Enhanced desalination performance and arsenate removal using semi-aromatic polyamide-based pervaporation membranes by modifying with amino-acids via interfacial polymerization

In this study, the semi-aromatic polyamide membranes were synthesized by the interfacial polymerization between piperazine (PIP) monomers in the water phase and Benzene-1,3,5-tricarbonyl chloride in the organic phase. To further modify the semi-aromatic pervaporation membrane, the two amino acids, glycine, and l -lysine, were mixed with PIP monomers for interfacial polymerization. The morphology and physicochemical properties of the synthesized membranes were analyzed using Fourier transform infrared (FTIR), field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), and contact angle measurements. The results show that the semi-aromatic polyamide membranes modified by the two amino acids possess a higher hydrophilic surface and lower thickness compared to the unmodified membrane. Additionally, the permeation flux of the semi-aromatic polyamide membranes was improved by 18.6% and 38.5% as modified with glycine and l -lysine, respectively, at the operating temperature of 70°C when the rejection of both NaCl and arsenic are higher than 99.8%. Furthermore, the operating temperature significantly influenced the permeation flux, while the salt rejections were insignificantly affected. The permeation flux increases by 3.2- and 4.0-folds for glycine and lysine-modified membranes, respectively, when elevating the feed temperature from 40°C to 70°C. The highest permeation flux of 29.5 kg m⁻² h⁻¹ with a 5 wt% NaCl rejection of 99.8% was obtained at 70°C by using 0.3 wt% l -lysine modified polyamide (PA) membrane. For elimination of 1.5 mg L⁻¹ As solution at the feed temperature of 70°C, such l -lysine modified PA membrane exhibited the permeation flux of 30.5 kg m⁻² h⁻¹ and As rejection of 99.6%, respectively. This work provides a cost-saving, facile, and eco-friendly preparation method for effectively improving the permeation flux while not sacrificing the high rejection of salts of the modified membranes.     

Fabrication of highly permeable PDMS@ZIF-8/PVDF hollow fiber composite membrane in module for ethanol-water separation

The construction of high-performance MOF-based hollow fiber composite membrane (HFCM) modules is a significant, yet challenging task for the biofuel production industry. In this study, a novel approach was taken to fabricate PDMS@ZIF-8/PVDF HFCMs in modules through a facile ZIF-8 self-crystallization synthesis followed by pressure-assisted PDMS infusion for pervaporation ethanol-water separation. The as-prepared HFCMs exhibited an ultrathin separation layer (thickness, 370 ± 35 nm), which was achieved through precise regulation of the ZIF-8 membrane and defect repair by PDMS infusion. Moreover, the strategy utilized in this study resolved the defect issues arising from MOF agglomeration in conventional composite membranes. Impressively, at the optimal packing density, the prepared membrane demonstrated a remarkable ethanol flux (1.11 kg m⁻² h⁻¹) with an PSI value (26.59 kg m⁻² h⁻¹) and showed promising long-term stability for the pervaporation of 5 wt% ethanol aqueous solution at 40°C.     

Pervaporation properties of a three‐layer structure composite membrane

A novel composite membrane with a three‐layer structure has been prepared. The top layer is a thin dense film of chitosan crosslinked with glutaraldehyde, and the support layer is made of microporous polyacrylonitrile (PAN). Between the dense and the microporous layer, there is an intermolecular crosslinking layer. The performance data show that this is an excellent pervaporation membrane for alcohol dehydration and one‐stage separation is attainable for some alcohol/water mixtures such as ethanol/water and isopropanol/water systems, which has a good separation factor of 1410 and a good flux of 0.33 kg m⁻² h⁻¹ for the EtOH/H₂O mixture, and 5000 and 0.43 kg m⁻² h⁻¹ for the i‐PrOH/H₂O mixture using 90 wt % alcohol concentration at 70°C.Using 90 wt % methanol aqueous solution at 60°C, a flux of 0.17 kg m⁻² h⁻¹ and selectivity of 123 are also obtained. The structure and performance of the novel composite membrane varies with conditions of membrane preparation, such as hydrolysis degree of PAN membrane, content of crosslinking agent, and heat‐curing temperature. The results indicate that the separation factor and the permeation rate of this novel composite membrane increase with the increase of operating temperature. At the same time, the pervaporation properties can be adjusted by changing the structure of the top layer and the middle layer. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 740–745, 2000     

Separation of acid–water mixtures by pervaporation using nanoparticle filled mixed matrix copolymer membranes

BACKGROUND: Low energy and less expensive membrane based separation of acetic acid‐water mixtures would be a better alternative to conventional separation processes. However, suitable acid resistant membranes are still lacking. Thus, the objective of the present study was to develop mixed matrix membrane (MMM) which would allow high flux and water selectivity over a wide range of feed concentrations of acid in water. RESULTS: Three MMMs, namely PANBA0.5, PANBA1.5 and PANBA3 were made by emulsion copolymerization of acrylonitrile (AN) and butyl acrylate (BA) with 5.5:1 comonomer ratio and in situ incorporation of 0.5, 1.5 and 3 wt%, sodium montmorilonite (Na‐MMT) nanofillers, respectively. For a feed concentration of 99.5 wt% of acid in water the membranes show good permeation flux (2.61, 3.19, 3.97 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and very high separation factors for water (1473, 1370, 1292 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at 30 °C. Similarly for a dilute acid–water solution, i.e. for 71.6 wt% acid the membrane showed a very high thickness normalize flux (8.67, 9.44, 11.56 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and good water selectivity (101.7, 95.3, 79 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at the same feed temperature. The permeation ratio, permeability, diffusion coefficient and activation energy for permeation of the membranes were also estimated. CONCLUSION: Unlike most of the reported membranes, the present MMMs allowed high flux and selectivity over a wide range of feed concentrations. These membranes may also be effective for separating other similar organic‐water mixtures. Copyright © 2012 Society of Chemical Industry     

One-step preparation of asymmetric ceramic membranes based on sea urchin-like mullite whisker skeletons and their oil-water separation properties

In this work, novel sandwich-type asymmetric ceramic microfiltration membranes with a sea urchin-like mullite whisker skeleton were prepared one step. Their structural properties and oil-water separation performance were investigated. The results show that after sintering at 1400 °C, the prepared membrane possesses good hydrophilic, underwater oleophobic, and anti-fouling properties. During the continuous separation of a 300 mg/L oil-in-water emulsion, a maximum stable flux of 267 L·m⁻²·h⁻¹ was achieved without membrane cleaning. After chemical cleaning and simple physical cleaning, the membranes recovered to a steady flux of 397 L·m⁻²·h⁻¹ and 305 L·m⁻²·h⁻¹, respectively, and maintained a 95% oil rejection. The good underwater oleophobicity and selective permeability brought about by the flat-lying whiskers on the top surface, coupled with the efficient water channels between the sea urchin-like structures inside the membrane, are considered to be the main reasons for its improved separation characteristics over conventional low-cost ceramic membranes.     

Poly(vinyl alcohol)/carboxyl graphene mixed matrix membranes: High-power ultrasonic treatment for enhanced pervaporation performance

High-power ultrasonic treatment was conducted during the mixing process to obtain poly(vinyl alcohol) (PVA)/carboxyl graphene (CG) mixed matrix membranes (MMMs). Results from X-ray photoelectron spectrometer and thermogravimetric analysis confirmed the enhanced esterification reaction. The increased amorphous region and free volume were investigated by wide-angle X-ray diffraction and positron annihilation lifetime spectroscopy. Scanning electron microscope and atomic force microscope measurements suggested that ultrasonic could uniformly disperse CG in PVA polymer matrix. The mechanical properties and hydrophilicity of as-prepared membrane were enhanced due to ultrasonic treatment. The permeation flux and separation factor of PVA/CG-US membrane for 90 wt % ethanol aqueous solution were 0.79 kg m⁻² h⁻¹ and 860, respectively. For methanol (15 wt %)/methyl tert-butyl ether mixture, its permeation flux and separation factor were also increased significantly compared with membranes without ultrasonic treatment. Due to the simplicity of the ultrasonic process and the versatility of the inorganic fillers, this method may contribute to the design of various MMMs and extend the application of these membranes in different uses. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48526.     

A selective organosilica membrane for ethyl acetate dehydration by pervaporation

Organosilica bis(triethoxysilyl) ethane (BTESE) membranes were explored for pervaporation dehydration of binary and ternary mixtures of ethyl acetate (EA) by undiluted sol coating combined with flash firing. Three BTESE membranes (M1, M2, and M3) were fabricated on macroporous supports by varying BTESE concentrations (0.5, 2.5, and 5 wt% BTESE, respectively) in polymer sols. The membranes were characterized by DLS, SEM, FTIR, XRD, contact angle, AFM, and pervaporation performance to discuss the effect of the BTESE contents in the polymer sol on the formation and dehydration performance of resulting organosilica membranes. It was found that 5 wt% loading of BTESE led to a highly selective membrane for dehydration of EA/H₂O mixture. Among the synthesized membranes, M3 delivered flux of 0.84 ± 0.05 kg.m⁻².h⁻¹ with a selectivity of >10,000 for EA/H₂O mixture (98/2 wt%) at 60°C. The time course of pervaporation dehydration for the EA/H₂O mixture (95/5 wt%) confirms the stability of BTESE membrane in the investigated time period of 120 h. Further, the membrane exhibited excellent selectivity larger than 10,000 for separation of ternary mixtures (90/2/8 wt%) of ethyl acetate/ethanol/water and n-propyl acetate/isopropanol/water respectively, the composition of which is similar to the top product of the distillation column used in the industrial esterification process. The best separation performance and excellent acid stability of BTESE membranes in this study suggest that the simple synthesis protocol of undiluted sol coating and flash firing will provide a cost-effective, quick, and efficient synthesis route for practical membrane based applications.     

Enhanced glycerol dehydration of pervaporation cross-linked PVA membranes modified by VUV/UV-C treatments

The high glycerol miscibility in water needs more efficient processes to decrease the cost of dehydration. Water stable poly(vinyl alcohol) based membranes cross-linked with 15% w/w of maleic acid were used for dehydrating glycerol-water mixtures using pervaporation (PV). The membranes were characterized using water contact angle, profilometry, Fourier transformed infrared spectroscopy-attenuated total reflectance, x-ray photoelectron spectroscopy, water stability, swelling tests, and PV. Membranes were treated using dry methods with vacuum ultraviolet (VUV; 162 nm) or ultraviolet (UV)-C (254 nm) radiation and exposed to O₂ or acrylic acid vapors, respectively. The VUV and UV-C treatments improve PV performances, increasing the water separation selectivity more than 4 and 8.5 times, respectively. UV-C treatments exhibit a water flux (kg m⁻² h⁻¹), selectivity and PSI (kg m⁻² h⁻¹) of 0.3, 250, and 87.4 respectively. Highly hydrophilic functional groups grafted onto the surface of the membranes after irradiation favor the selective transfer of water through the membrane. Overall, the VUV or UV-C membrane treatments show great PV prospect in glycerol dehydration.     

Pervaporation separation of water/alcohol mixtures through hydroxypropylated chitosan membranes

The present study investigated the pervaporation performance of novel hydroxypropylated chitosan (HPCS) membranes to separate water from an aqueous alcohol solution. Hydroxypropylated chitosan was prepared from the reaction of chitosan and propylene oxide. The results show that the separation factor decreases and the flux increases with increasing of the substitution degree of the hydroxypropylated chitosan membrane. Crosslinking with glutaraldehyde or treatment with Cu²⁺ can improve the pervaporation performance of modified chitosan membrane grately. The performance data indicate that the crosslinking hydroxypropylated chitosan membrane treated with Cu²⁺ is an excellent pervaporation membrane for the separation of alcohol–water mixtures, and one-stage separation is attainable for some alcohol–water mixtures such as an n-propanol–water and an isopropanol–water system, which has a good separation factor of 220 for the n-PrOH/water system and 240 for the i-PrOH/water system using 85 wt % alcohol concentration at 60°C. The flux for both cases is around 0.5 kg m⁻² h⁻¹. At the same time, the structure of the chemically modified chitosan membranes and their separation characteristics for aqueous alcohol solutions are also discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2035–2041, 1998     

Electrospinning superhydrophobic–superoleophilic PVDF-SiO2 nanofibers membrane for oil–water separation

Oil–water separation has attracted research interest due to the damages of oily wastewater caused to the environment and human beings. Electrospun fiber membrane has high oil–water separation performance. A nanofibers membrane with multi-stage roughness was prepared by electrospinning using poly(vinylidene fluoride)(PVDF)-silica blend solution as raw material. The result shows that the water contact angle (WCA) of the nanofibers membrane was promoted from 138.5 ± 1° to 150.0 ± 1.5° when the SiO₂ content was increased from 0 to 3 wt%. The nanofibers membranes exhibited excellent separation efficiency (99 ± 0.1%) under gravity drive, with high separation flux of 1857 ± 101 L·m⁻²·h⁻¹. More importantly, the obtained PVDF-SiO₂ nanofibers membranes showed excellent multi-cycle performance and stable chemical resistance, which would make them great advantages for the practical application of oil–water separation.     

新型侧链型聚酰亚胺膜的制备及其渗透汽化分离性能

针对苯/环己烷混合物体系的特点,采用两种新型侧链二胺3,5-二氨基苯甲酸苯酯(PDA)和3,5-二氨基苯甲酸-4-三氟甲基苯酯(FPDA),制备了一系列由不同二酐与二胺单体如4,4'-二氨基二苯醚(ODA)和3,5-二氨基苯甲酸(DABA)聚合而成的用于渗透汽化分离苯/环己烷的聚酰亚胺膜,对其结构和各项性质进行了表征,并对膜材料的微观结构与宏观分离性能之间的关系进行了较为深入的研究。随着侧链二胺的引入,聚酰亚胺膜的分离效率随之持续增大,分离能力得以改善。渗透汽化实验结果表明,以6FDA为二酐单体的两类聚酰亚胺膜具有较优异的分离性能。乙二醇交联的6FDA-FPDA/ODA/DABA(1:7:2)膜综合渗透汽化分离性能最优。在50℃时,对于含苯50 %(质量)的苯/环己烷混合物,其渗透通量为9.84 kg·μm·m^-2·h^-1,分离因子达6.1。     

Preparation and characterization of nanoparticle-filled,mixed-matrix membranes for the pervaporation dehydration of isopropyl alcohol

Novel polymeric mixed-matrix membranes (MMMs) were prepared by the incorporation of different amounts of 13X zeolite into a sodium carboxymethylcellulose (NaCMC)/poly(vinyl alcohol) (PVA) blend matrix. The resulting MMMs were characterized by attenuated total reflectance–Fourier transform infrared spectroscopy to analyze the possible chemical reactions between NaCMC, PVA, zeolites, and glutaraldehyde. Scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction were used to analyze the surface morphology, thermal stability, and crystallinity, respectively, of the membranes. Swellings studies were performed at 35°C, and we found that membranes containing 20 wt % zeolite showed higher values (960 kg m⁻² h⁻¹) at 17.5 wt % water in an isopropyl alcohol (IPA)/water mixture. Pervaporation (PV) experiments were also performed to evaluate the membrane performance in different compositions of the IPA/water mixture at 35°C. The mechanical properties were also tested, and we found that the optimum mechanical strength and percentage elongation at break were 42.24 N/mm² and 3.38, respectively, for the membrane containing 15 wt % zeolite. The experimental results show that both the flux and selectivity increased with increasing zeolite content. The membrane containing 20 wt % zeolite showed the highest separation selectivity (5118) with a substantial flux of 0.121 kg m⁻² h⁻¹ at 35°C and with 10 wt % water in the feed; this suggested that the membranes could be used effectively to break the azeotropic point of the water–IPA mixture, so as to remove a small amount of water from IPA. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis,characterization, and pervaporation properties of segmented poly(urethane‐urea)s

Poly(urethane‐urea)s (PUUs) from 2,4‐tolylene diisocyanate (2,4‐TDI), poly(oxytetramethylene)diols (PTMO) or poly(butylene adipate)diol (PBA), and various diamines were synthesized and characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, and density measurements. Transport properties of the dense PUU‐based membranes were investigated in the pervaporation of benzene–cyclohexane mixtures. It was shown that the pervaporation characteristics of the prepared membranes depend on the structure and length of the PUU segments. The PBA‐based PUUs exhibit good pervaporation performance along with a very good durability in separation of the azeotropic benzene–cyclohexane mixture. They are characterized by the flux value of 25.5 (kg μm m⁻² h⁻¹) and the separation factor of 5.8 at 25°C, which is a reasonable compromise between the both transport parameters. The PTMO‐based PUUs display high permeation flux and low selectivity in separation of the benzene‐rich mixtures. At the feed composition of 5% benzene in cyclohexane, their selectivity and flux are in the range of 3.2 to 11.7 and 0.4 to 40.3, respectively, depending on the length of the hard and soft segments. The chemical constitution of the hard segments resulting from the chain extender used does not affect the selectivity of the PUU membranes. It enables, however, the permeability of the membranes to be tailored. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1615–1625, 1999     

Charged membranes prepared by SPEEK of very low degree of sulfonation

Novel charged membranes were prepared with sulfonated poly(ether ether ketone) (SPEEK). Methylsulfonic acid was used as solvent to accommodate the very low degree of sulfonation of the SPEEK. Membranes were prepared by immersion phase inversion method, using coagulation baths of different composition and temperature. Low molecular weight and negatively charged dye molecules were used as model solutes to test the nanofiltration (NF) performance of the membranes. Higher than 93% rejection of the two dye molecules, Rose Bengal and Reactive Brilliant Red, was observed at normal operating temperature. A permeate flux as high as 497 L m^?2 h^?1 and higher than 90% of solute rejection at 80°C was achieved in the NF of Reactive Brilliant Red aqueous solution, in contrast to a flux of 226 L m^?2 h^?1 and about 78% of solute rejection at the same temperature in the case of Rose Bengal solute. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A polyvinyl alcohol-based mixed matrix membrane with uniformly distributed Schiff base network-1 for ethanol dehydration

In this study, Schiff base network (SNW)-1 nanoparticles with high hydrophilicity and large specific surface area were used to prepare polyvinyl alcohol (PVA)-based mixed matrix membranes (MMMs), which were evaluated for ethanol dehydration. Because of the low difference of density between SNW-1 and PVA, the as-prepared nanoparticles can be uniformly distributed into the PVA active layer. The effects of SNW-1 loading, feed temperature, and water concentration on pervaporation (PV) performance were further studied. The results showed the MMM with 10 wt% of SNW-1 loading exhibited a separation factor of 1,501 and a permeation flux of 187 g m⁻² h⁻¹ for feeding 95 wt% ethanol/water binary solution at 75°C. Overall, the SNW-1/PVA MMMs showed great prospect in ethanol dehydration via PV.     

Synthesis and characterization of sulfonated poly(phthalazinone ether sulfone ketone) for ultrafiltration and nanofiltration membranes

Modification of poly(phthalazinone ether sulfone ketone) (PPESK) by sulfonation with concentrated or fuming sulfuric acid as sulfonation agents was carried out to prepare membrane materials with increased hydrophilicity and potentially increased fouling resistance. Sulfonated PPESK (SPPESK) copolymers, with a degree of sulfonation ranging from 10–300%, were prepared and characterized. Factors affecting the sulfonation reaction were studied, and reaction conditions for the preparation of SPPESK with different degrees of sulfonation were determined. Compared with the properties of PPESK, the hydrophilicity of SPPESK was increased, as shown by a reduced contact angle with water. The glass transition temperature was increased from 278°C (PPESK) to a maximum of 323°C for the highly sulfonated derivative, due to the strong polarity of  SO₃H and hydrogen bonding. Ultrafiltration membranes prepared with PPESK and SPPESK were compared. For a SPPESK asymmetric membrane, the PEG12000 rejection was 98% and the water flux was 876 kg · m⁻² · h⁻¹. SPPESK/PPESK composite nanofiltration membranes were also prepared and were shown to have short‐term operational stability up to 120°C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1685–1692, 2001     

Cellulose triacetate/LUDOX-SiO2 nanocomposite for synthesis of pervaporation desalination membranes

A series of cellulose triacetate/Ludox-silica nancomposite pervaporation membranes was successfully prepared via solution casting, aiming to improve the performance of cellulose triacetate membranes for desalination. The fabricated nanocomposite membranes were characterized to study the membrane morphology, chemical composition, mechanical properties, and surface hydrophilicity. Furthermore, the desalination performance was investigated as a function of silica (SiO₂) loading (ranging from 1 to 4 wt%) and feed concentration at 30 and 60 g/L of sodium chloride (NaCl). Pervaporation experiments showed that incorporating 4 wt% SiO₂ into a cellulose triacetate (CTA) membrane increased the water flux by a factor 2.5 compared with pristine CTA (from 2.2 to 6.1 kg m⁻² h⁻¹) for a 30 g/L NaCl feed solution at 70°C, while the salt rejection remained above 99%. The CTA/4 wt% SiO₂ membrane was found to have only 21% flux reduction when tested with a 60 g/L NaCl feed solution, without changes in membrane selectivity. This suggests that the developed CTA/Ludox-SiO₂ nanocomposite pervaporation membrane is suitable for desalination.     

Fabrication and characterization of silane-functionalized Na-bentonite polysulfone/polyethylenimine nanocomposite membranes for dye removal

In this study, tetraethoxysilane (TEOS)-functionalized Na-bentonite incorporated into polysulfone/polyethylenimine (PSF/PEI) membranes were fabricated by phase inversion method for the efficient removal of methylene blue dye. For the preparation of PSF/PEI nanocomposite membranes, silane-functionalized Na-bentonite and pure Na-bentonite were used at three different concentrations (0.5, 1, and 2 wt%). The prepared membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, porosity, hydrophilicity, and water permeability measurements. Antifouling behaviors and methylene blue dye rejections of the PSF/PEI nanocomposite membranes were also tested. The obtained results showed that the addition of pure Na-bentonite and silane-functionalized Na-bentonite both increased the water permeability of the membranes. The PSF/PEI membrane containing 2 wt% silane-functionalized Na-bentonite showed the highest water flux of 105 L m⁻² h⁻¹, while the lowest water flux of 1.2 L m⁻² h⁻¹ was recorded for pure PSF membrane. Filtration results demonstrated that the antifouling capacity was significantly increased due to the negatively charged surface of the newly generated silane-functionalized Na-bentonite PSF/PEI membranes. In summary, TEOS-functionalized Na-bentonite can be used to fabricate PSF/PEI nanocomposite membranes with effective filtration ability, antifouling capacity with lower decay ratio, higher flux recovery ratio, and 99% methylene blue dye removal performance.     

Production of calcium hexaluminate porous planar membranes with high morphological stability and low thermal conductivity

High-quality Al₂O₃ porous ceramic planar membranes suffer from severe deformation and cracking, which occur during sintering process. This study reports on solving this problem, by introducing calcium hydroxide powder in the alumina slurry. Phase-inversion tape-casting technology, applied during molding, and sintering at 1550 °C, favored an in-situ expansion reaction, which effectively suppressed deformation, and well-formed and crack-free calcium hexaluminate porous planar membranes were obtained. The produced membranes had a low thermal conductivity (0.69 W·m⁻¹ K⁻¹ at 85 °C), ascribed to the in-situ formed plate-like structure of calcium hexaluminate (CA₆) and to the high porosity. After hydrophobic modification, the membranes were applied in membrane distillation processing. High rejection rate (>99.9%) and water flux (19.8 L·m^-2 h⁻¹) were achieved at 85 °C, using a 4 wt% NaCl solution as a feed solution.     

Synthesis and characterization of PES/PSF/PEG by immersion precipitation for Mediterranean seawater desalination by FO membrane

In the present study, a simple, inexpensive, nontoxic, and environmentally friendly polyethylene glycol (PEG) polymer was used to enhance the hydrophilicity of the forward osmosis (FO) membrane using various PEG concentrations as a pore forming agent in the casting solution of polyethersulfone/polysulfone (PES/PSF) blend membranes. A nonwoven PES/PSF FO blend membrane was fabricated via the immersion precipitation phase inversion technique. The membrane dope solution was cast on polyethylene terephthalate (PET) nonwoven fabric. The results revealed that PEG is a pore forming agent and that adding PEG promotes membrane hydrophilicity. The membrane with 1 wt% PEG (PEG1) had about 27% lower contact angle than the pristine blend membrane. The PEG1 membrane has less tortuosity (which reduces from 3.4–2.73), resulting in a smaller structure parameter (S value) of 277 μm, due to the presence of open pores on the bottom surface structure, which results in diminished ICP. Using 1 M NaCl as the draw solution and distilled water as the feed solution, the PEG1 membrane exhibited higher water flux (136 L m⁻² h⁻¹) and lower reverse salt flux (1.94 g m⁻² h⁻¹). Also, the selectivity of the membrane, specific reverse salt flux, (J_s/J_w) showed lower values (0.014 g/L). Actually, the PEG1 membrane has a 34.6% higher water flux than the commercial nonwoven-cellulose triacetate (NW-CTA) membrane. By means of varied concentrations of NaCl salt solution (0.6, 1, 1.5, and 2 M), the membrane with 1 wt% PEG showed improved FO separation performance with permeate water fluxes of 108, 136, 142, and 163 L m⁻² h⁻¹. In this work, we extend a promising gate for designing fast water flux PES/PSF/PEG FO blend membranes for water desalination.