The Experts below are selected from a list of 1149 Experts worldwide ranked by ideXlab platform
Menachem Elimelech - One of the best experts on this subject based on the ideXlab platform.
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Pressure Retarded Osmosis for power generation from salinity gradients is it viable
Energy and Environmental Science, 2016Co-Authors: Anthony P. Straub, Akshay Deshmukh, Menachem ElimelechAbstract:The enormous potential of harvesting energy from salinity gradients has been discussed for decades, and Pressure-Retarded Osmosis (PRO) is being increasingly investigated as a method to extract this energy. Despite advancements in membranes and system components, questions still remain regarding the overall viability of the PRO process. Here, we review PRO focusing on the net energy extractable and the ultimate feasibility of the most widely explored configurations. We define the maximum energy that can be obtained from the process, quantify losses and energetic costs that will reduce the net extractable energy, and explain how membrane modules can be improved. We then explore the potential of three configurations of PRO: systems designed to control mixing where rivers meet the sea, power plants that utilize the high concentration gradients available from hypersaline solutions, and PRO systems incorporated into reverse Osmosis desalination plants to reduce electricity requirements. We conclude by considering the overall outlook of the process and identifying the most pressing challenges for future research.
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Adverse Impact of Feed Channel Spacers on the Performance of Pressure Retarded Osmosis
2016Co-Authors: Yu Chang Kim, Menachem ElimelechAbstract:This article analyzes the influence of feed channel spacers on the performance of Pressure Retarded Osmosis (PRO). Unlike forward Osmosis (FO), an important feature of PRO is the application of hydraulic Pressure on the high salinity (draw solution) side to retard the permeating flow for energy conversion. We report the first observation of membrane deformation under the action of the high hydraulic Pressure on the feed channel spacer and the resulting impact on membrane performance. Because of this observation, reverse Osmosis and FO tests that are commonly used for measuring membrane transport properties (water and salt permeability coefficients, A and B, respectively) and the structural parameter (S) can no longer be considered appropriate for use in PRO analysis. To accurately predict the water flux as a function of applied hydraulic Pressure difference and the resulting power density in PRO, we introduced a new experimental protocol that accounts for membrane deformation in a spacer-filled channel to determine the membrane properties (A, B, and S). PRO performance model predictions based on these determined A, B, and S values closely matched experimental data over a range of draw solution concentrations (0.5 to 2 M NaCl). We also showed that at high Pressures feed spacers block the permeation of water through the membrane area in contact with the spacer, a phenomenon that we term the shadow effect, thereby reducing overall water flux. The implications of the results for power generation by PRO are evaluated and discussed
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impaired performance of Pressure Retarded Osmosis due to irreversible biofouling
Environmental Science & Technology, 2015Co-Authors: Edo Barzeev, Anthony P. Straub, Francois Perreault, Menachem ElimelechAbstract:Next-generation Pressure-Retarded Osmosis (PRO) approaches aim to harness the energy potential of streams with high salinity differences, such as wastewater effluent and seawater desalination plant brine. In this study, we evaluated biofouling propensity in PRO. Bench-scale experiments were carried out for 24 h using a model wastewater effluent feed solution and simulated seawater desalination brine pressurized to 24 bar. For biofouling tests, wastewater effluent was inoculated with Pseudomonas aeruginosa and artificial seawater desalination plant brine draw solution was seeded with Pseudoalteromonas atlantica. Our results indicate that biological growth in the feed wastewater stream channel severely fouled both the membrane support layer and feed spacer, resulting in ∼50% water flux decline. We also observed an increase in the pumping Pressure required to force water through the spacer-filled feed channel, with Pressure drop increasing from 6.4 ± 0.8 bar m−1 to 15.1 ± 2.6 bar m–1 due to spacer blockage f...
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selectivity and mass transfer limitations in Pressure Retarded Osmosis at high concentrations and increased operating Pressures
Environmental Science & Technology, 2015Co-Authors: Anthony P. Straub, Tzahi Y Cath, Chinedum O Osuji, Menachem ElimelechAbstract:Pressure-Retarded Osmosis (PRO) is a promising source of renewable energy when hypersaline brines and other high concentration solutions are used. However, membrane performance under conditions suitable for these solutions is poorly understood. In this work, we use a new method to characterize membranes under a variety of Pressures and concentrations, including hydraulic Pressures up to 48.3 bar and concentrations of up to 3 M NaCl. We find membrane selectivity decreases as the draw solution concentration is increased, with the salt permeability coefficient increasing by a factor of 2 when the draw concentration is changed from 0.6 to 3 M NaCl, even when the applied hydraulic Pressure is maintained constant. Additionally, we find that significant pumping energy is required to overcome frictional Pressure losses in the spacer-filled feed channel and achieve suitable mass transfer on the feed side of the membrane, especially at high operating Pressures. For a meter-long module operating at 41 bar, we estima...
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comparison of energy efficiency and power density in Pressure Retarded Osmosis and reverse electrodialysis
Environmental Science & Technology, 2014Co-Authors: Menachem ElimelechAbstract:Pressure Retarded Osmosis (PRO) and reverse electrodialysis (RED) are emerging membrane-based technologies that can convert chemical energy in salinity gradients to useful work. The two processes have intrinsically different working principles: controlled mixing in PRO is achieved by water permeation across salt-rejecting membranes, whereas RED is driven by ion flux across charged membranes. This study compares the energy efficiency and power density performance of PRO and RED with simulated technologically available membranes for natural, anthropogenic, and engineered salinity gradients (seawater–river water, desalination brine–wastewater, and synthetic hypersaline solutions, respectively). The analysis shows that PRO can achieve both greater efficiencies (54–56%) and higher power densities (2.4–38 W/m2) than RED (18–38% and 0.77–1.2 W/m2). The superior efficiency is attributed to the ability of PRO membranes to more effectively utilize the salinity difference to drive water permeation and better suppres...
Tai-shung Chung - One of the best experts on this subject based on the ideXlab platform.
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advanced anti fouling membranes for osmotic power generation from wastewater via Pressure Retarded Osmosis pro
Environmental Science & Technology, 2018Co-Authors: Gang Han, Jiang Tao Liu, Tai-shung ChungAbstract:A facile and versatile approach was demonstrated for the fabrication of low-fouling Pressure Retarded Osmosis (PRO) membranes for osmotic power generation from highly polluted wastewater. A water-soluble zwitterionic random copolymer with superior hydrophilicity and unique chemistry was molecularly designed and synthesized via a single-step free-radical polymerization between 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-aminoethyl methacrylate hydrochloride (AEMA). The P[MPC-co-AEMA] copolymer was then chemically grafted onto the surface of PES/Torlon hollow fibers via amino groups coupling of poly(AEMA) with the polyimide structures of Torlon, leaving the zwitterions of poly(MPC) in the feed solution. Because of the outstanding hydrophilicity, unique cationic and anionic groups, and electrical neutrality of the zwitterionic brush, the newly developed membrane showed great resistances to both inorganic scaling and organic fouling in PRO operations. When using a real wastewater brine comprising mul...
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Advanced Anti-Fouling Membranes for Osmotic Power Generation from Wastewater via Pressure Retarded Osmosis (PRO)
2018Co-Authors: Gang Han, Jiang Tao Liu, Tai-shung ChungAbstract:A facile and versatile approach was demonstrated for the fabrication of low-fouling Pressure Retarded Osmosis (PRO) membranes for osmotic power generation from highly polluted wastewater. A water-soluble zwitterionic random copolymer with superior hydrophilicity and unique chemistry was molecularly designed and synthesized via a single-step free-radical polymerization between 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-aminoethyl methacrylate hydrochloride (AEMA). The P[MPC-co-AEMA] copolymer was then chemically grafted onto the surface of PES/Torlon hollow fibers via amino groups coupling of poly(AEMA) with the polyimide structures of Torlon, leaving the zwitterions of poly(MPC) in the feed solution. Because of the outstanding hydrophilicity, unique cationic and anionic groups, and electrical neutrality of the zwitterionic brush, the newly developed membrane showed great resistances to both inorganic scaling and organic fouling in PRO operations. When using a real wastewater brine comprising multifoulants as the feed, the P[MPC-co-AEMA] modified membrane exhibits a much lower flux decline of 37% at ΔP = 0 bar after 24-h tests and a smaller power density decrease of 28% at ΔP = 15 bar within 12-h tests, compared to 61% and 42% respectively for the unmodified one. In addition to the low fouling tendency, the modified membrane shows outstanding performance stability and fouling reversibility, where the flux is almost fully recovered by physical backwash of water at 15 bar for 0.5 h. This study provides valuable insights and strategies for the design and fabrication of effective antifouling materials and membranes for PRO osmotic power generation
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carbon quantum dots grafted antifouling membranes for osmotic power generation via Pressure Retarded Osmosis process
Environmental Science & Technology, 2017Co-Authors: Die Ling Zhao, Subhabrata Das, Tai-shung ChungAbstract:Osmotic power generated by Pressure-Retarded Osmosis (PRO) has attracted global attention as a clean, abundant and renewable energy resource. However, the substrates of PRO membranes are particularly prone to fouling because of their direct contact with various foulants in raw water. This leads to a significant decline in power density and impedes the commercialization of PRO technology. In this work, a facile surface modification method has been developed to obtain a new type of nanoparticle functionalized antifouling PRO membranes. Carbon quantum dots (CQDs), with an average size around 3.2 nm, are fabricated from citric acid via a simple method. Subsequently, they are immobilized onto the polydopamine (PDA) layer grafted on the substrate surface of poly(ether sulfone) (PES) membranes via covalent bonding. The bacteria diffusion tests show that the CQD modified PRO membranes possess much enhanced antibacterial activity and antibiofouling propensity. The continuous PRO operations at 15 bar also confirm t...
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energy recovery by Pressure Retarded Osmosis pro in swro pro integrated processes
Applied Energy, 2016Co-Authors: Chun Feng Wan, Tai-shung ChungAbstract:Abstract Pressure Retarded Osmosis (PRO) is a promising technology to reduce the specific energy consumption of a seawater reverse Osmosis (SWRO) plant. In this study, it is projected that 25.6–40.7 million kW h/day of energy can be recovered globally, if the brines from SWRO are used as the draw solution and diluted to the seawater level in a PRO system. Detailed integrated SWRO–PRO processes are developed in this study with the option to form a closed-loop SWRO–PRO process that can substantially reduce the pretreatment cost of desalination. The governing mathematical models that describe both the transport phenomena on a module level and the energy flow on a system level are developed to evaluate the performances of the SWRO–PRO processes. The model aims to investigate the performance of the hollow fibers as dilution occurs and provides guidelines on hollow fiber module design and process operation. Determining the dilution factor and the corresponding operating Pressure of PRO is the key to optimize the integrated process. The specific energy consumptions of three SWRO-involved processes; namely, (1) SWRO without a Pressure exchanger, (2) SWRO with a Pressure exchanger, and (3) SWRO with Pressure exchangers and PRO are compared. The results show that the specific energy consumptions for the above three processes are 5.51, 1.79 and 1.08 kW h/(m3 of desalinated water) for a 25% recovery SWRO plant; and 4.13, 2.27 and 1.14 kW h/(m3 of desalinated water) for a 50% recovery SWRO plant, using either freshwater or wastewater as the feed solution in PRO.
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hybrid Pressure Retarded Osmosis membrane distillation pro md process for osmotic power and clean water generation
Environmental Science: Water Research & Technology, 2015Co-Authors: Gang Han, Tai-shung Chung, Jian Zuo, Chun Feng WanAbstract:A novel Pressure Retarded Osmosis–membrane distillation (PRO–MD) hybrid process has been experimentally conceived for sustainable production of renewable osmotic power and clean water from various waters. The proposed PRO–MD system may possess unique advantages of high water recovery rate, huge osmotic power generation, well-controlled membrane fouling, and minimal environmental impacts. Experimental results show that the PRO–MD hybrid process is promising such that not only it can harvest osmotic energy from freshwater but also from wastewater. When employing a 2 M NaCl MD concentrate as the draw solution, ultrahigh power densities of 31.0 W m−2 and 9.3 W m−2 have been demonstrated by the PRO subsystem using deionized water and real wastewater brine as feeds, respectively. Simultaneously, high-purity potable water with a flux of 32.5–63.1 L (m−2 h−1) can be produced by the MD subsystem at 40–60 °C without any detrimental effects of fouling. The energy consumption in the MD subsystem might be further reduced by applying a heat exchanger in the hybrid system and using low-grade heat or solar energy to heat up the feed solution. The newly developed PRO–MD hybrid process would provide insightful guidelines for the exploration of alternative green technologies for renewable osmotic power and clean water production.
Chuyang Y Tang - One of the best experts on this subject based on the ideXlab platform.
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fabrication and characterization of fabric reinforced Pressure Retarded Osmosis membranes for osmotic power harvesting
Journal of Membrane Science, 2016Co-Authors: Qianhong She, Rong Wang, Jing Wei, Victor Siang Tze Sim, A G Fane, Chuyang Y TangAbstract:Abstract In recent years, Pressure Retarded Osmosis (PRO) has attracted increasing interest in the harvesting of the renewable osmotic power. However, its performance can be significantly influenced by the membrane deformation in the operation when the PRO membrane is lack of sufficient mechanical strength. In this study, we fabricated three different fabric-reinforced thin-film composite (TFC) flat-sheet PRO membranes for osmotic power harvesting. These membranes were prepared through integrating three different types of fabric reinforcement (i.e., tricot fabric, woven fabric and nonwoven fabric) in the membrane substrate layer. It was found that the fabric reinforcement plays an important role in the membrane structural property and mechanical property, both of which can significantly influence the PRO performance. The nonwoven-fabric-reinforced membrane had the greatest structural parameter and thus exhibited the lowest performance. Although the tricot-fabric-reinforced membrane and the woven-fabric-reinforced membrane had similar performance in the forward Osmosis (FO) condition (∆P=0), the former showed superior performance in the PRO condition (∆P>0). This is mainly because the tricot-fabric-reinforced membrane had better mechanical resistance to the multi-directional tensile stretching, which rendered it less prone to changes in structural and separation properties in the PRO operation. This further suggests that the tricot fabric has high potential for future PRO membrane fabrication. The current study also elaborates the coupled effects of compression and stretching on PRO membrane deformation and performance. The results obtained in this study may provide important insights into reinforced PRO membrane design.
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Fabrication and characterization of nanocomposite Pressure Retarded Osmosis (PRO) membranes with excellent anti-biofouling property and enhanced water permeability
Desalination, 2016Co-Authors: Xin Liu, Li Xian Foo, Jian Yuan Lee, Ye Li, Chuyang Y TangAbstract:Membrane biofouling is a critical barrier for prolonged membrane operations. In the current study, silver nanocomposite osmotic membranes were fabricated to impart anti-microbial properties. The PAN-Ag nanocomposite substrates were prepared using one-step phase inversion. With additional crosslinked layer-by-layer (xLbL) assembly on the nanocomposite substrates, xLbL3.0-Ag nanocomposite osmotic membranes were obtained. At the silver nanoparticle (AgNP) loading concentration of 0.02 wt.%, water permeability of xLbL3.0-Ag(0.02) nanocomposite osmotic membrane increased by 24.4% compared with the AgNP-free control. In addition, the silver nanocomposite membranes exhibited excellent anti-biofouling performances, with ~ 6 log colony-forming units (CFU) reduction against Gram-positive Bacillus subtilis and ~ 5 log CFU reduction against Gram-negative Escherichia coli at an AgNP loading of 0.10 wt.%. Water flux reduced to 66.9% (AgNP-free control) and 88.2% (xLbL3.0-Ag(0.10) nanocomposite osmotic membrane) of their respective original values for membranes fouled by Comamonas testosteroni I2 in PRO test mode. This study presents a convenient method to synthesize nanocomposite osmotic membranes with excellent anti-biofouling property for potential use for Pressure Retarded Osmosis (PRO). Our results provide significant implications for anti-fouling nanocomposite osmotic membrane fabrication as well as PRO fouling control.
A G Fane - One of the best experts on this subject based on the ideXlab platform.
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Pressure Retarded Osmosis with wastewater concentrate feed fouling process considerations
Journal of Membrane Science, 2017Co-Authors: Rong Wang, Qianhong She, Lizhi Zhang, William B Krantz, A G FaneAbstract:Abstract Pressure-Retarded Osmosis (PRO) has attracted worldwide attention for its potential applications in renewable osmotic energy harvesting, low energy seawater desalination, and industrial waste brine disposal. However, membrane fouling is one of the major issues limiting PRO performance with the use of a high-salinity draw solution and a low-value impaired feedwater. This study systematically investigated membrane fouling in the PRO process using a real wastewater retentate (a waste byproduct from wastewater reclamation plants) as the PRO feed. Organic fouling (e.g., by humic substances) and inorganic fouling (e.g., by calcium phosphate) were identified to be the major types of fouling, where the latter dominated the overall water-flux decline. The internal PRO membrane fouling was exacerbated by internal concentration polarization (ICP) and intermolecular interactions between the organic macromolecules and the scaling precursor ions (e.g., Ca2+). A limiting flux that was independent of the initial flux (i.e., applied Pressure) was observed during the PRO fouling and was explained by a novel PRO limiting flux model. A membrane with a smaller structural parameter could achieve a higher limiting flux in PRO. A simple and effective Pressure-assisted osmotic backwashing protocol was developed to clean the internally fouled membrane that could restore over 92% of the water flux within a short cleaning period (15 mins). The PRO performance could also be significantly improved by decreasing the feedwater pH that mitigated alkaline scaling. Finally, performing the PRO membrane fouling test in the active-layer-facing-feed-solution (AL-FS) orientation revealed that the integral cellulose triacetate (CTA) membrane exhibited strong mechanical stability and anti-fouling tendency whereas the thin-film composite (TFC) membrane was not mechanically stable in this orientation. This study for the first time identified that an integral membrane instead of a TFC membrane is an excellent candidate for PRO operation in the AL-FS mode for fouling control.
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fabrication and characterization of fabric reinforced Pressure Retarded Osmosis membranes for osmotic power harvesting
Journal of Membrane Science, 2016Co-Authors: Qianhong She, Rong Wang, Jing Wei, Victor Siang Tze Sim, A G Fane, Chuyang Y TangAbstract:Abstract In recent years, Pressure Retarded Osmosis (PRO) has attracted increasing interest in the harvesting of the renewable osmotic power. However, its performance can be significantly influenced by the membrane deformation in the operation when the PRO membrane is lack of sufficient mechanical strength. In this study, we fabricated three different fabric-reinforced thin-film composite (TFC) flat-sheet PRO membranes for osmotic power harvesting. These membranes were prepared through integrating three different types of fabric reinforcement (i.e., tricot fabric, woven fabric and nonwoven fabric) in the membrane substrate layer. It was found that the fabric reinforcement plays an important role in the membrane structural property and mechanical property, both of which can significantly influence the PRO performance. The nonwoven-fabric-reinforced membrane had the greatest structural parameter and thus exhibited the lowest performance. Although the tricot-fabric-reinforced membrane and the woven-fabric-reinforced membrane had similar performance in the forward Osmosis (FO) condition (∆P=0), the former showed superior performance in the PRO condition (∆P>0). This is mainly because the tricot-fabric-reinforced membrane had better mechanical resistance to the multi-directional tensile stretching, which rendered it less prone to changes in structural and separation properties in the PRO operation. This further suggests that the tricot fabric has high potential for future PRO membrane fabrication. The current study also elaborates the coupled effects of compression and stretching on PRO membrane deformation and performance. The results obtained in this study may provide important insights into reinforced PRO membrane design.
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robust and high performance hollow fiber membranes for energy harvesting from salinity gradients by Pressure Retarded Osmosis
Journal of Membrane Science, 2013Co-Authors: Shuren Chou, Rong Wang, A G FaneAbstract:Abstract Pressure Retarded Osmosis (PRO) is a promising membrane process to harvest the vast amount of free energy from the mixing of fresh and salty waters without adverse environmental impacts. A competent membrane for PRO should possess the features of high water permeability to allow water permeation, excellent salt rejection to maintain the osmotic driving force, low structure parameter to minimize the internal concentration polarization (ICP), and robust strength to withstand the required hydraulic Pressure. In this work, we have developed a novel hollow fiber membrane by balancing these competing factors based on our prior experience in the thin-film composite (TFC) membranes. The newly developed TFC hollow fiber membrane can achieve a power density of 20.9 W/m2 at a Pressure of 15 bar, using synthetic seawater brine (1.0 M NaCl) as the draw solution and synthetic river water (1 mM NaCl) as the feed water, respectively. The simultaneous specific reverse salt flux was found to be 0.03 mol/L, which is much lower than reported flat-sheet membranes, as the self-supported hollow fiber membrane can eliminate the deformation-enhanced reverse salt diffusion that is typical for flat-sheet membranes. However it was observed that the water permeability and structure parameter of the TFC hollow fiber membrane varied noticeably corresponding to the change in the hydraulic Pressure imposed in the fiber lumen. Over a certain range (ΔP
Jeffrey R Mccutcheon - One of the best experts on this subject based on the ideXlab platform.
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impact of temperature on power density in closed loop Pressure Retarded Osmosis for grid storage
Journal of Membrane Science, 2015Co-Authors: Daniel Anastasio, Jason T. Arena, Emily A Cole, Jeffrey R MccutcheonAbstract:Abstract Closed-loop Pressure Retarded Osmosis (PRO) has been recently proposed as a means of transforming unusable forms of energy, such as waste heat, into valuable electricity. The process, which is also referred to as an osmotic heat engine (OHE), also enables a form of osmotic grid storage for intermittently available renewable energy sources, where available energy is stored as an osmotic potential and that energy is released via PRO when energy demand is high. The OHE has the potential to generate greater power than conventional open loop PRO because the draw solution can be engineered to have very high osmotic Pressures, via enhanced temperature, solute concentration, or a combination of both. These variables change fluid properties and the performance of the membrane, which may or may not be beneficial to overall OHE operation. Using a custom-built, bench-top PRO system, a commercially available forward Osmosis membrane from Hydration Technology Innovations™ (HTI) was evaluated for water flux and power density at two temperatures (20 °C and 40 °C) and three draw solution concentrations (0.5, 1.0, and 1.5 M sodium chloride) that are similar to temperatures and draw solution osmotic Pressures capable in an osmotic heat engine. In general, power densities increased with the increasing draw solution concentration and system temperature. The highest observed power density (18.0±2.3 W/m 2 ) was measured at 20.7 bar (300 psi) using a 1.5 M sodium chloride draw solution at a system temperature of 40 °C. Experimental data compared favorably to predicted performance using previously published governing equations for PRO water flux and power density.
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surface modification of thin film composite membrane support layers with polydopamine enabling use of reverse Osmosis membranes in Pressure Retarded Osmosis
Journal of Membrane Science, 2011Co-Authors: Jason T. Arena, Bryan D Mccloskey, Jeffrey R MccutcheonAbstract:Abstract Previous investigations of forward Osmosis and Pressure Retarded Osmosis identified asymmetric membrane support layer hydrophilicity as critical to obtain high water flux. In this study, the support layers of two commercially available thin film composite reverse Osmosis membranes were modified to enhance their hydrophilicity. The membrane support layers were coated with polydopamine, a novel bio-inspired hydrophilic polymer. This resulted in increased hydrophilicity and a corresponding increase in ‘wetted porosity’ and reduced internal concentration polarization. The modified membranes were then characterized for contact angle, salt rejection, hydraulic permeability, salt flux, and osmotic flux. The results were promising, indicating that the modified reverse Osmosis membranes exhibited an eight to fifteen fold increase in flux performance under test conditions when compared to baseline control data. This modification method, which is scalable, has the potential to enable the use of existing thin film composite membranes for all engineered Osmosis applications.