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Thin film nanocomposite (TFN) organic solvent nanofiltration (OSN) membrane with improved separation performance was fabricated via interfacial polymerization reaction between amine-functionalized graphene quantum dots (af-GQDs) doped aqueous monomer solution of m -phenylenediamine (MPD) and n -hexane solution containing trimesoyl chloride (TMC) monomer. We emphasize the employment of extra-low content for both af-GQDs and MPD, so that we could maximize the function of these nanomaterials and eliminate their aggregation at the same time. The af-GQDs nanomaterials could regulate the interfacial polymerization process and could be strongly anchored in the polyamide film via covalent bonding, hence could prevent their loss while providing more channels for faster solvent penetration. As a result, the optimized OSN membrane, TFN-50, shows a super-smooth surface, with a surface roughness as low as 4.3 ± 0.2 nm, and excellent pure solvent permeances which reach 135.8, 112.7, and 69.8 L m−2 h−1 MPa−1 for methanol, DMF and ethanol, respectively, as well as a very high Rhodamine B (RDB, 479 Da) rejection of up to 99.2%, and an ethanol permeance of 61.4 L m−2 h−1 MPa−1. Furthermore, the TFN-50 OSN membrane still shows excellent filtration performance after being submerged in DMF for 336 h or continuous crossflow filtration with Rose bengal (RB, 1017 Da)/DMF solution for 136 h, demonstrating its excellent solvent resistance. [Display omitted] • TFN OSN membrane incorporated with af-GQDs nanomaterials is prepared via interfacial polymerization method. • Ultra-low content for af-GQDs and MPD is used in the aqueous phase during the interfacial polymerization process. • Af-GQDs effectively manipulate the interfacial polymerization process and help to form a selectivity layer with ultra-smooth surface. • Higher solvent permeance and excellent dye rejection performance are achieved with the aid of af-GQDs. • The af-GQDs doped OSN membrane has excellent durability performance in harsh strong polar solvents. [ABSTRACT FROM AUTHOR]

[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]

Covalent organic frameworks (COFs) nanomaterials have broad application prospects for the fabrication of separation membranes due to their high porosity, adjusted pore size, and excellent chemical stability. In this work, we in-situ constructed an ultra-thin layer of two-dimensional COFs nanomaterial using interfacial condensation between p -phenylenediamine and 1,3,5-triformylphloroglucinol, both with ultra-low concentration, on polyimide substrate surface to manipulate the subsequent interfacial polymerization between m -phenylenediamine of ultra-low concentration and trimesoyl chloride to fabricate a kind of thin film nanocomposite (TFN) membrane for organic solvent nanofiltration (OSN). The fabricated TFN OSN membrane achieves a Rhodamine B (479 Dalton) rejection and an ethanol permeance of higher than 99% and of 60 L m−2 h−1 MPa−1, respectively. Moreover, it has ultra-smooth surface with much thin skin layer, and high permeance for polar solvents such as methanol and ethanol. Besides, it has a molecular weight cut-off of about 375 Dalton. Moreover, it can maintain good separation performance after more than 10 days' immersion in N , N -dimethylformamide (DMF) at 80 °C, or after 120 h crossflow filtration with 100 mg L−1 Rose Bengal (1017 Dalton) - DMF solution as feed at 25 °C, indicating its vast potential for industrial application in harsh solvent environment. [Display omitted] • In-situ constructing nano-porous interlayer of two-dimensional COFs using Tp and Pa. • COFs interlayer effectively regulated the interfacial polymerization process. • COFs interlayer has profound effect on structure and performance of the OSN membrane. • The fabricated OSN membrane has ultra-smooth and ultra-thin barrier layer. • The fabricated OSN membrane has demonstrated superior solvent resistance. [ABSTRACT FROM AUTHOR]

An ultra-thin interlayer of two-dimensional covalent organic frameworks (COFs) was in-situ formed on polysulfone hollow fiber (HF) substrate surface to manipulate the interfacial polymerization process for the construction of thin film nanocomposite (TFN) HF nanofiltration (NF) membrane with greatly improved separation performance. p-Phenylenediamine and 1,3,5-Triformylphloroglucinol monomers were used for constructing the COFs interlayer, piperazine and trimethyl chloride were used for the fabrication of the HF NF polyamide skin separation layer. A series of optimization of the membrane preparation conditions were carried out to achieve the good separation performance. The results demonstrated that the two-dimensional COFs nanomaterials could effectively control the pore size distribution and hydrophobicity of the HF substrate surface, realize a uniform distribution of piperazine on the interlayer surface, thus effectively manipulate the interfacial polymerization process. Under the optimal conditions, the rejections of Na 2 SO 4 , Cr 2 (SO 4) 3 , CuSO 4 , ZnSO 4 and MnSO 4 can achieve 96.6 %, 95.4 %, 94.3 %, 91.7 % and 91.0 %, respectively, and the water permeance reaches 86.6 L m−2 h−1 MPa−1. Meanwhile, the fabricated TFN HF NF membrane shows good long-term stability, fouling resistance, acid and alkali resistance, as well as chlorine resistance, providing its vast potential for application in desalination and heavy metal wastewater treatment. [Display omitted] ● Two dimensional covalent organic frameworks constructed as ultra-thin interlayer ● TFN HF NF membrane based on COFs interlayer was successfully prepared ● Achieved high water permeance (86.6 L m−2 h−1 MPa−1) and Na 2 SO 4 rejection (96.6%) ● The TFN HF NF membranes has high rejection on heavy metal ions and dyes ● Good long-term stability, and acid/alkaline, chlorine and fouling resistance [ABSTRACT FROM AUTHOR]

• TFN NF membrane was prepared on PVA modified GO interlayer and crosslinked by GA. • The interlayer optimized physicochemical and interfacial properties of substrate. • The NF membrane has a skin layer thickness of 15 nm and surface roughness of 5 nm. • The fabricated NF membrane has an extremely higher Na 2 SO 4 rejection (99.7%). • The fabricated NF membrane has enhanced fouling resistance and chlorine resistance. Nanofiltration (NF) membranes prepared by conventional interfacial polymerization (IP) method still have relative low water flux. This paper reports a kind of high-flux, ultra-thin and ultra-smooth thin-film nanocomposite (TFN) NF membranes by IP reaction with both low concentration of piperazine (PIP) and trimesoyl chloride (TMC) on the surface of a tailor-made hydrophilic interlayer. This interlayer, which was made of polyvinyl alcohol (PVA)-modified graphene oxide (GO) and was followed by further glutaraldehyde post-crosslinking, greatly helps to manipulate the IP reaction, remarkably decrease the skin layer thickness (down to 15 nm) and roughness (down to 5 nm), and increase apparently the separation performance of the TFN NF membrane. Under optimal conditions (PVA concentration of 1.0 wt%, GA concentration of 1.0 wt% and GO concentration of 10 mg L−1), the fabricated TFN NF membrane has a relative high water permeance (158 L m−2 h−1 MPa−1), an extremely high Na 2 SO 4 rejection (99.7%), an extremely high separation factor (230) of Na 2 SO 4 to NaCl among those of the membranes with Na 2 SO 4 rejection higher than 98%, as well as greatly enhanced fouling resistance and chlorine resistance. The much superior advantages of the prepared TFN NF membrane over most of the state-of-the-art literature works demonstrate its vast potential in industrial separation and purification of aqueous electrolytes or organic solute solutions. [ABSTRACT FROM AUTHOR]

• A TA-Cu complex interlayer was in-situ formed for the preparation of OSN membrane. • TA-Cu interlayer optimized interfacial properties of substrate. • The optimized OSN membrane has ultra-thin and ultra-smooth skin layer. • The interlayered TFC OSN membrane achieved excellent enhanced separation performance. • The TA-Cu interlayered OSN membrane exhibited satisfying long-term stability. In this work, a novel organic solvent nanofiltration (OSN) membrane was engineered precisely via interfacial polymerization on the surface of an interlayer which was in-situ constructed using tannic acid – copper (TA-Cu) complex on the surface of a polyimide substrate membrane, and then was followed by crosslinking and activation procedures. The most promising aspect of this work is the high separation and solvent permeation performances due to the ultrathin film obtained in the interfacial polymerization reaction using ultra-low concentration monomers, 0.025 wt% aqueous m-phenylenediamine (MPD) and 0.0050 wt% trimesoyl chloride (TMC) in organic solution, respectively The optimized interlayered thin film composite (TFC) OSN membrane achieved a rejection of 98.36% for Rose Bengal (RB, 1017 Da) and a DMF permeance of 150.05 L m−2h−1 MPa−1 for 100 mg L−1 RB-DMF solution, much higher than most of the state-of-the-art literature works. Furthermore, after a 75 h' filtration, it remained a 98.7% rejection for RB of the RB-DMF solution, proving a high resistance to strong polar solvent. Meanwhile, it has an average surface roughness of less than 4.5 nm, a thickness of about 15 nm for the PA skin layer. This OSN membrane fabrication strategy is much economical and much environmentally friendly, and shows great potential for the application in the separation of organic solvent systems. [ABSTRACT FROM AUTHOR]

Solvent resistant nanofiltration (SRNF) membranes are highly demanded in processing organic solutions especially those contain large molecules with molecular weight between 200 to 2000 Da, yet they have some drawbacks such as relatively poor solvent resistance and low solvent permeance. The current work presented an innovative class of amino-functionalized graphene quantum dots (aGQDs) embedded thin film nanocomposites (TFN) for SRNF membranes which were prepared via interfacial polymerization (IP) and subsequent steps (chemical imidization, crosslinking, and solvent activation). The prepared membranes enabled covalent interactions not only between the IP skin layer and the substrate, but also between the IP layer and the embedded aGQDs. The ethanol permeance and surface porosity increased by 44% and 69%, respectively, with the embedment of aGQDs under the optimal conditions, while the Rhodamine B (RDB, 479 Da) rejection maintained essentially stable above 99%. Furthermore, our novel membranes exhibited excellent long-term stability, with a rejection of over 99% for Rose Bengal (RB, 1017 Da) during the continuous filtration of 100 mg L−1 RB/ N , N -dimethyl formamide (DMF) solution at room temperature for more than 768 h. They also exhibited good organic solvent resistance and high-temperature tolerance in both DMF and NMP solvents, with a RDB rejection of over 99% and an ethanol permeance of about 38 L m−2 h−1 MPa−1 after being immersed in DMF at 80 oC for 248 h, and a RDB rejection of over 99% and an ethanol permeance of about 41 L m−2 h−1 MPa−1 after being immersed in NMP at 80 oC for 232 h. The results demonstrated that the aGQDs-embedded TFN OSN membrane has vast potential in SRNF applications. Image 1 • (PI-aGQDs/PI) XA membrane was prepared via IP, imidization, crosslinking, activation. • The (PI-aGQDs/PI) XA SRNF membrane owns a wholly covalent bonding chemical structure. • aGQDs improve greatly the surface morphology and performance of the SRNF membrane. • The SRNF membranes kept >99% RB rejection in filtration of DMF at 25 oC for 30 days. • The SRNF membranes kept good solvent resistance in DMF and NMP at 80 oC for 10 days. [ABSTRACT FROM AUTHOR]

[Display omitted] • High separation performance TFC and TFN HF OSN membranes are prepared via interfacial polymerization method. • Ultra-smooth polyamide surface with average roughness of <3 nm is achieved with the use of TEA and lower concentration MPD. • The TFC membrane achieves an ethanol permeance of 12.1 L m−2 h−1 MPa−1 with RDB rejection close to 100%. • The TFN membrane achieves an ethanol permeance of 19.8 L m−2 h−1 MPa−1 with RDB rejection close to 100%. • Both TFC and TFN HF OSN membranes show good solvent swelling resistance. Hollow fiber (HF) organic solvent nanofiltration (OSN) membrane has unique self-supporting structure and larger specific surface area over flat OSN membranes, which is much more beneficial for separation processes intensification in chemical related industries. The key of this technology is HF OSN membrane. However, the research works on HF OSN membranes was relatively less till now. In this work, an outer-skinned polyimide HF substrate membrane was spun, and then thin film composite (TFC) membrane was prepared via interfacial polymerization (IP) between ultra-low concentration m -phenylenediamine (MPD) in the aqueous phase and trimesoyl chloride (TMC) in the organic phase on the HF substrate surface, with sodium dodecyl sulfate (SDS) as aqueous additives and triethylamine (TEA) as aqueous catalyst, and subsequently accompanied by crosslinking and solvent activation procedures. Further, thin film nanocomposite (TFN) HF OSN membrane incorporated with graphene oxide (GO) was also prepared. The combination of lower MPD concentration with SDS and TEA as additives in the aqueous monomer solution promote the formation of a TFC HF OSN membrane with average roughness of less than 3 nm, and a rhodamine B (RDB) rejection close to 100%, together with an ethanol permeance higher than 12 L m−2 h−1 MPa−1 under the optimum fabrication conditions. The optimal TFN membrane at a doping GO content of 5.0 mg L−1 achieves up to 20 L m−2 h−1 MPa−1 for the ethanol permeance without sacrificing the RDB rejection (nearly 100%). Moreover, both HF OSN membranes possess good swelling resistance, which proves their application potential in organic solvent system. [ABSTRACT FROM AUTHOR]

Reverse osmosis (RO) is widely used in water purification process. However, most commercial RO membranes have low water permeance, and encounter a "trade-off" effect between permeance and rejection. In this work, a kind of RO membrane with an in-situ formed film of sodium alginate (SA) hydrogel as an interlayer on the surface of a polysulfone (PSf) substrate has been extensively investigated. The SA hydrogel interlayer significantly controls and reduces the diffusion rate of the aqueous monomer, m-phenylenediamine (MPD) during the interfacial polymerization (IP), leading to the formation of a relatively smooth (−58 nm) polyamide (PA) separation skin layer with more unreacted acryl chloride groups remaining thereon, which makes it more hydrophilic after the hydrolysis of these groups. Under the optimal fabrication conditions, the water permeance achieves 27.8 L m−2 h−1 MPa−1 with a salt rejection maintaining at 99.2 % for 2000 mg L−1 NaCl solution, indicating that the prepared RO membrane has a broad prospect for the application in brackish water desalination, which is beneficial for the future development of RO membranes with high performance. [Display omitted] • A SA hydrogel interlayer was formed by crosslinking on PSf substrate surface. • Hydrogel interlayer effectively manipulated the interfacial polymerization process. • Greatly improved water permeance of RO membrane with high rejection maintained. [ABSTRACT FROM AUTHOR]

• The TFN hollow fiber NF membrane with GO interlayer was fabricated via IP reaction. • The surface roughness of the TFN hollow fiber NF membrane can be as low as 7.9 nm. • The optimal GO loading for high water permeance and salt rejection is 20 mg m−2. • High water permeance (80 L m−2h−1 MPa−1) and Na 2 SO 4 rejection (96%) were achieved. • Good fouling resistance and long-term stability were obtained. In this study, a kind of thin-film nanocomposite (TFN) hollow fiber nanofiltration (NF) membranes was fabricated via incorporating graphene oxide (GO) interlayer using the interfacial polymerization (IP) reaction between piperazine (PIP) and trimesoyl chloride (TMC). The surface morphology and cross-sectional structure of the fabricated TFN hollow fiber NF membrane were extensively investigated. The effects of the PIP concentration, species of the aqueous additives, and the GO loading on the structure and performance of the hollow fiber NF membrane were also investigated in detail and the optimal preparation conditions were achieved. Fourier transform infrared spectroscopy (FTIR) confirmed the successful introduction of the GO interlayer into the composite hollow fiber NF membrane. Moreover, the incorporation of GO interlayer helped to reduce the skin thickness of the composite hollow fiber NF membrane remarkably, and thus helped to increase greatly the water permeance while maintaining a high salt rejection. Under an optimal GO loading of 20.0 mg m−2, the TFN hollow fiber NF membrane achieved a water permeance of 80 L m−2 h−1 MPa−1 and a Na 2 SO 4 rejection of 96.1% for 2000 mg L−1 aqueous Na 2 SO 4 solution, much higher than the interlayer-free thin-film composite (TFC) membrane. Meanwhile, the TFN hollow fiber NF membrane showed an excellent selectivity of Na 2 SO 4 over NaCl, as well as good fouling resistance and long-term stability, demonstrating the vast potential in application for the selective separation of monovalent salt and divalent salt. [ABSTRACT FROM AUTHOR]