Thin Film Nanocomposite Hollow Fiber Research Articles

On performance and anti-fouling properties of double-skinned thin film nanocomposite hollow fiber membranes in forward osmosis system

This study involves the preparation of a double-skinned thin film composite (TFC) and thin film nanocomposite (TFN) hollow fiber (HF) membrane for forward osmosis (FO) applications. The porous substrate consisted of a Polyvinyl chloride (PVC) / Polycarbonate (PC) blend HF membrane. Interfacial polymerization (IP) was then applied to coat a polyamide (PA) layer on the lumen surface and the porous substrate's outer surface. In addition, the impact of the outer PA active layer and the addition of nanoparticles to the outer selective layer on the FO flux and internal concentration polarization (ICP) were studied. By adding the second active layer to the substrate, water flux, reverse salt flux and ICP decreased. Also, the decline of water flux decreased over time due to the fouling agent. To compensate for the decrease in water flux in the double-skinned membrane, graphene oxide (GO) nanoparticles with 0.05% and 0.1%wt were added to the outer active layer. Addition of 0.1%wt graphene oxide nanoparticle to the outer active layer can help to improve water flux about 78% without spoiling the reverse salt flux. Moreover, the performance of double-skinned membranes against osmotic dilution process for oily wastewater treatment was investigated. The findings of this study demonstrated that the novel double-skinned TFN HF membrane exhibited high FO performance with low ICP and fouling.

Removal of arsenic from water using a CuBTC incorporated thin film nanocomposite hollow fiber membrane by interfacial polymerization on lumen side

A thin film nanocomposite (TFN) low-pressure driven hollow fiber (HF) nanofiltration (NF) membrane of CuBTC incorporated in polyamide layer was developed via interfacial polymerization (IP) of m-phenylenediamine (MPD) and CuBTC/trimesoyl chloride (TMC). The inner surface of the polysulfone (PSF) hollow fiber substrate was covered with a thin polyamide coating. During the IP process, a small quantity of CuBTC (0.2 wt%) was mixed into the TMC solution, which significantly enhanced the pure water permeate flux of the developed TFN hollow fiber membrane. The characteristics of developed HF membranes were studied using the scanning electron microscope (SEM), energy dispersive X-ray (EDX), atomic force microscopy (AFM), molecular weight cut-off (MWCO), pure water permeability, X-ray photoelectron spectroscopy (XPS), contact angle, Fourier transform infrared spectroscopy (FTIR) and surface zeta potential. As CuBTC was included in the polyamide layer, the pure water permeability of the TFN membrane increased from 4.4 l/m2h.bar (TFC) to 16.6 l/m2h.bar, as supported by an increment in average pore radius from 6.9 Å to 10.6 Å and MWCO from 693 Da to 1723 Da. The TFN hollow fiber membrane exhibits 85.8 % rejection of arsenate with enhanced permeated flux compared to the nascent thin film composite membrane. Thus, the developed low-pressure driven TFN HF membrane was capable of arsenate rejection. Performance of the developed TFN HF membrane was tested for artificially arsenic-contaminated groundwater with a rejection of 79.7–84.5 % arsenate, 41.6 % TDS, 41.2 iron and 42.8 % hardness at 1 bar transmembrane pressure (TMP) with 12.5 l/m2h permeate flux.

Inner‐coated highly selective thin film nanocomposite hollow fiber membranes for the mixture gas separation

AbstractPolyamide‐based thin film nanocomposite (TFN) membranes were prepared by incorporating nanoparticles in an aqueous phase containing m‐phenylenediamine (MPD) and an organic phase containing trimesoyl chloride (TMC) by interfacial polymerization (IP) method. The 3‐aminopropyltrimethoxy silane grafted mesoporous synthetic hectorite (APTMSH) was synthesized and added in an aqueous monomer solution while the IP. In this work, the TFN layer interfacial compatibility has been enhanced by building the covalent bond between APTMSH and other two monomers by IP method. The coating of the TFN selective layer was done on the inner surface of polysulfone hollow fiber membranes. The interesting results were obtained for the binary mixture gas separation containing water vapor/N2 and CO2/CH4. Improved gas permeance and selectivity have been obtained using APTMSH‐incorporated TFN membranes. The developed TFN membranes have been characterized using several physicochemical methods. The results show that with the addition of APTMSH in MPD solution up to 0.5 w/w% the best water vapor permeance 2485 GPU and CO2 permeance 22.3 GPU were obtained along with water vapor/N2 selectivity 725.5 and CO2/CH4 selectivity 26.68 respectively through APTMSH@TFN‐3 membrane.

Novel Thin-Film nanocomposite hollow fiber membranes in modules with reduced reverse solute flux for pressure retarded osmosis

Osmotic energy is released when mixing solutions with different salinities. Pressure retarded osmosis (PRO) is a promising membrane technology to harvest this osmotic energy. However, the current polymeric PRO membranes suffer from the high reverse solute fluxes during PRO processes, which would dramatically diminish the membrane performance, especially in big membrane modules. In order to control the reverse solute flux, two cup-like calix[n]arenes, sulfocalix[4]arene (SCA4) and sulfothiacalix[4]arene (STCAss) were incorporated into the polyamide network to enhance the PRO performance of thin-film nanocomposite (TFN) hollow fiber membranes in 1-inch modules. Due to the unique structures and the enhanced molecular-sieving abilities of both macrocyclic molecules, they were able to effectively improve the selectivity of the resultant TFN hollow fiber membranes. After optimizing the concentration of each nano-filler, it was found that the TFN membrane with 0.20 wt% of STCAss produced a PRO power density of 15.0 W/m2 and a reverse salt flux of 28.3 gMH, while the other containing 0.10 wt% of SCA4 produced a PRO power density of 14.2 W/m2 and a reverse salt flux of 31.6 gMH. In long-term PRO tests at 20 bar, the SCA4-incorporated membrane was more efficient in controlling the concentration polarization (CP) and maintaining the power density comparing to the STCAss membrane because the former has a smaller cavity opening than the latter. This research work may provide useful insights to further design PRO membranes and membrane modules for osmotic power generation.

Functionalized-MXene Thin-Film Nanocomposite Hollow Fiber Membranes for Enhanced PFAS Removal from Water.

Due to adverse health effects and the broad sources of per- and polyfluoroakyl substances (PFAS), PFAS removal is a critical research area in water purification. We demonstrate the functionalization of thin-film composite (TFC) hollow fiber nanofiltration (HFN) membranes by MXene nanosheets during the interfacial polymerization (IP) process for enhanced removal of perfluorooctane sulfonic acid (PFOS) from water. A MXene-polyamide (PA) selective layer was fabricated on top of a polysulfone (PSF) hollow fiber support via IP of trimesoyl chloride (TMC) and a mixture of piperazine (PIP) and MXene nanosheets to form MXene-PA thin-film nanocomposite (TFN) membranes. Incorporating MXene nanosheets during the IP process tuned the morphology and negative surface charge of the selective layer, resulting in enhanced PFOS rejection from 72% (bare TFC) to more than 96% (0.025 wt % MXene TFN), while the water permeability was also increased from 13.19 (bare TFC) to 29.26 LMH/bar (0.025 wt % MXene TFN). Our results demonstrate that both electrostatic interaction and size exclusion are the main factors governing the PFOS rejection, and both are determined by PA selective layer structural and chemical properties. The lamella structure and interlayer of MXene nanosheets inside the PA layer provided different transport mechanisms for water, ions, and PFAS molecules, resulting in enhanced water permeability and PFAS rejection due to traveling through the membrane by both diffusions through the PA layer and the MXene intralayer channels. MXene nanosheets showed very promising capability as a 2D additive for tuning the structural and chemical properties of the PA layer at the permeability-rejection tradeoff.

High separation performance thin film composite and thin film nanocomposite hollow fiber membranes via interfacial polymerization for organic solvent nanofiltration

Hollow fiber (HF) organic solvent nanofiltration (OSN) membrane has unique self-supporting structure and larger specific surface area over flat OSN membranes, which is much more beneficial for separation processes intensification in chemical related industries. The key of this technology is HF OSN membrane. However, the research works on HF OSN membranes was relatively less till now. In this work, an outer-skinned polyimide HF substrate membrane was spun, and then thin film composite (TFC) membrane was prepared via interfacial polymerization (IP) between ultra-low concentration m-phenylenediamine (MPD) in the aqueous phase and trimesoyl chloride (TMC) in the organic phase on the HF substrate surface, with sodium dodecyl sulfate (SDS) as aqueous additives and triethylamine (TEA) as aqueous catalyst, and subsequently accompanied by crosslinking and solvent activation procedures. Further, thin film nanocomposite (TFN) HF OSN membrane incorporated with graphene oxide (GO) was also prepared. The combination of lower MPD concentration with SDS and TEA as additives in the aqueous monomer solution promote the formation of a TFC HF OSN membrane with average roughness of less than 3 nm, and a rhodamine B (RDB) rejection close to 100%, together with an ethanol permeance higher than 12 L m−2 h−1 MPa−1 under the optimum fabrication conditions. The optimal TFN membrane at a doping GO content of 5.0 mg L−1 achieves up to 20 L m−2 h−1 MPa−1 for the ethanol permeance without sacrificing the RDB rejection (nearly 100%). Moreover, both HF OSN membranes possess good swelling resistance, which proves their application potential in organic solvent system.

Two dimensional COFs as ultra-thin interlayer to build TFN hollow fiber nanofiltration membrane for desalination and heavy metal wastewater treatment

An ultra-thin interlayer of two-dimensional covalent organic frameworks (COFs) was in-situ formed on polysulfone hollow fiber (HF) substrate surface to manipulate the interfacial polymerization process for the construction of thin film nanocomposite (TFN) HF nanofiltration (NF) membrane with greatly improved separation performance. p-Phenylenediamine and 1,3,5-Triformylphloroglucinol monomers were used for constructing the COFs interlayer, piperazine and trimethyl chloride were used for the fabrication of the HF NF polyamide skin separation layer. A series of optimization of the membrane preparation conditions were carried out to achieve the good separation performance. The results demonstrated that the two-dimensional COFs nanomaterials could effectively control the pore size distribution and hydrophobicity of the HF substrate surface, realize a uniform distribution of piperazine on the interlayer surface, thus effectively manipulate the interfacial polymerization process. Under the optimal conditions, the rejections of Na2SO4, Cr2(SO4)3, CuSO4, ZnSO4 and MnSO4 can achieve 96.6 %, 95.4 %, 94.3 %, 91.7 % and 91.0 %, respectively, and the water permeance reaches 86.6 L m−2 h−1 MPa−1. Meanwhile, the fabricated TFN HF NF membrane shows good long-term stability, fouling resistance, acid and alkali resistance, as well as chlorine resistance, providing its vast potential for application in desalination and heavy metal wastewater treatment.

A new perspective of functionalized MWCNT incorporated thin film nanocomposite hollow fiber membranes for the separation of various gases

As the increasing demand for gas separation technologies in the industry, the polymeric membrane separation technology has received wide attention based on the advantages of high gas permeance, and low cost. Thin film nanocomposite (TFN) membranes used for the gas separation in industrial level is one of the best choices, because of applied nanoparticles synergistic properties influence to enhance gas permeance and selectivity. In this study thin selective nanocomposite layer has been developed using interfacial polymerization between 3,5-diaminobenzoic acid (DABA) with carboxylated multi-walled carbon nanotubes (C-MWCNTs) and trimesoyl chloride (TMC) on the surface of polysulfone hollow fiber substrate for the separation of various gases like water vapor, H2, CO2, CH4 and N2. Different concentrations of C-MWCNTs are used for the preparation of various TFN membranes. All prepared TFN membranes were well characterized using different physiochemical characterization techniques like ATR-FTIR, AFM, SEM, XPS, contact angle etc. It is found that the prepared membranes are not only used for the separation of water vapor but also utilize for the separation of different gases like H2, CO2, CH4, and N2. The TFN hollow fiber membranes prepared with 0.04 % C-MWCNTs, (C-MWCNT@DT-M4) show good performance in the form of permeance and selectivity among all the prepared membranes, as a water vapor permeance 2570 GPU, H2 permeance 92.5 GPU, along with the water vapor/N2 641, H2/CO2 4.41 and CO2/N2 24.74 and CO2/CH4 18.45 selectivities respectively. The prepared TFN membranes show superior performance to C-MWCNT-based membranes because of their synergetic bonding chemistry and hydrophilic nature. This study has proven that slight addition of functional MWCNTs in polymeric nanocomposite membranes responsible to obtain better performance of the TFN membranes.

Graphene oxide interlayered thin-film nanocomposite hollow fiber nanofiltration membranes with enhanced aqueous electrolyte separation performance

In this study, a kind of thin-film nanocomposite (TFN) hollow fiber nanofiltration (NF) membranes was fabricated via incorporating graphene oxide (GO) interlayer using the interfacial polymerization (IP) reaction between piperazine (PIP) and trimesoyl chloride (TMC). The surface morphology and cross-sectional structure of the fabricated TFN hollow fiber NF membrane were extensively investigated. The effects of the PIP concentration, species of the aqueous additives, and the GO loading on the structure and performance of the hollow fiber NF membrane were also investigated in detail and the optimal preparation conditions were achieved. Fourier transform infrared spectroscopy (FTIR) confirmed the successful introduction of the GO interlayer into the composite hollow fiber NF membrane. Moreover, the incorporation of GO interlayer helped to reduce the skin thickness of the composite hollow fiber NF membrane remarkably, and thus helped to increase greatly the water permeance while maintaining a high salt rejection. Under an optimal GO loading of 20.0 mg m−2, the TFN hollow fiber NF membrane achieved a water permeance of 80 L m−2 h−1 MPa−1 and a Na2SO4 rejection of 96.1% for 2000 mg L−1 aqueous Na2SO4 solution, much higher than the interlayer-free thin-film composite (TFC) membrane. Meanwhile, the TFN hollow fiber NF membrane showed an excellent selectivity of Na2SO4 over NaCl, as well as good fouling resistance and long-term stability, demonstrating the vast potential in application for the selective separation of monovalent salt and divalent salt.

Thin film nanocomposite hollow fiber membranes incorporated with surface functionalized HKUST-1 for highly-efficient reverses osmosis desalination process

A new class of thin film nanocomposite (TFN) hollow fiber (HF) membrane of polydopamine (PDA) modified HKUST-1 (mHKUST-1) incorporated in polyamide (PA) matrix supported by polyethersulfone (PES) substrate was constructed via interfacial polymerization method for brackish water desalination in low-pressure reverse osmosis (RO) process. The PDA modification facilitated the HKUST-1 even dispersion, thus resulting in better compatibility between the inorganic nanofillers and the organic matrix. The impact of HKUST-1 loadings on the overall performances of the resultant HKUST-1@PA/PES membranes was investigated. Introducing the mHKUST-1 nanofillers not only enhanced surface hydrophilicity and negative surface charges for the selective layer, which improved membrane's fouling resistance to humic acid (HA), but also led to nearly doubled water permeance when comparing with the pristine PA membrane (increasing from 3.51 to 6.94 Lm−2h-1bar−1), without obvious salt rejection deterioration (~98.2% at 2 bar and 97.4% rejections at 4 bar for 500/2000 ppm NaCl solutions, respectively). The integrity of the HKUST-1@PA/PES membrane was examined and verified after 30-days operation. Overall, the results achieved in this work demonstrate promising potential of the metal organic framework (MOF)-based TFN membranes used for desalination in low-pressure RO process. To sum up, this work has exhibited a facile method to incorporate the metal organic framework (MOF) into the PA layer, and the resultant MOF-based TFN membrane indicates its great potential for desalination in low-pressure RO process.

Thin film nanocomposite hollow fiber membranes comprising Na+-functionalized carbon quantum dots for brackish water desalination

We have incorporated Na+-functionalized carbon quantum dots (Na-CQDs) into the polyamide layer via interfacial polymerization reaction and developed novel thin film nanocomposite (TFN) hollow fiber membranes for brackish water desalination. Comparing with the conventional thin film composite (TFC) membranes, the TFN membranes comprising Na-CQDs have a larger effective surface area, thinner polyamide layer and more hydrophilic oxygen-containing groups in the polyamide layer. Besides, the interstitial space among the polyamide chains becomes larger due to the presence of Na-CQDs. As a result, the incorporation of 1 wt% Na-CQDs into the polyamide layer could improve the pure water permeability (PWP) of the membranes from 1.74 LMH/bar to 2.56 LMH/bar by 47.1% without compromising their NaCl rejection of 97.7%. Interestingly, stabilization of the TFN hollow fiber membranes containing 1 wt% Na-CQDs at 23 bar could further promote the PWP to 4.27 LMH/bar and the salt rejection to 98.6% under the same testing conditions due to the deformation of the membranes under a high hydraulic pressure. When using a 2000 ppm NaCl aqueous solution as the feed, the optimal water flux and rejection of the newly developed TFN membranes at 15 bar are 57.65 ± 3.26 LMH and 98.6% ± 0.35% respectively. The Na-CQDs incorporated TFN hollow fiber membranes show promising applications in the field of brackish water desalination.

Thin Film Composite and/or Thin Film Nanocomposite Hollow Fiber Membrane for Water Treatment, Pervaporation, and Gas/Vapor Separation.

Thin film composite (TFC) polymeric hollow fiber (HF) membranes are widely used in industrial gas/vapor separations and water treatment. There are many advantages of TFC HF membranes, such as low energy requirements, simplicity of operation, and high specificity. In the present article, a review is made on the progress that has been achieved during the past 15 years in the preparation of the HF substrate and the preparation/modification of the thin selective layer. The review also includes their applications in water treatment, dehydration of alcohols via pervaporation, and gas/vapor separation.

Fabrication and characterization of polyamide-fullerenol thin film nanocomposite hollow fiber membranes with enhanced antifouling performance

Fullerenol C60(OH)22–24 was incorporated into the polyamide (PA) selective layer to develop novel thin film nanocomposite (TFN) hollow fiber membranes for low molecular weight cut-off ultrafiltration. TFN membranes were fabricated via interfacial polymerization technique by alternately pumping fullerenol dispersion in triethylenetetramine (TETA) aqueous solution and isophthaloyl chloride solution in hexane through polysulfone hollow fiber membranes. Developed TFN PA/fullerenol membranes were investigated by FTIR, Raman spectroscopy, SEM, TEM, AFM, contact angle measurements and evaluated by determining the permeability, rejection and antifouling performance. Introduction of fullerenol to the PA skin layer was revealed to yield in the decrease of pure water flux and slight increase of lysozyme rejection which is attributed to the increase of the thickness of PA layer. Water contact angle of the skin layer was found to decrease sharply from 34° to 21° when the concentration of fullerenol increased up to 0.5wt% in the TETA aqueous solution. Antifouling properties of the PA/fullerenol membranes were found to be superior to initial membrane. Fouling recovery ratio increased from 54% for the pristine membrane to 93% for the membrane with 0.5wt% of fullerenol in the TETA aqueous solution. Irreversible fouling ratio was found to decrease from 38% to 6%, respectively. A correlation between surface properties and fouling behavior of TFN membranes upon increase of fullerenol concentration was established.

Development of carboxylated TiO2 incorporated thin film nanocomposite hollow fiber membranes for flue gas dehydration

In this work, thin film nanocomposite (TFN) membranes for water vapor removal have been fabricated by incorporation of carboxylated TiO2 nanoparticles in the polyamide membrane matrix. Surface of pure TiO2 was modified to introduce functional groups on the TiO2 surface and increase the hydrophilicity of the nanoparticles. Modified nanoparticles were then homogeneously dispersed in the aqueous phase monomer (3, 5-diaminobenzoic acid) and reacted with trimesoyl chloride (TMC) to form a thin film nanocomposite membrane (TFN) on top of the polysulfone hollow fiber membrane (HFM) substrate. The carboxylation of TiO2 was confirmed by FTIR spectra. Intrinsic properties of the TFN were analyzed by ATR-FTIR, scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle. Introduction of carboxylated TiO2 caused a more dense and cross-linked polyamide layer due to its high binding affinity with the polyamide layer, which was also confirmed by SEM analysis. Furthermore, the addition of modified nanoparticles also increased the hydrophilicity of the TFN membrane due to excess carboxylic groups. Water vapor permeance and selectivity drastically improved due to the increased water vapor permeation paths provided by the modified nanoparticles. A maximum water vapor permeance and selectivity of 1340 GPU and 486 respectively, were obtained at optimum conditions. In addition, effect of reaction time and monomer concentration have also been studied and correlated.

Fabrication of a thin film nanocomposite hollow fiber nanofiltration membrane for wastewater treatment

A thin film nanocomposite (TFN) hollow fiber membrane containing nanoporous SAPO-34 nanoparticles was prepared on the dual-layer (PES/PVDF) hollow fiber substrate. The nanoparticle exposed TFN membrane (TFN(DOX)) was fabricated via the co-solvent (dioxane) assisted interfacial polymerization process. The TFN(DOX) had a larger nanoporosity and a higher crosslinking degree, which simultaneously led to an increased pure water permeability but a decreased salt permeability than the TFN membrane. The larger nanoporosity of TFN(DOX) membrane was ascribed to the effective exposure of nanoparticles, proved by the less PA coverage and the stable dispersion of nanoparticles in organic solution. Contributed by the exposed nanoparticles, the TFN(DOX) showed superior hydrophilicity and lower streaming potential than the TFN membrane. Compared to the NF-90, the TFN(DOX) membrane simultaneously improved the water flux and the rejections against tris(2-chloroethyl) phosphate, tris(1-chloro-2-propyl) phosphate and tris(1,3-dichloro-2-propyl) phosphate molecules. In addition to the elevated pure water permeability of 20.1Lm−2h−1bar−1, the newly developed TFN(DOX) hollow fiber nanofiltration membranes have high rejections to both the multivalent electrolytes and micropollutant molecules, showing the potential applications in industrial wastewater treatment and drinking water purification.