Evaluation of FO membranes performance using a modelling approach (original) (raw)
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Desalination, 2020
Recently, forward osmosis (FO) has attracted a great deal of attention in desalination and wastewater treatment. Nevertheless, there are several critical challenges such as the need for new advances in designing membranes that must be met to enhance the water flux in FO processes, control the reverse salt flux, concentration polarization and fouling. Therefore, designing a suitable membrane with a high-water flux, low reverse salt flux, low fouling, and controlled concentration polarization seems to be essential. Thin film composite (TFC) membranes are the most widely used membranes in the FO field. Extensive research has been performed to fabricate and design high performance TFC membranes which can be exclusively used in FO processes. This paper aims to review three types of TFC membranes i.e. TFC's with polyamide active layer (TFC-A), thin film nanocomposites (TFC-N) and double-skinned TFC membranes (TFC-D) in flat sheet and hollow fiber configuration. Finally, an attempt is made to generate a general performance curve based on the water flux and reverse salt flux of these three TFC FO types and the future direction of the R and D on the FO membrane are discussed.
Fabrication of high-performance nanofiber-based FO membranes
DESALINATION AND WATER TREATMENT, 2019
Being partially commercialized and has specific application areas, where the reverse osmosis technology cannot serve, forward osmosis (FO) technology is continually receiving extensive research to promote its performance. In this study, high-performance FO nanofiber-based substrate membrane was fabricated for potential application of saline water desalination. Sulfonated polysulfone (sPSU) with definite sulfonation level was used to fabricate support layer. Tubular beadless fiber network owning scaffold-like structure with a fiber diameter of 247 nm was formed. Polysulfone was sulfonated by heterogeneous method using chlorosulfonic acid as a sulfonation agent. The substrate and FO membranes were characterized mainly by means of scanning electron microscopy (SEM), water permeation flux, porometry, contact angle, Fourier transform infrared (FTIR), as well as other tests, while the characterization of thin-film composite separation layer was restricted to SEM and FTIR. The characterization illustrates that the sPSU support layer is highly porous with a narrow pore size distribution. FO performance evaluation of two commercial and newly developed membranes was probed using FO and pressure-retarded osmosis (PRO) modes with cocurrent and counter-current flow scheme. The active layer presents excellent intrinsic properties with A/B of 17.31 and a high salt separation ratio of 99.54%. The newly developed membrane can achieve a high FO and PRO water flux of 65.7 and 313 L m −2 h −1 , respectively, using a 1 M NaCl draw solution and deionized water feed solution. The corresponding salt flux is only 2.5 and 5.3 g m −2 h −1. The reverse flux selectivity represented by the ratio of water flux to reverse salt flux (J w /J s) was kept as high as 26.3 and 58.8 L g-1 for FO and PRO modes. To the best of our knowledge, the performance of the current work-developed membrane is superior to all FO membranes previously reported in the literature.
Journal of Membrane Science, 2011
Osmotically driven membrane processes have the potential to treat impaired water sources, desalinate sea/brackish waters, and sustainably produce energy. The development of a membrane tailored for these processes is essential to advance the technology to the point that it is commercially viable. Here, a systematic investigation of the influence of thin-film composite membrane support layer structure on forward osmosis performance is conducted. The membranes consist of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation. By systematically varying the conditions used during the casting of the polysulfone layer, an array of support layers with differing structures was produced. The role that solvent quality, dope polymer concentration, fabric layer wetting, and casting blade gate height play in the support layer structure formation was investigated. Using a 1 M NaCl draw solution and a deionized water feed, water fluxes ranging from 4 to 25 L m −2 h −1 with consistently high salt rejection (>95.5%) were produced. The relationship between membrane structure and performance was analyzed. This study confirms the hypothesis that the optimal forward osmosis membrane consists of a mixed-structure support layer, where a thin sponge-like layer sits on top of highly porous macrovoids. Both the active layer transport properties and the support layer structural characteristics need to be optimized in order to fabricate a high performance forward osmosis membrane.
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.
Forward Osmosis Process: State-Of-The-Art of Membranes
Separation & Purification Reviews, 2019
Forward osmosis (FO) is a membrane-based process that explores the osmotic pressure difference between a feed solution and a draw solution to induce water transport across a semipermeable membrane. Water transport results in the dilution of the draw solution which is reconcentrated using a recovery process. Different from the reverse osmosis process, FO requires lower grade energy and has other advantages, namely, a wide range of applications and a reversible fouling phenomenon of FO membranes. In spite of its many advantages, the FO process is facing drawbacks among which the lack of high-performance membranes. Today, the development of improved FO membranes, capable of achieving a high water flux with a very low reverse salt flux is one of the biggest concerns of membrane scientists. This paper summarizes the basic principle of the FO process, some modern applications, and the main challenges related to membranes. It also describes the progresses in FO membrane development, particularly regarding the membrane manufacturing techniques, commercially available, and R&D membranes.
DESALINATION AND WATER TREATMENT, 2021
In this study, two main key features are used for the successful forward osmosis desalination process. The first key is the thin-film nanocomposite membrane fabrication. This key is achieved by consolidating different concentrations of zeolite nanoparticles in the polysulfone supporting sheet (ranging from 0%wt. to 0.6% wt.) to enhance the hydrophilicity and porosity of the membrane. A thin polyamide layer is formed on the top surface of the modified polysulfone by interfacial polymerization of Metaphenylenediamine (MPD) and Trimesoyl chloride (TMC) to fabricate thinfilm nanocomposite (TFNC) forward osmosis membranes for forward osmosis (FO) application. The other key feature that makes the FO practical is selecting the ideal draw solute achieved by selecting sodium chloride as inorganic salt. Sodium chloride is characterized by high osmotic pressure, chemically inert, low membrane reverse solute flux, and easily regenerated. The fabricated TFNC membranes were first tested using a cross-flow RO module to evaluate the effect of different loadings of zeolite nanoparticles on the membrane performance. The FO membrane with 0.4 wt% zeolite in polysulfone matrix (TFNC-0.4%) shows the most promising results through increasing the water flux by 126% than the TFC membranes. Then were tested using a cross-flow FO module with 0.02-0.8 M NaCl concentration as feed solution. Results indicate that the water flux of the TFNC-0.4% was increased by (55%-64%) than the TFC Control membrane depending on the membrane orientation and draw solution concentration. It is observed that the solute reverse flux increased with the increase of the concentration of draw solution. Different characterization tests have been carried out on the forward osmosis membranes to verify their successful preparation and modification and specify the various effects of the zeolite nanoparticles added to the membrane substrate. A sponge-like structure is developed by adding zeolite nanoparticles compared to the TFC membrane, enhancing water permeability. Moreover, an increase in mechanical and thermal properties is detected. Furthermore, the power consumption for the forward osmosis process was [0.72-4.66%] only from the total power consumption of the FO-RO process. The current power cost as OPEX for FO TFNC-0.4% membrane desalination process ranges from 0.072 to 0.132 EGP/m 3 compared to the commercial SWRO+PX [5.53 EGP/m 3 ] operated in Hurghada, Red sea, Egypt.
DESALINATION AND WATER TREATMENT
The performance evaluation of forward osmosis (FO) nanofibers based membranes against model solutions and real seawater were investigated. The desalination of seawater performed using 2 M NaCl as a draw solution. Performance data showed that when real seawater used as a feed solution, the newly fabricated FO membrane has a water flux of 15.1 and 49.4 LMH in both co-current FO and co-current pressure retard mode (PRO) respectively. Two different model solutions (NaCl and MgSO 4), have a salt concentration equal to that of the real seawater sample, were prepared to characterize the performance of the fabricated membrane against them under the same operating conditions. The flux obtained in 1.1% model NaCl in FO mode was 8 LMH, whereas in PRO mode was 54 LMH and 10.3 LMH in FO mode, whereas 45.6 LMH in PRO mode for model 1.1% MgSO 4 solution using 2 M NaCl solution as a draw solution. The structural parameter (S-value) of the sulfonated polysulfone (sPSf) thin-film-composite membrane is estimated to be 125 µm, which is considered one of the smallest values ever reported in the literature. In this manuscript, the performance study of thin-film composite (TFC-FO) nanofiber flat-sheet membrane on sPSf substrate is proven that fabricated membranes are perfectly meet the high rejection ratios whether strong enough to sustain high flux and durability through the operation.
Journal of Membrane Science, 2013
We present a simple and rapid methodology to characterize the water and solute permeability coefficients (A and B, respectively) and structural parameter (S) of forward osmosis (FO) membranes. The methodology comprises a single FO experiment divided into four stages, each using a different concentration of draw solution. The experimental water and reverse salt fluxes measured in each stage are fitted to the corresponding FO transport equations by performing a least-squares non-linear regression, using A, B, and S as regression parameters. Hand-cast thin-film composite (TFC) FO membranes and commercial TFC FO, TFC reverse osmosis (RO), and cellulose acetate-based asymmetric FO membranes are evaluated following this protocol. We compare the membrane properties obtained with our FO-based methodology with those derived from existing protocols based on an RO experiment followed by an FO experiment. For all membranes, the FO-based protocol gives more accurate predictions of the water and salt fluxes than the existing method. The numerical robustness of the method and the sensitivity of the regression parameters to random errors in the measured quantities are thoroughly analyzed. The assessment shows that confidence in the accuracy of the determined membrane parameters can be enhanced by simultaneously achieving close fitting of the predicted fluxes to experimental measurements (i.e., high R 2 values) and constant water to salt flux ratios in each stage. Additionally, the existing and proposed approaches yield consistently dissimilar results for some of the analyzed membranes, indicating a discrepancy that might be attributed to the different driving forces utilized in RO and in FO that should be further investigated.
Synthesis and evaluation of nanocomposite forward osmosis membranes for Kuwait seawater desalination
DESALINATION AND WATER TREATMENT, 2020
Multistage flash (MSF) and reverse osmosis (RO) are the two major desalination technologies currently serving the needs of freshwater in Kuwait. MSF is energy intensive and suffer from low water recovery, while RO desire energy to fulfil its pressure requirement for the process. Thus, globally the scientists are focusing on the innovative desalination technologies which could be operated at low cost and environmentally friendly. In this regard, forward osmosis (FO) is one such emerging technology which can be operated under "Non-Pressure" requirement conditions to reduce the energy/cost of the desalination process. The principle of FO involves flow of the pure water across the semipermeable membrane by maintaining an osmotic pressure gradient between the feed solution (low concentration solution) and draw solution (high concentration solution). Related to this concept, a project was conducted at Kuwait Institute for Scientific Research to fabricate potential and fouling control membranes for the FO desalination. The aim of this paper is to present the important outcomes of the project in fabricating different types of membranes and results related to the high-performance thin film nanocomposite (TFN) membranes obtained in the project compared with commercial FO membranes. The TFN membrane with 0.05 wt.% nanoparticle composition resulted in high flux of vs. the commercial CTA membrane. Therefore, this work concluded that a suitable selection of nanoparticles and their proper modification is essential to fabricate potential membranes for FO application. Further, a nano-based FO membrane showed a potential application in FO desalination compared with commercial FO membranes.
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.