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[Display omitted] • The interfacial polymerization is regulated by the inverse diffusible organic phase additive polypyrrole nanoparticles (PPYN). • The modified reverse osmosis (RO) separation layer features abundant free volume. • The flux of the modified RO membrane increases nearly 3 times compared with the pristine RO membrane without sacrificing separation selectivity. • The modified RO membrane exhibits excellent anti-biofouling property. Highly permeable thin film composite (TFC) reverse osmosis (RO) membranes with abundant free volume are desirable for water treatment. However, the strategy of controlling the microstructure of the separation layer with high free volume rate is still a challenge. In this work, a modified strategy for the preparation of high-performance TFC RO membrane with inverse diffusible polypyrrole nanoparticles (PPYN) as organic phase additive was developed. The combination of PPYN and trimesoyl chloride (TMC) would diffuse backwards from the organic phase into the aqueous phase during the reaction process to disrupt the normal interfacial polymerization (IP) and thus introduce more free volume in the RO membrane due to the nanobubbles from violent reactions. Moreover, the thickness of the modified membrane decreased and the hydrophilicity increased based on the modulation of IP by PPYN, which facilitated the water molecules to transport. The prepared RO-PPYN membranes showed nearly three times the flux compared with the pristine RO membrane without sacrificing separation selectivity. Furthermore, the anti-biofouling property of the modified membrane was also improved. This work successfully demonstrated the potential use of PPYN as an organic filler to enhance the performance of seawater desalination in RO membranes. Our modification strategy provides an efficient and convenient way to prepare novel RO membranes with high permeability. [ABSTRACT FROM AUTHOR]

• Novel TFC membrane was designed for pervaporation dehydration. • Separation layer with descending crosslinking degree formed with LBL assembled IP. • Ten folds increase of separation factor was achieved with the TFC membrane. • TFC membranes showed high separation performance and good stability. Thin-film composite (TFC) pervaporation membranes is of widespread interest for the alcohol dehydration, since the thin selective layer allows a high permeation flux. However, how to obtain the desired flux and separation selectivity simultaneously is still the bottleneck of industrial application with pervaporation technology. In this study, a novel ultrathin multi-layer polyurea or polyamide pervaporation membrane was designed and assembled via layer-by-layer (LBL) interfacial polymerization (IP) method on the hydrolyzed polyacrylonitrile (HPAN) substrate membrane. During the LBL assembly process, the controllable crosslinking degree of the separation layer formed through changing the concentration of the oil phase monomer while remaining the concentration of the aqueous phase monomer constant based on the solution-diffusion mechanism of pervaporation separation process. The surface characterization revealed that the tris(2-aminoethyl) amine (TAEA) 1.5 -toluene 2,4-diisocyanate (TDI) 1-0.5-0 /HPAN composite membrane exhibited much rougher surface than that of the membranes with the same crosslinking degree. The optimized composite membrane exhibited a high separation factor of 844.6 with a desirable permeation flux of 1284.3 g·m−2·h−1 for the pervaporation dehydration 95 wt% ethanol aqueous solution at 80 °C, which was 10-fold increase of separation factor compared with the control membrane. Moreover, the excellent operation stability of the TFC membrane demonstrated the promising prospect for the alcohol dehydration separation. This preparation methodology has potential application in other membrane separation process on the basis of solution-diffusion mechanism, such as gas separation and reverse osmosis membrane. [ABSTRACT FROM AUTHOR]

Advanced reverse osmosis (RO) membranes for desalination, typically thin-film composite (TFC) membranes, have emerged as a prominent research direction to combat water scarcity. The substrate properties, such as the amine monomer adsorption capacity, are considered important for the interfacial polymerization (IP) process. Herein, inspired by Marangoni convection, a tailored dendrimer interlayer based on the plasma-treated polyethylene substrate was developed via the in-depth modification driven by surface tension gradient to precisely adjust the substrate properties. In addition, sodium dodecyl sulfate (SDS) was introduced as an additive to synergistically improve the desalination performance, and its role was reinvestigated. The quantitative experiments of amine monomer adsorption show that the substrate with in-depth modification possesses enhanced adsorption capacity. Therefore, massive amines can be enriched at the substrate surface, which can erupt and react violently in IP, thereby forming a polyamide layer with thick apparent thickness and abundant nanovoids. The RO membrane after optimization exhibits 99.19 % of rejection to NaCl and 3.87 L m−2 h−1 bar−1 of permeance, which shows good competitiveness compared with the advanced polymer-based RO membranes. This work provides constructive suggestions for the screening of interlayers to RO membranes and the application of polyethylene-based TFC membranes. [Display omitted] • In-depth dendrimer interlayer was tailored based on Marangoni convection. • The role of SDS was reinvestigated in the PE-based system. • Quantitative experiment was designed to detect the MPD adsorption at the substrate. • The novel PE-based RO membrane shows competitive desalination performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Monomers developed in recent years for preparation of TFC membranes is summarized. • The relationship between monomer structure and membrane properties is established. • The application problems of the IP monomers are summarized. • The outlook for future development of the monomer is also discussed. The thin-film composite (TFC) membranes fabricated by interfacial polymerization (IP) can be applied in the fields of nanofiltration (NF) and reverse osmosis (RO), which has the unparalleled advantages, such as high selectivity and permeability, small capital investment and low energy consumption, thus attracting great research interest in industry and academia field. The performance of TFC membranes is determined by their microstructure and physicochemical properties while IP monomer plays a decisive role regarding both. Over the past few decades, the researchers have paid intensive and sustained efforts to develop new IP monomers. This paper reviews these monomers and the corresponding membranes developed in recent years with the aim of establishing an intrinsic relationship between monomer structure and membrane properties. The excellent performances based on new monomers in enhancing the permeability, selectivity, anti-fouling and chemical stability of NF and RO membranes for liquid treatment are highlighted. Finally, various problems in the monomer development are summarized and the outlook for future development is also discussed. [ABSTRACT FROM AUTHOR]

Thin-film nanocomposite (TFN) membrane based on polyamide (PA) chemistry was widely applied for water purification and desalination process due to the improved water permeance. It remains a great challenge to significantly enhance rejection because of the non-selective defects caused by the aggregation of nanomaterials in the PA layer. Novel interlayer-based TFN (iTFN) membrane containing nanomaterial interlayer between the porous substrate and PA layer is the promising candidate to improve PA integrity and thus overcome the ubiquitous trade-off between permeability and selectivity. The nanomaterial interlayer not only promotes the subsequent interfacial polymerization (IP) but also provides improved pathways for water transport, which leads to simultaneous improvement in membrane permeability and selectivity. This review systematically categorizes nanomaterial interlayers into three types according to construction methods, namely, direct deposition, in situ growth and functional group-anchored in situ assembly (FAISA). The mechanism of interlayer modulating IP process and PA structure, as well as the effects on water transport, are comprehensively analyzed. Encouraging results reveal that using MOFs interlayer prepared by FAISA is the most promising way to break the trade-off in manufacturing reverse osmosis membranes. Finally, challenges and future efforts are presented for advancing iTFN membranes. [Display omitted] • Recent advances in the porous nanomaterial interlayer enhanced iTFN membranes have been summarized. • Nanomaterial interlayers are categorized into three types according to the construction methods. • The effects of nanomaterial interlayer on interfacial polymerization and separation performance have been explored. • Functional group-anchored in situ assembly MOFs interlayer is a promising candidate to overcome the trade-off between membrane permeability and selectivity. • Challenges and future efforts of promoting nanomaterial interlayer-based iTFN membranes are proposed. [ABSTRACT FROM AUTHOR]

Conventional thin-film composite (TFC) reverse osmosis (RO) membranes prepared by ultrafast and uncontrolled interfacial polymerization (IP) generally have unsatisfactory permeability and high fouling propensity, which distinctly impedes their development and wide application. Controllable thickness and roughness offer an opportunity to optimize the permeability and fouling resistance of RO membranes. In this work, we propose spin-coating assisted multilayer interfacial polymerization (SMIP) as a promising approach to fabricating high-performance RO membranes using polyethyleneimine (PEI) and 1, 3, 5-benzoyl chloride (TMC). SMIP integrates the high efficiency and uniformity of spin-coating technology, the nano-level and individual properties control of multilayer interfacial polymerization, and the simplicity of the IP process. Combining the strong hydrophilicity with low diffusion efficiency and positive charge of PEI, a thin, intrinsically hydrophilic, smoother and almost electro-neutral polyamide (PA) nanofilm was obtained. The optimal RO membrane with a controlled thickness of the selective layer (≈61 nm) has a water permeance of 3.12 L m−2 h−1 bar−1 and an acceptable NaCl rejection of 97.5%, while the strong hydrophilicity, minimal surface roughness and almost neutral surface charge afford it excellent fouling resistance. SMIP technology not only provides a new approach to preparing highly permeable and low-fouling RO membranes using macromolecular monomers, but also has great application potential in other separation membranes due to its precise control of the selective layer. [Display omitted] • A novel RO membrane was fabricated by spin-coating assisted multilayer interfacial polymerization (SMIP) with PEI and TMC. • The prepared RO membrane featured controllable thickness, minimal surface roughness and electro-neutral surface at pH 6–7. • Molecular simulation results showed that the SMIP increased the cross-linkage of the polyamide layer. • The RO membrane exhibited high permeability and excellent antifouling properties. • SMIP provides an approach for the controllable preparation of high-performance RO membranes. [ABSTRACT FROM AUTHOR]

• β-FeOOH nanorods were anchored onto polysulfone (PSF) ultrafiltration (UF). • Two kinds of interactions guaranteed nanorods attaching onto the surface. • Photo-Fenton catalytic of nanorods strengthened the self-cleaning of the membrane. • The membrane exhibited a high-efficient flux recovery for wastewater remediation. Membrane fouling problems severely hindered the integrated development of membrane technology. Currently, construction of a fouling-resistance membrane was an everlasting and ubiquitous research focus. In this study, β-FeOOH nanorods were anchored onto commercial polysulfone (PSF) ultrafiltration (UF) membranes surface via in-situ mineralization to fabricate an anti-fouling UF membrane for organic and dyes wastewater treatment. The ion-dipole interaction and π-cation interaction between Fe3+ and PSF chains guaranteed β-FeOOH nanorods attaching onto the surface without an intermediate layer. A satisfying flux recovery ratio (93.6% and 94.3%) and a low irreversible fouling ratio (6.4% and 5.9%) for bovine albumin (BSA) and sodium alginate (SA) solutions, respectively, were acquired on account of the photo-Fenton catalytic property and hydrophilicity of nanorods without sacrificing the permeation flux sharply. Importantly, the resultant membrane exhibited a desirable separation performance for various dyes solutions, with high permeation flux (53.6–100.0 L·m−2·h−1·bar−1) and appropriate rejection rates (60.9–92.6%). This work not only improved the anti-organic fouling performance extensively, but also provided a novel insight to decorate the conventional UF membrane surface straightforward without an intermediate layer. [ABSTRACT FROM AUTHOR]