membranes were used to prepare organic solvent nanofiltration (OSN) membranes with thermal crosslinking method. The chemical structure and pore structure evolutions of membrane during hydrolysis and thermal crosslinking were systematically investigated. The influences of hydrolysis carboxylation on permeation performances of membranes were studied in detail. Benefiting from the carboxylic groups generated by hydrolysis reaction of nitrile groups, the cyclization reaction of HPAN molecular chains was more easily initiated by ionic mechanism at a lower temperature, and the pore structure fusion of thermally crosslinked membranes was effectively inhibited. The permeances of the thermally crosslinked membranes derived from HPAN membranes were greatly improved. Furthermore, the thermally crosslinked membrane showed stable OSN performance due to the generation of ladder structure during thermal crosslinking. Therefore, the OSN membranes prepared in this work have great potential for practical applications.

Surfactant-assisted interfacial polymerization towards high-crystallinity COF membranes for organic solvent nanofiltration

Preparing high-crystallinity covalent organic framework (COF) membranes by interfacial polymerization remains a grand challenge. Herein, a monomer pre-assembly process is proposed to prepare high-crystallinity COF membranes by surfactant-assisted interfacial polymerization (SAIP) strategy. The self-assembled chains of amphiphilic surfactants across interface can gather and pre-assemble monomers and improve their interphase transport for complete topological growth. Apart from the reduction in polymerization time from over 72 h–48 h, the crystallinity and pore uniformity of COF membranes are highly enhanced. This strategy is universal and four kinds of amine monomers are utilized to tune COF pore size. The 1.8 nm-sized COF membrane shows highly enhanced rejection from 65.5% to 95.7% for reactive black with a size of 2.0 nm, when compared to that without surfactants. Importantly, the orderly stacked pores permit fast molecule transport with a 76% increase in acetonitrile permeance (366.9 L m−2 h−1 bar−1). Meanwhile, the robust crystal properties endow this COF membrane with excellent solvent resistance, compressive strength, and hence operational stability for over 100 h. The amphiphilic molecule-assisted interface engineering may represent a technology for scalable fabrication of high-crystallinity framework materials for molecule separation.

Methanol recovery: potential of nanolaminate organic solvent nanofiltration (OSN) membranes.

Researchers have made a significant breakthrough by merging the energy-saving attribute of organic solvent nanofiltration (OSN) with the remarkable solvent permeance and solute rejection of two-dimensional (2D) laminated membranes. This innovative approach brings forth a new era of sustainable and cost-effective separation techniques, presenting a promising solution to the issue of industrial solvents contaminating the environment. This development paves the way for new opportunities in building a sustainable future. Specifically, our mini-review has cast a spotlight on the separation and recovery of methanol-a solvent abundantly used in industrial processes. We systematically evaluated a diverse array of free-standing 2D nanolaminate OSN membranes. The analysis encompasses the assessment of pure methanol permeance, solute rejection capabilities, and the simultaneous evaluation of methanol permeance and solute rejection performance. Notably, this study sheds light on the considerable potential of 2D laminated OSN membranes in revolutionizing separation processes for the industrial use of methanol.

Recent advances in the fabrication of organic solvent nanofiltration membranes using covalent/metal organic frameworks.

Organic solvent nanofiltration (OSN) has evolved as a vital technological frontier with paramount significance in the separation and purification of organic solvents. Its implication is particularly prominent in industries such as pharmaceuticals, petrochemicals, and environmental remediation. This comprehensive review, meticulously navigates through the current state of research in OSN membranes, unveiling both the critical challenges and promising opportunities that beckon further exploration. The central focus of this review is on the unique utilization of covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) in OSN membrane design, leveraging their distinctive structural attributes-tunable porosity, robust chemical stability, and molecular sieving capabilities. These qualities position them as exceptional candidates for crafting membranes tailored to the intricacies of organic solvent environments. Our investigation extends into the fundamental principles that render COFs and MOFs adept in OSN applications, dissecting their varied fabrication methods while offering insights into the advantages and limitations of each. Moreover, we address environmental and sustainability considerations in the use of COF and MOF-based OSN membranes. Furthermore, we meticulously present the latest advancements and innovations in this burgeoning field, charting a course toward potential future directions and emerging research areas. By underscoring the challenges awaiting exploration, this review not only provides a panoramic view of the current OSN landscape but also lays the groundwork for the evolution of efficient and sustainable OSN technologies, specifically harnessing the unique attributes of COFs and MOFs.