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The performance of a newly commercialized aquaporin (AQP)‐based biomimetic forward osmosis (FO) membrane was evaluated with several commonly used fertilizers ((CO (NH2)2, KCl, CaCl2, (NH4)2SO4 and (NH4)2HPO4) as a draw solutions (DSs) to verifying the possible implementation of this AQP‐FO membrane in the fertigation industry. Also, DS and feed solution (FS) concentrations were evaluated under FO and pressure retarded osmosis (PRO) operation modes. The results showed that CaCl2 seems to be a more suitable DS in terms of the tradeoff between water flux and salt permeability, compared to the other DSs used in this study. However, KCl gained the highest performance in terms of water flux which was 13.9 and 24.1 Lm−2 h−1 in the FO and PRO mode, respectively. The performance of the AQP membrane in terms of water flux and reverse solute flux can be improved by modifying the structural and the membrane inhibitor layer characteristics for utilizing in commercial scales to compete with other available membranes of the FO process. [ABSTRACT FROM AUTHOR]

BACKGROUND Novel nanocomposite membranes with spatial distribution of nanoparticles (NPs) were fabricated for forward osmosis (FO) applications. In this work, TiO2 and Al2O3 NPs were used as hydrophilic additives in order to improve the performance and fouling resistance of cellulose acetate (CA) FO membrane. RESULTS: Attenuated Total Reflection Fourier Transform Infrared (ATR‐FTIR) and x‐ray diffraction (XRD) analyses confirmed the successful incorporation of the NPs into the synthesized membranes. The specific reverse salt flux (SRSF) of the TiO2 modified membrane was reduced from 0.88 to 0.56 g L−1, which was attributed to enhanced hydrophilicity, porosity, and the simultaneously improved water and salt permeability coefficients. After the evaluation of CA membranes with various contents of TiO2 NPs, Al2O3 NPs were added to the membrane structure as a secondary additive under the optimized content of TiO2 NPs. Al2O3 NPs have a higher dispersion in the membrane sublayer beneath, which can affect the hydrophilicity and surface charge of the membranes. Al2O3 and TiO2 modified membranes showed the lowest values of contact angle and zeta potential in neutral pH, which was 56.7°and − 68.4 mV, respectively. This membrane showed a water flux (WF) of 15 L m−2h−1 and an SRSF of 0.36 g L−1 when using 1 mol L−1 NaCl as a draw solution. The fouling behavior of sodium alginate on the neat and modified membranes was also investigated, and the results showed a reduced fouling propensity and a superior fouling reversibility in the modified membranes. CONCLUSION: Based upon these findings, using low‐density hydrophilic NPs in the membrane structure can fabricate membranes with more hydrophilicity, excellent FO performance, and high organic fouling resistance. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

• Thin film composite forward osmosis (FO) membranes with permeate spacer fabric were synthesized. • The water-soluble polymer (PVP) employed as paste on the back of the fabric. • Polymer penetration and thickness were controlled thanks to applied PVP. • PVP washed up during phase inversion in water bath. A repeatable method was introduced for developing liable flat sheet thin-film forward osmosis (FO) membranes on spacer backing fabric support. Pasting of a water-soluble polymer (Polyvinylpyrrolidone (PVP)) on the backside of the fabric was investigated to prevent the penetration of the polymer dope (Polyethersulfone (PES)) into the backing fabric during phase inversion. All samples were prepared on spacer fabric with a 250 μm in thickness. First, PVP as a water-soluble polymer was cast in 100 μm thickness on a glass plate and then the spacer fabric was pulled from the top on the pasted PVP to fill the bottom side of the fabric. The lower bottom side of the fabric was filled with PVP. This helped to limit PES polymer penetration and to achieve a thinner polymeric support layer during phase inversion. After interfacial polymerization and forming rejection, thin-film composite (TFC) FO membranes were obtained. Water flux of 17.1 Lm−2h−1 and reverse solute flux (RSF) of 9.2 g m−2h−1 were achieved when 1 M NaCl as draw solution and deionized water as feed solution (FS) were used under pressure retarded osmosis (PRO) operating mode for TFC 2 sample. [ABSTRACT FROM AUTHOR]

• Treatment of saline oily wastewater via FO process with aquaporin membrane. • Fertilizers as a draw solution after dilution can be applied for farm fertigation. • Feeding the oily wastewater under the PRO mode can lead to significant flux decline. • Flux decline is due to oil droplet and fouling propensity of membrane backing fabric. The hypothesis that petrochemical oily wastewater containing high amounts of total dissolved solids (TDS), chemical oxygen demand (COD) and total organic carbon (TOC) can be effectively treated by a new biomimetic forward osmosis (FO) membrane for fertigation purposes was assessed. The biomimetic FO membrane was characterized, and its intrinsic properties were evaluated. The fertilizer-driven FO (FDFO) process was evaluated in terms of water flux (WF), reverse solute flux (RSF), specific RSF (SRSF), and oil rejection at various draw solution (DS) concentrations and cross-flow velocities. Under optimized conditions, deionized water was used as feed and 3 M KCl, the most widely used potassium fertilizer, was used as DS at a cross-flow velocity of 0.1 m·s−1. WF and RSF of 67.22 Lm-2 h−1 and 48.3 gm−2 h−1, respectively, were obtained. Using saline oily wastewater as the feed, the orientation of the feed facing the membrane support layer exhibited a lower WF due to oily layer fouling within the membrane support. Apart from almost complete rejections of organic chemicals, the biomimetic FO membrane demonstrated a better performance (WF = 11.31 Lm−2 h−1) than the typical polyamide thin film composite (TFC) membrane (WF = 5.23 Lm−2 h−1) during mid-term fouling tests. This study demonstrates that FO process is an effective strategy for sustainable management of hazardous petrochemical oily wastewater by recycling the diluted fertilizer solution for direct fertigation without further treatment. [ABSTRACT FROM AUTHOR]

Due to the lack of affordable and feasible wastewater treatment technologies, various industries in developing countries are discharging chromium (Cr) without meeting the environmental standards. Here, the aim was to employ forward osmosis (FO) using aquaporins (AQP)‐based biomimetic membranes and optimize the Cr rejection through response surface methodology (RSM). The initial concentration of draw solution, feed solution, and time was selected as independent variables in order to optimize Cr rejection and water flux. A high Cr rejection efficiency and water flux were achieved under the optimal conditions. These results revealed that the FO process applying an AQP membrane beside the RSM could be considered to treat wastewaters containing heavy metals. [ABSTRACT FROM AUTHOR]

Cellulose acetate (CA) and thin film composite (TFC) membranes for forward osmosis (FO) process by hydration technology innovations (HTI) were the most innovative and also commercialized for research and field scale. Most recently, biomimetic Aquaporin (AQP) membrane has been commercialized on a large scale and product outlet is available for industrial and academic applications. In this work, we present the characterization and evaluating the performance of the biomimetic AQP forward osmosis (FO) membrane from aquaporin Asia Pte. Ltd in Singapore, using DI water and brackish water (BW) (5000 mg·L-1 of KCl) as feeds and KCl as draw solution (DS). Scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier-transform-infrared (FTIR), and contact angle analysis were utilized to characterize AQP membrane. The intrinsic properties of the membrane were also assessed using a reverse osmosis (RO) setup followed by investigating FO performance in a lab-scale FO setup. Under FO tests, the membrane achieved high water flux of 12.8 and 17.1 L m-2 h-1 with a modest RSF of 14.8 and 17.5 g m-2 h-1 using 1.0 M KCl against DI water in FO and pressure retarded osmosis (PRO) modes, respectively. The results were also equaled to 9.1 and 10.1 L m-2 h-1 of water flux under FO and PRO modes as BW was used as FS. [ABSTRACT FROM AUTHOR]

Abstract: Cellulose acetate (CA) flat sheet membranes were fabricated and evaluated in a forward‐osmosis process. Effects of CA concentration, coagulation bath temperature, and annealing thermal treatment on both membrane structure and performance were investigated. NaCl rejection of the optimum membrane was determined utilizing a reverse‐osmosis setup based on conductivity measurements. Two validated models were obtained by means of response surface methodology based on Box‐Behnken design. The optimum operating pressure, temperature, and draw solution concentration were assessed as well. [ABSTRACT FROM AUTHOR]

The water flux in forward osmosis (FO) process declines substantially when the draw solution (DS) concentration reaches closer to the point of osmotic equilibrium with the feed solution (FS). Using external hydraulic pressure alongside the osmotic driving force in the pressure assisted osmosis (PAO) has been found effective in terms of enhancing water flux and even potentially diluting the DS beyond osmotic equilibrium. The net gain in water flux due to the applied pressure in the PAO process closely depends on the permeability of the FO membrane. The commercial flat sheet cellulose triacetate (CTA) FO membrane has low water permeability and hence the effective gain in water flux in the PAO process is low. In this study, a high performance thin film composite membrane was developed especially for the PAO process through casting polyethersulfone (PES) polymer solution on a compacted woven fabric mesh support followed by interfacial polymerisation for polyamide active layer. This PAO membrane possesses a water flux of 37 L m 2 h − 1 using 0.5 M NaCl as DS and deionised water as the feed at an applied hydraulic pressure of 10 bar. Besides, the membrane was able to endure the external hydraulic pressure required for the PAO process owing to the embedded backing fabric support. While the membranes with low structural parameters are essential for higher water flux, this study shows that for PAO process, polymeric membranes with larger structural parameters may not be suitable for PAO. They generally resulted in compaction and poor mechanical strength to withstand hydraulic pressure. [ABSTRACT FROM AUTHOR]

Sulphonated polyethersulfone (SPES) has been synthesized for developing high performance thin film composite (TFC) forward osmosis (FO) membranes with enhanced hydrophilic support layer. Sulphonated substrate not only affects the membrane performance but also changes the membrane morphology from finger-like structure to a sponge-like morphology at higher degree of sulphonation thereby affecting the mechanical strength of the FO membrane. Non-sulphonated TFC-FO membrane with 12 wt.% polymer concentration shows a faint finger-like structure while sulphonated samples at a similar polymer concentration show a fully sponge-like structure with a much higher performance. For example, a water flux of 35 Lm − 2 h − 1 and 0.28 g L − 1 specific reverse solute flux was achieved with sulphonated TFC-FO membrane sample (50 wt.% SPES) under the FO mode using 2 M NaCl as the draw solution and deionized water as feed. Substrate sulphonation also considerably decreased the membrane structural parameter from 1096 μm without sulphonation to 245 μm at 50 wt.% sulphonation. This study therefore shows that, besides surface morphology, the water flux of the FO membrane can also be enhanced by improving its substrate hydrophilic property. [ABSTRACT FROM AUTHOR]

Adequate dilution of fertiliser draw solution (DS) during fertiliser drawn forward osmosis (FDFO) desalination is important to meet nutrient concentration level for direct fertigation. The maximum DS dilution, however, occurs until the point of osmotic equilibrium between DS and feed solution (FS) thereby limiting the extent of DS dilution. Post-treatment such as nanofiltration (NF) process is required to reduce the fertiliser concentration. In this study however, pressure assisted fertiliser drawn osmosis (PAFDO) process was investigated to enhance DS dilution beyond the point of osmotic equilibrium and potentially eliminate NF post-treatment. The hydraulic pressure applied enhanced water flux significantly depending on the pressure. The applied pressure was found more effective at lower DS concentrations than at higher DS concentrations. For example, when a pressure of 10 bar was applied to 10 g/L NaCl FS with 0.1 M (NH 4 ) 2 SO 4 DS, the water flux increased by 1928% against 38% with 3.0 M (NH 4 ) 2 SO 4 DS. This additional water flux could dilute the fertiliser DS beyond the osmotic equilibrium concentrations thereby meeting the fertigation standard. PAFDO could potentially eliminate NF post-treatment significantly helping reduce the footprint and capital cost. However, the effective gain in water flux due to applied pressure at osmotic equilibrium decreased with the increase in the FS concentrations. [ABSTRACT FROM AUTHOR]

Continued efforts are made in improving the performance of the low-cost forward osmosis (FO) membrane process which utilizes naturally available osmotic pressure of the draw solution (DS) as the driving force. Selection of a suitable DS and development of a better performing membrane remained the main research focus. In this study, the performance of a hollow fiber forward osmosis (HFFO) membrane was evaluated with respect to various operating conditions such as different cross-flow directions, membrane orientation, solution properties, and solution flow rates (Reynolds number). The study observed that operating parameters significantly affect the performance of the FO process. FO comparatively showed better performance at counter-current orientation. NaCl, KCl, and NH4Cl were evaluated as DS carrying common anion. Properties of the anionic part of the DS were found important for flux outcome, whereas reverse solute flux (RSF) was largely influenced by the properties of DS cationic part. FO was operated at different DS and feed solution (FS) flow rates and FO outcome was assessed for varying DS and FS Reynolds number ratio. FO showed better flux outcome as Re ratio for DS and FS decreases and vice versa. Results indicated that by adjusting FO processes conditions, HFFO membrane could achieve significantly lower specific RSF and higher water flux outcome. It was observed that using 2 M NaCl as DS and deionized water as FS, HFFO successfully delivered flux of 62.9 LMH which is significantly high compared to many FO membranes reported in the literature under the active layer-DS membrane orientation mode. [ABSTRACT FROM PUBLISHER]

Fertilizer-drawn forward osmosis is a low-energy desalination concept particularly developed for the irrigation use of desalinated water. It has an advantage of not requiring regeneration of the draw solution (DS), thus, it can be used directly for the purpose of irrigation without any additional treatment. The current study was aimed to evaluate the real application of forward osmosis (FO) targeting irrigation of tomato crops based from their fertilizer requirements. Fertilizer-DSs were prepared to drive seawater desalination using commercially available fertilizers such as NH4NO3, NH4Cl, KNO3, KCl, NH4H2PO4, and urea. DSs were prepared to represent varying nitrogen:phosphorous:potassium (N:P:K) ratios used in assorted tomato growth stages. The FO performance evaluated in terms of the flux and reverse solute flux (RSF) showed significant variations in outcome. The resultant flux for different DSs was influenced by the particular fertilizer present in DS mixture and its concentration. This flux varied from 2.50 to 12.49 LMH. Comparatively, DS carrying high osmotic pressure components showed high-flux outcome. The fraction Jw/∆π of these fertilizer-DSs varied from 0.062 to 0.19 LMH/bar, which indicates a changing flux outcome against the same osmotic pressure. To select the best performing fertilizer-DS, nitrogen source fertilizers like urea, NH4NO3, and NH4Cl were further evaluated for 10-0-10 NPK value. It was found that NH4Cl-based DS mixtures performed better than urea- and NH4NO3-based DS. The RSF results indicated that all nitrogen- and potassium-based DS exhibited higher N- and K-RSF. However, the DS using NH4H2PO4 delivered extremely low P-RSF of 12.35 g/m²/h. Long-term run tests with seawater quality feed solution resulted in FO producing a final DS enriched in nutrients greater than the tomato plant’s requirement. This implies that the use of dilution or any other technique to reduce excessive nutrients is essential before using the final DS for tomato irrigation. [ABSTRACT FROM AUTHOR]

This study describes the fabrication of sulfonated polyethersulfone (SPES) as a super-hydrophilic substrate for developing a composite forward osmosis (FO) membrane on a nonwoven backing fabric support. SPES was prepared through an indirect sulfonation procedure and then blended with PES at a certain ratio. Applying SPES as the substrate affected membrane properties, such as porosity, total thickness, morphology, and hydrophilicity. The PES-based FO membrane with a finger-like structure had lower performance in comparison with the SPES based FO membrane having a sponge-like structure. The finger-like morphology changed to a sponge-like morphology with the increase in the SPES concentration. The FO membrane based on a more hydrophilic substrate via sulfonation had a sponge morphology and showed better water flux results. Water flux of 26.1 L m−2 h−1 and specific reverse solute flux of 0.66 g L−1 were attained at a SPES blend ratio of 50 wt % when 3 M NaCl was used as the draw solution and DI water as feed solution under the FO mode. This work offers significant insights into understanding the factors affecting FO membrane performance, such as porosity and functionality. [ABSTRACT FROM AUTHOR]

In this study, a novel thin-film nanocomposite forward osmosis (FO) membrane incorporated with plasma functionalized graphene nanoplatelets (GNPs) was developed. The well distributed GNPs in the polyethersulfone (PES) support increased the substrate porosity by 8%, and significantly improved the substrate tensile modulus even at a higher loading of GNPs. Unlike graphene oxide (GO), the linear increase in tensile strength with increasing the GNPs loading is due to the good dispersion properties of GNPs. The results indicated that in terms of water flux improvement, the optimal amount of GNPs incorporation is 0.3 wt%, while in terms of tensile strength, adding higher amounts of GNPs does not decrease the membrane stiffness even at 1 wt% of loading. The GNPs addition also significantly reduced the membrane structural parameter from 1323 µm with 0 wt% to 449 µm with 0.5 wt% loadings. Under the FO mode, water flux of 28.1 LMH was obtained for the membrane with the 0.5 wt% GNPs loading using 2 M NaCl as draw solution and DI water as feed. Overall, this study recommends that applying GNPs for the FO membrane development may be promising considering all types of FO applications where different membranes with different properties are required. [Display omitted] • A novel thin-film nanocomposite forward osmosis (FO) membrane was synthesized. • Plasma functionalized GNPs were incorporated into PES support as nanofillers. • The well distributed GNPs in the PES support increased the substrate porosity by 9%. • The flux of 29.3 LMH was obtained for the membrane with 0.5 wt% GNPs loading. • The tensile modulus of the substrate improved even at a higher loading of GNPs. [ABSTRACT FROM AUTHOR]

In this study, charcoal-based carbon nanomaterial (CNM) was used to modify thin film composite (TFC) membranes for forward osmosis (FO) process. Different amounts of CNM were incorporated into polyethersulfone (PES) and the effects of CNM addition on hydrophilicity, roughness, and morphology of the prepared substrates were investigated. To fabricate the TFC-FO membranes, m-phenylenediamine (MPD) and trimesoyl chloride (TMC) were used for polyamide (PA) layer formation on the substrate surface. FO performance of the prepared TFC membranes was evaluated in both FO and pressure retarded osmosis (PRO) modes using deionized (DI) water as feed solution (FS) and 1 M NaCl solution as draw solution (DS). Also, to study the TFC membranes capability for desalination purposes, the Caspian Seawater was used as FS. It was found that incorporation of CNM into the TFC membrane substrate leads to the reduced structural parameter (S), significantly. The membrane containing 0.5 wt% CNM showed the best performance with water flux of 12.08 and 32.25 L.m−2.h−1 (LMH) in FO and PRO modes, respectively (approximately 3 times higher than that for the neat membrane). Also, J s /J w value significantly reduced from 1.40 to 0.25 g/L. This research demonstrated that charcoal-based CNM is a proper candidate for modification of the TFC-FO membranes to achieve high water flux and selectivity. ga1 • Novel TFC membrane was synthesized for FO process, successfully. • Charcoal-based CNM was used to modify the TFC membrane substrate. • CNM incorporation into the TFC membrane substrate reduced structural parameter. • Performance of the prepared TFC membrane was evaluated in both FO and PRO modes. • High water flux as well as high membrane selectivity was achieved. [ABSTRACT FROM AUTHOR]

• Novel carboxylated CNFs incorporated TFC forward osmosis membranes were developed. • The effect carboxylated carbon nanofibers (CNFs) on FO membrane was assessed. • With incorporation of 0.3 wt% CNFs, WCA of substrate reduced from 72.0 to 60.2º. • With incorporation of 0.3 wt% CNFs, porosity of substrate increased from 82.5 to 91.0 %. • FO membrane with lower structural parameters and least ICP was achieved. In this study, thin film composite (TFC) membranes were modified using carbon nanofibers (CNFs) for forward osmosis (FO) applications. Carboxyl functionalization of CNFs was performed to increase their surface hydrophilicity and dispersion in a polysulfone (PSF) matrix as the membrane substrate. Different concentrations of both carboxyl functionalized CNFs (f-CNFs) (0.1, 0.3, and 0.5 wt%,) and raw CNFs (0.3 wt%) were incorporated in the polymer matrix and hydrophilicity, porosity, surface roughness, tensile strength and morphology of the nanocomposite substrates were characterized. The optimal membrane was achieved based on the best performance (higher water flux and lower reverse solute flux). Thereby, the TFC membrane containing 0.3 wt% of the f-CNFs was selected as the optimal membrane. The FO water flux of this membrane was almost 2 times higher than the neat TFC membrane in both FO (active layer facing FS) and PRO (active layer facing DS) modes of operation. Water flux of 13.08 L m− 2 h− 1 and specific reverse solute flux of 0.24 g L− 1 were achieved when 1 M NaCl was used as the draw solution (DS) and Deionized (DI) water was used as the feed solution (FS) under the FO mode. Furthermore, incorporation of the f-CNFs decreased the structural parameter (S) of the TFC membranes leading to lower internal concentration polarization (ICP). From the results, it was concluded that the f-CNFs is a suitable candidate for TFC-FO membranes modification to achieve high membrane performance. [ABSTRACT FROM AUTHOR]

A novel low-cost polyvinyl chloride (PVC) membrane was synthesized by phase inversion and fast and facile bio-inspired technique was used for substrate modification of a thin-film composite (TFC) forward osmosis (FO) membrane. Using DI water as feed solution (FS) and 1 M NaCl as draw solution (DS), water flux (WF) ranging from 4.15 to 15.95 LMH and reverse salt flux (RSF) ranging from 0.87 to 3.50 gMH were produced when the dope polymer solution concentration decreased from 17 to 10 wt%. Then, the substrate with 10 wt% PVC was selected for modification and the substrate was coated by dopamine (DA) solution for 1 and 3 h to enhance the membrane hydrophilicity and facilitate interfacial polymerization. Compared to the pristine membrane, the 1 h polydopamine (PDA) modified membrane displayed higher WF (18.90 LMH) and lower RSF (3.35 gMH). Whereas, for the longer coating time, WF decreased (9.70 LMH) due to the membrane surface pores blocking by the PDA layer. Finally, for understanding whether the experimental data can be supported by a theoretical model, the obtained experimental results were compared with a developed computational fluid dynamics (CFD) model and the results showed acceptable agreement with each other. The results of this work introduce a low-cost and facile approach for FO membrane fabrication by utilizing PVC polymer and PDA coating. [ABSTRACT FROM AUTHOR]

• A 2D finite element model was developed for FO. • Concentration profile in support layer results from both ICP and reverse solute diffusion. • Porosity and tortuosity have big impacts on forward water and reverse salt fluxes. • Increasing porosity or decreasing tortuosity is not always desirable. • This work offers useful insights into developing high performance FO membranes. A 2D finite element model was developed to describe the forward osmosis (FO) process under steady-state conditions. Two approaches are applied to study forward water and reverse salt fluxes. In the first approach, the mathematical equations are formulated based on the bulk concentration differences between the feed and the draw solutions. Transfer resistances arising from internal concentration polarization, external concentration polarization and reverse salt flux are considered. The second approach is based on a complete computational fluid dynamic (CFD) model, both the constrictivity factor and the sorption coefficient are considered to enhance the accuracy of prediction. The CFD model provides a more realistic representation of the FO process than the first simple approach. Our CFD model shows that the concentration profile within the membrane support layer is a result of the coupled interaction between the dilutive internal concentration polarization and the reverse solute diffusion from the draw. Increasing porosity or decreasing tortuosity is not always desirable since it will also increase reverse salt flux. Forward water and reverse salt fluxes are independent on tortuosity or porosity alone, but dependent on their ratios. This work offers significant insights into developing high performance FO membranes with suitable porosity and tortuosity, thereby reducing internal concentration polarization and reverse salt diffusion. [ABSTRACT FROM AUTHOR]