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Abstract: The effects of pH, feed concentration and operation pressure on the recovery of vanadium from acid leach solution of stone coal using nanofiltration membrane technology were investigated. The rejection and permeate flux of vanadium with two kinds of membranes in nanofiltration process were also studied. After pre-treatment of leach solution to remove calcium by the addition of sodium carbonate, the vanadium in the final concentrated solution can be up to 30g/L from 1.429g/L in the feed under the optimum conditions of pH6–6.5 and operation pressure of 2069kPa at room temperature during nanofiltration process with the rejection of vanadium more than 95%. The final concentrated solution can be directly used to produce the V2O5 by traditional method, and the permeate stream can be recycled to leaching. The conceptual flow sheet for the extraction of vanadium from acid leach solution using nanofiltration membrane has been developed. [Copyright &y& Elsevier]

Abstract: N,O-carboxymethyl chitosan (NOCC) composite nanofiltration membranes having a polysulfone (PS) UF membrane as the substrate were prepared using a method of coating and cross-linking, in which a glutaraldehyde (GA) aqueous solution was used as the cross-linking agent. Attenuated total reflection infrared spectroscopy (ATR-IR) was employed to characterize the resulting membrane. The effects of the composition of the casting solution of the active layer, the concentration of the cross-linking agent, and the membrane preparation techniques on the performance of the composite membrane were investigated. At 13–15°C and 0.40MPa the rejections of the resulting membrane to Na2SO4 and NaCl solutions (1000mgL−1) were 92.7 and 30.2%, respectively, and the permeate fluxes were 3.0 and 5.1kgm−2 h−1, respectively. The rejection of this kind of membrane to the electrolyte solutions decreased in the order of Na2SO4, NaCl, MgSO4, and MgCl2. This suggests that the membrane active layer acquires a negative surface charge distribution by the adsorption of anions from the electrolyte solution and this charge distribution mainly determines the membrane performance. [Copyright &y& Elsevier]

Membrane separation technology is one of the cost effective and most efficient technologies for treatment of wastewater from textile industry. However, development of membranes with better performance and thermal stability is still a highly challenging task. In this study, successful preparation of a novel thermally stable polyimide (PI) polymer was demonstrated using 2,4,6-trimethyl-1,3-phenylenediamine, 4,4′-diaminodiphenylmethane and 1,2,4,5-benzenetetracarboxylic dianhydride components. PI was selected as representative candidate because of its excellent thermal stability (decomposition temperature of 529 °C), as revealed by thermogravimetric analysis. Furthermore, PI polymer was used to fabricate ultrafiltration (UF) membrane by phase inversion process. This UF membrane is especially interesting as it allowed for almost complete penetration of monovalent (NaCl) and divalent (Na 2 SO 4) inorganic salts because of its molecular weight cut off of 9320 Da. Moreover, the membrane exhibited very good surface hydrophilicity with the water contact angle of 67.6°. This PI-based UF membrane was found to be substantially effective as it showed high pure-water and dye-permeation fluxes of 345.10 and 305.58 L m−2 h−1 at 0.1 MPa, respectively. Besides, the membrane exhibited a rejection of 98.65% toward the direct red 23 dye (100 ppm) at 0.1 MPa. Thus, this PI-based UF membrane is highly beneficial and acts as a potential candidate for dye removal from wastewater produced by textile industry. [ABSTRACT FROM AUTHOR]

Abstract Performance enhancement of the TFC membrane depends on the fine design of the functional layer. In this study, a gradient cross-linking strategy has been successfully applied to fabricate an ultra-thin gradient cross-linked PVA (GC-PVA) functional layer with the aid of surfactant on a polysulfone (PSF) support membrane. Such a strategy was accomplished by impregnating the crosslinker (Trimesic acid) on the porous support membrane prior to PVA coating. As confirmed by XPS and EDX studies, the GC-PVA membrane features a gradient cross-linked structure, where the bottom surface is densely cross-linked while the top is only slightly cross-linked. Overall, the lowest thickness achieved by the gradient-crosslinked ultrathin functional layer was 75.4 nm. This strategy significantly improved water flux compared with the conventional fully cross-linked PVA membranes while similar salt rejections can be maintained. In addition, the impact of key fabrication parameters, such as the concentration of PVA, surfactant, crosslinker, and the post-treatment temperature has been systematically studied. The optimized membrane had a significantly high water flux of 72.9 L m−2 h−1 at 0.2 MPa and showed rejection rates of 38.2% and 90.7% towards NaCl, Na 2 SO 4 aqueous solution (500 mg/L), respectively. Highlights • Preparation of bottom dense and top crisp gradient cross-linked structures by diffusion of cross linker. • Gradient cross-linking to prepare ultra-thin functional layer, improve water flux at low pressure, and showed good distinguishability for NaCl and Na 2 SO 4. • The surfactant (SDS) enhances the wettability of the PSF membrane and the dispersibility of the cross-linker. [ABSTRACT FROM AUTHOR]

Abstract In this study, the novel technique, namely interfacial polymerization (IP) coupled with surface amidation, was proposed to fabricate polyamide thin-film composite (TFC) membranes for improved reverse osmosis performance. TFC membrane with loose polyamide separation layer was firstly prepared through conventional IP process. Surface amidation was then performed through covering the surface of the loose polyamide layer with aqueous 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) solution. Amidation reaction between the free carboxylic and amino groups on membrane surface was confirmed through ATR-FTIR and XPS analyses. Permeation tests revealed that the step of surface amidation could effectively improve the ability of membrane rejection to solute, showing significant increases of NaCl, NaNO 3 and glycerol rejections from about 96.4%, 90.5% and 78.4% to 97.8%, 93.7% and 91.3%, respectively. The water permeability of the membrane obtained via IP followed with surface amidation was at least 22.3% higher than the membrane of the same NaCl rejection obtained via conventional IP process. Thus, the method developed was attractive for the fabrication of TFC reverse osmosis membranes with improved permeability to water and rejection ability to solutes. Additionally, the step of surface amidation of present work can be potentially applied to the in-situ rejuvenation of used polyamide reverse osmosis membranes. Highlights • TFC membrane was fabricated via interfacial polymerization and surface amidation. • Surface amidation was facilely implemented via using acidic EDC aqueous solution. • PA selective layer composed of a top dense skin on loose bulk was obtained. • PA TFC membrane with improved reverse osmosis performance could be obtained. [ABSTRACT FROM AUTHOR]

Effective oil/water separation is urgently demanded but still remains a global challenge. Membranes with super-wettability have been rapidly developed, but most of the membranes are suffered from the complicated fabrication procedures and inability of separating different types of emulsions. In this work, super-amphiphilic PVDF composite membranes were developed via synchronous in-situ growth and immobilization of Ag nanoparticles during phase inversion. This method allowed the membrane formation and nanoparticle immobilization at the same time. The impact of silver growth time on the surface morphology and wettability was comprehensively investigated. The introduction of Ag nanoparticles endowed the membranes with micro/nano-structures and super-wetting property, which made the membrane possess reversible under-liquid superamphiphobicity. The PVDF composite membranes exhibited high permeate flux and outstanding separation efficiency for different surfactant-stabilized oil/water emulsions. Moreover, the prepared membranes could be regenerated through a facile method of rinsing and drying and the high separation performance could be maintained after repeated cycles, indicating the outstanding anti-fouling performance of the membranes. Furthermore, the PVDF composite membranes exhibited superior antibacterial performance. This work made progress in fabricating super-wetting membranes with excellent emulsion separation performance and the membranes can be prospective candidate for oily-mixture separation in practical applications. [Display omitted] • Under-liquid superlyophobic PVDF membrane was successfully fabricated. • A novel synchronous in-situ growth and immobilization of Ag NPs was adopted. • The impact of Ag growth time on morphology and wettability was investigated. • The membrane could effectively separate various surfactant-stabilized emulsions. • The membrane exhibited excellent durability and anti-fouling performance. [ABSTRACT FROM AUTHOR]

Polyvinyl alcohol (PVA) has the advantages of excellent hydrophilicity, good film-forming properties and competitive prices, thus it is an ideal membrane material. However, rare reports about PVA membrane for monovalent/divalent salt separation, which is widespread in chemical industry can be found. Herein, we developed a novel boric acid (BA)-loosened PVA/glutaraldehyde (GA) membrane with high flux and selectivity for monovalent/divalent salt separation. Our idea is based on the fact that BA and PVA can form a complex due to some special interactions (including chemical bonding and H-bonding). In general, PVA membrane needs to crosslink with GA for obtaining a high salt rejection. However, PVA/GA membrane is usually too compact, leading to a low membrane water flux. The formation of PVA/BA complex reduced PVA/GA membrane crystallinity and increased its pore size, thereby improving the membrane flux obviously (by 16 times). PVA/GA/BA membrane flux is high: under 7.5 bar, its pure water flux was 20.20 L/m2·h. Besides, a high monovalent/divalent salt selectivity (64.21) was also achieved since the rejection of monovalent salt (NaCl) declined sharply and meanwhile the high rejection of divalent salt (Na 2 SO 4) was maintained. Moreover, the developed PVA/GA/BA membrane exhibited a good alkali resistance, antifouling performance and stability of permselectivity, which has a bright application prospect. This work may pave a novel avenue to develop high-performance PVA monovalent/divalent salt separation membranes. [Display omitted] • The introduction of boric acid greatly improves the PVA NF membrane permeability. • PVA/GA/BA membrane has high selectivity for monovalent/divalent salt separation. • The membrane exhibited a good alkali resistance, antifouling performance. [ABSTRACT FROM AUTHOR]

In this study, heterostructured MOF/lamellar talc composites was successfully synthesized by in-situ growth of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles on acidified black talc (ABT) and introduced into polydimethylsiloxane (PDMS) matrix to prepare high-performance mixed matrix membranes (MMMs) via spin coating and thermal cross-linking. The submicron-size natural lamellar black talc (BT) was first explored as stable carrier to synthesize laminated composite with continuous MOF phase. Owing to its silica-oxygen tetrahedral structure, the resultant laminated composite presented good compatibility with PDMS matrix, avoiding the formation of interfacial defect between polymer and nanoparticles. Moreover, well-dispersed and continuous ZIF-8 nanoparticles on lamellar nanosheets had preferential adsorption effect for alcohol, enhancing the selectivity of membranes. The coupling effects of graphene-like lamellar structure from talc and sequential transport channels from ZIF-8 attributed to greatly enhance permeation flux. Various techniques such as FESEM, TEM, FTIR, XRD and EDS were applied to investigate the morphology and structure of composites and membranes, and pervaporation experiments were applied to probe the behavior of polymer-based composite membranes. High performance defect-free ZIF-8@ABT/PDMS MMMs exhibited excellent total permeate flux of 1711 g m−2 h−1 with very competitive separation factor of 41 for low concentration n-butanol recovery. [Display omitted] • Heterostructured composite was first achieved by in-situ growth of MOF on talc nanosheet. • MMMs were obtained by introducing lamellar composites into PDMS matrix via spin-coating. • Interfacial defect was avoided by good compatibility between ZIF-8@ABT and PDMS matrix. • Preferential adsorption and unobstructed pathway were achieved by MOFs and lamellar ABT. • Stable ZIF-8@ABT/PDMS membranes exhibited excellent performance for butanol recovery. [ABSTRACT FROM AUTHOR]

Abstract: In this study, asymmetric polysulfone (PSf) membranes with capsaicin-mimic groups were prepared from PSf/P(H-M)/DMAc system via phase inversion induced by immersion precipitation. Effects of coagulation bath temperature and composition on morphology, wettability, pure water permeability (L p), separation performance and anti-fouling property of the prepared membranes were systematically studied by scanning electron microscopy, contact angle measurement and fouling–filtration experiments. The results demonstrated that the elevation in the coagulation bath temperature resulted in greater formation of macrovoids and lower surface hydrophilicity, which attributed to higher both pure water permeability and permeation flux for filtration of HA solution, yet lower both HA rejection and anti-fouling capacity. Either ethanol or glacial acetic acid with different concentrations was used as non-solvent coagulation bath in this study. It was shown that pores on the membrane surface changed larger in size and then obviously shrank with an increase in either ethanol or GAA concentration in the testing range, while the surface hydrophilicity of the membranes was gradually enhanced. When 25% ethanol solution was used in coagulation bath, the membranes exhibited the excellent permeability, separation performance as well as anti-fouling capacity. Moreover, ethanol has several advantages over GAA on the fabrication of the membranes with higher hydrophilicity, permeability, permeation flux and anti-fouling capacity, while GAA favors the improvement in HA rejection of the membranes. On the whole, adjusting coagulation bath condition is an effective approach to tailor the separation performance and anti-fouling capacity of the formed P(H-M)-containing PSf membranes. [Copyright &y& Elsevier]

Abstract: Using molecular dynamics simulations, we study the transport of Li+ and Mg2+ through membranes formed from armchair type (8,8) to (11,11) single wall carbon nanotubes (SWNTs) under hydrostatic pressure, and investigate the potential of mean force(PMF), conductance and axial density distributions of ions in the carbon nanotubes, the results show that under 100MPa, (9,9) and (10,10) SWNT are capable of extracting Li+; when adjusting pressure to 200MPa, (8,8), (9,9) and (10,10) tubes can separate Li+ and Mg2+ with higher ion fluxes which also augment with increasing tube diameters. By calculating the potential mean force for ion translocation, we show that Mg2+ face greater energy barrier than Li+ when passing the carbon nanotube with same diameter, and free energy difference of ∼8kJ/mol seem to be the threshold to effectively separate Li+ and Mg2+. Membrane incorporating narrow carbon nanotubes is found to be promising in Li+ and Mg2+ separation. [Copyright &y& Elsevier]

Divalent metal nitrates were pre-loaded on polysulfone support to modulate the interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC). It is found that the nano-porosity and nano-morphology of thus formed thin film composite polyamide (TFC-PA) nano-filtration (NF) membranes as well as their filtration performance could be effectively tuned by the type and concentration of the divalent metal salts, especially the divalent cations used. Main group cations, such as Mg (II) and Ca (II), increased the water flux of the NF membranes by increasing their surface nano-scale nodular arrays without altering the pore sizes and rejections of the membranes, while transitional metal cations such as Zn (II), Cu (II) and Co (II) increased the water flux of the NF membranes not only by the formation of high surface area nano-scale Turing type crisscrossed ridge networks, but also by the increase of their nano-pore sizes due to their coordination with the >NH groups of the PIP. The prepared NF membranes pore sizes adjustable from 0.54 Å to 0.90 Å could be developed to have varied selectivity and rejections among inorganic salts and organic dyes. [Display omitted] • Nano-porosity of NF membranes could be tuned in the IP processes. • Retention selectivity of TFC-PA NF membranes could also be tuned. • Divalent transitional metal cations increased both pore size and surface area. • Divalent main group metal cations increased water flux without changing selectivity. • Anions Cl- may act as a ligand to impeach the action of divalent transitional cations. [ABSTRACT FROM AUTHOR]

Abstract: In this study, several anti-fouling approaches including coagulation conditions (FeCl3 dosage and feed pH), air-enhanced backwash (AEB) conditions (backwash interval and AEB duration) and chemical cleaning conditions (reagents, soak time and temperature) were evaluated to enhance the feasibility of a commercial ultrafiltration (UF) membrane as a pretreatment of RO seawater desalination. A tubular commercial ceramic UF membrane with a surface layer of zirconium dioxide (ZrO2) and a supporting layer of α-alumina oxide (α-Al2O3) was employed in this study. The results showed that ferric coagulation was functional to enhance the performance of ceramic UF for seawater treatment, especially on COD removal. The trial of cleaning demonstrated that the performance of NaClO was much better than that of HNO3 under various evaluated pH values. The relevant additional experiments showed that the cleaning efficiency increased with NaClO concentration, soak time and soak temperature but decreases when soak temperature was up to 60°C. An important finding of this study is that the fouled membrane from coagulation-filtration trial can be easily and quickly recovered by acid cleaning regents followed by NaClO solution. Furthermore, short backwash interval performed more efficiently. However, it is certain that both backwash interval and AEB duration enhanced less than other approaches on the permeate quality. This study finally summarized the operating condition of each anti-fouling approach for the further potential application of UF ceramic membrane as a pretreatment of RO seawater desalination. [Copyright &y& Elsevier]

Abstract: A novel thin-film composite polyamide nanofiltration membrane was prepared through interfacial polymerization of polymeric polyamine polyvinylamine (PVAm) with isophthaloyl chloride (IPC) on a polysulfone supporting film. The composite membranes were prepared under different conditions and characterized in terms of chemical and morphological structures, surface zeta potential, pure water permeability, and rejection to different solutes including electrolytes and sucrose. The results showed that the membrane performance was significantly affected by the content of amine units of PVAm and the concentrations of PVAm and IPC. The increase of the content of amine units of PVAm and the concentration of IPC resulted in an augment in salt rejection and a decrease in permeability, while the increase of PVAm concentration led to enhancement in both the salt rejection and water flux. The obtained membranes were positively charged at pHs lower than 6.5 and negatively charged at pHs higher than 7.0. The rejection order of the membrane changed from MgCl2 >MgSO4 >NaCl>Na2SO4 at pH 3.0 to MgSO4 >Na2SO4 >MgCl2 >NaCl at pH 7.5. The decrease of feed pH from 7.5 to 3.0 resulted in an over 35.0% augment in permeability. Furthermore, the novel nanofiltration membrane is of good performance stability and particularly suitable for treating acidic feed. [Copyright &y& Elsevier]

Abstract: Commercial thin-film composite aromatic polyamide reverse osmosis membranes were modified by depositing N-isopropylacrylamide-co-acrylic acid copolymers (P(NIPAm-co-AAc)) on the membrane surface, and the modified membranes showed improved membrane properties. P(NIPAm-co-AAc) copolymers were synthesized by free radical copolymerization and their aqueous solutions of different concentrations were used to modify the polyamide membranes through in situ surface coating technique. The deposition of P(NIPAm-co-AAc) layer was shown to increase membrane surface hydrophilicity and surface charge at neutral pH, but offer additional resistance to water permeation. The effect of surface modification on membrane salt permeability was investigated through permeation tests with different salts under different pHs. The membrane modification was found to decrease the salt permeability of NaCl and Na2SO4 under neutral and alkaline conditions, and the decrease was significant for Na2SO4 that has divalent anions than for NaCl that has monovalent anions. The results of the fouling experiments with bovine serum albumin (BSA) aqueous solution and washing experiments with de-ionized water of different temperatures also revealed that the P(NIPAm-co-AAc) coating layer improved the fouling resistance to BSA and the cleaning efficiency. The phase transition of the coating layer under temperatures above its LCST would facilitate the removal of foulants located on the membrane surface. [Copyright &y& Elsevier]

Abstract: A novel thin-film composite (TFC) seawater reverse osmosis membrane was developed by the interfacial polymerization of 5-chloroformyloxyisophthaloyl chloride (CFIC) and metaphenylenediamine (MPD) on the polysulphone supporting membrane. The performance of the TFC membrane was optimized by studying the preparation parameters, which included the reaction time, pH of the aqueous-MPD solution, monomer CFIC concentration, additive isopropyl alcohol content in aqueous solution, curing temperature and time. The reverse osmosis performance of the resulting membrane was evaluated through permeation experiment with synthetic seawater, and the structure of the novel membrane was characterized by using SEM, AFM and XPS. Furthermore, the separation properties of the TFC membrane were tested by examining the reverse osmosis performances of various conditions, the boron rejection performance and the long-term stability. The results show that the desired TFC seawater reverse osmosis membrane has a typical salt rejection of 99.4% and a flux of about 35L/m2 h for a feed aqueous solution containing 3.5wt.% NaCl at 5.5MPa, and an attractive boron rejection of more than 92% at natural pH of 7–8; that the novel seawater reverse osmosis membrane appears to comprise a thicker, smoother and less cross-linking film structure. Additionally, the TFC membrane exhibits good long-term stability. [Copyright &y& Elsevier]

Metal-organic frameworks (MOFs) are an increasingly popular class of porous materials due to their tailorable structure comprised of ordered porous cavities, high specific surface areas, and versatile functional organic ligands. Implementation of these porous materials into membrane separation technologies can create an energy-efficient alternative for ion-selective separation. However, their low stability in aqueous environments and other challenges has limited their industrial breakthrough. In the past five years, many developments have improved MOF-based membranes for the selective separation of target ions. Novel insight into MOF-based membranes' structure-property relationships improves dispersibility, stability, size-sieving, electrostatic repulsion, and ionic conductivity for ideal membrane performance. The latest design principles for MOF-based membrane use advanced confinement conversion, in situ self-assembly, layer-by-layer assembly, and interfacial polymerization methods for enhanced separation performance. Analysis of separation mechanisms in MOF-based membranes now extends applications to desalination, lithium extraction, removal of heavy metal ions, and separation of ions from organic solvents. Overall, further development of MOF-based membranes presents numerous opportunities and challenges in target ion separation. This review provides guidelines for the preparation methods and properties of MOF-based membranes for target ions separations. [Display omitted] • This review focused on the latest advancements in MOF-based membranes for selective separation of target ions. • The fundamental properties and novel design strategies for MOFs in ion separation were analyzed and concluded. • The theoretical simulations and separation mechanisms of ion transport in MOFs, were analyzed and concluded. • Applications in selective ion separation and future opportunities for MOF-based membranes were provided. [ABSTRACT FROM AUTHOR]

Abstract: A novel composite nanofiltration (NF) membrane was prepared by over-coating the PAN ultrafiltration (UF) membrane with a glycolchitin (GC) thin layer. The effects of the membrane preparation techniques and operating conditions on the rejection performance of the composite membranes were studied. The structure of the composite NF membrane was characterized by scanning electron microscopy (SEM) and infrared spectroscopy (IR). And the surface roughness of the composite membrane was also characterized by atomic force microscope (AFM). The pressure osmobic coefficient (β) was about −2mV/MPa and the molecular weight cut-off (MWCO) was obtained at 540Da or so. Rejections of the composite membrane of Na2SO4, K2SO4, MgSO4, NaCl, KCl, MgCl2 solutions (1.0g/L) were 95.2%, 91.5%, 41%, 31.1%, 31% and 20.1% at 25°C under 1.0MPa, and permeation fluxes are 10.0, 10.1, 19.2, 19.7, 20.8 and 13.0L/m2 h, respectively. The results suggest that rejection performance is governed by solute–membrane and solute–solute electrostatic interactions. This charge distribution mainly determined the performances of the membranes. [Copyright &y& Elsevier]

Abstract: A novel positively charged composite nanofiltration membrane is prepared by using PAN UF membrane as support layer, quaternized chitosan, i.e. called 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) as active layer and diisocyanate as cross-linking reagent, respectively. Effects of membrane forming and testing variables on membrane properties are reported. The results indicate that a membrane from 2.0wt% HACC casting solution, cured at 50°C for 2h, cross-linked at 50°C for 9h with hexamethylene diisocyanate (HDI) and toluene diisocyanate (TDI) (HDI/TDI (w/w)=0.3g/0.3g) in 50g ethanol, heat-treated at 50°C for 20min is found to have optimum performance. The membrane, called HACC/PAN composite NF membrane is positively charged, with a RMS roughness of 12.3±0.52×103 nm. And the molecular-weight cut-off (MWCO) is approximately 560Da (NF range) by measuring the rejections of glucose, sucrose and polyethylene glycols (PEG) (MW=600–1000Da) at a concentration of 1000mg/L at 1.0MPa, respectively. At 25°C, the pure water permeability of this membrane is 10.59kgh−1 m−2 MPa−1. The rejection to different salt solutions follows the decreasing order of MgCl2, CaCl2, NaCl, KCl, MgSO4, Na2SO4 and K2SO4, which is typical characteristics of positively charged NF membranes. Besides, the curve about the streaming potential illustrates the positively charged characteristics of this membrane, with a pressure osmotic coefficient of 7.73mVMPa−1. [Copyright &y& Elsevier]

Pore size distribution is crucial for the application of nanofiltration membrane in size-selective separation of industrial fluids. In this work, a novel combined interfacial polymerization (IP) and in-situ sol-gel strategy was proposed to fabricate composite nanofiltration membrane with narrow pore size distribution. Aqueous solution of piperazine and polyvinyl alcohol (PVA) was employed to perform interfacial polymerization with organic solution of trimesoyl chloride and tetraethyl orthosilicate (TEOS) on porous support. The non-reactive additive TEOS within the interfacially synthesized selective separation layer was then employed to perform sol-gel. The space-limited hydrolysis and condensation of TEOS molecules and their chemical bonding with PVA molecules were confirmed by analyzing membrane physico-chemical property and were found to be effective in tuning mean pore diameter, narrowing the pore size distribution and thus enhancing membrane perm-selectivity. Compared to those of membrane PA1 with similar mean pore size fabricated by only IP technique, the water permeability and rejection ratio of PEG1000 to raffinose (R PEG1000 /R raffinose) of membrane PA-TEOS0.5 fabricated by combined IP and sol-gel technique were higher by 25.0 and 20.1%, respectively. Moreover, static adsorption and dynamic deposition tests using aqueous bovine serum albumin solution proved that in-situ sol-gel process could endow the membrane with better protein fouling resistance. Image 1 • A combined interfacial polymerization and in-situ sol-gel technique was proposed. • Structure of interfacailly synthesized barrier layer was tuned via in-situ sol-gel. • In-situ sol-gel led to decreased mean pore size and narrowed pore size distribution. • Membrane fabricated by the combined technique exhibited improved perm-selectivity. • In-situ sol-gel endowed the membrane with improved anti-protein-fouling property. [ABSTRACT FROM AUTHOR]

Ultrathin polyamide (PA) nanofilm based separation membranes have attracted drastically increasing attention recently. Typically, PA nanofilms with the thickness of around tens of nanometers are supported by a PSF substrate membrane which provides mechanical support. However, the low surface porosity of the PSF substrate membrane has required the transverse diffusion (parallel to the membrane plane) of water molecules in the nanofilm, which causes much longer mean diffusion paths compared to the thickness of the nanofilm. In this study, we address this problem by introducing a much looser polypiperazinamide (PPA) interlayer in between the PA nanofilm and the PSF support membrane, with the PPA nanofilm serving as a low resistance region for water molecules. A dual interfacial polymerization strategy was applied to create an asymmetrical ultrathin polyamide selective layer comprised of a high permeability loose PPA sublayer and a high selectivity dense PA top layer. Quartz crystal microbalance with dissipation (QCMD) techniques and Doppler broadening energy spectroscopy (DBES) were applied to study the asymmetry structure of the ultrathin polyamide nanofilms. Compared with the home-made traditional ultrathin polyamide (uPA) membrane, the asymmetrical ultrathin polyamide (A-uPA) membrane has 2–2.5 folds higher permeability while maintaining higher salt rejection. Our study demonstrates that the asymmetrical structure can significantly enhance the flux for ultrathin polyamide membranes. Further, the impact of the structure of the top layer and the sublayer on the membrane separation performance was explored by tuning the recipe of the PA top layer and the PPA sublayer. Image 1 • A novel strategy was proposed to enhance the permeance of ultrathin PA membranes. • The physiochemical asymmetry was realized by fabricating a PPA interlayer. • QCMD and DBES techniques confirm the physiochemical asymmetry of A-uPA nanofilm. • The compatibility between the PSU substrate and PA nanofilm was improved. [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]