Commercial Polyethersulfone Research Articles

Effect of Water and Organic Pollutant in CO2/CH4 Separation Using Hydrophilic and Hydrophobic Composite Membranes.

Membrane technology is a simple and energy-conservative separation option that is considered to be a green alternative for CO2 capture processes. However, commercially available membranes still face challenges regarding water and chemical resistance. In this study, the effect of water and organic contaminants in the feed stream on the CO2/CH4 separation performance is evaluated as a function of the hydrophilic and permselective features of the top layer of the membrane. The membranes were a commercial hydrophobic membrane with a polydimethylsiloxane (PDMS) top layer (Sulzer Chemtech) and a hydrophilic flat composite membrane with a hydrophilic [emim][ac] ionic liquid–chitosan (IL–CS) thin layer on a commercial polyethersulfone (PES) support developed in our laboratory. Both membranes were immersed in NaOH 1M solutions and washed thoroughly before characterization. The CO2 permeance was similar for both NaOH-treated membranes in the whole range of feed concentration (up to 250 GPU). The presence of water vapor and organic impurities of the feed gas largely affects the gas permeance through the hydrophobic PDMS membrane, while the behavior of the hydrophilic IL–CS/PES membranes is scarcely affected. The effects of the interaction of the contaminants in the membrane selective layer are being further evaluated.

Evaluation of a quaternized polyethersulfone membrane enhanced with amine functionalized carbon nanotubes for forward osmosis application

Multiwall carbon nanotubes (CNTs) were quaternized with trimethylamine to form an anionic conductive CNTS (QCNTs) then blended with quaternized polyethersulfone membrane (QPES) by phase invasion method to obtain a composite membrane with higher permeation, improved rejection and enhanced antifouling properties for forward osmosis application. The membranes and QCNTs were characterized using SEM, TGA, NMR, Raman and FTIR. The fabricated composite membranes showed that addition of QCNTs can improve membrane basic properties when compared to commercial polyethersulfone membranes. This observed improvement could be attributed to the incorporated oxygen and amine functionalities in the CNTs. The 0.1 wt % QCNTs showed a contact angle of 64, reverse solute flux of 7.4 and 6.2 Lm-2h-1 for NaCl and MgSO4 respectively compared to an original pure water flux of 8.058 Lm-2h-1. Humic acid was used as a foulant, when the composited was fouled using humic acid, the 0.1wt.% QCNTs showed a reverse solute flux of 5.7 and 5.0 Lm-2h-1 respectively at room temperature.

Effect of Surface Modification with Electrospun Nanofibers on the Performance of an Ultrafiltration Membrane

Electrospinning of nanofibrous mats to create new membranes has been widely investigated, however surface modification of commercial membranes by electrospinning of nanofiber layer has received limited attention. In this work, the surface of a commercial polyethersulfone (PES) ultrafiltration membrane was coated with electrospun polyvinylidene fluoride (PVDF) hydrophobic nanofibers (NFs) for different time periods, i.e., 25 min, 125 min, and 250 min., and the effect of coating on the filtration performance was investigated. The membranes were characterized by scanning electron microscopy (SEM), contact angle measurement and further subjected to pure water permeation experiments, as well as the filtration of Ottawa River Water (ORW) and various protein solutes. By a thorough statistical analysis, it was concluded that the coating with the electrospun nanofiber layer enhanced the pure water permeation (PWP) flux. However, the fouling of the composite nanofiber/PES membranes was more severe due to the compaction of the soft nanofiber layer and the entrapment of foulants in the spaces between nanofibers. The nanofiber mat did not impact the separation of protein solutes as the composite and base PES membranes had the same protein removals.

Improved Performance of Ultrafiltration Membranes after Surface Modification

Commercial polyethersulfone (PES) membrane was modified and evaluated for the removal of metal ions from an aqueous solution. Modifications were carried out by a radical polymerization technique, using acrylic acid as monomer. The grafting polymerization on the membrane was developed in an aqueous medium at 60°C. Two molar initiator/monomer (3 and 7%) ratios were used to study PES-grafted-polyaceylic acid membranes. Both unmodified and modified membranes were analyzed by attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) in order to look into their morphologies. In addition, contact angle measurements were used for membrane hydrophilicity. The ATR-FTIR spectra, SEM and AFM images confirmed that the modification on the PES membrane surface was carried out by grafting polymer of acrylic acid monomers. The results obtained show that acrylic acid may be used for the preparation of a selective membrane functionalized with carboxylic groups. Water permeability was evaluated by varying the feed pressures (4–10 bars). The flux water of unmodified membrane decreased from 10 to 6 L/h m2 bar for modified membranes. The rejections of sodium chloride, copper chloride, and aluminum chloride were also studied for each sample. Among the metal ions tested, thevmaximum removal was reported for aluminium for grafted membrane at 7% ratio. The rejection values for grafted membranes (3 and 7%) were higher than those obtained for unmodified membranes and increased with the grafting rate.

Membrane Bioreactor-Treated Domestic Wastewater for Sustainable Reuse in the Lake Victoria Region.

Lake Victoria is a shared water resource between Kenya, Uganda, and Tanzania, which is the second largest freshwater lake in the world. It has long since suffered from the consequences of overexploitation of its resources, mainly fish stocks, and increasingly high pollution. The closure of 58% of the fish processing plants (FPPs) is attributed to the declining fish stocks due to overfishing and pollution in particular. The installation and operation of a pilot membrane bioreactor (MBR) in Kisumu, Kenya, adopts an integrated approach by providing an integral, sustainable, cost-effective, and robust solution for water sanitation, which also meets the demand for clean water in the fish processing industry, aquaculture, and irrigation. The innovative system comprises a pilot MBR coupled with a recirculation aquaculture system (RAS). The RAS is able to recirculate 90% to 95% of its water volume; only the water loss through evaporation and drum filter back flushing has to be replaced. To compensate for this water deficit, the MBR treats domestic wastewater for further reuse. Additionally, excess purified water is used for irrigating a variety of local vegetables and could also be used in FPPs. The pilot-scale MBR plant with around 6 m2 submerged commercial polyethersulfone (PES) membranes provides treated water in basic agreement with Food and Agriculture Organization (FAO) standards for irrigation and aquaculture, showing no adverse effects on tilapia fingerlings production. A novel membrane module with a low-fouling coating is operating stably but has not yet shown improved performance compared to the commercial one. Integr Environ Assess Manag 2020;16:942-954. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Mesoporous silica filled smart super oleophilic fibers of triblock copolymer nanocomposites for oil absorption applications

Super oleophilic fibers of styrene-isoprene-styrene (SIS) block copolymer/mesoporous silica (MS) nanocomposites are fabricated by electrospinning, and their oil absorption efficiency is monitored by following two different approaches. The first way is by using the fibers as tubular packing materials for oil absorption, whereas the second approach uses the fibers as filtration membrane after deposition on the commercial polyethersulfone (PES) support. All composites are made by adding inorganic MS in different concentrations (2, 4, and 7 wt.%) to SIS block copolymer. The addition of MS increases the fiber diameters and leads to enlarged and bead-like appearances, especially at higher filler concentrations. The oil absorption efficiency is explored based on the oil absorption capacity of the samples as well as with the gravity-driven oil filtration experiments. The best oil absorption efficiency is achieved by the 4 wt.% SIS-MS composite (150% higher oil absorption capacity compared to the neat SIS), and it is used to spin on the PES mechanical support of different pore sizes (0.2 μ and 8 μ). Ultrafiltration tests conducted on those coated membranes observe improved oil rejection performance as the fibrous SIS-MS are layered on the commercial mechanical support.

Photoactive polymer membranes for degradation of pharmaceuticals from water

Two different photosensitizer molecules were immobilized on a commercial polyethersulfone membrane by electron beam-mediated grafting. The resulting membrane surface generates singlet oxygen upon activation with light according to the photosensitizer‘s excitation wavelength. Thus, the immobilization procedure results in highly active membrane surfaces. The degradation of different pharmaceuticals (propranolol and ranitidine) by the photoactive membranes was investigated. The activity (singlet oxygen generation rate) and degradation efficiency regarding the two pharmaceuticals was studied next to membrane characteristics (scanning electron microscopy, permeance, contact angle, X-ray photoelectron spectroscopy). The immobilization led to increased surface hydrophilicity and permeance while preserving pore size and morphology. Both photosensitizer membrane systems showed high singlet oxygen generation activity. It was found that propranolol and ranitidine were efficiently converted by singlet oxygen to transformation products, but they were not completely mineralized as monitored by total organic carbon analysis and chromatography.

Zwitterion-Modified Ultrafiltration Membranes for Permian Basin Produced Water Pretreatment

Unconventional oil and gas extraction generates large quantities of produced water (PW). Due to strict environmental regulations, it is important to recover and reuse PW. In this study, commercial polyethersulfone (PES) ultrafiltration (UF) membranes were surface-modified with zwitterionic polymer 3-(3,4-Dihydroxyphenyl)-l-alanine (l-DOPA) solution to alleviate membrane fouling during the ultrafiltration of shale oil PW of the Permian Basin. UF membranes were coated in l-DOPA solution by using a dip coating technique. Membrane characterization tests confirmed successful l-DOPA coating on UF membranes. While performing the experiments, permeate flux behaviors of the uncoated and coated membranes and antifouling resistance of the zwitterionic coating were evaluated. Among the coated UF membranes with varying coating times from one day to three days, the three-day coated UF membrane showed a good flux performance and the highest fouling resistance. The flux reduced by 38.4% for the uncoated membrane, while the reduction was 16% for the three-day coated membrane after the 5 h ultrafiltration of PW. Both improvements of the flux performance and recovery ratio are attributed to a negatively-charged surface developed on the membranes after the zwitterionic coating. The UF pretreatment also improved the flux behavior of the later forward osmosis (FO) process for PW treatment.

Interlaminar Toughening of Epoxy Carbon Fiber Reinforced Laminates: Soluble Versus Non-Soluble Veils.

This work describes the evaluation of different interlaminar veils to improve the toughening of epoxy/carbon fiber composites manufactured by resin infusion. Three commercial veils have been used in the study: two electro spun thermoplastic nanofiber (Xantulayr® from Revolution Fibres) with different areal weight, and one micro carbon fibers veil (Optiveil® from TFP). Two laboratory made veils were also manufactured by electrospinning commercial polyethersulfone (PES) tougheners (Virantage by Solvay). The veils were selected to be either soluble or non-soluble in the epoxy resin matrix during curing. The solubility was analyzed by scanning electron microscopy and dynamic mechanical analysis testing on the cured laminates. The fracture energy was evaluated by double cantilever bending (DCB) testing under Mode I loading. The insoluble thermoplastic nanofibers showed the highest toughening efficiency, followed by the soluble nanofiber veils. The carbon fiber based veil showed no toughness improvement.

Heat-treated optimized polysulfone electrospun nanofibrous membranes for high performance wastewater microfiltration

The structure and morphology of self-sustained electrospun nanofibrous membranes (ENMs) are key factors determining membrane performance for filtration applications. In this study, heat post-treatment (HPT) method was applied to modify the structural and morphological properties of polysulfone (PSU) ENMs, to improve their filtration performance and to obtain membranes suitable for wastewater treatment. The influence of the HPT temperature and time on the morphological structure of the PSU ENMs as well as on fouling and filtration performance was investigated. Microfiltration (MF) tests were conducted using humic acid model solutions with a concentration of 15 mg/L at pH 11. Increasing the HPT temperature or time, led to an increase of the mean nanofiber diameter along with a decrease of the mean size of the inter-fiber space, the void volume fraction and the water contact angle of the membranes. ENMs treated with a higher HPT temperature and a longer time exhibited higher nanofibers interconnectivity and a more compact structure with a smaller size of inter-fiber spaces. Under the same MF operating conditions, a commercial polyethersulfone (PES) MF membrane (HPWP, Millipore) had lower filtration performance (i.e. lower performance index, PI, 82 kg/m2 h) than the treated-optimized PSU ENMs (i.e. 147 and 133 kg/m2 h for ENMs 9 and 10, respectively). The obtained results confirm the good performance of the developed PSU ENMs for MF applications.

Triple-Layer Nanofiber Membranes for Treating High Salinity Brines Using Direct Contact Membrane Distillation.

A composite, three-layered membrane for membrane distillation was prepared from electrospun polyvinylidene fluoride (PVDF) nanofibers supported by commercial polyethersulfone (PES) nanofiber based nonwoven from E.I. duPont de Nemours company (DuPont). The membranes were tested in direct contact membrane distillation (DCMD) using a 5.0 M sodium chloride brine as a feed solution. The triple layer membrane combines the hydrophobicity of PVDF and the robustness of the PES. The triple layer membrane demonstrated excellent performance in DCMD (i.e., relatively high water flux compared to the commercial PVDF membrane and a complete salt rejection of the brine) with mechanical properties imparted by the PES layer. This work is the first to demonstrate the use of a commercially produced nanofiber nonwoven for membrane distillation.

Vanillin as an Antifouling and Hydrophilicity Promoter Agent in Surface Modification of Polyethersulfone Membrane.

Fouling as an intricate process is considered as the main obstacle in membrane technologies, and its control is one of the main areas of attention in membrane processes. In this study, a commercial polyethersulfone ultrafiltration membrane (MWCO: 4000 g/mol) was surface modified with different concentrations of vanillin as an antifouling and hydrophilicity promoter to improve its performance. The presence of vanillin and its increasing adsorption potential trends in higher vanillin concentrations were clearly confirmed by observable changes in FTIR (Fourier transform infrared) spectra after modification. Membranes with better hydrophilicity (almost 30% lower contact angle in the best case) and higher polyethylene glycol solution (PEG) permeability were achieved after modification, where a 35–38% increase in permeability of aqueous solution of PEG was perceived when the membrane was modified at the highest exposure concentration of vanillin (2.8 g/L). After filtration of wood extract, surface modified membrane (2.8 g/L vanillin) showed better antifouling characteristics compared to unmodified membrane, as indicated by approximately 22% lower pure water flux reduction, which in turn improved the separation of lignin from the other organic compounds present in wood extract.

Performance of Ultrafiltration–Ozone Combined System for Produced Water Treatment

Oil exploration waste, also called produced water, contains hazardous pollutants, such as benzene; benzene, toluene, and xylene (BTX); naphthalene, phenanthrene, and dibenzothiophene (NDP); polyaromatic hydrocarbons (PAHs); and phenol. Produced water is characterized by high chemical oxygen demand (COD) and oil content, which exceed the standard limits of regulation. In this study, the combination of ultrafiltration (UF) and ozone pre-treatment and post-treatment were applied for treatment of produced water to minimize its environmental impact. Produced water and membrane were characterized, and their ultrafiltration performance for removal of oil content, benzene, toluene, xylene, and COD. Two commercial Polyethersulfone membranes, with molecular-weight cut-off values of 10 and 20 kDa, were used. The membrane flux profile illustrated that ozone pre-treatment had higher normalized flux than UF only. Separation performance was evaluated based on flux profile and removal of COD, oil and grease content, toluene, and xylene. Significant finding was found where the combination of UF with ozone pre-treatment and post-treatment could significantly eliminate COD, oil content, toluene, and xylene. The rejection of these components was found higher than conventional process, which was in the range of 80 % to 99 %. In addition, almost oil and grease can be removed by using this combined system. Permeate quality of this system confirmed the acceptable level as water discharge.

Biopolymer extracted from Moringa oleifera Lam. in conjunction with graphene oxide to modify membrane surfaces

ABSTRACT A novel modification through pressurized filtration technique of commercial polyethersulfone membranes was proposed using a biopolymer extracted from Moringa oleifera Lam. (MO) along with graphene oxide (GO), in order to decrease fouling and improve the membrane selectivity for the removal of methylene blue dye. The effect of these agents over the morphology and performance of the membranes were studied through the evaluation of permeability, dye removal and fouling parameters. The characterization of the membrane indicates a significant decrease in pore size, as confirmed by the filtration experiments. Also, according to FTIR and SEM analysis the modification was effectively accomplished. All modified membranes presented low fouling rates (<10.55%) and high dye removal rates (from 2.85% to 96.73%). Furthermore, it is the first time that MO has been used as a natural polymer to improve and confer new characteristics on membranes, creating new possibilities for further study of this promising environment-friendly biopolymer in membrane separation processes.

2D kaolin ultrafiltration membrane with ultrahigh flux for water purification

Membrane separation technology is an important option for the treatment of contaminated surface waters but the relatively high cost of materials and membrane fabrication represent a significant obstacle to the wider use of membrane processes. In this study, we describe the development and testing of a new kind of membrane made from two-dimensional (2D) kaolin nanosheets. The fabrication involved a layer-by-layer stacking of the nanosheets with a cationic polyacrylamide cross-linking agent, assembled on a cellulose acetate supporting layer. The kaolin membrane exhibited an ultrahigh flux (∼4000 L.m-2.h−1.bar−1) which was almost ten times greater than that of a commercial polyether sulfone (PES) ultrafiltration (UF) membrane. The membrane was tested using a range of influent water types, including samples of a lake water, river water and three natural organic matter solutions. The results showed that the kaolin membrane was stable and behaved as an UF membrane, in terms of its pore size distribution (peak distribution at 20–35 nm) and comparable treatment performance to the PES UF membrane. The kaolin membrane showed a substantially reduced rate of fouling, compared to PES membrane, despite a much greater flux, which was partly attributed to its highly hydrophilic nature. The advantages of lower cost, much higher flux and lower fouling propensity make the 2D-kaolin membrane a potentially important development in UF membrane technology for drinking water treatment, and possibly other applications.

UV-assisted surface modification of polyethersulfone (PES) membrane using TiO 2 nanoparticles

In this research commercial polyethersulfone (PES) membrane was modified using TiO2 nanoparticles (P-25 Degussa) and further irradiated using UV light to overcome the hydrophobicity and fouling nature of the membrane. Further the membranes were characterized using SEM and FTIR. Contact angle measurements study confirmed the hydrophilic tendency of the modified membrane by decreasing the contact angle from 73 degree to 20.28 degree. The modified membranes showed higher flux and better anti-fouling properties as compared to the unmodified counterparts. The optimum conditions were found to be 0.5 wt% TiO2 loading with 60 min membrane immersion and 10 min UV light illumination. The effect of different pH conditions of feed was analysed. Real wastewater filtration experiments also indicated better performance of modified membranes as opposed to neat PES membranes.

Cationically modified membranes using covalent layer-by-layer assembly for antiviral applications in drinking water

In this work, a new approach towards virus reduction is taken, where modified membranes with large pore sizes (>450 nm) can reach high log10-unit virus reductions. Polyelectrolyte coatings were used to modify microfiltration (MF) membranes to impart antiviral properties. A stable covalent layer-by-layer (LBL) approach was used to create multilayers from a single polyelectrolyte, polyethyleneimine (PEI). Here terephthalaldehyde (TA) crosslinking was used to create crosslinked multilayers, both on model surfaces and on commercial polyether sulfone, (PES) MF membranes. The substrates were further coated with antiviral silver, and copper nanoparticles (Ag and CuNPs) stabilised with PEI. The specific fabrication during the LBL assembly was stepwise characterised using multi-surface analysis including Fourier transform infrared spectroscopy (FTIR), Atomic Force Microscope (AFM), ellipsometry, zeta potential and contact angle measurements. Model surfaces demonstrated a 4 log10-units reduction of MS2 viral titre, independent of the crosslinked PEI layer thickness. The crosslinked PEI and Ag/CuNPs-modified membranes efficiently reduced 4.5–5 log10-units of infectious MS2 bacteriophages by both adsorption and inactivation of viral particles. This was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR), which showed a stable performance over time. Pure water flux measurements on modified-membranes showed good long-term stability. Thus, 5000 L/m2 of virus-free water was produced in approximately 2 h, using gravity-based filtration. Furthermore, there was no observable leaching of nanoparticles from the membranes during filtration.

Virus reduction through microfiltration membranes modified with a cationic polymer for drinking water applications

Virus penetration is a significant problem in water treatment membrane filtration. To effectively remove waterborne viruses nano-filtration, reverse osmosis or ultrafiltration must be used, all of which are high energy filtration schemes. Novel approaches and technologies for the production of virus-free drinking water are therefore warranted. In this study, we modified model surfaces and commercial polyether sulfone, (PES) microfiltration (MF) membranes to achieve a substantial virus reduction under gravity based filtration membranes. The successful modification using the cationic polymer polyethyleneimine (PEI) was confirmed by Fourier transform infrared spectroscopy (FTIR) and zeta potential measurements. MS2 bacteriophages, a surrogate for human pathogenic waterborne viruses like norovirus were used to challenge the modified surfaces. The membrane modification resulted in ∼22% loss of the membrane permeability while an increase of ≥3 log10-units (≥99.9%) in MS2 reduction was observed. These reductions were comparable to the reduction of PEI-coated model surfaces tested for contact reduction. This simple modification of a commercially available MF membrane led to substantial viral reductions with a significant flux of 5000 L/m2 in approximately 2.5 h. This work therefore, highlights the potential modified MF membranes for gravity-based filtrations to produce safe drinking water. Further studies should be done to show similarly enhanced reductions of human pathogenic viruses.

Forward osmosis membranes modified with laminar MoS2 nanosheet to improve desalination performance and antifouling properties

Internal concentration polarization (ICP) and membrane fouling are factors limiting the performance of forward osmosis (FO) membranes. Aiming at alleviating these problems, this study demonstrated the fabrication of FO membrane incorporated with MoS2 by layer-by-layer assembly with the synergistic effects of surface hydrophilicity, porosity and fouling-release properties. The grafting of MoS2 on the membrane surface was confirmed through the SEM, EDS and AFM analysis. The results demonstrated that the MoS2-coated-FO membrane could achieve transmembrane water flux of 27.15 LMH which was 35.34% higher than that obtained from a commercial polyethersulfone (PES) FO membrane. The reverse flux of NaCl ions was 16.42 gMH for the MoS2-coated-FO, 35.91% less than blank FO membrane. Meanwhile, coating MoS2 nanosheets endowed the resultant composites with higher water flux and lower reverse solute diffusion. In addition, the results of dynamic operation in a cross-flow test cell demonstrated that MoS2-coated-FO membrane exhibited good antifouling and fouling-release properties. This study indicates that use of MoS2 nanosheet is an attractive and feasible approach for the development of a dual-functional FO membrane by simultaneously improving the antifouling performance and reducing the ICP issues.

Potential of Advanced Nano‐structured Membranes for Landfill Leachate Treatment: A Review

AbstractRapid expansion of the world population has brought about serious water shortage problems in many countries around the world, especially developing countries. Treatment of leachate produced by landfilling municipal waste has recently been the focus of attention by both researchers and governments. This work therefore has been dedicated to comprehensively review all membrane separation techniques applied in leachate treatment and to introduce innovative modification of membranes in commercial applications. As reported in the literature, ultrafiltration membranes are the most common membranes that are made by commercial polyethersulfone, polysulfone, and poly (vinylidene fluoride) in full and pilot scale of MBR process. However, membrane fouling is an important drawback in the membrane processes. Towards this end, most emphasis has been given to the membrane modification by commercial membrane‐forming polymers as a cost‐effective technique of tailoring membranes for large‐scale industrial applications and to increase hydrophilicity and fouling‐resistant properties.