Thin Film Nanocomposite Nanofiltration Research Articles

Preparation of thin-film nanocomposite membrane with the addition of cysteine-modified MoS2 to enhance nanofiltration performance

Novel thin-film nanocomposite nanofiltration ((TFN)-NF) membrane was successfully fabricated by adding MoS2 functionalized with cysteine in a polysulfone (PSf) layer and the active layer to enhance separation performance in water and alcohol. A novel TFN-NF membrane was prepared through interfacial polymerization (IP), which reacts with an aqueous DETA solution containing MoS2-cys and a TMC organic solution onto the PSF/MoS2-cys support layer. A PSf support layer was incorporated with MoS2-cys, which enhanced the membrane permeability due to increasing porosity and hydrophilicity. Furthermore, MoS2 is essential in forming thin films and Turing structures of the NF membrane, resulting in enhanced permeability for water and alcohol. The prepared TFN-NF membrane has shown a notable permeability of 7.9 LMH/bar and a rejection rate of 99% for MgSO4. It also demonstrated excellent fouling resistance after three chemical cleaning cycles and long-term running. The TFN-NF membrane with MoS2 showed improved permeability for water and alcohol solvents, such as methanol and ethanol, of 5.5, 1.2, and 0.48 LMH/bar, respectively. This work would present a valuable strategy for preparing a TFN-NF membrane to retrieve alcohol solvents.

GO and surfactant assisted regulation of polyamide nanofiltration membranes for improved separation performance

Fabricating nanofiltration membranes with high water permeance and selectivity by tailoring the structure and morphology is crucial to efficient water purification. In this work, the fabrication of thin film nanocomposite (TFN) nanofiltration membranes by combining two methods, the surfactant-assembly interfacial polymerization (SARIP) and the addition of graphene oxide (GO) or ionic liquid functionalized graphene oxide (GO-IL) for the preparation of the selective PA layer on a novel porous substrate is reported. For the preparation of the porous substrate, mechanically robust, aromatic polyethers containing polar pyridine units (PDSPP) were chosen targeting to improved hydrophilicity and thus enhanced water permeability. The anionic sodium dodecyl sulfate (SDS) surfactant was used to regulate the interfacial polymerization thereby enabling the formation of dense PA layers with high cross-linking degree and consequently high salt rejections. On the other hand, the addition of GO/GO-IL nanosheets could impart hydrophilicity and antifouling properties. The novel porous PDSPP substrate was selected for the fabrication of TFN membranes due to its improved water permeability and superior salt rejection and increased hydrophilicity compared to commercial PSf substrate. The detailed study of the fabricated TFN membranes by ATR-FT-IR, SEM, AFM, XPS, contact angle measurements revealed the formation of polyamide selective layers with rougher surfaces, increased hydrophilicity and high cross-linking degrees (from 44 % to 94 %), resulted from the synergistic effect of SDS and GO incorporation. Moreover, the prepared TFN membranes exhibited high salt rejections while maintaining a moderate water permeability. In particular, the membrane containing the neat GO (TFNGO50) displayed excellent Na2SO4 and MgSO4 rejections (98.8 % and 99.5 %, respectively) while the NaCl rejection was 47.0 % and a water permeability value of 4.2 L m-2h−1 bar−1. The divalent salt rejections were among the highest values reported in the literature in comparison with commercial NF membranes and TFN membranes containing GO/functionalized GO. When GO-IL nanosheets were embedded in the PA layer, the water permeability was slightly improved while the salt rejections were significantly reduced compared to TFNGO50. Lastly, the incorporation of GO enhanced the anti-fouling properties of the prepared membranes due to increased hydrophilicity of the PA surface.

The synergistic effects of incorporating bi-sulfonated covalent-organic frameworks nanosheets and surface modification on the durability of thin-film nanocomposite nanofiltration membranes

Improving the membrane durability without sacrificing perm-selectivity is an essential challenge in membrane technology. To address this challenge, a combination of incorporating bi-sulfonated covalent-organic frameworks nanosheets (TpPa-(SO3H)2 CONs) and surface modification was used to modify thin-film composite (TFC) nanofiltration membranes. The nanofiltration experiments and molecular dynamics (MD) simulations revealed that nanosheets dispersed in n-hexane could significantly modulate the piperazine diffusion. At the optimal nanosheet addition amount of 0.004 g/100 ml n-hexane, the pure water permeance (PWP) and Na2SO4 rejection of the thin-film nanocomposite (TFN) membranes increased to 9.35 L·m−2·h−1·bar−1 and 99.26 %. Meanwhile the corresponding values of the pristine TFC membranes were only 5.45 L·m−2·h−1·bar−1 and 96.99 %, respectively. Membrane surface modification was performed on the optimal TFN surface. When the surface was modified with Tp at a concentration of 0.004 g/100 ml n-hexane for 9 s, the PWP further increased to 11.42 L·m−2·h−1·bar−1, which was almost 2.10 folds higher than the original TFC membranes. In contrast, the Na2SO4 rejection slightly increased to 99.36 %. Moreover, the static immersion experiments results indicated that the surface modification enhanced the membrane durability. This study proved that the association of these two methods provides a simple and effective strategy to design nanofiltration membranes with excellent separation performance and durability simultaneously.

Exploiting sulfonated covalent organic frameworks to fabricate long-lasting stability and chlorine-resistant thin-film nanocomposite nanofiltration membrane

Incorporating hydrophilic and charged porous nanofillers to prepare high-performance thin film nanocomposite (TFN) nanofiltration (NF) membranes is an effective method to achieve efficient water treatment. In this study, we synthesize the sulfonated covalent organic framework nanosheets (S-CONs) with higher hydrophilicity and electronegativity by immobilizing sulfonic acid groups (–SO3H) on TpPa-1 nanosheets. The S-CONs are incorporated in the PA layer by interfacial polymerization (IP) reaction. The results indicated that the S-CONs could modulate the hydrophilicity, thickness, and electronegativity of TFN-NF membranes. At the optimal addition of S-CONs (0.006 g), the pure water permeance increases to 8.84 L⋅m−2⋅h−1⋅bar−1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm{L}}\\cdot{\\rm{m}}^{-2}\\cdot{\\rm{h}}^{-1}\\cdot{\\rm{bar}}^{-1}$$\\end{document}, which is about 1.75 times than the TFC membrane, with a high Na2SO4 rejection reaching 98.97%. The improvement of the separation performance mainly results from the reduction of PA layer thickness (from ~178.00–198.00 to ~100.00–128.00 nm) and the increase of surface electronegativity (from −20.37 to −44.41 mV at pH = 7.00). More interestingly, the amide bond formed between the S-CONs and TMC improved the chlorine resistance of the membranes. This study reveals the potential of using functionalized 2D CONs as nanofillers to modify TFC membranes for efficient nanofiltration.

Tannic acid etched ZIF-8 incorporated thin-film nanocomposite nanofiltration membrane with enhanced performance

Incorporating functionalized nanomaterials in the selective layer of conventional polyamide nanofiltration (NF) membrane is a promising strategy for overcoming the trade-off between permeability and selectivity. Highly hydrodispersible TA/ZIF-8 composite nanomaterials were prepared by etching ZIF-8 with tannic acid, and the thin-film nanocomposite (TFN) NF membranes were prepared by introducing TA/ZIF-8 into the interfacial polymerization aqueous phase solution. The nanomaterials and NF membranes' structure, chemical composition, and hydrophilicity were comprehensively characterized. The influence and mechanism of introducing TA/ZIF-8 into the polyamide layer on the separation performance of the TFN membranes were discussed by separating typical mono- and divalent salts. The optimal TFN membrane had a water flux of 26.59 LMH-bar−1 (increased by 86.6% than that of the TFC-blank membrane) with 94.95% rejection of Na2SO4 while having good antifouling performance and stability. Furthermore, the inverse size exclusion phenomenon of chlorine-contained salts was explored through relevant control experiments. This work is valuable for expanding the application of 3D nanomaterials in membrane separation technology and preparing high-performance TFN nanofiltration membranes.

MXene-enhanced sulfonated TFN nanofiltration membranes for improved desalination performance

MXene, a recently identified 2D nanosheet, has drawn interest due to its potential application in the modification of thin film nanocomposite (TFN) membranes for the production of clean water. This study presents the development of MXene-based sulfonated TFN (STFN) nanofiltration membrane for the desalination application and chlorine resistance. A novel amine monomer approach of combination such as 1-(2-aminoethyl)piperazine (APIP) and 2,5-diaminobenzenesulfonic acid (DABSA) was proposed for the interfacial polymerization. The as-prepared MXene displayed a thin-layer nanoflakes-like structure. The surface morphology of the membrane indicated that the MXene bound well on the sulfonated TFN membrane. The hydrophilicity of the membrane was enhanced significantly in the STFN membrane, and the lower contact angle value was decreased up to 24°. The filtration performance showed that the water flux and salt rejection were improved in both sulfonated thin film composite (STFC) and STFN membranes. STFN membranes achieved a higher rejection of >93 % for Na2SO4 and MgSO4. The antifouling and chlorine resistance were also improved in STFC and STFN membranes. This study would be an insight for the development of novel STFN membranes for desalination applications.

Application of a functionalized thin-film composite nanofiltration membrane in water desalination

To prepare a thin-film nanocomposite (TFN) nanofiltration (NF) membrane, characterized with high desalination rate and antifouling performance, carboxylated multi-walled magnetic 1,2,3,4-butanetetracarboxylic acid carbon nanotubes (hereafter, the C-MWCNT-MBTCA) with a choice of hydrophilic groups were initially synthesized in this study, and then incorporated into the polyamide (PA) layer via interfacial polymerization (IP). After that, the surface morphology and hydrophilicity of the fabricated NF membrane was examined by the field emission scanning electron microscopy (FESEM) and water contact angle measurements, respectively. To assess the membrane application, the solutions (2000 mg/L) of sodium sulfate (Na2SO4), magnesium sulfate (MgSO4), calcium chloride (CaCl2), and sodium chloride (NaCl) were consistently tested. On account of the ample carboxylic acid (R-COOH) groups in the modified TFN membrane, the study outcomes revealed that the given membrane could enhance the flux along with the desalination rate upon the addition of the C-MWCNT-MBTCA (0.04 wt%). Likewise, the pure water flux significantly grew from 58.8 to 110.5 Lm-2h−1 after the utilization of the C-MWCNT-MBTCA (0.04 wt%), and the Na2SO4 removal rate promoted from 87 to 98 %. Ultimately, it was established that the C-MWCNT-MBTCA could be used as an economical modifying agent to boost the performance of NF membranes for water desalination purposes.

Water recovery from the high salinity brine: Effect of the interlayer structure in the polyamide nanofiltration membrane

Water recovery by nanofiltration (NF) from the high salinity brine is emerging as a promising technology to alleviate the water shortage. Thin film composite membranes with polyamide (PA) selective layer are the mainstream in the field of NF. Nevertheless, the trade-off between permeance and retention as well as the structural stability of the mainstream PA membrane still restrict their widespread application. Herein, a novel interlayered thin-film nanocomposite (TFNi) nanofiltration membrane was fabricated based on the interfacial polymerization. The PDA@MXene hybrid was employed as the interlayer to modulate the adsorption and diffusion process of amine monomers, giving rise to the formation of thin and rough PA selective layer, which could accelerate the transport of water molecules. Moreover, PM-TFNi membrane demonstrated higher crosslinking degree and more negatively charged surface, significantly benefiting the repulsion of inorganic salt ions. In this context, PM-TFNi membrane rendered a competitive permselectivity with the water flux of 18.3 L m−2 h−1 bar−1 and the Na2SO4 rejection of 98.0%. In addition, PM-TFNi membrane exhibited distinguished long-term stability and pH resistance. Overall, this work would provide a paradigm shift in designing high-performance and robust NF membrane for the water treatment.

Graphene oxide incorporated thin film nanocomposite nanofiltration membrane to enhance permeation and antifouling properties

Aiming at the problems of low permeation flux and low salt rejection of polyamide (PA) nanofiltration (NF) membrane, this study improved the surface properties and structure of PA layer by adding hydrophilic GO nanosheets. Polyethylimide (PEI), GO and trimethylchloride (TMC) were prepared on the surface of polyether sulfone (PES) substrate by interfacial polymerization. After adding GO, the hydrophilicity and zeta potential of NF membrane were improved. The NF test showed that when the amount of GO was 0.1%, the permeation flux of the membrane was increased from 7.06 to 12.285 L·m−2·h−1 (improve 73.94%), and the rejection of MgSO4 was increased from 90.23% to 95.9%. In the test of repulsion of univalent ion and bivalent ion, the repulsion value of bivalent ion is above 95%, and the repulsion degree of univalent ion is moderate. Compared with the original TFC membrane, the composite membrane also showed higher anti-fouling. This study provides a shortcut for improving the hydrophilicity and anti-fouling properties of NF membranes by using GO nanosheets.

Incorporating etched ZnO nanoparticles to fabricate positively charged composite membrane for heavy metal removal

The removal of heavy metal ions by nanofiltration (NF) membranes is attractive, but it is limited by a trade-off effect between permeation and solute rejection. Generally, the permeability of the NF membrane is closely related to its hydrophilicity, while the solute rejection is closely related to size exclusion and the Donnan effect. In this study, porous etched zinc oxide (ZnO) nanoparticles were prepared through alkali etching, and a thin-film nanocomposite (TFN) NF membrane was fabricated by interfacial polymerization (IP) method between PEI and TMC on a polysulfone (PSF) substrate. The incorporation of 0.01 wt% etched ZnO nanoparticles increased the hydrophilicity and positive charge of the NF membrane, resulting in an increase in the permeability (from 6.0 L m−2 h−1 bar−1 to 8.1 L m−2 h−1 bar−1) and rejection of heavy metal ions (Cu2+, Zn2+, and Ni2+ increased from 85 % to over 96 %). Long-term filtration experiments using the simulated wastewater demonstrated that the prepared NF membrane exhibited good stability and had the potential for industrial applications. It opens a new pathway for studying TFN NF membranes, indicating that alkaline etching can transform smooth nanoparticles into nanoparticles with higher specific surface area and porosity, thereby improving the performance of membranes.

Thin film nanocomposite nanofiltration with tannic acid-Fe(III) complexes functionalized Ti3C2Tx for enhanced divalent-salinity-water separation with a superior durability

Incorporating nanomaterials for a thin film nanocomposite (TFN) layer has been verified effective to improve the separation performance of nanofiltration (NF) membranes, whereas the poor compatibility between nanomaterials and polyamide (PA) matrix leads to a decrease in the salt rejection and pollution resistance. In this study, inspired by a new interface-bridging idea, Ti3C2Tx was bonded with tannic acid-Fe(III) (TA-Fe(III)) complexes, and then incorporated into a PA matrix for the first time to obtain a novel TFN NF membrane. The introduction of TA-Ti3C2Tx was found to effectively reduce the diffusion of piperazine, and thus result in the induction of a thinner, lower roughness, more hydrophilic, and defect-free PA layer. With the addition of 0.015 wt% TA-Ti3C2Tx, the TFN membrane obtained the highest water permeability of 12.17 L m−2 h−1 bar−1, almost twice that of the pristine membrane, with a high Na2SO4 rejection above 97 %. In addition, the TA-Ti3C2Tx-filled TFN membranes were verified to exhibit excellent antifouling performance and pressure resistance with a high durability, which is crucial for the practical application in salinity water treatment. This study provides an effective strategy to tailor the interfacial microstructural of nanoparticle-filled NF membranes for superior divalent-salinity-water separation.

Deep learning models for assisted decision-making in performance optimization of thin film nanocomposite membranes

The performance of thin film nanocomposite nanofiltration membranes (TFNNMs) is frequently constrained by the trade-off between the permeability and rejection/selectivity of the membrane. In this study, to provide assisted decision-making in performance optimization of TFNNMs, we utilized a dataset comprising four categories of impact parameters, including membrane manufacturing conditions, membrane performance, nanoparticle material performance, and organic solvent nanofiltration conditions, and trained a dual output neural network (D-ANN) to simulate the relative permeability (RP) and relative rejection/selectivity (RR) of TFNNMs. The D-ANN model outperformed conventional machine learning models and single-output neural networks in predicting both RP and RR, indicating its potential in uncovering correlations between output variables. The Shapley additive explanation method was employed to elucidate the contribution and marginal effects of each influencing parameter on RP and RR, among them, NP size, NP loading, water contact angle, and chloride concentration were influential parameters that are important for both RP and RR. Based on the D-ANN model, we extrapolated two sets of unknown data and achieved good predictive performance (RP-error <15%, RS-error <7% for most sample points). Furthermore, we observed that the predicted performance of the data points rarely exceeded the actual performance, indicating a low probability of overestimation. Based on these premises, the influential parameters can be optimized using the D-ANN model, which ultimately led to exceptional performance for a total of 22 datasets in four pairs of organic solvent and solute purifications guided by the D-ANN model. This study demonstrates that the D-ANN model can provide decisions for the performance optimization of TFNNMs while highlighting the enhancement of nanofiltration performance by thin film nanocomposites, significantly facilitating the design of high-performance TFNNMs.

Incorporating of β-cyclodextrin based nanosheet for advanced thin-film nanocomposite nanofiltration membrane with improved separation and anti-fouling performances

Nanotechnology has created numerous opportunities for the development of novel thin film nanocomposite (TFN) membranes. In this study, we prepared a novel β-cyclodextrin based nanosheets (β-CDNSs) with a lateral size of approximately 200–400 nm and thickness of ∼10 nm through the interfacial polymerization method and used it as the nanofillers in aqueous phase to prepare advanced nanofiltration (NF) membranes. The high microporosity, organic attribute, hydrophilic COOH and reactive OH groups present in β-CDNSs are conducive to the microstructural parameters fine-tuning of the resultant TFN membranes. The optimal membrane TFN-0.02 presented the PA selective layer with thinner thickness, less crosslinking degrees, prominent globule microstructures, and increased hydrophilic properties. As a result, it achieved a remarkable enhancement in pure water permeability (21.46 L m−2 h−1 bar− 1, versus 8.79 L m− 2 h− 1 bar− 1, nearly 2.4-fold increase), high rejection of divalent salt (above 98% for Na2SO4) and an outstanding selectivity of αNaCl/Na2SO4 = 50.27. Moreover, the tailored membrane TFN-0.02 exhibited superior resistance towards four typical organic foulants BSA, LYZ, DTAB and SDS. Overall, this work provides insightful guidance for the design of novel organic nanomaterials with desired properties for greatly enhanced separation performances of as-fabricated membranes.

Development of micropollutants removal process using thin-film nanocomposite membranes prepared by green new vapour-phase interfacial polymerization method

The presence of emerging micropollutants in water bodies and potable water, has become a topic of great concern globally. In this study, a newly modified vapour-phase interfacial polymerization (VP-IP) method has been used to fabricate thin-film composite (TFC) and thin-film nanocomposite (TFN) nanofiltration (NF) membranes to study the removal of micropollutants, diclofenac (DIC) and triclosan (TRI) from water. The method used is an economically and environmentally greener method as the reaction takes place between the aqueous monomer solution and vapours of the organic phase, thereby avoiding the utilization of organic solvent hence named as vapour-phase interfacial polymerization (VP-IP) method. Polydopamine (PDA) coated polyethersulfone (PES) membranes were used to support the TFC and TFN membranes. The TFN membranes were incorporated with different concentrations of amine-functionalized cloisite Na+ 2D clay nanosheets (NH2-CMMT) to enhance the physicochemical properties of the TFN membranes. The performance study of the prepared TFN membranes based on different hours and pressures demonstrated an excellent rejection percentage of ∼99 ± 0.5% for both DIC and TRI compared to the TFC membrane. The membranes showed improved water permeate fluxes of ∼109 ± 5 Lm-2h-1 for DIC and ∼150 ± 5 Lm-2h−1 for TRI. The prepared TFN membranes demonstrated positive results for the antifouling test as well as exhibited antibacterial activity tested against Escherichia coli (E. coli) bacteria. The findings of this study show that our prepared TFN membranes combined with NH2-CMMT 2D clay nanosheets exhibit enhanced hydrophilicity, improved flux rate, excellent removal efficiency, antibacterial activity, and improved antifouling properties, indicating the potential to be used for removing emerging micropollutants from water.

Incorporating imine-based covalent organic frameworks nanosheet as an active filler for long-term nanofiltration desalination

Covalent organic frameworks nanosheets (CONs) are two-dimensional porous nanomaterials exfoliated from covalent organic frameworks (COFs). The ordered permanent microchannels and excellent water stability of CONs make them attractive active fillers for the preparation of thin-film nanocomposite (TFN) nanofiltration (NF) membranes. Herein, we report the fabrication of TFN membranes by incorporating covalent organic framework nanosheets TpPa-1 CONs as an active filler in the organic phase during the interfacial polymerization (IP) reaction. The addition of TpPa-1 CONs promotes the formation of extra water channels (pores and interfacial cavities) in the PA layer, rendering the TFN membranes with a higher pure water permeance of 8.54 L m−2 h−1 bar−1, which is about 1.4 times compared to TFC membrane, and excellent Na2SO4 rejection of about 98.1%. Owing to the hydrophilic nature of TpPa-1 CONs, the synthesized TFN membranes also exhibited higher hydrophilicity and superior anti-fouling performance. Meanwhile, the 35-days stability experiment verified that the TpPa-1 CONs TFN membrane has superior long-term stability. As a 2D porous nanosheets, TpPa-1 CONs provided some guidance for the preparation of long-term stability NF membranes with excellent separation performance.

Conductive thin-film nanocomposite nanofiltration membrane comprising N-doped graphene quantum dots with relieved concentration polarization for sulfate separation from high-salinity solution

Conductive thin-film nanocomposite nanofiltration membrane comprising N-doped graphene quantum dots with relieved concentration polarization for sulfate separation from high-salinity solution

Construction of thin-film nanocomposite membranes by incorporating acyl chloride@MoS2 for enhanced nanofiltration performance

Incorporating suitable-sized nanoparticles into the organic phase of interfacial polymerization to form a nanomaterial-polyamide (PA) selective layer is a promising approach to enhancing membrane performance. In this work, we prepared novel thin-film nanocomposite (TFN) membranes by modifying the PA layer with acyl chloride@MoS2 nanoparticles. The nanoparticles added in the organic phase could obviously restrict the diffusion of piperazine monomers to the reaction zone during the interfacial polymerization process, demonstrated by both experiment results and molecular dynamics simulation. Compared to the thin-film composite (TFC) control membrane, the TFN membranes possessed a looser PA layer as well as a rougher and more hydrophilic surface with more negative charges, confirming the significant effects of the incorporated acyl chloride@MoS2 nanoparticles on the PA layer formation. The optimal TFN membrane achieved a high Na2SO4 rejection of 98.6% and a satisfying water permeance of 27.1 L m−2h−1 bar−1, over 2.9 times higher than that of the TFC membrane (9.3 L m−2h−1 bar−1). Moreover, attributed to the chemical affinities (including covalent connection, hydrogen bonds, and electrostatic attraction) between acyl chloride groups of the nanoparticles and the PA matrix, the TFN membranes exhibited excellent long-term operation stability. The beneficial effect of grafting acyl chloride groups on the surface of MoS2 nanoparticles was verified by the more superior membrane performance enabled by acyl chloride@MoS2 than that achieved by original MoS2. This study offers a feasible strategy to improve the performance of TFN nanofiltration membranes by utilizing proper nanoparticles as organic phase additives.

Two dimensional sulfonated molybdenum disulfide (S–MoS2) thin-film nanocomposite nanofiltration membrane for selective desalination

Nano-fillers will be an attractive strategy to improve salt fractionation of nanofiltration (NF) membrane if the integrity problem of nano-fillers in PA layer is well addressed. In this work, molybdenum disulfide (MoS2) nanosheets sulfonated with 1,3-propane sultone was added to the aqueous phase to participate in the interfacial polymerization reaction and construct a novel thin-film nanocomposite (TFN) nanofiltration membrane. A series of characterization and discussion were carried out on the obtained nanomaterials and membranes. The S–MoS2 nanosheet can be well wrapped by the resulted PA layer, thereby preserving the integrity of the PA skin. Furthermore, The TFN membranes possessed enhanced electronegativity and hydrophilicity and the PA layer became thinner and denser after introducing the sulfonated MoS2 nanosheets (S–MoS2) in the PA matrix. In particular, the optimal S–MoS2 composite membrane exhibits excellent performance, which approximately reach 99% divalent salt (Na2SO4) rejection and 1.4-fold water permeance of the pristine membrane. Overall, this study provided a novel way for separation treatment of hypersaline wastewater.

Polyvinyl alcohol/attapulgite interlayer modulated interfacial polymerization on a highly porous PAN support for efficient desalination

Interlayered thin film nanocomposite nanofiltration (TFNi-NF) membranes have the potential to overcome the permeability and selectivity limitations of conventional NF membranes. This work is the first attempt to construct the polyvinyl alcohol/attapulgite (PVA/ATP) nanocomposite interlayer by chemical cross-linking between PVA and glutaraldehyde (GA) in which the nanomaterial ATP was connected with covalent bonds. Meanwhile, the support layer of the NF membranes was chosen to be a microporous membrane with high porosity and a three-dimensional (3D) network porous structure prepared by the innovative atomization-assisted non-solvent induced phase separation (AA-NIPS) method, greatly enhancing the water transport channels. The ATP acted as a multifunctional regulator to tune the porous structure of the PVA/ATP nanocomposite interlayer through physicochemical interactions. By manipulating monomer diffusion behavior, a dense polyamide (PA) layer with only 12 nm in thickness was prepared, leading to enhanced permeability and rejection for divalent ions. In addition, the structure and performance of the TFNi-NF membranes are highly tunable by changing the ATP loading. The prepared TFNi-NF membranes have shown great potential for seawater desalination and the separation and purification of aqueous electrolytes.

Photo-Fenton reaction derived self-cleaning nanofiltration membrane with MOFs coordinated biopolymers for efficient dye/salt separation

Membrane technology has been widely used in textile industry for the separation of dye/salt mixtures. However, membranes inevitably suffered from the fouling issue, which greatly abated the water permeability and reduced the separation efficiency of membranes. Herein, a novel thin film nanocomposite (TFN) nanofiltration (NF) membrane was prepared by introducing photocatalytic sensitive material into the selective layer to directly degrade the foulants on the membrane surface. This functional selective layer was achieved by a complexation of carboxymethyl cellulose (CMC) and MIL-53 (Fe), which greatly enhanced the self-cleaning ability of the TFN membrane while MIL-53 (Fe) was served as nanofiller and photocatalyst simultaneously. The optimized TFN NF membrane modified with 0.5 mg CMC and 0.075 mg MIL-53 (Fe) exhibited a high pure water permeability of 39.83 L m−2 h−1 bar−1, while maintaining high dye rejections above 99.00 % for CR, G250 and MB. Meanwhile, the obtained membrane exhibited impressive rejections of salts (61.49 % for Na2SO4 and 17.22 % for NaCl). This simple fabrication strategy provided new insights to augment the separation performance of TFN NF membrane with self-cleaning ability in organic separation systems.