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The surface charge of a separation membrane is a critical factor affecting its performance in ion separation and fouling resistance. Thin-film composite (TFC) polyamide (PA) membrane, commonly used in water treatment, often suffer from excessive surface negative charges, which significantly limits their application and fouling resistance. To address this issue, this work introduces a carbon nanotubes (CNT) intermediate layer to adjust the surface charge of TFC PA membranes, aiming to achieve a PA layer with neutral properties. Novel grazing-incidence wide-angle x-ray scattering (GIWAXS) measurements were employed to elucidate the effect of CNT on the molecular chain stacking of PA. The CNT intermediate layer was found to influence the PA cross-linking, which is related to surface negative charge, by controlling the storage and release of the m- phenylenediamine monomer during interfacial polymerization. The neutral CNT-TFC membrane demonstrated improved NH 4 + retention and increased resistance to fouling by protein, surfactant, and E. coli. However, other surface properties, such as roughness and hydrophilicity, could counteract the antifouling benefits of a neutral surface. This work provides insights into additional advantages of CNT intermediate layer intercalation in TFC PA membranes, such as enhanced cross-linking and surface charge control. [Display omitted] • Carbon nanotube (CNT) intermediate layer facilitated the polyamide (PA) formation. • Cross-linking degree of PA positively correlated with surface charge. • Surface charge was regulated by CNT intermediate layer. • Neutral PA surface was obtained by adjusting the CNT intermediate layer amount. • Neutral CNT-PA membrane exhibited better NH 4 + retention and fouling-resistance. [ABSTRACT FROM AUTHOR]

One process involved in biorefinery for generation of value‐added products is fermentation. After fermentation, the downstream bioproduct purification process is conventionally performed by organic solvent extraction, which is environmentally‐hazardous and costly. Membrane‐based separation is a cost‐efficient and environmentally‐benign method for bioproduct separation and purification. In this study, a thin film composite (TFC) nanofiltration (NF) membrane was prepared and the pore size and charge of the polyamide layer were controlled by introducing iminodiacetic acid (IDA), a charged monoamine monomer, with piperazine (PIP) during interfacial polymerization (IP). The newly‐developed NF membrane was found to have a molecular weight cut‐off (MWCO) of 500 to 1350 Da, allowing the permeation of the fermentation product, while rejecting other higher molecular weight compounds. IDA addition in the aqueous amine solution during IP effectively engineered the MWCO values and pore sizes of TFC NF membranes for specific applications, such as separation of fermentation bioproducts. This study successfully showed that IDA reduced the diffusivity of PIP during IP, which negatively affected the polyamide formation and membrane performance. The optimal PIP:IDA concentration ratio was determined by MWCO and effective pore diameter for effective bioproduct separation and purification, which could not be performed by the current commercially‐available NF membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A carbon nanotube (CNT)-interlayered polyamide (PA) membrane was prepared. • The membrane was used in organic solvent reverse osmosis (OSRO) for the first time. • Polar/non-polar solvent mixture separation was conducted using CNT-PA membrane. • Solvent mixtures include methanol/toluene, methanol/ether, and acetonitrile/toluene. • Membrane-mixture interaction was first proposed to affect the solvent separation. The intercalation of carbon nanotubes (CNTs) interlayer has been considered an effective way to improve the membrane performance in water treatment process. However, the effectiveness of CNTs interlayer on membrane performance enhancement for organic solvent separation has not been examined yet. Herein, a polyketone (PK)-based CNTs-interlayered thin-film composite (TFC) polyamide (PA) membrane was fabricated and applied in organic solvent reverse osmosis (OSRO) process for the first time. The role of CNTs interlayer on both PA formation regulation and permeance enhancement was investigated. Results demonstrate that the membrane permeance was enhanced three times higher with rejection remained at 99.2% when using 5 wt% methyl tert -butyl ether (MTBE) in methanol. By comparing the separation performances of three different kinds of solvent combinations (methanol/toluene, methanol/MTBE, and acetonitrile/toluene), the interactions between selective layer and different solvent mixtures were first considered as one of the factors affecting the rejection, and were analyzed based on Hansen solubility parameters (HSP) theory. This work provides insights into the high-performance OSRO membrane design and the solvent separation mechanism. [ABSTRACT FROM AUTHOR]

In this study, the hydrophilic property of polyvinyl alcohol (PVA) was utilized to improve the hydrophilicity and mechanical strength of electrospun polyvinylidene fluoride (PVDF)-supported thin film composite (TFC) forward osmosis (FO) membranes. The PVDF nanofiber support was modified with PVA via dip coating and acid-catalyzed crosslinking with glutaraldehyde prior to formation of polyamide active layer on the support via interfacial polymerization. The influence of PVA modification on the morphology and physical properties of PVDF support was evaluated through several characterization techniques while the flux performance was assessed using lab-scale FO membrane unit. The fabricated PVA-modified TFC FO membranes exhibited high hydrophilicity, porosity, and mechanical strength. FO performance tests reveal excellent flux performance (34.2 LMH using 1 M NaCl and DI water as draw and feed solution, respectively) and low structural parameters (154 μm) of the PVA-modified TFC FO membrane. Dip coating of the nanofiber support in PVA is therefore a simple and effective method for the improvement of PVDF support hydrophilicity to fabricate high performance TFC FO membranes. [ABSTRACT FROM AUTHOR]

In this study, we aimed to develop a forward osmosis (FO) thin film composite (TFC) membrane which could retain NH 4 + from wastewater. The conventional TFC membrane has a microporous polymer support and a selective layer for salt rejection; however, the polyamide selective layer is known to not be able to reject NH 4 +. Our strategy was to develop tris(2-aminoethyl)amine (TAEA)-modified TFC membranes via secondary interfacial polymerization, and the modification factors were optimized. The NH 4 + rejection of the optimized membrane significantly increased from 64.9 % (pristine TFC) to 94.7 %. TAEA modification resulted in a smoother surface and thinner polyamide selective layers. The mechanism of NH 4 + rejection during FO operation was investigated and was found to be influenced by membrane surface carboxylic group density and the polyamide crosslinking, cation exchange between the draw and feed solutions, and size sieving. In conclusion, the TAEA-modified membrane showed high selectivity against NH 4 + and applicability for NH 4 + recovery. In the future, the TAEA-modified membrane may be applied for NH 4 + enrichment and recovery from real wastewater systems. [Display omitted] • Thin film composite (TFC) membrane was modified with tris(2-aminoethyl)amine (TAEA). • Secondary interfacial polymerization with TAEA was optimized by membrane performance. • Optimum TAEA-modified TFC membrane exhibited 94.7 % NH 4 + rejection in forward osmosis. • Size sieving, cation exchange, and carboxylic group density influenced NH 4 + selectivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thin film composite membranes were grafted with polyethylenimine (PEI). • Activation step converted carboxyl groups into amine-reactive esters. • Quaternization of amine with iodomethane further enhanced NH 4 + rejection. • Modified membranes dewatered real wastewater and enriched NH 4 +. • PEI grafting and quaternization are facile and practical methods for NH4+ recovery. In this study, we aimed to recover and enrich NH 4 + from real wastewater using forward osmosis (FO). Positively-charged thin film composite (TFC) membranes were developed via chemical grafting with positively-charged polyethyleneimine (PEI). The TFC membrane surface was first activated using 1-ethyl-3-(3-dimethylaminopropyl) carboimide (EDC) and n-hydroxysuccinimide (NHS) to convert the carboxyl groups of polyamide into amine-reactive NHS esters. PEI grafting significantly increased the NH 4 + retention in the feed solution. To further improve the NH 4 + rejection, quaternization of the amine functional groups of PEI was conducted with iodomethane. Quaternization was found to further increase NH 4 + rejection, up to over 98.5%, while maintaining similar water permeability with the PEI-grafted TFC membrane. Fouling control of the pristine and amine-modified TFC membranes were also demonstrated, and the quaternary amine-modified TFC membrane exhibited superior fouling resistance against organic and biological foulants. The amine-modified TFC membranes were evaluated for applicability for dewatering and NH 4 + enrichment of real industrial wastewater. NH 4 + enrichment using the PEI-grafted membranes was observed following wastewater dewatering, indicating the high NH 4 + retention ability of the TFC membranes modified via amine grafting and quaternization. Wastewater dewatering of 90.3 and 92.4% were achieved using TFC-PEI-10 and TFC-qPEI, respectively. [ABSTRACT FROM AUTHOR]

Polydopamine (PDA), formed from self-polymerization of dopamine, was coated on aliphatic polyketone membrane substrate prior to interfacial polymerization (IP), preparing a pressure retarded osmosis (PRO) thin film composite (TFC) membrane with a PDA interlayer. The effect of the formation of two types of PDA interlayers — smooth and particulate — on substrate morphology, polyamide formation, and PRO osmotic performance were investigated. Also, the effect of pH on the particulate PDA interlayer was studied. It was found that the introduction of both smooth and particulate PDA contributes to enhanced water flux and power density of the PRO membranes. pH was found to have significantly affected the formation of particulate PDA and the polyamide formation, as well. At higher pH, PDA self-polymerization led to the formation of more nanoparticles, the subsequent increase in surface roughness and decline in the polyketone substrate porosity. The particulate PDA interlayer formed looser polyamide, compared to the thinner and denser polyamide formed on pristine and smooth PDA-interlayer-coated TFC membranes. The membrane performance was evaluated using deionized water and 1.0 M NaCl as feed and draw solutions, respectively. The TFC membrane with nanoparticulate PDA layer formed at pH 9.0 exhibited the best initial water flux of 40.8 L m−2 h−1, and this membrane also showed the highest power density of 17.1 W m−2 at 25 bar. The results of this study indicate that nanoparticulate PDA interlayer formation is a simple and scalable TFC membrane development method for engineered osmosis. [Display omitted] • PRO TFC membranes with smooth and particulate polydopamine interlayer were prepared. • Particulate polydopamine interlayer formation was controlled by pH. • Membrane morphology, polyamide formation, and membrane performance were influenced. • Particulate polydopamine led to higher surface roughness and looser polyamide. • Polydopamine formation at pH 9 provided best osmotic power generation performance. [ABSTRACT FROM AUTHOR]

This study describes the fabrication of sulfonated polyethersulfone (SPES) as a super-hydrophilic substrate for developing a composite forward osmosis (FO) membrane on a nonwoven backing fabric support. SPES was prepared through an indirect sulfonation procedure and then blended with PES at a certain ratio. Applying SPES as the substrate affected membrane properties, such as porosity, total thickness, morphology, and hydrophilicity. The PES-based FO membrane with a finger-like structure had lower performance in comparison with the SPES based FO membrane having a sponge-like structure. The finger-like morphology changed to a sponge-like morphology with the increase in the SPES concentration. The FO membrane based on a more hydrophilic substrate via sulfonation had a sponge morphology and showed better water flux results. Water flux of 26.1 L m−2 h−1 and specific reverse solute flux of 0.66 g L−1 were attained at a SPES blend ratio of 50 wt % when 3 M NaCl was used as the draw solution and DI water as feed solution under the FO mode. This work offers significant insights into understanding the factors affecting FO membrane performance, such as porosity and functionality. [ABSTRACT FROM AUTHOR]

During pressure retarded osmosis (PRO) operation, thin film composite (TFC) membranes are continuously exposed to chemicals present in the stream that can deteriorate the membrane's selective layer with exposure time. Following this observation, TFC membranes are placed in controlled oxidative degradation conditions using aqueous NaOCl solutions. Active chlorine, along with heat, can thin out the dense layer and, when controlled and optimized, can tune the membrane surface properties and separation efficiency as desirable for specific applications. The chlorine oxidative degradation is optimized in terms of chlorine exposure (a factor of both exposure time and chemical dosage), solution pH, and the subsequent heating time. After the chemical modification process, the membrane surface properties were characterized and the PRO performance as well as the osmotic energy harvesting capability were determined. The modified membranes exhibited different levels of polyamide degradation and increase in water permeability, which came along with decrease in selectivity. Optimization of the chlorine oxidative degradation using response surface methodology was performed to maximize the water permeability and extractable osmotic power while keeping salt rejection satisfactory. After performing chlorine oxidation at the following optimized conditions: 3025 ppm Cl 2 ·h, pH 10.72, and 3 min heating time, initial non-pressure retarded water flux of 73.2 L m−2 h−1, specific reverse solute flux of 1.17 g L−1, and power density of 18.71 W m−2 (corresponding to water flux of 56.1 L m-2 h-1) at 12 bar were obtained using 0.6 M NaCl as draw and deionized water as feed. [Display omitted] • PRO TFC membranes were placed in chlorine oxidative degradation conditions. • Chlorine exposure, pH, and reaction time were optimized using RSM. • Membrane properties and PRO performance were characterized and evaluated. • Modified membranes exhibited different levels of polyamide deterioration. • Water permeability was maximized while keeping salt rejection satisfactory. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dopamine and MPC-co-AEMA polyampholyte were co-deposited on TFC FO membrane. • MPC-co-AEMA/PDA layer exhibited superhydrophilicity and superoleophobicity. • PK-TFC-PDA/MPC membrane exhibited superior protein adhesion mitigation. • PK-TFC-PDA/MPC membrane showed high fouling resistance against BSA and oil. Thin film composite (TFC) membranes easily suffer from fouling induced by oil and other pollutants during forward osmosis (FO) due to the relatively hydrophobic chemistry and rough structure of polyamide (PA). To achieve comprehensive anti-fouling properties, poly(2-methacryloyloxyethyl phosphorylcholine-co-2-aminoethyl methacrylate hydrochloride) (MPC-co-AEMA) was immobilized on top of a polyketone (PK)-based TFC membrane following a single-step simultaneous deposition with dopamine. The adhesive properties of polydopamine (PDA), as well as the covalent interactions between PDA and MPC-co-AEMA, ensured the firm immobilization of the MPC-co-AEMA on PA layer. As a result of the simultaneous deposition of PDA and MPC-co-AEMA, a high-performance and superhydrophilic and underwater superoleophobic TFC membrane was engineered. In addition, the outstanding water adsorption capacity of the polyamphoteric layer resulted in better protein adhesion mitigation. FO operation using various foulants also demonstrated a high fouling resistance of the PK-TFC-PDA/MPC membrane, especially during the treatment of wastewater emulsion containing high concentration of oil and bovine serum albumin (BSA). In summary, the findings in this study could provide insights into the preparation of anti-fouling membranes for wastewater purification using FO. [ABSTRACT FROM AUTHOR]

Forward osmosis (FO) has proven to be a suitable process for treatment of problematic oily wastewater, due to its relatively higher water recovery rate and lower energy requirement, as opposed to pressure-driven membrane processes. Despite the lower membrane fouling propensity during FO operation, the development of comprehensively fouling-resistant membranes is further desired in FO as a suitable oily wastewater treatment process. In this current work, reduced aliphatic polyketone (rPK)-based thin film composite (TFC) membranes were developed. Reduction conditions using NaBH 4 were tested, and the suitability of reduction was evaluated with membrane morphology, water wettability, and resistance to oil. The resultant rPK-TFC membrane, whose substrate was reduced with 0.5% (w/w) NaBH 4 for 10 min, exhibited 37.8 L m−2 h−1 water flux in PRO mode. Using a foulant solution containing 1% (v/v) soybean oil, and 100 ppm humic acid, sodium alginate, and bovine serum albumin, the resultant rPK-TFC membrane maintained an outstanding 95% average flux recovery ratio, while the pristine PK-TFC membrane achieved an average flux recovery ratio of 67%. The results indicate that reduction of aliphatic polyketone is a facile method to develop membranes with outstanding water permeability and fouling resistance. [Display omitted] • Polyketone (PK) reduced with NaBH 4 was used as TFC membrane substrate. • Polyamide delamination occurred with use of PK with longer reduction. • Suitability of reduction was evaluated with wettability and oil resistance. • Reduced PK showed comprehensive fouling resistance and flux recovery ability. • TFC membrane with reduced PK can be applied for oily wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, a hydrophobic porous organic polymer (PP) synthesized via Friedel-Crafts alkylation of dichloro- p -xylene, was functionalized with hydrophilic sulfonate functional group to form PP-SO 3 H, prior to incorporation into the polyamide layer of a hollow fiber pressure retarded osmosis (PRO) TFN membrane. Sulfonate functionalization of the PP material improved the compatibility of the nanomaterial with the aqueous amine precursor during the in situ interfacial polymerization, leading to a decrease in aggregation of the nanoparticles. The effect of nanomaterial loading on the membranes' performance was also elucidated. PP-SO 3 H incorporation resulted in significant improvement of surface hydrophilicity, which along with improved porosity, facilitated enhanced water transport across the membrane and maintained an acceptable salt rejection of the selective layer. The best-performing membrane with PP-SO 3 H loading of 0.002 wt% showed a 46.3 L m−2 h−1 water flux and power density of 14.6 W m−2, which are both the highest values recorded. This study suggests that the functionality and chemical properties of the nanomaterial in a TFN membrane is essential in improving altogether the osmotic performance and salinity gradient power harvesting capability during PRO. • Melamine-based COF nanomaterial, SNW-1, was prepared via Schiff-based synthesis. • SNW-1 was successfully incorporated in the polyamide of PRO TFN membranes. • PRO TFN membrane surface hydrophilicity and porosity were enhanced. • Water permeability and power generation were improved at 0.02 wt% loading of SNW-1. Unlabelled Image [ABSTRACT FROM AUTHOR]

Electrospun nanofiber-supported thin film composite membranes are among the most promising membranes for seawater desalination via forward osmosis. In this study, a high-performance electrospun polyvinylidenefluoride (PVDF) nanofiber-supported thin film composite (TFC) membrane was successfully fabricated after molecular layer-by-layer polyelectrolyte deposition. Negatively-charged electrospun polyacrylic acid (PAA) nanofibers were deposited on electrospun PVDF nanofibers to form a support layer consisted of PVDF and PAA nanofibers. This resulted to a more hydrophilic support compared to the plain PVDF nanofiber support. The PVDF-PAA nanofiber support then underwent a layer-by-layer deposition of polyethylenimine (PEI) and PAA to form a polyelectrolyte layer on the nanofiber surface prior to interfacial polymerization, which forms the selective polyamide layer of TFC membranes. The resultant PVDF-LbL TFC membrane exhibited enhanced hydrophilicity and porosity, without sacrificing mechanical strength. As a result, it showed high pure water permeability and low structural parameter values of 4.12 L m−2 h−1 bar−1 and 221 µm, respectively, significantly better compared to commercial FO membrane. Layer-by-layer deposition of polyelectrolyte is therefore a useful and practical modification method for fabrication of high performance nanofiber-supported TFC membrane. [ABSTRACT FROM AUTHOR]

This study focused on the development of pressure retarded osmosis (PRO) thin film composite (TFC) membranes for enhanced osmotic power using hollow fiber polyethersulfone (PES) support structure modified by incorporating hydrophilic graphene oxide (GO) nanosheets. The GO loadings in the hollow fiber substrates were varied to improve water flux performances without compromising the mechanical strength. GO embedded (≤0.2 wt%) PES hollow fiber supports revealed noticeable improvements in pure water permeability, improved structural morphologies, as well as the hydrophilicity within the support layer, without deteriorating the mechanical properties. The GO (0.2 wt%)-incorporated TFC-PRO membrane appeared to have an initial PRO flux (without any applied pressure) of 43.74 L m−2 h−1, lower specific reverse salt flux of 0.04 g L−1 and structural parameter (S) of 522 μm, significantly better than the control membrane. The maximum power density of 14.6 W m−2 was achieved at an operating pressure of 16.5 bar under the condition of DI water and 1 M NaCl as feed and draw solutions, respectively. The results obtained in this study indicate that modification of PRO hollow fiber support layer by incorporating nanoparticles such as GO nanosheet can be a useful tool to improve the PRO performance. Unlabelled Image • Mixed-matrix PES/GO hollow fiber supports were fabricated for TFC PRO membranes. • A small amount of GO incorporation in support layer improved PRO performances. • GO-incorporated membrane support revealed competitive mechanical properties. • The power density of 14.6 W m−2 was achieved with GO (0.2 wt%) added PRO membrane. [ABSTRACT FROM AUTHOR]

Thin film composite (TFC) polyamide (PA) membranes are typically prepared using the interfacial polymerization (IP) method, which synthesizes the PA layer by soaking in aqueous diamine and organic acyl chloride solutions and allowing the occurrence of amidation. The conventional IP process has been used over several decades in the industrial production of TFC membranes for water purification and excess amounts of monomer solutions are used for PA thin film layer synthesis, generating a lot of chemical wastes. In this work, we first demonstrated the TFC PA membrane fabrication using simple inkjet printing of aqueous and organic inks to effectively prepare a PA layer with no chemical wastes. The organic acyl chloride ink was newly formulated by the combination of dodecane and toluene solvents to allow printability. Precise and uniform depositions of monomer inks via the inkjet printing approach were able to coat a dense and defect-free PA film onto the support membrane using only small volumes of chemicals. After multiple printing numbers of inks, the PA layer was optimized with two printing cycles (30.17 mL m−2) and three printing cycles (8.36 mL m−2) of diamine and triacyl chloride inks, respectively, followed by heat treatment. The inkjet-printed TFC-M2T3-15 membrane exhibited a high salt rejection (95.33 %) which showed higher performance compared to that of the conventional IP-prepared TFC membrane (89.64 %). [Display omitted] • Thin film PA membrane was synthesized via inkjet printing assisted IP process. • Printable TMC ink was prepared with the combination of toluene and dodecane solvents. • Multiple printing cycles of monomer inks enabled the effective synthesis of PA layer. • A defect-free PA layer formed using minimal volume of MPD and TMC solutions. • The optimal TFC-M2T3-15 membrane performed a high NaCl rejection of 95.33 %. [ABSTRACT FROM AUTHOR]

Reverse osmosis (RO) is a widely used pressure-driven membrane process for desalination. Advancements in membrane materials have driven RO technologies' development and widespread application. Thin-film composite (TFC) membranes of a thin polyamide (PA) layer, porous substrate, and nonwoven fabric support are considered the gold standard in desalination technology. These membranes exhibited excellent separation performance and mechanical strength. Recently, TFC membranes with PA layers have been successfully employed in organic solvent reverse osmosis (OSRO) to differentiate organic liquids molecularly. Developing TFC membranes with improved solvent resistance and permeance is required to expand the applications of TFC membranes beyond solvent-solute systems. This study explored polyketone (PK) membranes as porous substrates in TFC membranes for general reverse osmosis processes. PK membranes offer excellent solvent resistance and are easier to prepare than other membranes. Furthermore, a surface modification approach was proposed to enhance the interfacial polymerization (IP) of the polyamide layer on both PK and polysulfone (PSf) substrates, resulting in improved TFC membranes with enhanced water permeance for RO and increased organic liquid permeance for OSRO while maintaining permselectivity. These findings highlight surface chemistry's significance in controlling crumpled PA layers' formation, ultimately improving the filtration efficiency for general RO applications. This study provides an example of the design of composite structures of TFC membranes for broader RO applications. [Display omitted] • Thin-film composite membrane with solvent resistance were fabricated. • A versatile substrate surface modification method was developed. • Reverse osmosis and organic solvent reverse osmosis were evaluated. • The membranes exhibited enhanced permeance for water and organic solvents. [ABSTRACT FROM AUTHOR]

Membrane fouling as well as the "trade-off effect" between water permeability and selectivity are the grand challenges for nanofiltration (NF) membranes. In this study, a macrocyclic molecule, Noria, was embedded in the polyamide layer to fabricate a thin film nanocomposite (TFN) membrane with high performances of separation and antifouling. Noria was first synthesized and dissolved in a piperazine (PIP) aqueous solution. Then the TFN membrane (i.e., PIP-Noria-TMC membrane, TMC is the abbreviation of 1,3,5-benzenetricarbonyl trichloride) was prepared by interfacial polymerization using PIP-Noria mixture as aqueous phase. The optimal PIP-Noria-TMC membrane reached 147.6 L m-2h-1MPa-1 of water permeability, which was almost twice that of the pristine NF membrane (i.e., PIP-TMC membrane). Meanwhile, the PIP-Noria-TMC membrane exhibited comparable Na 2 SO 4 rejection (∼98%) to the PIP-TMC membrane and outstanding mono/divalent salt selectivity. Besides, static adsorption tests using E.coli and bovine serum albumin (BSA) as the model foulants revealed that the surface of PIP-Noria-TMC membranes with high hydrophilicity and electronegative charge could effectively resist foulant attachment, which was also exhibited in the dynamic BSA filtration tests. Therefore, this work provided a practicable pathway to simultaneously overcome the permeability-selectivity trade-off and membrane fouling problems for the NF process. [Display omitted] ● A novel TFN membrane was fabricated by incorporating Noria. ● PIP-Noria-TMC membrane possessed a wrinkled structure and a thinner PA layer. ● Incorporation of Noria enhanced hydrophilicity and negative charge of membranes. ● Permeability-selectivity trade-off and membrane fouling was addressed jointly. ● Mono/divalent salt selectivity of PIP-Noria-TMC membrane can be as high as 47. [ABSTRACT FROM AUTHOR]

Thin film composite (TFC) membranes are the most widely used technology in reverse osmosis (RO)-based desalination processes, due to their desirable separation performance derived from the combined structure of the porous support and thin film active layer. Typically, TFC membranes are fabricated via an interfacial polymerization (IP) technique, where the porous substrate plays an indispensable role in forming the thin film layer. In this study, a porous polyketone membrane with a fibrous structure and intrinsically moderate hydrophilicity prepared using non-solvent induced phase separation (NIPS) was employed as the substrate to explore its suitability for fabricating high-performance TFC membranes. Investigations on structure control and chemistry regulation via the NIPS process and in-situ post-treatment revealed that porous polyketone substrates display different morphologies and chemistries, significantly altering the thin layer formation during IP. The resulting TFC membranes exhibited up to 14-fold permeance difference, which was attributed to the variance of "ridge-and-valley" structures in different thin film layers formed on different polyketone substrates. It was found that a polyketone membrane with an appropriate surface roughness could generate favorable "ridge-and-valley" structures in the thin film layer to enhance the surface area, realizing high water permeance as well as high salt rejection in reverse osmotic desalination of NaCl solution. [Display omitted] • Highly porous polyketone membranes were fabricated. • The structure and chemistry of polyketone membranes could be controlled. • Polyketone membranes were used as support for thin film composite membranes. • Promising reverse osmosis performance was obtained. [ABSTRACT FROM AUTHOR]

Inkjet printing process enables rapid deposition of inks with precise amount and location. Moreover, the process can be automated and provide control such as repetitive printing of the inks. Utilizing the advantageous features of the inkjet printing process, we demonstrate the synthesis of thin film composite (TFC) flat-sheet membrane for NF application where single walled carbon nanotube (SWCNT) was deposited via an inkjet printing process, acting as an interlayer between the polyamide (PA) selective layer and polyethersulfone (PES) MF membrane support. By controlling the number of SWCNT printings on the PES membrane, we investigated how the SWCNT interlayer thickness influences the formation of PA selective layer. The best membrane performance was achieved from the TFC membrane synthesized using 15 cycles of SWCNT printing, where both high water flux (18.24 ± 0.43 L m−2 h−1 bar−1) and the high Na 2 SO 4 salt rejection (97.88 ± 0.33%) rates were demonstrated. SWCNT interlayer provided highly porous, interconnected structure with uniform pore size distribution which led to the formation of a defect-free ultrathin PA selective layer. Designing of TFC membrane using the SWCNT deposition via inkjet printing is the new approach and successfully demonstrated the significant improvement in the NF membrane performances. Image 1 • Formation of ultrathin active layer using SWCNT interlayer via inkjet printing. • TFC NF membrane with SWCNT interlayer exhibited high flux and high salt rejection. • Investigate SWCNT interlayer & printing parameters on NF membrane performances. • Role of SWCNT interlayer on ultrathin active layer formation via membrane autopsy. [ABSTRACT FROM AUTHOR]