Investigation of water and salt flux performances of polyamide coated tubular electrospun nanofiber membrane under pressure (original) (raw)
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Drinking Water Engineering and Science
The forward osmosis (FO) process has been considered to be a viable option for water desalination in comparison to the traditional processes like reverse osmosis, regarding energy consumption and economical operation. In this work, a polyacrylonitrile (PAN) nanofiber support layer was prepared using the electrospinning process as a modern method. Then, an interfacial polymerization reaction between m-phenylenediamine (MPD) and trimesoyl chloride (TMC) was carried out to generate a polyamide selective thin-film composite (TFC) membrane on the support layer. The TFC membrane was tested in FO mode (feed solution facing the active layer) using the standard methodology and compared to a commercially available cellulose triacetate membrane (CTA). The synthesized membrane showed a high performance in terms of water flux (16 Lm −2 h −1) but traded the salt rejection (4 gm −2 h −1) compared with the commercial CTA membrane (water flux = 13 Lm −2 h −1 and salt rejection = 3 gm −2 h −1) at no applied pressure and room temperature. Scanning electron microscopy (SEM), contact angle, mechanical properties, porosity, and performance characterizations were conducted to examine the membrane.
Assessment and optimization of electrospun nanofiber-membranes in a membrane bioreactor (MBR)
The feasibility and optimization of low-cost nanofiber-membranes as potential MBR-membranes is studied. The nanofiber-membranes have a unique surface architecture, a high surface porosity and permeability and adjustable pore sizes. The materials, their heat treatment as well as the diameters and area-weights of nanofiber sheets were optimized. The comparative performance of a nanofibermembrane to lab-made polysulfone (PSF L ) and commercial polyvinylidene fluoride (PVDF T ) and polyethylene (PE K ) membranes was performed. The critical flux (CF) and trans membrane pressure (TMP) profiles were used as evaluation parameters. A heat treatment was efficient to prevent layered fouling on the nanofiber-sheets. The electrospun nanofiber-membranes showed performances comparable to those of the tested commercial membranes at short and long term. Further developments on nanofibermembranes are still required to further improve their performance and enhance their competitiveness in MBRs applications.
2013
Engineered osmosis (EO) is a state-of-the-art technology which harnesses the natural phenomenon of osmosis to address global issues related to water and energy. In this process, an osmotic pressure drives water across a semi-permeable membrane from a dilute feed solution to a concentrated draw solution. EO has the potential to sustainably produce fresh water at low energy cost, generate electricity and recover high-value dissolved solids. However, EO has not progressed beyond conceptualization and lab scale studies due to obstacles in membrane design, draw solution recovery, system integration, scale-up, and definitive process economics. This study focuses on addressing the primary obstacle to EO development: the lack of adequately designed membrane. Departing from traditional design of polyamide composite membrane, this dissertation presents one of the first known studies in which a novel thin-film composite/nanocomposite membrane supported on an effective nanofibrous structure was tailored for EO applications. With the integration of nanotechnology and membrane science, this membrane design shows immense promise as a next generation membrane platform for EO. Furthermore, this work shed insight on the critical structureperformance relationships with respect to mass transfer models for further advancing membrane design and EO development. It will eventually lead to widespread adoption of this emerging technology platform in sustainable waterenergy production and life sciences.
A low-pressure filtration unit incorporated with polymeric electrospun polyvinyl chloride (PVC) fiber membranes was designed and fabricated for the treatment of waste water in order to improve its quality. This custom-made pressure filter was designed according to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC). A scanning electron microscope (SEM) was used to characterize the electrospun membranes. In order to increase the hydrophilicity and filtration rates of PVC membranes, a lower dosage of poly (ethylene oxide) was added to the PVC solution prior to the electrospinning process. The filter was found to be well suited for the reduction of larger suspended solids, turbidity, and odor. It was demonstrated that this type of filtration membrane could be manufactured at a lower cost and not require electricity or any other external power source to achieve high flow rates. This technology could even be used to enhance the quality of tap water in many places, such as Africa. Another application could be a pre-filtration of reverse osmosis (RO) or other ultrafine filtration systems, to increase the life of the primary filter while decreasing fouling and maintenance.
Thin Film Composite Membranes for Forward Osmosis Supported by Commercial Nanofiber Nonwovens
Industrial & Engineering Chemistry Research, 2017
Nanofiber supported thin film composite (TFC) for forward osmosis (FO) have shown great promise as a viable FO membrane in comparison to commercially available forward osmosis membranes. In numerous studies on the subject, nanofiber supports for TFC membranes are commonly made by electrospinning. In this study, we have chosen a different nanofiber medium to use as a support for a FO TFC membrane. This nonwoven, which is a commercially available, nanofiber mats from E.I. duPont de Nemours company (DuPont). This unique nanofiber based nonwoven is produced as long rolls and is unsupported, unlike other nanofiber products that are produced on top a typical spunbond or wetlaid nonwoven due to the lack of mechanical integrity. The DuPont PES materials demonstrated better strength than typical electrospun materials and was used to support a polyamide selective layer formed by in-situ interfacial polymerization. The Dupont PES TFC membrane was tested in FO and found to generate twice the water flux and one-tenth the reverse solute flux compared to a commercial TFC FO membrane. The membrane was also found to match performance of laboratory based electrospun nanofiber supported TFC, but exhibited better selectivity and strength.
Journal of Membrane Science, 2016
Nanofibers fabricated with electrospinning method have several prominent properties such as high specific surface area, high porosity and uniform pore size distribution in nanoscale or microscale. These unique features are vital for separation processes in water and wastewater treatment applications. In this study, we have developed a new type of nanofiber electrospun membrane for the first time by collecting nanofibers on a hollow braided rope. The nanofiber membranes were characterized with Scanning Electron Microscope images, pore size, contact angle and porosity measurements. Filtration performances of tubular nanofiber and a commercial hollow braided reinforced membrane were determined for both standard particle solutions and surface water under low vacuum pressures. The novel tubular nanofiber (TuEN) membranes exhibited high water fluxes in even low vacuum pressures, relatively high removal efficiencies of turbidity (% 95), total organic carbon (29 %) and UV 254 (45%) compared to other microfiltration membranes. We claim that the tubular nanofiber membrane will attract more attention in coming years in the fields of water and wastewater treatment.
Desalination, 2018
This work investigated the influence of a new polymeric blend of polysulfone/polyacrylonitrile (PSf/PAN) nanofibers prepared via the electrospinning process as substrate to produce thin film composite forward osmosis (TFC-FO) membrane. The solvents in the electrospinning process were optimized. A polyamide (PA) thin layer was successfully fabricated on the electrospun nanofibrous substrate via interfacial polymerization. The performance of the nanofiber-based thin film composite (NTFC) membranes was compared with the in-house-made (PSf/PAN) TFC membrane, in which its substrate was fabricated by phase inversion. The NTFC membrane demonstrated significant improvement in hydrophilicity and water permeability, and the reverse salt flux (RSF) was reduced. In addition, the structural parameter (S) value of the fabricated NTFC decreased considerably which represented the reduction of internal concentration polarization (ICP) during the FO process. These achieved results were due to nanofiber structural characteristics such as high porosity and interconnected open pore structure. The effects of different salts as draw solutions (NaCl, KCl, MgCl 2 , MgSO 4) on the osmotic performance of the NTFC and TFC membranes were evaluated. Among the tested draw solutions with the same osmotic pressure, the NTFC membrane exhibited higher water flux (38.3 LMH) than that of the TFC membrane (14.3 LMH) for KCl draw solution.
Electrospun Membranes for Desalination and Water/Wastewater Treatment: A Comprehensive Review
Journal of Membrane Science and Research, 2017
Polymeric nanofbers, specifcally fabricated by electrospinning, offer viable means useful for a wide range of applications such as health, energy and environmental issues. However, among the mentioned sectors, desalination and water/wastewater treatment applications have been highlighted during the past decade. This article focuses on the present status and recent development of electrospun nanofbrous membranes and their potential impact in two major areas, i.e., desalination and water/wastewater treatment. Specifc applications for desalination and high-quality water/wastewater treatment, including pressure-driven and osmotic membrane processes (MF, UF, NF, FO, etc.), thermal-driven membrane processes, coalescing fltration and adsorptive application of nanofbers, are described. Also, benefts, limitations and challenges are discussed, comprehensively. Electrospun membranes can play a critical role in improving membrane-based desalination and water/wastewater treatment systems. These f...
Electrospun Nanofibrous Membranes for Water Treatment
Advances in Membrane Technologies
Nanofibrous structures offer a lot of fascinating features due to large specific surface area. This makes them promising for a wide range of applications, most specifically water treatment. This new generation of highly porous membranes exhibits great prospect to be used in various separation applications due to their distinguished features such as remarkably high porosity (≥90%) and interconnected 3D pore structure. As compared with the conventional techniques, Electrospinning has been highlighted for developing unique porous membranes. Electrospun nanofibrous membranes have been more and more investigated to a lot of advanced water treatment purposes. This chapter reviews the updates on electrospun nanofibrous membranes with a particular prominence in recent accomplishments, bottlenecks, and future perspectives in water treatment. To start, the basic principles of electrospinning are discussed. Next, past and recent efforts for fabricating electrospun MF membranes for various applications are reviewed. The application of electrospun nanofibers as the scaffold for TFC (thin-film composite) membranes in the pressure-and osmotic-membrane processes is then introduced. The new application of electrospun nanofibrous membranes for the thermally-driven MD (membrane distillation) process for water treatment as well as strategies for performance enhancement is discussed. To finish, conclusions and perspectives are stated according to recent developments.