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Carbon nanotube (CNT) membranes with nano-enhanced superwettability show great potential in high-efficient oil/water separation. In this study, we present a novel polyphenol-metal manipulated nanohybridization strategy to prepare CNT nanohybrid membranes embedded with FeOOH nanorods (NRs). The polyphenol-metal manipulated nanohybridization strategy lies in the assembly of polyphenol-metal (chitosan/tannic acid-Fe3+) complex primer on the CNT membranes followed by in situ FeOOH NRs mineralizating. The polyphenol-metal complex modulates the uniform distribution of in situ mineralized FeOOH NRs in the as-prepared CNT@CS/TA-FeOOH nanohybrid membrane, which endows the CNT nanohybrid membrane with both superhydrophilicity and underwater superoleophobicity. By integrating the high permeability of CNT membranes and the hydrophilicity and photo-degradation activity of FeOOH NRs, the CNT@CS/TA-FeOOH nanohybrid membrane possesses achieved a high water permeability above 8000 Lm-2h-1bar-1 and greatly elevated flux recovery ratio above 97% for oil/water separation. Both hydration-induced antifouling property and photo-induced self-cleaning capability contributed to the robust flux recovery for highly efficient oil/water separation. The CNT@CS/TA-FeOOH nanohybrid membrane is promising for oily wastewater treatment applications, and the proposed polyphenol-metal manipulated nanohybridization strategy shows great potential for engineering various multifunctional nanohybrid membranes. Image 1 • The nanohybrid membrane is prepared via polyphenol-metal manipulated nanohybridization. • FeOOH nanorods are in situ mineralized and evenly distributed on the nanohybrid membrane. • The nanohybrid membrane shows robust superhydrophilicity and underwater superoleophobicity. • The nanohybrid membrane possesses superior water flux and high oil/water separation efficiency. • The nanohybrid membrane integrates both antifouling and self-cleaning mechanisms. [ABSTRACT FROM AUTHOR]

Ion-conductive polymers having highly ordered and well-defined phase-separated structures are potential materials for use as monovalent anion-selective membranes (MASMs). In this work, to investigate the effect of hydrophobic spacers, four side-chain-type imidazolium salt-tethered poly(arylene ether sulfone) anion-exchange membranes (AEMs) with different alkyl spacer lengths (–CH 2 – number: 3, 6, 9, and 12) were fabricated for use in electrodialysis (ED). Our investigations using atomic force microscopy, small angle X-ray scattering and X-ray diffraction demonstrate that the extended alkyl spacers change the nano-phase-separated structures, with an increased ion cluster space ranging from 3.29 nm to 7.76 nm, resulting from increased immiscibility between the additional hydrophobic alkyl spacers and (i) the hydrophobic aromatic backbones and (ii) the hydrophilic ion-conductive groups. In addition, with the extension of the alkyl spacer, chloride (Cl−) ion conductivity at 25 °C decreases from 16.4 mS cm−1 to 11.4 mS cm−1 and water uptake is reduced to 12.8% (20 °C). It is found that the as-prepared AEM with a hexyl alkyl spacer shows the superior perm-selectivity (Cl−/SO 4 2−) of 7.10 (separation efficiency: 70.3%), as compared with three others (3.48, 6.81, and 4.26). This work thus presents an efficient strategy to guide the architectural design of novel MASMs. Image 1 • Four side-chain-type AEMs with different alkyl spacer lengths were fabricated. • Pronounced phase-separated morphologies verified by AFM and SAXS are obtained. • Extended alkyl spacer decreases the ion conductivity and lowers the water uptake. • Perm-selectivity of PAES-6C-IM AEM attains a maximum of 7.10 at 5.0 mA cm−2. [ABSTRACT FROM AUTHOR]

The state-of-the-art graphene oxide (GO) has been wildly used in water purification due to its tunable nanoscale interlayer between the two-dimensional nanosheets. However, the structural instability and flux decline performances significantly limit the practical application of GO-based membranes. Herein, a novel GO/DTiO 2 -PDA-PEI (dopamine modified TiO 2) composite nanofiltration membrane has been prepared via a multi-coupled strategy, combining with the self-assembly, copolymerization and surface grafting. Tuning the nanoscale interspace between the GO nanosheets, and constructing the membrane with positively charged surface and negatively charged subsurface, the loose GO/DTiO 2 -PDA-PEI composite nanofiltration membrane (GDP 1 P 2 -0.6 membrane with a mean pore size = 0.87 nm) show the filtration performance with water permeance as high as 41.6 L m−2 h−1 bar−1 and dye rejection around 99.9%, and the molecular selective factor (Eriochrome black T/Na 2 SO 4) of α = 47.6. Long-term performance and stimulation have been investigated to further analyze the dye concentration and salt removing. The investigations demonstrate that the GO/DTiO 2 -PDA-PEI composite nanofiltration membrane enriches 14.9-fold Eriochrome black T (ET) and reduces Na 2 SO 4 to 0.36% in the term of the concentration factor 15 and batch diafiltration factor 5. Image 1 • A novel GO/DTiO 2 -PDA-PEI composite nanofiltration membrane is synthesized via a multi-coupled strategy, combining with self-assembly, copolymerization and surface grafting. • Tuning the nanoscale interspace between the GO nanosheets and constructing the membrane with positively charged surface resulted in high permeation of pure water and ions. • The GO/DTiO 2 -PDA-PEI composite nanofiltration membrane (GDP 1 P 2 -0.6) shows the satisfied filtration performance with effective molecular selectivity. • GO/DTiO 2 -PDA-PEI composite nanofiltration membrane could enrich 14.9-fold Eriochrome black T (ET) and reduce Na 2 SO 4 to 0.36% after the diafiltration process. [ABSTRACT FROM AUTHOR]

• TFN RO membranes were prepared by incorporating p -aminophenol modified GO into polyamide skin layer. • The incorporation of mGO reduced the hydrophilicities and the thickness of functional layers. • The optimized RO membrane shows the superior water flux of 23.6 L·m−2·h−1 and NaCl rejection rate of 99.7%. • RO membrane with mGO exhibits bacterial killing ratios of 96.78% and 95.26% against E. coli and S. aureus. Innovative approaches to restraint bacterial adhesion and growth on membranes are significantly needed to avoid membrane performance decaying for biofouling. In this work, a series of thin film nanocomposite (TFN) reverse osmosis (RO) membranes has been prepared by incorporating nano-fillers of p -aminophenol-modified graphene oxide (mGO) into the polyamide skin layer via interfacial polymerization. Our investigations demonstrate that the introduction of mGO nano-fillers into the functional skin layers reduces the hydrophilicities with the water contact angles drop from 69.6° to 48.2° and meanwhile decreases the thickness of functional skin layers from 240 nm to 50 nm, relative to pristine polyamide RO membrane without nano-fillers. As a result, the as-prepared TFN RO membrane at optimized conditions shows a water flux of 23.6 L·m−2·h−1 and a NaCl rejection rate of 99.7%, reflecting a remarkable promotion in water flux (by 24.5%) compared with the pristine RO membrane. In addition, the data statistics of the live/dead fluorescent imaging assay demonstrate that TFN RO membrane with mGO exhibits bacterial killing ratios of 96.78% and 95.26% against E. coli and S. aureus at the additive loading of 0.005 wt%, which are much higher than RO membrane with GO (90.64%; 90.43%) and pristine RO membrane (4.95%; 2.48%). This work demonstrates a facile way to TFN RO membranes with good separation performance and desirable antibacterial capacities. [ABSTRACT FROM AUTHOR]

The removal of small and neutral boron molecules from seawater remains a critical challenge in energy-saving and low-cost desalination. In this paper, a high boron removal reverse osmosis (RO) membrane was designed by embedding sulfonyl moleculars in the polyamide (PA) network. The swelling PA structure has enlarged free volumes. It would induce more facile penetration of 4-nitrobenzenesulfonyl chloride (NBS). Evaporation of solvent molecules contracts the PA network and leads to the fixation of the NBS molecules into the PA network. The swelling of the polyamide network was studied systematically. The most suitable swelling solvent was selected based on the solubility parameter and the restoration capability. The "swelling-embedding-shrinking (SES)" strategy reconstruct the free volume of PA chains. It resulted in significantly higher rejection of neutral boron molecules due to enhanced steric hindrance by embedded NBS plugs and synergistic exclusion effect by –SO 3 H groups. Meanwhile, the alteration of membrane composition and structure were kept minimal. Further, the impacts of key determining factors (polarity, steric hindrance, and affinity) on boron separation performance were systematically analyzed by boron-containing compounds with different numbers of hydrogen bonding sites (or dipole moments) or molecular volumes. Under simulated seawater conditions, the boron rejection of the SES modified reverse osmosis membranes increased from 82.12% to 93.10%, and the salt rejection rate increased to 99.57%. Our study shows that the swelling induced embedding of NBS molecules can be readily adopted to regulate the permselectivity of the PA layer towards removal of boron species. • Modified molecules were embedded in the PA network by a "swelling-embedding-shrinking" (SES) strategy. • The boron removal rate of the SES modified RO membranes increased from 82.12% to 93.10%. The impacts of key determining factors on the boron separation performance were analyzed by boron-containing compounds.. • The mechanism of embedding –SO3H group to facilitate boron removal. The pKa value of the modified molecule is associated with the rejection of the modified membrane. [ABSTRACT FROM AUTHOR]

In this work, nanofiltration membrane with an asymmetric selective separation layer and improved surface negative charge was designed and fabricated to efficient remove anionic dyes from aqueous solution. Firstly, loose polyester selective separation layer was formed through interfacial polymerization of triethanolamine and trimesoyl chloride. Surface carboxylation was then implemented via esterification using poly(acrylic acid) to generate a dense skin. Membrane characterizations verified the asymmetric structure and enrichment of surface carboxyl group, which endowed the carboxylated membrane with improved perm-selectivity and anti-dye-deposition property to anionic dye aqueous solutions. The desired surface carboxylated membrane exhibited 99.6% methyl blue removal, 8.05 l/m2 h bar steady-state water permeability and 14.3% relative flux decline ratio under 5.0 bar. The water permeability of carboxylated membrane to methyl blue aqueous solution was higher than those of most reported membranes and even at least two times higher than that of the polyester-based membrane having nearly the same dye removal ability. The attractive results indicate that surface carboxylated polyester based thin-film composite membrane is a promising material for high-efficiency nanofiltration of anionic dye aqueous solution. This study provides valuable insights into the construction and fabrication of high performance nanofiltration membrane for efficient treatment of anionic dye aqueous solution. Unlabelled Image • Efficient removal of anionic dyes was attained through nanofiltration. • Surface carboxylation was performed with polyester thin-film composite membrane. • High perm-selectivity was achieved by constructing asymmetric separation layer. • Improved anti-deposition of anionic dye was achieved by enhancing negative charge. • Water permeability to methyl blue solution was higher than most reported membranes. [ABSTRACT FROM AUTHOR]

This study reported a series of thin film composite (TFC) membranes with single-walled nanotubes (SWCNTs) interlayers for the forward osmosis (FO) application. Pure SWCNTs with ultrahigh length-to-diameter ratio and without any functional group were applied to form an interconnect network interlayer via strong π-π interactions. Compared to the TFC membrane without SWCNTs interlayer, our TFC membrane with optimal SWCNTs interlayer exhibited more than three times the water permeability (A) of 3.3 L m−2h−1bar−1 in RO mode with 500 mg L−1 NaCl as feed solution and nearly three-fold higher FO water flux of 62.8 L m−2 h−1 in FO mode with the deionized water as feed solution and 1 M NaCl as draw solution. Meanwhile, the TFC membrane with SWCNTs interlayer exhibited significantly reduced membrane structure parameters (S) to immensely mitigate the effect of internal concentration polarization (ICP) in support layer with micro-sized pores in favor of higher water flux. It showed that the pure SWCNTs interlayer could be an effective strategy to apply in FO membranes. [ABSTRACT FROM AUTHOR]

In this work, a novel and simple strategy, i.e., solvent activation before heat-treatment was proposed to improve reverse osmosis (RO) membrane performance. This activation strategy is different from that adopted in previous reports. With this strategy, solvent activation was conducted before heat-treatment. While in previous reports, solvent activation was conducted after heat-treatment. By systematic characterization, solvent activation before and after heat-treatment were compared for the first time. The results showed that exchanging the order of solvent activation and heat-treatment created completely different effects on the RO membrane structures and performance. Specifically, solvent activation before heat-treatment affected the RO membrane structures more obviously and was superior in terms of improving RO membrane performance. Besides, the solvent activation was discussed deeply. The results showed that it had better choose an activation solvent, which is non-polar and low viscous as well as molecular size is small. By using an appropriate activation solvent, such as hexane, solvent activation before heat-treatment improved the RO membrane performance markedly: the flux was improved from 46 ± 1 L m−2· h−1 to 75 ± 5 L m−2 h−1 (by 63%) and meanwhile a high rejection of 98.97 ± 0.08% was retained (the testing condition: 15.5 bar pressure, 2000 ppm NaCl feed and 25 °C). Additionally, an unexpected phenomenon was found: increasing the activation time led to the decrease of flux and increase of rejection, which is because more activation solvent (hexane) molecules remained in the polyamide layer and then impeded the transport of water and salt. Image 1 • Solvent activation before heat-treatment was proposed to improve RO membrane performance. • Solvent activation before heat-treatment was superior to solvent activation after heat-treatment. • The activation could improve the flux by 63% meanwhile retaining a high rejection (98.97%). • More activation solvent molecules could remain in the polyamide layer when increasing the activation time. [ABSTRACT FROM AUTHOR]

Electrodialysis (ED) technique is a typical and promising membrane process, for applications like water treatment and ion separation. Especially, the separation between monovalent and multivalent cations is a current central issue in many industries and academic researches. Herein, a series of novel cation exchange membranes were prepared from quaternized polyaniline modified sulfonated polyphenyl sulfone (SPPSU) by in-situ polymerization-deposited polyaniline followed by quaternizing with methyl iodide. Restricted divalent cation penetration and regulated monovalent cation transport were achieved by elevating the kinetic effect of electrostatic repulsion and narrowing water channel. Importantly, positive charge density of modification layer could be adjusted by controlling the degree of quaternization, which was accompanied by the change of water channel. When evaluated in a simulated mixed salt system (Mg2+/Na+ and Mg2+/Li+), the optimal quaternized polyaniline membrane exhibited a higher perm-selectivity (PNa Mg =4.1, PLi Mg =1.75) than initial polyaniline modified cation exchange membrane (PNa Mg =0.8, PLi Mg =0.75), and commercial monovalent-selective cations exchange membrane CIMS (PNa Mg =3.56, PLi Mg =1.11). This presented strategy is straightforward and effective, demonstrating the effect of surface positive charge layer on perm-selectivity. Image 1 • CEMs were fabricated based on SPPSU modified by quaternized polyaniline. • The positive charge density of surficial layer could be adjusted by controlling the degree of quaternization. • The prepared membranes were successfully applied separation of mixed salt system (Mg2+/Na+ and Mg2+/Li+). • The as-prepared membrane showed better perm-selectivity (P Na Mg) than polyaniline modified one and commercial CIMS. [ABSTRACT FROM AUTHOR]

In this work, a support modified by tannic acid (TA) and a green co-solvent (dimethyl carbonate (DMC)) were used jointly to prepare high performance polyamide (PA) reverse osmosis (RO) membranes. The membrane characterization results showed that (1) the leaf-like structure became more pronounced on the membrane surface owing to the addition of DMC and (2) TA made the PA active layer thinner and denser. Because of these improvements of skin layer structure, the RO membranes prepared using TA and DMC (i.e., polysulfone (PSf)/TA-RO@DMC) had a better performance than the membranes prepared without using TA and DMC (i.e., PSf-RO) and those prepared using only TA (i.e., PSf/TA-RO) or only DMC (i.e., PSf-RO@DMC). By joining hands, TA and DMC endowed the RO membranes with a high flux of 64.2 ± 1.8 L m−1 h−2 and a high salt rejection of 99.03 ± 0.02% (the testing condition: 15.5 bar pressure, 2000 ppm NaCl feed and 25 °C). Besides, chlorination was used to improve the membrane performance further. The chlorination results showed that chlorinated PSf/TA-RO@DMC had a higher performance than chlorinated PSf-RO@DMC. This is because TA increased the compactness of PA active layer, which weakened the effect of chlorine attack on PA. After chlorination, the flux and salt rejection of PSf/TA-RO@DMC can be improved further to 90.5 ± 6.3 L m−1 h−2 and 99.25 ± 0.02%, respectively (the testing condition: 15.5 bar pressure, 2000 ppm NaCl feed and 25 °C). Image 1 • Using TA-modified supports and a green co-solvent jointly for preparing RO membranes. • The as-prepared RO membrane possessed a skin layer with thin and dense active layers as well as a big surface roughness. • RO membranes with high flux-rejection combinations were obtained. [ABSTRACT FROM AUTHOR]

• Smooth (R a less than 2 nm) surface of the GQDs-interlayered membrane was achieved. • The 25 nm-thick skin layers of the GQDs-interlayered membranes. • The GQDs-PEI interlayer covalent bonded between substrate and skin layer. • The prepared membrane maintained stable performance in DMF for 45 days at 80 °C. Novel thin film nanocomposite (TFN) organic solvent nanofiltration (OSN) membranes with sandwich-like structure were developed via interfacial polymerization (IP) using both low concentration m-phenylenediamine (MPD) and trimesoyl chloride (TMC), on graphene quantum dots (GQDs)-polyethyleneimine (PEI) modified polyimide substrate surface, and followed by post-IP crosslinking and solvent activation. Such GQDs-interlayered OSN membranes have exhibited a remarkable reduced thickness (about 25 nm) and an ultra-low average surface roughness (less than 2 nm) of their IP skin layers, respectively. Both material features are rarely reported in literature. Meanwhile, our GQDs-interlayered OSN membranes have shown an increased Rhodamine B (479 Da) rejection (from 87.4% to 98.7%) and an increased ethanol permeance (from 33.5 to 40.3 L m−2 h−1 MPa−1) compared with the pristine OSN membrane. Superior solvent resistance was demonstrated after long immersion in pure N , N -dimethylformamide (DMF) at room temperature for 81 days, and at 80 °C for 45 days, and after a long-term consecutively filtration with Rose Bengal (1017 Da) DMF solution at 25 °C for 5 days, without scarifying solute rejection. Antifouling properties during the long-term filtration were also indicated. This paper presents a novel GQDs-interlayered strategy in developing high-performance TFN membranes for OSN application. [ABSTRACT FROM AUTHOR]

• Three composite AEMs from QPSU and PVA blends have been fabricated for ED. • The swelling ratio of optimized M 2 -0.05 AEM was significantly reduced to 4.7% at 20 °C. • The chloride ion conductivity of M 2 -0.05 reaches 23.5 mS cm−1 at 20 °C. • M 2 -0.05 has the superior NaCl removal ratio of 74.6% within 120 min (vs. 61.06% of AEM-Type II). It is significant to develop anion exchange membranes (AEMs) with efficient ionic transport and desirable stabilities (mechanical and dimensional) for various applications, including electrodialysis (ED). In this paper, three types of composite AEMs based on quaternized polysulfone (QPSU) and polyvinyl alcohol (PVA) blends: QPSU/PVA composite AEM (M 0), potassium thioacetate (PT) modified QPSU blending with PVA (M 1) and QPSU blending with 4-formylbenzoic acid (FBA) modified PVA (M 2 -X, X = mass ratio of the FBA with the values of 0.05 and 0.20), have been investigated. Our investigation demonstrates that the swelling ratios of M 1 and M 2 -0.05 were significantly reduced to 10.9% and 4.7% at 20 °C, much lower than M 0 (16.9%). This can be due to the formed hydrogen-bonding network via OH from PVA and >C O from PT structure on PSU within M 1 or the ionic crosslinking interactions between COO– from FBA and >N+– on QPSU within M 2. Though the free volume inside AEM matrix is reduced, the chloride ion conductivities of M 1 and M 2 -0.05 reach 20.5 mS cm−1 and 23.5 mS cm−1 at 20 °C. In ED application, the optimized M 2 -0.05 has the highest NaCl removal ratio of 74.6% within 120 min (vs. 61.06% of the commercial AEM-Type II), and exhibits better desalination performance with high current efficiency (98.0% vs.92.8%) and lower energy consumption (2.2 kWh kg−1 NaCl vs. 2.4 kWh kg−1). The simple preparation process and good ED performance of M 2 -0.05 are indicative of its potential ED application. [ABSTRACT FROM AUTHOR]

Oil/water separation membranes with high flux efficiency and robust anti-oil-fouling property have attracted numerous attention, and superwetting carbon nanotube (CNT) membranes are promising candidates. The key challenges focus on the versatile integration of multiple materials/structures and the facile functionalization towards superhydrophilicity/underwater superoleophobicity. In this study, a polyzwitterion/titania functionalized carbon nanotube membrane for antifouling and high-flux oil/water emulsion separation is synthesized by a novel and simple dual-bioinspired strategy. The strategy involves the co-assembly of polyzwitterion and bioinspired-adhesive polydopamine (PDA) modified CNTs and the bioinspired mineralization of titania nanoparticles (TNPs). The as-prepared CNT membrane is evenly decorated with polyzwitterion and TNPs mediated by the comprehensive adhesive capability of PDA. The integration of the hydrophilic advantages of polyzwitterion and titania and the integration of the multiscale structures of CNTs and TNPs endow membranes with superhydrophilicity, underwater superoleophobicity and anti-oil-adhesion property. The nanoscale porous structures of CNT assembled network ensure the high permeability (about 3400 L m−2 h−1) and separation efficiency (over 99.5% for emulsified oils) of membranes. Furthermore, when applied to oil-in-water emulsion separation, the as-prepared CNT membrane exhibits good recycle performance throughout several filtration cycles and maintains high recovery ratio of 95% after several cycles, indicating excellent antifouling property. The dual-bioinspired strategy combining bioinspired adhesion and bioinspired mineralization provides new insights into the design and construction of nano-structured membranes for oil/water separation. Polyzwitterion/titania co-functionalized carbon nanotube membrane is fabricated via a novel dual-bioinspired strategy combining bioinspired adhesion and bioinspired mineralization for antifouling and high-flux oil/water emulsion separation. Image 1 • Bioinspired adhesion and mineralization combined dual-bioinspired strategy is developed. • The polyzwitterion and titania functionalized CNTM is prepared via dual-bioinspired strategy. • The CNTM shows both hierarchical organized structures and hydrophilic composite composition. • Superhydrophilicity, underwater superoleophobicity and anti-oil-adhesion are achieved. • The CNTM enables antifouling and high-flux oil/water emulsion separation. [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]

Smart gating membranes with self-regulating nanopores/nanochannels are highly desirable for water gating and separation of small molecules. Based on the nanochannels in the graphene oxide (GO) membrane, we designed positive thermo- and negative pH-responsive GO/hydrogel composite membranes (GOGMs) through a simple filtration-accumulation of GO sheets and hydrogels. The shape-flabby hydrogels can be perfectly inlaid between two GO sheets by changing their shape, and also act as a bond between GO and substrates. Thermo- and pH-responsive hydrogels embedded between the GO sheets impart adjustable water channels to the GO membrane. The channel tunability of hydrogel-studded GO membrane derives from the size conversion of hydrogel and the constant layer spacing of GO sheets. The hydraulic permeability of GOGMs was explored within the wide pH range of 2–6 and the temperature interval of 20–44 °C. The results revealed that the hydraulic permeability of the GOGMs can be reversibly adjusted with a high thermo- and pH-responsive gating coefficients. The GOGMs with self-regulated channels have various permeability properties for small molecules under different conditions. Moreover, the membrane thickness and the ratio of microgel to GO both have an effect on the water permeation and response performance of the GOGMs. These environmental stimuli-responsive membranes with thermo- and pH-responsive channels has numerous potential for applications in smart gating systems, liquid-based controlled release systems and smart separation systems. Thermo- and pH-responsive graphene oxide membranes with self-adjusted effective pore size according to the changes of the external environment exhibits different interception properties for small molecules under different conditions. Image 1 • Facile fabrication of dual thermo- and pH-responsive GO/hydrogel composite membranes. • Hydrogels embedded in the GO sheets can self-regulate their size. • GOGMs have self-tunable water gating and excellent gating coefficients. • Pore-adjustable GOGMs showed potential applications in permeation of small molecules. [ABSTRACT FROM AUTHOR]

A facile membrane surface modification process for improving permselectivity and antimicrobial property was proposed. A polydopamine (PDA) coating was firstly fabricated on pristine anion exchange membrane (AEM), followed by in situ reduction of Ag without adding any extra reductant. Finally, 2,5-diaminobenzene sulfonic acid (DSA) was grafted onto PDA layer via Michael addition reaction. The as-prepared AEM exhibited improved permselectivity (from 0.60 to 1.43) and effective inhibition of bacterial growth. In addition, the result of the long-term (90-h continuous electrodialysis) test expressed the excellent durability of the modified layer on membrane surface, because the concentration of Cl− and SO42− in diluted chamber fluctuated ~0.024 and 0.030 mol·L−1 with no distinct decline. The method described in this work makes the full use of multifunctional PDA layer (polymer-like coating, in situ reduction and post-organic reaction), and a rational design of functional AEM was established for better practical application. [ABSTRACT FROM AUTHOR]

A ternary nanocomposite consisting of N-doped graphene (NGR)/TiO2/activated carbon (NGRT@AC) was prepared, and the components' synergetic effect on dye degradation was investigated after deposition on the surface of a polysulfone membrane (PSF). As far as we know, this ternary composite catalyst has never previously been used to degrade dyes nor been used as a functional layer for separation membranes. The surface morphology and structure of the as-prepared membranes were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The NGRT@AC-modified PSF membrane (NGRT@AC-PSF) presents excellent photodegradation efficiency to methyl orange (MO) under both UV (95.2%) and sunlight (78.1%) irradiation, much higher than those values of PSF, TiO2- modified PSF (TiO2-PSF), and N-doped graphene/TiO2 (NGRT)-modified PSF membranes (NGRT-PSF) under the same conditions. The high flux recovery ratio (95.5%) demonstrates that the NGRT@AC-PSF membrane shows improved antifouling performance. The photocatalytic results prove that surface deposition method (95.2%) was better than the blending method (31.1%) for forming high-performance membranes. Therefore, the NGRT@AC-PSF membrane has the potential for broad applications in dye degradation to treat waste water from textile industries. [ABSTRACT FROM AUTHOR]

In this study, polyelectrolyte assembled functionalized graphene oxide (PE-GO) membranes were fabricated through a one-step charge facilitated deposition method for high performance dye/salt separation. According to the intercalation of polydopamine (PDA) and (ionic liquid) IL functional moieties into the GO membranes, the pore size of the resulted PE-pGO and PE-iGO membrane increased from 2.69 nm to 4.13 nm and 6.54 nm, respectively. Correspondingly, a pure water flux of 13.8 ± 2.2, 36.7 ± 3.4, and 52.1 ± 6.7 L m−1 h−1 bar−1 was achieved for PE-GO, PE-pGO and PE-iGO membrane, respectively. PE-iGO membrane with the largest pore size could be operated with significant water permeability (28.3 to 38.3 L m−1 h−1 bar−1) at a low operating pressure range of 0.5–2 bar (dye concentration = 100 ppm, salt concentration = 5 g/L). More importantly, functionalities introduced to the GO nanosheets are found to impact the dye adsorption to the membrane surface. The IL intercalation promotes the elution of dye molecules from the IL moieties at elevated pH, therefore enhancing the efficiency of alkaline washing of the membrane. By contrast, the intercalation of PDA weakens such efficiency due to its strong adhesion force to the dye molecules even at the alkaline condition. [ABSTRACT FROM AUTHOR]

A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl−/SO42− separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl−/SO42− permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later. [ABSTRACT FROM AUTHOR]

Aquaporin (AQP) based biomimetic membranes have attracted considerable attention for their potential water purification applications. In this paper, AQP1 incorporated biomimetic membranes were prepared and characterized. The morphology and structure of the biomimetic membranes were characterized by in situ atomic force microscopy (AFM), infrared absorption spectroscopy, fluorescence microscopy, and contact angle measurements. The nanofiltration performance of the AQP1 incorporated membranes was investigated at 4 bar by using 2 g l−1 NaCl as feed solution. Lipid mobility plays an important role in the performance of the AQP1 incorporated supported lipid bilayer (SLB) membranes. We demonstrated that the lipid mobility is successfully tuned by the addition of monoolein (MO). Through in situ AFM and fluorescence recovery after photo-bleaching (FRAP) measurements, the membrane morphology and the molecular mobility were studied. The lipid mobility increased in the sequence DPPC < DPPC/MO (RMO = 5/5) < DOPC/MO (RMO = 5/5) < DOPC, which is consistent with the flux increment and salt rejection. This study may provide some useful insights for improving the water purification performance of biomimetic membranes. [ABSTRACT FROM AUTHOR]