Thin Film Composite Polyamide Research Articles

Polyamide Thin-Film Composite Membranes with Enhanced Interfacial Stability for Durable Organic Solvent Nanofiltration

Polyamide thin-film composite (TFC) membranes present a promising option for organic solvent nanofiltration (OSN) due to their superior advantages in facile fabrication and high separation efficiency. However, existing TFC-based OSN membranes are heavily limited by their weak interfacial stability in organic solvents, because many solvent-resistant porous supports are hydrophobic and have poor interfacial compatibility to polyamide. Herein, we report a polyamide TFC membrane with enhanced interfacial stability and durable OSN performance, by multifunctional surface modification and in-situ interfacial polymerization on a hydrophobic and solvent-resistant polypropylene substrate. Distinct from nascent ones, the polypropylene substrates modified by tannic acid/aminopropyltriethoxysilane coating possess excellent hydrophilicity and more functional groups, in which the former allows for the in-situ synthesis of integral polyamide layers via interfacial polymerization and the latter greatly enhances the binding strength between the polyamide layer and PP substrate by 30 times. With this method, the TFC membranes exhibit excellent thermal stability in 80 °C dimethylformamide solution. Meanwhile, the TFC membranes display high ethanol permeance (9.2 L m-2 h-1 bar-1) and acid fuchsin rejection (98.5%), outperforming the performance of most OSN membranes reported. This straightforward method, robust structural stability, and extraordinary performance make the TFC membranes a step closer to commercial OSN membranes.

Piezoelectric reverse osmosis (RO) membrane: Fabrication and anti-fouling effect

In this study, a novel piezoelectric RO membrane with vibrating mechanism when exposed to an electric field was developed. The vibration due to the piezoelectric effect can disturb the concentration polarization layer on the membrane surface and minimize membrane fouling. Polyvinylidene fluoride (PVDF) which has piezoelectric properties was selected as the porous substrate for a thin film composite (TFC) polyamide RO membrane in this study. Electrical poling was performed to enhance the piezoelectric properties of the PVDF substrate. RO membranes fabricated via interfacial polymerization using different PVDF substrates (i.e., with and without pre-wetting the PVDF substrate, with and without polyethylene terephthalate (PET) non-woven fabric support (denoted as NWF and no-NWF, respectively), with and without electrical poling) were systematically investigated. The results indicated that RO membrane fabricated on poled PVDF-NWF substrate shows reasonable pure water permeability of ∼2 LMH/bar and sodium chloride (NaCl, 2000 ppm) rejection of ∼98.9 % when tested at 15 bar. In the accelerated fouling study using colloidal silica particles (∼20 nm in diameter, 200 ppm with background of 2000 mg/L NaCl), when the RO membrane fabricated using both unpoled and poled PVDF-NWF substrates were excited with AC signal, membrane fouling was significantly reduced. These findings suggested that electrical poling may not be necessary for such piezoelectric RO membrane.

Polyamide Nanofilms through a Non‐Isothermal‐Controlled Interfacial Polymerization

AbstractEfficient thin film composite polyamide (PA) membranes require optimization of interfacial polymerization (IP) process. However, it is challengeable owing to its ultrafast reaction rate coupled with mass and heat transfer, yielding heterogeneous PA membranes with low performance. Herein, a non‐isothermal‐controlled IP (NIIP) method is proposed to fabricate a highly permeable and selective PA membrane by engineering IP at the cryogenic aqueous phase (CAP) to achieve synchronous control of heat and mass transfer in the interfacial region. The CAP also enables the phase transition of the aqueous solution from the liquid to solid state, providing a more comprehensive understanding of the fundamental mechanisms involved in different phase states in the IP process. Consequently, the PA membrane exhibits excellent separation performance with ultrahigh water permeance (42.9 L m−2 h−1 bar−1) and antibiotic desalination efficiency (antibiotic/NaCl selectivity of 159.3). This study provides new insights for the in‐depth understanding of the precise mechanism linking IP to the performance of the targeting membrane.

Effect of poly(2-(dimethylamino)ethyl methacrylate) brush-grafted graphene oxide on polyamide layer formation and nanofiltration performance

Thin film composite (TFC) membrane performance is often restricted by permeability and selectivity trade-off effect, even with the modification of nanoparticles. Graphene oxide-poly(2-(dimethylamino)ethyl methacrylate) (GO-PDMAEMA) with brush structure has abundant hydrophilic oxygen-containing functional groups and amine groups. It was synthesized via the atom transfer radical polymerization method and incorporated into TFC polyamide layer using interfacial polymerization. The GO-PDMAEMA-modified thin film nanocomposite membranes (TFNG-P) with Turing structure and higher surface hydrophilicity enhanced water permeability by 40.7–55%, with relatively low nanoparticle loading (0.005–0.02 wt%). Besides, TFNG-P2 (0.01 wt% GO-PDMAEMA) has the highest Na2SO4 rejection (97.8%), 4.4% higher than TFC. The PDMAEMA brushes on GO with additional amine groups promoted the amide linkage and increased the PA layer cross-linking by 16.2%. The higher cross-linking did not negatively affect the membrane flux, as the better hydrophilicity offset this effect. The utilization of the modified membranes in the treatment of palm oil mill effluent demonstrated enhanced resistance to fouling with TFNG-P2, which exhibited the highest flux recovery rate, reaching 89.4%. Thus, this study showed GO modification by grafting PDMAEMA brushes had enhanced the membrane properties, resulting in TFNG-P with higher permeability, promising separation and antifouling performance.

Solvent-free polyamide TFC membrane fabrication based on TMC vaporization for saline water recovery

While thin film composite (TFC) membranes have dominated the global desalination process, using large amounts of organic solvent during membrane manufacturing remains a major concern. Thus, a greener approach to prepare TFC membranes based on solvent-free trimesoyl chloride monomer vaporization is presented in this work. This study fabricated the solvent-free membranes by varying relevant parameters during the vapor interfacial polymerization (VIP) process and studied their impacts on the membrane properties. Evidently, the VIP membranes exhibited thinner polyamide layers than conventionally prepared membrane following the slow polymerization rate. This resulted in higher pure water permeability (2.93 L/m2.h.bar) than the conventional membrane (2.53 L/m2.h.bar) when both membranes were tested at 8 bar. Despite demonstrating slight decrease in salt rejection, the saline water recovery performance of VIP membrane was unaffected, as high salt rejection was unnecessary. Under the best synthesis conditions, a VIP membrane with lower salt rejection could rival the conventional membrane with a >98 % dye rejection while attaining substantially higher NaCl/dye selectivity (up to 330) than the conventional ones (68.75). Pertinently, the study findings demonstrated the potential of the solvent-free IP-fabricated TFC membrane for saline water recovery.

Ultrahigh-permeance polyamide thin-film composite membranes enabled by interfacial polymerization on a macro-porous substrate toward organic solvent nanofiltration

Organic solvent nanofiltration (OSN) membranes have become a powerful separation platform in a myriad of chemical and pharmaceutical fields owing to their superior merits in high separation efficiency and low energy consuming. Despite extensive progress in exploiting polyamide thin film composite (TFC) membranes for OSN, they are heavily limited by inferior solvent permeability, especially when using conventional low-porous polyimide as TFC substrate. Herein, we report a facile substrate engineering strategy to leverage macro-porous Nylon66 microfiltration membrane to replace the conventional low-porous polyimide substrates for fabricating TFC membranes by interfacial polymerization, enabling high and robust solvent permeability during OSN. Distinct from conventional polyimide, Nylon66 substrates take advantage of their high porosity, macro-porous size and excellent hydrophilicity to realize more monomers storage and uniform monomers distribution, allowing to create crumpled and defect-free polyamide layers. With this method, the polyamide TFC membranes show a 2.1-fold increase in ethanol permeance (up to 16.0 L h−1 m−2 bar−1) meanwhile possessing 98 % rejection of dye, surpassing the most reported TFC membranes. We also demonstrate that the TFC membranes exhibit excellent long-term stability in both polar and non-polar solvent, as well as hold huge promise in the precise separation of dye mixture, pharmaceutical ingredient, and catalyst.

Constructing nanofiltration membrane on hydrophobic PVDF and PTFE substrates via reverse interfacial polymerization

Polyvinylidene fluoride (PVDF) and polytetrafluoroethylene(PTFE) porous membranes are ideal substrates for preparing thin-film composite (TFC) polyamide (PA) membranes with improved solvent resistance. However, it remains difficult to construct PA skin layers on PVDF and PTFE substrates via conventional interfacial polymerization (IP) due to the hydrophobic nature of these materials. To address this challenge, a reverse IP process was proposed to construct a defect-free PA skin layer on PVDF and PTFE substrates, in which the hydrophobic PVDF and PTFE substrates were soaked with the organic phase to ensure uniform coverage of reacted solution on the substrates. This novel strategy can effectively tackle the issue of uneven wetting of the aqueous phase on hydrophobic substrates in the conventional IP process. The resultant TFC membranes (i.e. Mrev-PVDF and Mrev-PTFE) exhibit excellent nanofiltration (NF) performance in both aqueous and organic solutions. Mrev-PVDF and Mrev-PTFE have MgCl2 rejections of 96.12% and 95.17%, alongside the water permeances of 12.8 LMH/bar and 11.2 LMH/bar, respectively (Mrev-PTFE was activated with DMF). It is further shown that Mrev-PVDF and Mrev-PTFE could also reject 99.4% and 98.5% of Congo red in methanol solution at solvent permeances of over 3.3 LMH/bar, while they also perform excellently in other polar protic solvents. Consequently, this work opens a new window for constructing high-performance TFC PA membranes on hydrophobic substrates and expands the application of the TFC PA NF membrane.

Thin film composite polyamide nanofiltration membranes with interlayer constructed with core-shell structured polystyrene-polyacrylamide nanospheres for antibiotics separation

Nanofiltration (NF) is an efficient and economic separation technology which has great application potential in solving worldwide water shortage. Constructing interlayer is an effective approach to fabricate thin film composite (TFC) polyamide (PA) NF membranes with better performance. Herein, the polystyrene-polyacrylamide nanospheres with core-shell structure were synthesized using an emulsion polymerization method. The PA NF membranes were prepared via interfacial polymerization (IP) on the mixed cellulose esters microfiltration (MCE MF) membranes which modified with the core-shell structured nanospheres. The fabricated PA NF membranes showed good performance with a pure water permeability of 18.9 L·m−2·h−1·bar−1 and Na2SO4 rejection of 97.4 %. The NF membranes also showed good antibiotics separation performance with rejection to levofloxacin (LEV), penicillin G (PG), tetracycline (TC), and erythromycin (ERY) of 97.1 %, 86.9 %, 92.2 %, and 96.4 %, respectively and efficient separation to antibiotics and NaCl. This work provides a feasible strategy to construct an interlayer of PA NF membranes with the core-shell structured polystyrene-polyacrylamide nanospheres.

Biomimetic peptoid-assisted fabrication of antibiofouling thin-film composite membranes

Polyamide (PA) thin-film composite (TFC) membranes are extensively used in water purification but suffer from chronic biofouling, which has spurred extensive research on the development of antibiofouling membranes. In this study, we present a facile method to fabricate a biofouling-resistant, high-performance PA TFC membrane by adding a biomimetic antimicrobial peptoid (i.e., oligo-N-substituted glycines) to the reaction medium during an interfacial polymerization (IP) process. The amphiphilic peptoid facilitates IP by acting like a surfactant, thereby enabling the formation of a highly crosslinked and permeable PA separation layer. Consequently, the peptoid-added TFC (pept-TFC) membrane exhibits superior separation performance compared with pristine, commercial, and other laboratory-made TFC membranes. Furthermore, because the peptoid is strongly incorporated into the PA separation layer network, the resultant pept-TFC membrane is endowed with excellent antimicrobial and antibiofouling properties. Importantly, the enhanced separation and antibiofouling performances of the pept-TFC membrane persist during long-term membrane operation, indicating the robust implantation of the peptoid and permanent changes in the structure and properties of PA. The proposed strategy provides a versatile and environmentally benign platform for fabricating functional membranes by simply employing structurally tailored peptoids with specific functions.

Modulation of charge properties inside thin-film composite polyamide membranes towards enhanced nanofiltration performance

Nanofiltration (NF) is receiving increasing attention worldwide as a high-efficiency technology for water purification. One viable approach to enhance the performance of NF membranes involves the meticulous optimization of their physicochemical and structural attributes through the introduction of additives. Nonetheless, the predominant NF membrane additives currently accessible primarily exert their influence at the membrane's surface. In this context, we introduce a novel strategy for fabricating polyamide (PA) NF membranes endowed with augmented negative charge density, capable of permeating the innermost stratum of the separation layer. This innovation hinges on the straightforward inclusion of 2-Methylimidazole (Hmim) into the aqueous phase. The ramifications of Hmim's incorporation of the structural configuration, morphological composition, physicochemical characteristics, and overall performance of the thin-film composite (TFC) membrane were meticulously scrutinized through an array of comprehensive characterizations. The integration of Hmim affords PA nanofiltration membranes the remarkable capability to achieve a rejection rate as formidable as 99.5% for Na2SO4 and 42.8% for NaCl, all the while maintaining an unswerving flux. As a result, a high SO42-/Cl- separation factor of up to 116.1 was achieved. Our work provides insights and directions for the development of additives in the preparation of NF membranes.

UF fractionation of fish protein hydrolysate

A commercial fish protein hydrolysate was fractionated using polymeric spiral wound ultrafiltration (UF) membranes. As protein hydrolysates are electrolytes, the effects of pH and ionic strength were investigated. Three different polyethersulfones (PES) membranes with different nominal molecular weight cut-offs (10, 5, and 3 kDa) and a polyamide-thin film composite (PA) membrane with a nominal molecular weight cut-off of 3 kDa were used. The membrane flux and retention profile, and the selectivity for <4 kDa peptides were analyzed and discussed. The PES membranes were suitable for fractionation of the hydrolysate, while the PA membrane showed high retention for all components because of the adsorption of solutes to the membrane surface. The results showed that with charged solutes, the nominal molecular weight cut-off as supplied by manufacturers was not the decisive parameter for choosing a membrane. The permeate flux at pH 8 was higher than that at pH 5 for all PES membranes. The presence of salt in the hydrolysate significantly improved the flux and selectivity. The overall retention mainly was dependent on the retention of small peptides (<4 kDa). The mass transfer mechanism of charged peptides within the concentration polarization during UF separation was simplified and presented regarding size and charge exclusions.

RO membrane with a surface tethered polymer brush layer for enhanced rejection of nitrate, boron, and arsenic

Thin-film composite (TFC) polyamide (PA) RO membrane modified with a layer of tethered poly(acrylic acid) (PAA) chains displayed intrinsic rejections of nitrate, boron, As(III), and As(V) of 98.0%, 90.7%, 96%, and 99.6%, respectively. The solute permeability coefficients for nitrate, boron, As(III), and As(V) by the SNS-PAA-PA membrane were lower by 31–38%, 49–63%, 57–72% and 87–93% relative to tested commercial membranes. The above results indicate that the SNS-PAA-PA membrane should be suitable for purification of brackish source water contaminated with nitrate, boron, As(III), and As(V) to levels 1219 ppm, 2 ppm, 95 ppb, and 948 ppb, respectively. The study results suggest that there is merit in further exploration of the potential of the present approach for enhancing RO membranes performance for targeted solute removal.

Complexation of cellulose nanocrystals and amine monomer for improved interfacial polymerization of nanofiltration membrane

Thin film composite (TFC) polyamide membranes prepared by the interfacial polymerization (IP) of reactive monomers are widely utilized for desalination. However, the trade-off between the permeability and selectivity of TFC membranes limits further improvements in separation performance. In this study, the complexation of amine monomers with cellulose nanocrystals (CNC) and subsequent deposition on a substrate for the IP reaction was employed to modify the polymerization process and the resulting interlayered-thin film nanocomposite (i-TFN) membrane structure. This method can optimize the amine loading and distribution for the IP reaction, and CNC with favorable functional groups can limit the release and diffusion behavior of the amine monomer, resulting in a crumpled membrane structure with a retained continuous polymer network. The optimized membrane had a three-fold higher water permeance than the pristine membrane without compromising salt rejection performance. This study provides a strategy for regulating the monomer distribution and reaction at the IP interface for improved performance.

Novel lignosulfonated polyester membranes with remarkable permeability and antifouling characteristics

Polyamide thin film composite (TFC) membranes are the most common nanofiltration and reverse osmosis membranes for wastewater treatment and desalination. Even though polyamide membranes excel in these applications, they can be fouled easily. In this work, we used an alternative approach for these applications: polyester membranes made via interfacial polymerization of terephthaloyl chloride (TPC) and sulfonated kraft lignin (SKL). The novel polyester TFC membranes had much higher negative surface charges than a reference polyamide TFC membrane, helping them reject negatively-charged solutes such as reactive red, reactive black, methyl orange, and most foulants like proteins. The polyester TFC membrane prepared with 7 wt% SKL and 0.2 wt% TPC reached a water flux greater than 50 LMH (liter per square meter per hour) and over 90% dye rejection, which is more than 3 times the water flux of a polyamide TFC membrane at almost the same dye rejection. We propose that compared with more reactive monomers, such as piperazine (PIP) and trimesoyl chloride (TMC), the slower polymerization rate between SKL and TPC increased the free volume in the polyester membrane, which, in turn, increased the membrane permeability while keeping the dye rejection constant. Our findings indicate a promising pathway for developing non-polyamide membranes with competitive separation performance and antifouling properties that could rival current commercial nanofiltration membranes.

Enhancing the antifouling and chlorine resistance capabilities of thin-film composite reverse osmosis via surface grafting of dipeptide

There has been constant progress in the development of innovative polyamide (PA) thin-film composite (TFC) reverse osmosis (RO) membranes to address limitations in fouling potential, chlorine resistance, salt rejection and water flux trade-offs. In this work, dipeptide of zwitterionic amino acid L-arginine, i.e., arginyl-arginine (Arg-Arg), was grafted on the surface of PA TFC RO membrane in order to simultaneously improve the antifouling properties, chlorine resistance, and separation performance. The interactions between the Arg-Arg dipeptide and PA layer were evidenced by Fourier transforms infrared spectroscopy and nuclear magnetic resonance spectroscopy, which have indicated the distinguished chemical grafting of Arg-Arg dipeptide on the RO membrane surface. The grafting of Arg-Arg dipeptide led to a thinner, smoother, more hydrophilic, and less negatively charged PA surface. The surface-modified membranes simultaneously exhibited enhanced desalination performances, antifouling and chlorine resistance properties. Compared to the neat TFC membrane, the water flux of Arg-Arg dipeptide-modified membrane was improved by 26.19%. The salt rejection also slightly increased from 96.25% to 98%. The roles of Arg-Arg dipeptide in altering the surface chemistry and the structure of the membranes are discussed to highlight the potential of surface-modified membranes in heightening the desalination performances of RO TFC membranes.

Organic solvent separation using carbon nanotube-interlayered thin film composite membrane

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.

High flux and highly fouling-resistant polyamide reverse osmosis membrane having inner and outer zwitterion-like layers

The development of high flux and highly fouling-resistant reverse osmosis (RO) membranes is crucial for addressing water crisis. However, it is still challenged to enhance the antifouling performance of the membrane against organic foulants, particularly charged small organic foulants. We herein reported the fabrication of antifouling thin-film composite (TFC) polyamide (PA) RO membranes having inner and outer zwitterion-like layers by a scalable layer-by-layer interfacial polymerization process. The inner zwitterion-like layer is constituted by the positive charges from the incorporated cationic surfactant of benzalkonium chloride (BAC) and the negative charges from carboxylic acid groups in the PA. Then, the outer zwitterion layer is the L-arginine molecules grafted on the PA. The modified RO membranes have a high water permeance of 3.92 L m−2 h−1 bar−1, while maintaining a NaCl rejection rate of 99.18 %. In addition, the obtained membranes exhibit excellent antifouling properties with the flux decline rate (FDR) of below 40 % and the flux recovery rate (FRR) of above 98 % against 200 ppm of positively and negatively charged surfactants as small organic foulant models, surpassing most of the reported membranes. Our work provides insights to engineer the polyamide RO membrane surface with superior separation performance and efficient anti-fouling properties.

Inhibiting Polyamide Intrusion of Thin Film Composite Membranes: Strategies and Environmental Implications.

Thin film composite polyamide (TFC) nanofiltration (NF) membranes represent extensive applications at the water-energy-environment nexus, which motivates unremitting efforts to explore membranes with higher performance. Intrusion of polyamide into substrate pores greatly restricts the overall membrane permeance because of the excessive hydraulic resistance, while the effective inhibition of intrusion remains technically challenging. Herein, we propose a synergetic regulation strategy of pore size and surface chemical composition of the substrate to optimize selective layer structure, achieving the inhibition of polyamide intrusion effective for the membrane separation performance enhancement. Although reducing the pore size of the substrate prevented polyamide intrusion at the intrapore, the membrane permeance was adversely affected due to the exacerbated "funnel effect". Optimizing the polyamide structure via surface chemical modification of the substrate, where reactive amino sites were in situ introduced by the ammonolysis of polyethersulfone substrate, allowed for maximum membrane permeance without reducing the substrate pore size. The optimal membrane exhibited excellent water permeance, ion selectivity, and emerging contaminants removal capability. The accurate optimization of selective layer is anticipated to provide a new avenue for the state-of-the-art membrane fabrication, which opens opportunities for promoting more efficient membrane-based water treatment applications.

Polyethyleneimine (PEI) based positively charged thin film composite polyamide (TFC-PA) nanofiltration (NF) membranes for effective Mg2+/Li+ separation

To effectively separate Mg2+ and Li+ from high Mg2+/Li+ ratio salt lake brine, positively charged thin film composite polyamide (TFC-PA) nanofiltration (NF) membranes were prepared by the interface polymerization involving polyethyleneimine (PEI) with benzenetricarbonyl chloride (TMC). In this work, the structures and performances of PEI based TFC-PA NF membrane prepared on polysulfone (PSF) ultrafiltration substrates from the normal interface polymerization process PSF(NIP), was compared with those on the same substrates from the reverse-phase interface polymerization (RIP) process PSF(RIP), and those on polyethylene substrates from RIP process PE(RIP). Results showed that PSF(RIP) showed improved Mg2+/Li+ separation factor SLi/Mg from PSF(NIP) with an increased surface positive charge, but with greatly reduced water flux values due to reduced surface roughness, increased surface hydrophobicity, and decreased MWCO Stokes pore radius. PE(RIP) NF membrane showed not only higher Mg2+/Li+ separation factor SLi/Mg, but also higher water flux values due to increased surface roughness, decreased PA cross-linking degree, reduced PA separation layer thickness, and increased MWCO Stokes pore radius. PE(RIP) NF membrane also showed high rejection rates to a variety of divalent metal salts with high separation factors SLi/Mg of 40–49, high brine permeability values of 10.5 L·m−2·h−1·bar−1, and excellent chemical and operational stability.

Organic solvent-free fabrication of thin film polyamide/zeolitic imidazolate framework membranes for removal of dyes from water

Thin film composite (TFC) polyamide (PA) membranes in combination with zeolitic imidazolate frameworks (ZIF), such as ZIF-8 and ZIF-93, have been fabricated using a novel approach based on vapor phase interfacial polymerization (VIP). These membranes have been investigated for nanofiltration (NF) of aqueous solutions of organic dyes, such as Rose Bengal (RB, 1017 Da), Sunset Yellow (SY, 452 Da) and Acridine Orange (AO, 265 Da). The preparation of the PA layer by VIP technique avoids the use of any organic solvent that is typically required in the conventional PA synthesis. Both ZIF-8 and ZIF-93 were initially synthesized using conventional procedures (methanol-based route) and incorporated to the PA layer in two different configurations: i) thin film nanocomposite with ZIF embedded within the PA film, and ii) bilayer membranes with a layer of ZIF between the support and the PA layer. The synthesis of ZIF-93 using a water-based route was developed for the bilayer configuration allowing for an organic solvent-free fabrication of PA/ZIF-93 bilayer VIP-TFC. These membranes showed the highest water permeances of 2.6, 3.4 and 2.2 L m-2h−1 bar−1 for RB, SY and AO, respectively. As compared to the control membrane VIP-TFC, this represents permeance increases of 69–117% and maintains high (greater than 99%) rejection of all the organic dyes. Membrane characterization demonstrated that the permeance enhancement for bilayer PA/ZIF-93 VIP-TFCs is related to an improved hydrophilicity, higher surface roughness and thinner selective layers. The prepared membranes demonstrated excellent cycle stability, maintaining their initial water permeance and dye rejection throughout 34 h of long-term operation, and being able to operate across the entire pH range studied (pH 3 to 9) without any detrimental effects on performance.