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a Pure water contact angle and overall porosity of PAN and its MMMs, b–e the contact angle images of PAN, GO/PAN, SiO2/PAN and GO/SiO2/PAN, respectively
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The novel graphene oxide (GO)/silica (SiO2)/polyacrylonitrile (PAN) mixed matrix membranes (MMMs) with high filtration flux and excellent antifouling performance were designed and fabricated in situ by the method of non-solvent induced phase separation (NIPS) from the precursor of PAN hybridized with GO, tetraethoxysilane and 3-aminopropyltriethoxy...
Citations
... The ATR-FTIR test was done to analyze the chemical structures of both the pure PAN membrane and its MMMs. Figure 2 shows the ATR-FTIR spectra, across all spectra, a distinct peak at 2243 cm À1 corresponding to the nitrile group in PAN was evident, along with an absorption peak at 1070 cm À1 associated with the CN groups. 27,28 Also, some absorption peaks are observed in 1235, 1733, and 2937 cm À1 , which are related to the presence of CH, C O, and CH functional groups, respectively, which is due to the vibration and tension of the PAN. 16 Comparing the pure PAN membrane with PAN-SiO 2 and PAN-MCM41, two weaker absorption peaks at 3619 and 3558 cm À1 were discernible in the latter two spectra, attributed to OH groups. ...
... This may be due to the hydrophilicity of NPs and their movement toward water baths and entrapment in the top surface of membranes. 28,34,35 EDX analysis was employed to closely examine the chemical composition of the upper layers of the membrane. According to Table 2, the top layers of pure PAN membranes exhibited the presence of only C, N, and a small quantity of O atoms. ...
In this study, the morphology of the nanostructures is evaluated on the surface characterization and performance of the polyacrylonitrile (PAN) ultrafiltration mixed matrix membranes (MMM). To this end, silica nanoparticles (NPs) such as spherical (SiO2) and hexagonal mesoporous (MCM‐41) with high hydrophilicity were incorporated at 0.5, 1, and 2 wt%. Attenuated total reflectance‐Fourier transform infrared analysis illustrated the placement of NP on the surface of the MMM. Atomic force microscopy studies also showed that SiO2 NP added to PAN exhibited a smoother surface than MCM‐41 NP. Field‐emission scanning electron microscope analysis of the MMM identified that all membranes are composed of a finger‐like porous structure. Contact angle measurements indicate that the morphology of the NPs has no significant effect on MMM hydrophilicity. Moreover, the performance of the MMM was evaluated, and regardless of NP morphology, the MMM showed better permeate flux with increased loading. A higher pure water flux was observed in the PAN‐MCM41‐1% membrane (237 L/m² h), possibly because of inherent porosity and high hydrophilicity of MCM‐41 compared to SiO2 NP. Further, the PAN‐SiO2‐1% membrane exhibited superior antifouling properties due to a lower surface roughness. The present studies reveal that the morphology of the NP greatly influence on the structure, permeation, and antifouling properties of PAN membranes.
... The added GO nanosheets and TiO 2 nanoparticles increased the phase-separation speed in the polymeric matrix during the NIPS process for the synthesis of the M2 membrane. [48,49] The synergistic effects that arose during the NIPS caused GO and TiO 2 nanoparticles to migrate to the top surface and wall of the M2 membrane pores, where they contributed to the formation of the homogenous and hydrophilic channels. ...
As a novel crystalline polymeric material, covalent organic framework (COF) has been paid the most attention by membrane separation researchers all over the world due to its pre-designable, regular pore structures, and reliable chemical stability. However, the fabrication of a homogenous, stable, thin COF layer on the support membrane remains challenging. In this work, electrostatic interaction between amino monomer and support was used to generate a stable and clear interface between the aqueous and organic phases through the interfacial polymerization (IP) process. Specifically, the hydrophilicity and large pore size of polyacrylonitrile (PAN) mixed matrix membrane (MMM) allowed ethidium bromide monomers (EB) from the aqueous phase to penetrate and reach the negatively charged porous surface of the MMM. This assisted the fixation of the EB monomers at the interface with highly electrostatic interaction between the MMM’s surface and the EB monomers. The Tp (1,3,5-triformylphloroglucinol) monomer of the organic phase was polymerized with surface entangle EB, resulting in the TpEB COF with very thin, hydrophilic, stable, homogeneously distributed tiny pores, and cationic surface charge. The prepared TpEB COF composite membrane had a water permeability of 32.34 L·m−2.h−1.bar−1, highly selective sieving performances for dye molecules of different charges and sizes. This membrane could reject ∼ 99.99 % of anionic dyes like Potassium permanganate (PP), Congo red (CR), and Coomassie brilliant blue G-250 (CBB), meanwhile maintaining high solvent permeability for a long time. But for cationic or neutral dyes, the rejection rates mainly depended on their molecular sizes.
... Because of the use of a woven mesh with a wide-open area, water ow is facilitated, as seen by the membrane substrates' decreased tortuosity (s ¼ 3), increased porosity, and wettability. 87,88 As a result, the SG3 membrane is projected to outperform several commercial membranes in FO applications, including the CTA membrane, as demonstrated in Table 4. ...
Mixed matrix woven forward osmosis (MMWFO) membranes made of polyethersulfone (PES)/graphene oxide nanosheets (GO NSs) were made by inserting varying wt% ratios of GO NSs (zero to 0.1 wt%) into the PES matrix. A coated woven fabric material was used to cast the membrane polymer solution. The physical characteristics and chemical structures of the produced PES/GO MMWFO membranes were studied, including contact angle, hydrophilicity, porosity, tortuosity, function groups, chemical and crystallographic structures, nanomorphologies, and surface roughness. The performance of the prepared PES/GO FO membranes for water desalination was evaluated in terms of pure water flux (J w), reverse salt flux (J s), and salt rejection (SR). The hydrophilicity and porosity of the FO membrane improved with the addition of GO NSs, as did water permeability due to the development of multiple skin-layer structures with greater GO NS loading. These GO NSs establish shortcut pathways for water molecules to move through, reducing support layer tortuosity by three times, lowering support layer structural features, and minimizing internal concentration polarization (ICP). The PES/0.01 wt% GO MMWFO membrane with a total casting thickness of 215 μm and 1 M NaCl concentration had the best performance, with the highest J w (114.7 LMH), lowest J s (0.03 GMH), and lowest specific reverse solute flux (J s/J w = 0.00026 g L-1), as well as a more favorable structural parameter (S = 149 μm). The performance of our optimized membrane is significantly better than that of the control woven commercial cellulose triacetate (CTA) FO membrane under optimal FO conditions. As the NaCl concentration increased from 0.6 to 2 M, J w increased from 105 to 127 LMH which is much higher than the J w of the commercial one (7.2 to 15 LMH). Our FO membranes have an SR of 99.2%@0.65 M NaCl, which is significantly greater than that of the CTA membrane.
... Because of its widespread use as a cost-effective material in the fabrication of hydrophilic/ hydrophobic surfaces, SiO 2 is placed at the center of special interest. Simultaneously, the existence of SiO 2 NPs acts as a reinforcing agent where the mechanical and thermal properties of the membranes can be modified as well [20,32]. To meet the problem of membrane fouling, the hydrophilic/oleo-phobic variant is beginning to receive a lot of attention from researchers, where high hydrophilicity along with hierarchical surface morphology is the main cause of water passing through the membrane. ...
... Porosity is an important parameter for the characterization of membranes. Overall porosity of the membranes (ε) was measured using the gravimetric method according to the following equation [32]: ...
In this paper, a special sandwich structure of the PAN/GO/SiO2 microfiltration membrane was developed using the electrospinning/electrospraying method for efficient oil/water separation. The results of morphological and structural studies confirmed that spraying SiO2 nanoparticles (NPs) to the outer surface of PAN/GO nanofibers (NFs) increased the surface roughness and decreased the water contact angle value, which is responsible for the improved hydrophilicity. Moreover, the addition of SiO2 NPs to the middle layer enhanced the porosity and the membrane flux up to 78 % and 423.7 ± 7.1 (L/m².h), respectively. The values of oil/water rejections indicated the good performance of the PAN//GO-SiO2(1:1)//PAN-SiO2 membrane. Results supported that the presence of SiO2 NPs with a hydrophilic nature led to optimum oil/water separation with rejection over 98 %, obtained under the driving of gravity for free-surfactant Toluene emulsion, and above 97 % for the other types of oils (Pump oil and sunflower oil).
... There are various removal methods that are used to remove pollutants from water such as bioreactors [14], degradation and photodegradation [15][16][17][18], filtration [19], photocatalysis [20,21], photo-Fenton and Fenton-like [22,23], coagulation [24] and adsorption [25,26]. Among these methods, adsorption is a widely used and most efficient method for wastewater treatment. ...
Recently, pharmaceutical pollutants in water have emerged as a global concern as they give threat to human health and the environment. In this study, graphene nanoplatelets (GNPs) were used to efficiently remove antibiotics sulfamethoxazole (SMX) and analgesic acetaminophen (ACM) as pharmaceutical pollutants from water by an adsorption process. GNPs; C750, C300, M15 and M5 were characterized by high-resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction and Brunauer–Emmett–Teller. The effects of several parameters viz. solution pH, adsorbent amount, initial concentration and contact time were studied. The parameters were optimized by a batch adsorption process and the maximum removal efficiency for both pharmaceuticals was 99%. The adsorption kinetics and isotherms models were employed, and the experimental data were best analysed with pseudo-second kinetic and Langmuir isotherm with maximum adsorption capacity (Q m ) of 210.08 mg g ⁻¹ for SMX and 56.21 mg g ⁻¹ for ACM. A regeneration study was applied using different eluents; 5% ethanol-deionized water 0.005 M NaOH and HCl. GNP C300 was able to remove most of both pollutants from environmental water samples. Molecular docking was used to simulate the adsorption mechanism of GNP C300 towards SMX and ACM with a free binding energy of −7.54 kcal mol ⁻¹ and −5.29 kcal mol ⁻¹ , respectively, which revealed adsorption occurred spontaneously.
... However, GO sheets have low compatibility with most polymers and are inclined to aggregations in the polymer matrix owing to the van der Waals force [10,11], which leads to inferior dispersion and exfoliation of GO sheets and inferior interfacial interaction between GO sheets and the matrix, as well as a restriction of stress transfer from the matrix to the GO sheets [12,13]. Therefore, it is important to improve the dispersion of GO sheets in the polymer matrix and interfacial adhesion with the matrix to achieve a satisfactory mechanical performance and applications of graphene/epoxy composites [14]. ...
An effective approach to the fabrication of progressive epoxy nanocomposites by the incorporation of hydroxyl-terminated dendrimers functionalized graphene oxide (GO-TCT-Tris) is reported. The relationship between surface grafting, chemical construction, morphology, dispersion, and interfacial interaction as well as the corresponding mechanical properties of the composites were studied in detail. It was shown that hydroxyl-terminated triazine derivatives have been resoundingly bonded onto the GO surface through covalent bonding, which effectively improved the dispersion and compatibility of GO sheets in epoxy resin. The tensile and flexural tests manifested that the GO-TCT-Tris/epoxy composites exhibited greater tensile/flexural strength and modulus than either the pure epoxy or the GO/epoxy composites. For GO-TCT-Tris (0.10 wt%)/epoxy composite, the tensile strength and elastic modulus increased from 63 ± 4 to 89 ± 6 MPa (41.27%) and from 2.8 ± 0.1 to 3.6 ± 0.2 GPa (28.57%), and the flexural strength and modulus increased from 106 ± 5 to 158 ± 6 MPa (49.06%) and from 3.0 ± 0.1 to 3.5 ± 0.2 GPa (16.67%), respectively, compared to the pure epoxy matrix. Moreover, the fractographic analysis also illustrated the ameliorative interfacial interaction between GO-TCT-Tris and epoxy matrix.
... PAN-based MMMs were fabricated in situ by the NIPS process as reported previously. 23 The brief preparation procedure is as follows. First, TEOS, APTES, or TBT was dissolved in a mixture of DMAc and HAc. ...
... As shown in Figure 3, three membranes all had the characteristic peaks of PAN polymer chains. 23 The moderate-intensity peaks from 3300 cm −1 to 3650 cm −1 in the PAN-SiO 2 and PAN-TiO 2 membrane's top surfaces are ascribed to OH and NH 2 groups, which demonstrates the surface migration of SiO 2 and TiO 2 nanoparticles generated in situ. 37 And the strong peaks from 500 cm −1 to 1000 cm −1 in the PAN-TiO 2 membrane's top surfaces are attributed to Ti─O─Ti structures, which indicates more surface migration of TiO 2 nanoparticles than of SiO 2 nanoparticles. ...
Mixed matrix membrane (MMM) structures and performances are greatly affected by the distribution of nanoparticles in the polymeric matrix. Until now, there has been little research on the effects of nanoparticle distribution states on polyacrylonitrile (PAN)‐based MMM structures and performances. In this paper, different intermolecular interactions between nanoparticles and PAN molecules were generated by in situ fabricated amino‐functionalized SiO2 and TiO2 nanoparticles to create absolutely different distribution states of nanoparticles in a PAN matrix. The results indicated that, due to the strong interactions between amino and cyano groups, SiO2 is distributed in the PAN membranes homogeneously, while most of the TiO2 migrates to the membrane's top surfaces or the walls of pores or even escape from the membranes during the nonsolvent index phase separation (NIPS) process. PAN‐TiO2 MMMs have more hydrophilic top surfaces, higher porosity, larger mean pore size, and stronger antifouling performances than pure PAN and PAN‐SiO2 membranes. The PAN‐TiO2 MMMs have an ultrahigh water flux of 1204.6 L/(m² h), which is more than 44 times that of PAN membranes. And the good pore structures and hydrophilicity of the membranes derived from special interactions between in situ TiO2 nanoparticles and PAN molecules can give high‐performance PAN‐based ultrafiltration membranes a bright future. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47902.
... However, it has the inherent disadvantages of brittleness, poor of attention in the past few years [7,8]. In addition, considerable efforts have been made to demonstrate that graphene and graphene oxide (GO) sheets are potent reinforcements in polymer composites because of their fantastic and outstanding mechanical properties [9][10][11][12]. However, there are two major problems to limit the mechanical properties and applications of graphene or GO sheets/epoxy composites: (1) Graphene and GO sheets tend to aggregate irreversibly in the composites due to the strong van der Waals forces, which results in the reduced dispersion/exfoliation of graphene or GO sheets in the matrix; (2) the interfacial interaction with the matrix is weak due to the poor dispersion/exfoliation of graphene or GO sheets, which leads to a limitation of the load transfer from the matrix to the sheet. ...
Interface interactions are the important problems in improving the mechanical properties of graphene and polymer composites. In this work, a simple method is proposed to prepare epoxy composites with admirable properties through constructing dendrimers with cyanuric chloride (TCT) and diethylenetriamine (DETA) onto graphene oxide (GO) surface. The FTIR, XRD, XPS, Raman spectroscopy, SEM and TEM were used to confirm the successful grafting of TCT and DETA molecules onto the surface of GO. The interfacial adhesion between GO–TCT–DETA and epoxy resin is enhanced due to the formation of a strong chemical bond between the amino group on the GO surface and the epoxy resins. The tensile and flexural strength of GO–TCT–DETA/epoxy composites have considerable improvement (40.79 and 48.56%) compared with that of epoxy resin due to stronger interfacial interaction. In addition, the strengthening mechanism and dispersion of GO–TCT–DETA in epoxy matrix were also demonstrated.
... The finger-like pores for GO-PES membranes were wider as compared to pristine PES membranes. These changes in the membrane structure can be attributed to the hydrophilic nature of GO [57]. The addition of GO in the solution casting mixture made it more hydrophilic, which caused a solvent (NMP) and nonsolvent (water) exchange during the phase inversion to yield this wider finger-like channel effect with increased porosity and the lateral structure formation with increasing GO concentration in the prepared membranes [39,58,59]. ...
The present work is focused on preparation, characterization, and antibacterial activity evaluation of graphene oxide/polyethersulfone mixed matrix filtration membranes. Graphene oxide (GO) was synthesized via improved Hummer’s method and characterized by XRD, FTIR, and SEM. FT-IR spectra showed the presence of carboxylic acid and hydroxyl groups on GO nanosheets. Different concentrations of the synthesized GO at 0.25, 0.5, and 1.0 wt. % were incorporated in polyethersulfone (PES) matrix via phase inversion method to fabricate GO-PES membranes. Increasing porosity and formation of wider, finger-like channels were observed with increased GO concentrations relative to pristine membranes as evident from scanning electron microscopy (SEM) micrographs of the fabricated membranes. However, membranes prepared with 1 wt. % GO appear to contain aggregation and narrowing of pore morphology. GO-incorporated membranes demonstrated enhanced flux, water-retaining capacities, and wettability as compared to pristine PES membranes. Shake flask and colony counting methods were employed to carry out antibacterial testing of synthesized GO and fabricated GO-PES membranes against Salmonella typhi ( S. typhi )—a gram-negative bacteria present in water that is known as causative agent of typhoid. Synthesized GO showed significant reduction up to 70.8% in S. typhi cell count. In the case of fabricated membranes, variable concentrations of GO are observed to significantly influence the percentage viability of S. typhi , with reduction percentages observed at 41, 60, and 69% for 0.25, 0.5, and 1.0 wt. % GO-incorporated membranes relative to 17% in the case of pristine PES membranes. The results indicate a good potential for applying GO/PES composite membranes for water filtration application.
Forward osmosis (FO) has emerged as a highly promising and energy‐efficient technology for seawater desalination. This study investigates the enhancement of polyethersulfone/polysulfone FO membranes by incorporating graphene oxide (GO) for seawater desalination. The effects of different GO concentrations on membrane properties and FO desalination performance were examined. Among the tested membranes, the one with 0.04 wt% GO exhibited optimal hydrophilicity, as indicated by a lower contact angle (53.93° ± 5.61°), higher porosity (69.86 ± 0.66), and a minimal structure parameter (312.33 μm). The GO.04 membrane demonstrated significantly improved water flux ( J w ) of 106 L/m ² h and low reverse salt flux ( J s ) of 0.69 g/m ² h. Compared to the GO0 membrane without GO, the water flux was 103% higher without compromising salt selectivity ( J s / J w = 0.0065 g/L) when using distilled water as the feed solution (FS) and 1 M NaCl as the draw solution. However, over a threshold of 0.09%, GO concentration on membrane surfaces and pores can impede water flow, reducing porosity and increasing resistance to membrane transport. The GO.04 membranes also exhibited high water flux (113, 94.28, and 84.64 L/m ² h) when brackish water with different NaCl concentrations (5000, 10,000, and 15,000 mg/L) was used as the FS. Moreover, under real seawater conditions from the Suez Canal, the GO.04 FO membrane showed a significantly higher water flux of 94.3 L/m ² h. These findings provide valuable insights into the desalination of actual seawater from the Suez Canal, offering significant potential for the advancement of water treatment and resource management practices.
