Draw Solution Research Articles

Thermoresponsive Ionic Liquid with Different Cation-Anion Pairs as Draw Solutes in Forward Osmosis.

We synthesized various phosphonium- and ammonium-based ionic liquids (ILs), using benzenesulfonate (BS) and 4-methylbenzenesulfonate (MBS) to establish the criteria for designing an ideal draw solute in a forward osmosis (FO) system. Additionally, the effects of monocationic, dicationic, and anionic species on FO performance were studied. Monocationic compounds ([P4444][BS], [P4444][MBS], [N4444][BS], and [N4444][MBS]) were obtained in one step via anion exchange. Dicationic compounds ([(P4444)2][BS], [(P4444)2][MBS], [(N4444)2][BS], and [(N4444)2][MBS]) were prepared in two steps via a Menshutkin SN2 reaction and anion exchange. We also investigated the suitability of ILs as draw solutes for FO systems. The aqueous [P4444][BS], [N4444][BS], [N4444][MBS], and [(N4444)2][BS] solutions did not exhibit thermoresponsive behavior. However, 20 wt% [P4444][MBS], [(P4444)2][BS], [(P4444)2][MBS], and [(N4444)2][MBS] had critical temperatures of approximately 43, 33, 22, and 60 °C, respectively, enabling their recovery using temperature. An increase in IL hydrophobicity and bulkiness reduces its miscibility with water, demonstrating that it can be used to tune its thermoresponsive properties. Moreover, the FO performance of 20 wt% aqueous [(P4444)2][MBS] solution was tested for water flux and found to be approximately 10.58 LMH with the active layer facing the draw solution mode and 9.40 LMH with the active layer facing the feed solution.

Antifouling forward osmosis membranes by ε-polylysine mediated molecular grafting for printing and dyeing wastewater: Preparation, characterization, and performance

Membrane fouling during forward osmosis (FO) seriously affects the service life of the membrane and increases the treatment cost. A facile strategy was developed to mitigate membrane surface fouling and simultaneously achieve high pollutants rejection. The amino group on ε-Polylysine (PL) reacted covalently with the active sites (acyl chloride and carboxyl group) on the polyamide (PA), thereby grafting the ε-PL onto the PA active layer of PAN/LiCl supported membrane. Effects of membrane orientation, concentration of draw solution (DS), and pH of feed solution (FS) on pollutants rejection were investigated. Results showed that rejection efficiencies of TOC, Ca, Mg, Sb, Cr, and aniline in wastewater by the 0.5 wt% PL-grafted PAN-1.5LiCl TFC-FO membrane (FO-0.5 PL) attained 93.3%, 96.7%, 99.3%, 98.3%, 99.9%, and 99.8%, respectively. The high rejection efficiencies were mainly attributed to the improvement of the surface hydrophilicity of the grafted membrane, the reduction of the roughness, and the improvement of membrane surface potential. The microbubble-assisted cleaning experiment showed that the flux recovery efficiency of the FO-0.5 PL membrane could reach 98.8%, which is 6% higher than that of the FO-P membrane. The PL-grafted FO membrane simultaneously improves the stability of permeation flux (15.2 L m−2 h−1) and fouling resistance performance of the membrane. This study revealed that the PL grafted method can improve the antifouling performance of the membrane and can be used as a feasible treatment method for printing and dyeing wastewater. The research results provided a new idea for facile preparation and application of FO membranes and had a certain reference value for the development of antifouling FO membrane.

Forward Osmosis Technology and Its Application on Microbial Fuel Cells: A Review.

As a new membrane technology, forward osmosis (FO) has aroused more and more interest in the field of wastewater treatment and recovery in recent years. Due to the driving force of osmotic pressure rather than hydraulic pressure, FO is considered as a low pollution process, thus saving costs and energy. In addition, due to the high rejection rate of FO membrane to various pollutants, it can obtain higher quality pure water. Recovering valuable resources from wastewater will transform wastewater management from a treatment focused to sustainability focused strategy, creating the need for new technology development. An innovative treatment concept which is based on cooperation between bioelectrochemical systems and forward osmosis has been introduced and studied in the past few years. Bioelectrochemical systems can provide draw solute, perform pre-treatment, or reduce reverse salt flux to help with FO operation; while FO can achieve water recovery, enhance current generation, and supply energy sources for the operation of bioelectrochemical systems. This paper reviews the past research, describes the principle, development history, as well as quantitative analysis, and discusses the prospects of OsMFC technology, focusing on the recovery of resources from wastewater, especially the research progress and existing problems of forward osmosis technology and microbial fuel cell coupling technology. Moreover, the future development trends of this technology were prospected, so as to promote the application of forward osmosis technology in sewage treatment and resource synchronous recovery.

Effects of feed and draw solution temperature on the performance of Aquaporin HFFO.6 membrane in forward osmosis

Recently, forward osmosis (FO) has attracted attention in many potential applications including food processing, fertilizers and manufacturing industries. This study investigates the effects of feed solution (FS) and draw solution (DS) temperature on the water flux, reverse salt flux, and specific reverse salt flux. The temperature of both the DS and FS were varied at the same time. Four typical temperatures such as 20 °C, 25 °C, 30 °C and 35 °C were selected to maintain at FS and DS sides, respectively, for each iteration. Except for the temperature, the other operating conditions like concentration, flow rates, and the type of membrane used were not varied in this experiment. The experiments were performed with tap water as FS and 1.5 M of NaCl as DS. The flow rates of the DS and FS were maintained at 15 L min−1 and 25 L min−1, respectively. The membrane used was the hollow fiber forward osmosis (HFFO.6) membrane procured from Aquaporin A/S, Denmark. The results showed that as temperature increased from 20 °C to 35 °C, the water flux, reserve salt flux (RSF), and specific reverse salt flux were enhanced. This was due to the enhanced diffusion coefficient of both DS and FS on increasing the temperature. This further reduces the concentration polarization and in turn augments the water flux. However, consequently, reverse and specific reverse solute flux also increased on temperature, which is not desirable for an efficient FO system. Hence, it is recommended to operate the FO at a minimum required temperature considering the other influencing other operational parameters such as specific reverse solute flux, recovery and rejection percentage.

Performance evaluation of deep eutectic solvent as a draw solute and vertical up-flow forward osmosis module for desalination of seawater.

Forward osmosis (FO) has gained prominence in recent years particularly in desalination due to its ability to operate at low or no hydraulic pressure, with relatively limited membrane fouling and high-water recovery. However, pre-treatment of seawater is required to reduce membrane fouling caused by the presence of suspended solid particles. Also, a significant area of research in forward osmosis is still finding a suitable draw solute(DS) with the ideal characteristics. In this study, a novel deep eutectic solvent (DES) draw solute was used and able to extract water after the 500% dilution of DS. This signifies it as the potential candidate for the ideal DS. A comparative study of plate and frame and vertical up-flowforward osmosis (VUF) FO modules has been evaluated to eliminate the drawbacks associated with FO in terms of membrane fouling and draw solute. In addition, the performance of a novel DES as reline (choline chloride-urea) has been tested in both the modules. In VUF module, significantly less fouling was observed than in the plate and frame module. The initial water flux in plate and frame module was 2.30 LMH with seawater (without pre-treatment) as feed. However, it dropped to 1 LMH after 26h of run. However, initial water flux in VUF was 1.90 LMH, and it was maintained to 1.50 LMH after 89h of run. Regeneration of draw solute was carried out using a phase separation method and it was observed that phase separation was only observed for 10% dilution of DES.

Modeling and Evaluation of the Permeate Flux in Forward Osmosis Process with Machine Learning

Predicting the permeate flux is critical for evaluating and optimizing the performance of the forward osmosis (FO) process. However, the solution diffusion models have poor applicability in accessing the FO process. Recently, the data-driven eXtreme Gradient Boosting (XGBoost) algorithm has been proven to be effective in processing structure data in engineering problems and has not been utilized to assess the FO process. Herein, a combination of the XGBoost model with a genetic algorithm (GA) was first proposed to predict the permeate flux, highlighting its superiority in the FO process through comparison of the support vector regression (SVR) model, the artificial neural network (ANN), and the multiple linear regression (MLR). Moreover, the performance of these models was optimized by tuning hyperparameters with a genetic algorithm (GA) and compared via Taylor Diagram. Among these machine learning (ML) models, the GA-based XGBoost model is superior to the other three models in terms of mean square error (MSE, 2.7326) and coefficient of determination (R2, 0.9721) on the test data, and its prediction power was compared to that of the solution diffusion (SD) model in the literature. Finally, further insight into the feature importance that affects the permeate flux in the FO process was examined by utilizing the SHapley Additive exPlanations (SHAP) to estimate the contribution value of various variables. The results demonstrated that the XGBoost model could predict the permeate flux in the FO system with high accuracy and good generalization ability for the given data set and even on the unseen data. Furthermore, the findings of the SHAP method show that the osmotic pressure difference, the osmotic pressure difference of draw solution and FS solution, the crossflow velocity of the feed solution and draw solution, and the water permeability coefficient have a significant impact on water flux.

Zwitterionic forward osmosis membrane with low structural parameter based on highly porous polyvinylidene fluoride substrate for desalination

Polyamide thin-film composites (PA-TFC) forward osmosis (FO) membranes have great potential in wastewater treatment and desalination. However, they are continuously studied to further enhance the FO performances from the improvement of the PA layer and the substrate individually. Here, a polyvinylidene fluoride/poly(hydroxyethyl methacrylate) (PVDF/PHEMA) membrane with a highly porous surface was fabricated and used as the substrate to engineer a thin and rough PA layer. After being post-modified by zwitterionic groups, the resulting membrane (namely TFC90-Z) has a much lower structure parameter ( S , 216 ± 12 µm) in comparison to common FO membranes in literature, thus decreasing internal concentration polarization and increasing FO performances. Specific salt flux ( J s /J w ) and water flux ( J w ) of TFC90-Z are 0.03 ± 0.01 g/L and 18.5 ± 0.4 L m -2 h -1 under the active layer-facing draw solution (AL-DS) orientation using 1.0 M NaCl as the draw solution and deionized water as the feed solution. Meanwhile, NaCl rejection is 91.6 ± 0.1%. This work offers an efficient way to engineer excellent PA-TFC FO membranes for aqueous separation and desalination. • PA-TFC FO membranes were fabricated on highly porous PVDF/PHEMA substrates via IP. • The PA layer was post-modified by zwitterionic groups via co-deposition of TA and AEPPS. • ICP is weakened due to the low structure parameter of the zwitterionic PA-TFC FO membrane. • The as-prepared FO membrane has excellent FO performances especially specific salt flux ( J s /J w ).

Polyamidoamine and carboxylated cellulose nanocrystal grafted antifouling forward osmosis membranes for efficient leachate treatment via integrated forward osmosis and membrane distillation process

Organic fouling remains an intractable challenge for forward osmosis (FO) and integrated FO-membrane distillation (MD) strategy to treat landfill leachate. To address this challenge, polyamidoamine (PAMAM)/polydopamine (PDA) and carboxylated cellulose nanocrystal (CCN) were grafted gradually on the commercial thin film composite (TFC) FO membranes via chemical coupling to achieve excellent antifouling capacity. PAMAM dendrimers, with abundant terminal amines, hyperbranched structure and open interior cavity, served as a unique intermediate platform for chemically covalent attachment of CCN with high water affinity, then cooperated with CCN to form a hydrophilic and robust antifouling layer. Compared to the raw TFC membrane, the PAMAM/PDA-CCN modified TFC membrane exhibited a similar water flux of 30.6 L m−2 h−1 (LMH) accompanied with a decreased reverse salt flux of 6.9 g m−2 h−1 (gMH) by using 1 M NaCl solution as draw solution (DS) and DI water as feed solution (FS). When actual leachate was used as FS, the modified FO membranes possessed significantly enhanced antifouling capacity with a lower flux decline (≤43.7%) and a higher flux recovery rate (≥94.2%) than the raw TFC membrane (flux decline ≤59.4% and flux recovery rate ≥79.0%, respectively). The improved fouling resistance could be further demonstrated by the reduced thickness of the organic fouling layer. Eventually, the employment of the modified FO membranes improved the compatibility of the FO and MD water fluxes and achieved sustained water production. The construction of synergistic dendritic PAMAM and CCN grafted surface paves a new way for the development of high-performance water treatment membranes.

A cobalt-based forward osmosis draw solute synthesized from lithium-ion battery wastes for cobalt-containing wastewater purification

The demand to remove Co2+ ions from industrial wastewater is escalated due to the rapid growth of lithium-ion batteries (LIB) as power storage in personal electronic devices. Herein we report a novel cobalt-based draw solute, Co-Bet-Tf2N, synthesized from lithium-ion battery (LIB) wastes, in a forward osmosis (FO) process to purify Co2+-containing wastewater discharged from the LIB industry. Co-Bet-Tf2N possesses abundant –NMe3+ groups and releases multiple ionic species in water, allowing it to produce a high osmotic pressure to drive FO separation efficiently; meanwhile its three-dimensional structure prevents the reverse Co-Bet-Tf2N diffusion in FO experiments. Consequently, a dilute Co-Bet-Tf2N solution (0.2 mol/L) generates a water flux as high as 14.7 LMH along with a negligible solute loss (< 0.02 g/L), outperforming other reported draw solutes. Moreover, Co-Bet-Tf2N extracts water from the Co2+-containing wastewater more efficiently with a water flux 232 % and 174 % higher than those of the conventional NaCl and MgCl2 draw solutes, respectively. Particularly, Co-Bet-Tf2N is easily regenerated via the [Hbet][Tf2N]-based extraction without energy input, thus more practical than the recycling of other draw solutes reported elsewhere. This study not only demonstrates the superiority of Co-Bet-Tf2N as a novel draw solute, but achieves effective waste reuse and wastewater reclamation.

Unraveling effects of multivalent salts on internal fouling by proteins in NF-like forward osmosis

Multivalent salts are preferentially used as the draw solute for forward osmosis (FO) with a nanofiltration (NF)-like membrane, which promises advantages in the treatment of protein-containing feeds. When assessing the phenomenon of back diffusion, particular concerns are raised about the complex interplay between the protein foulants and the polymeric network of the substrate in the presence of various multivalent salts. This study employed a composite membrane (fabricated by the Layer-by-Layer assembly of polyelectrolytes on a hydrolyzed polyacrylonitrile substrate) to filter a feed solution containing proteins having a distinct isoelectric point (i.e., bovine serum albumin and lysozyme), while varying the cationic valence and the acidity/basicity of the draw solution (using sodium sulfate, magnesium sulfate, ammonium sulfate, and sodium citrate). Individual effects on the proteins and the substrate were examined by ex-situ characterization based on model-predicted concentrations of the multivalent salts back-diffused into the porous network. Optical coherence tomography was exploited to noninvasively detect the spatiotemporal evolution of protein-polymer interactions, which was quantified by evaluating the surface-averaged intensity. In terms of the characterization results, the protein-polymer interactions were varied by the back-diffusion of neutral and acidic salts such that the internal fouling by proteins could evolve in a bottom-up or top-down way; in contrast, the use of basic salt would mitigate the internal fouling probably owing to the stronger electrostatic repulsion. This study provides a clearer picture of how the substrate network could be fouled by proteins, thereby shedding light on the development of anti-fouling strategies for NF-like FO.

Assessment of ultrasound-assisted forward osmosis process performance for seawater desalination using experimental factorial design

The effect of ultrasound on water flux through forward osmosis membrane for seawater desalination was investigated using the factorial design approach. Sodium chloride (NaCl) was used to simulate the dissolved solids content. In every test, the initial draw solution (DS) concentration was fixed at 4.5 M for NaCl and 2 M for MgCl2. Parameters considered in the investigation included membrane crossflow velocity (0.25 and 1.0 cm/s), flow configuration (co-current versus counter-current), direction of ultrasound waves relative to the membrane side (active layer versus support layer), and type of draw solution (NaCl versus MgCl2). A two-level factorial design was considered in the analysis of the results obtained from the experimental work. Based on the factorial design analysis, crossflow velocity and use of ultrasound have a positive effect on water flux enhancement for both draw solutions. However, the velocity effect on water flux enhancement was more pronounced than that of the use of ultrasound. The effect of flow configuration was statistically insignificant for both draw solutions. The interaction effect between crossflow velocity and ultrasound was statistically significant for both draw solutions. However, the interaction between crossflow velocity and flow configuration was only significant for the case of MgCl2. The three-way interaction was insignificant for both draw solutions. The developed factorial model equations were used to predict other flux data in ultrasound-assisted FO systems and showed adequate representation of these data at relatively similar conditions after adjustment of the model for the baseline conditions of the evaluated cases.

Industrial scale thin-film composite membrane modules for salinity-gradient energy harvesting through pressure retarded osmosis

The current work highlights development of novel thin-film composite hollow fiber membranes for pressure retarded osmosis applications to harvest salinity gradient energy. The membranes were developed with a specific target of harnessing the salinity gradient energy between wastewater reverse osmosis retentate and seawater reverse osmosis brine via osmotic mixing. The hollow fiber membranes were prepared by coating a polyethersulfone substrate with a thin-film composite polyamide layer via interfacial polymerization, which were assembled into modules of different diameters for lab scale and pilot scale evaluation. As the module size increased from 1-in. to 2-in., and 4-in., the water permeability, tested against a 1000 mg/L sodium chloride solution at 15 bar, decreased from 2.6 L m−2 h−1 bar−1 to 2.0 L m−2 h−1 bar−1, and 1.2 L m−2 h−1 bar−1, respectively. The power density, measured in the lab-scale unit using 1 M sodium chloride draw solution, and DI water feed solution, also decreased from 9.1 W/m2 to 5.3 W/m2 with increasing module size. Pilot scale evaluation of the 4-and 8-in. modules on a 24 m3/day unit resulted in lower power densities of 2.5 W/m2 and 1.5 W/m2 which translated to 0.024 kWh/m3 and 0.05 kWh/m3 of salinity-gradient energy harvested, respectively.

Complete parametric investigation of a forward osmosis process using sodium chloride draw solution

The design and operation of FO systems require accurate prediction of performance according to the operating parameters. Performance parameters such as water flux, reverse solute flux (RSF), specific reverse solute flux (SRSF), recovery and rejection are influenced by operating parameters including temperature, concentration difference (CD), and flow rates of feed solution (FS) and draw solution (DS). Whereas previous studies analysed the effect of only one or two operating parameters on one or two output parameters, this study provides a complete investigation into the effects of all operating parameters on all output parameters important for performance. A bench-scale FO setup using an advanced FO membrane and NaCl draw solution has been studied and compared to a predictive model, giving agreement within 10 %. Water flux and RSF increased with temperature, CD and flow rate. SRSF decreased with temperature, increased with CD, and increased as flow rates of FS and DS increased. Increasing temperature or CD increased the recovery; whereas increasing the flow rate of FS or DS reduced the recovery. Rejection dropped at higher CD and flow rates. Hence, it is recommended to operate at lower CD and flow rates to achieve higher recovery and rejection.

Effect of the Structural Changes in a Styrenesulfonate-Based Draw Solute Having a Lower Critical Solution Temperature for the Forward Osmosis Process

Effect of the Structural Changes in a Styrenesulfonate-Based Draw Solute Having a Lower Critical Solution Temperature for the Forward Osmosis Process

Highly permeable thin film nanocomposite membrane utilizing a MoS2@NH2-UiO-66 interlayer for forward osmosis removal of Co2+, Sr2+ and Cs+ nuclide ions

Novel MoS2@NH2-UiO-66 thin-film nanocomposites with interlayer (TFNi) membranes were developed to improve forward osmosis (FO) membrane performance. The prepared TFNi membrane shows a high water permeability of 38.13 ± 0.8 L m−2h−1 and low reverse salt flux (JS/JV) of 0.038 when using 2.0 mol/L sodium chloride as the draw solution (DS) and deionized water as the feed solution (FS) under AL-FS mode. This is attributed to MoS2@NH2-UiO-66 modifications of substrate properties, which fix m-phenylenediamine (MPD) on the nanomaterial surface, increase the polyamide (PA) layer crosslinking degree on the material surface, and allow trimesoyl chloride (TMC) to stay on the substrate surface during interfacial polymerization (IP) and prevent accumulation in the pores of the substrate. Therefore, the trade-off between permeability and selectivity of TFN membranes is overcome. The MoS2@NH2-UiO-66 TFNi membrane effectively removes Co2+, Sr2+ and Cs+ from aqueous solution via FO retention. When Co2+, Sr2+ and Cs+, nuclide ions with small hydration radii, are present in the FS at 20 mg/L, the retention rates are maintained at 99.6%, 99.7% and 97%, respectively, which are higher than those of existing commercial membranes. These results indicate the potential of MoS2@NH2-UiO-66-TFNi membranes for treatment of nuclide ions in wastewater.

Feasibility of Poly (Vinyl Alcohol)/Poly (Diallyldimethylammonium Chloride) Polymeric Network Hydrogel as Draw Solute for Forward Osmosis Process.

Forward osmosis (FO) has been identified as an emerging technology for the concentration and crystallization of aqueous solutions at low temperatures. However, the application of the FO process has been limited due to the unavailability of a suitable draw solute. An ideal draw solute should be able to generate high osmotic pressure and must be easily regenerated with less reverse solute flux (RSF). Recently, hydrogels have attracted attention as a draw solution due to their high capacity to absorb water and low RSF. This study explores a poly (vinyl alcohol)/ poly (diallyldimethylammonium chloride) (PVA-polyDADMAC) polymeric network hydrogel as a draw solute in forward osmosis. A low-pressure reverse osmosis (RO) membrane was used in the FO process to study the performance of the hydrogel prepared in this study as a draw solution. The robust and straightforward gel synthesis method provides an extensive-scale application. The results indicate that incorporating cationic polyelectrolyte poly (diallyldimethylammonium chloride) into the polymeric network increases swelling capacity and osmotic pressure, thereby resulting in an average water flux of the PVA-polyDADMAC hydrogel (0.97 L m-2 h-1) that was 7.47 times higher than the PVA hydrogel during a 6 h FO process against a 5000 mg L-1 NaCl solution (as a feed solution). The effect of polymer and cross-linker composition on swelling capacity was studied to optimize the synthesized hydrogel composition. At 50 °C, the hydrogel releases nearly &gt;70% of the water absorbed during the FO process at room temperatures, and water flux can be recovered by up to 86.6% of the initial flux after 12 hydrogel (draw solute) regenerations. Furthermore, this study suggests that incorporating cationic polyelectrolytes into the polymeric network enhances FO performances and lowers the actual energy requirements for (draw solute) regeneration. This study represents a significant step toward the commercial implementation of a hydrogel-driven FO system for the concentration of liquid-food extract.

Selective and high-efficient removal of tetracycline from antibiotic-containing aqueous solution via combining adsorption with membrane pre-concentration

The antibiotics in the livestock sewerage are responsible for antimicrobial resistance, causing a global public health crisis and necessitating high-efficient and environmental-friendly antibiotic treatment processes. Herein, one membrane pre-concentration and MOF-based selective adsorption hybrid system is proposed to high-efficiently remove tetracycline (TC) from the aqueous solution containing other two representative antibiotics (sulfamethoxazole (SMZ), and trimethoprim (TMP)) in the livestock sewage. In this work, two common MOFs-based materials (MIL-101-Fe and NH2-MIL-101-Fe) are employed as the adsorbents to selectively remove TC from the solution. Adsorption experiments showed that the selective coefficient of NH2-MIL-101-Fe for TC could reach up to 95 %, because of stronger interaction between TC and MIL-101s calculated via the theoretical simulation. Also, experimental results demonstrated that the desired operating conditions necessitated thermal input and pre-concentration operation. Accordingly, temperature-enhanced forward osmosis (T-FO) and temperature-enhanced osmotic membrane distillation (T-OMD) were proposed to concentrate the solution containing these three antibiotics in the cost-effective way where the fertilizer solution (KCl in this work) was used as the draw solution (DS) and diluted DS solution could be used in agricultural fertigation. Membrane pre-concentration experiments showed that TC, TMP, and SMZ could be theoretically concentrated in T-FO, but high TC and KCl leakage and inevitable water flux decline behavior significantly sacrificed the concentration efficiency, thereby initiating the application of T-OMD. Higher and more stable water flux occurred in T-OMD, and 99.76 % of antibiotic and KCl leakage could be mitigated compared to T-FO, thereby providing one option to high-efficiently remove antibiotics in livestock sewerage and achieve agricultural fertigation.

Effect of the Alkyl Chain Length on Assessment as Thermo-Responsive Draw Solutes for Forward Osmosis.

A series of thermo-responsive tetrabutylphosphonium 1-alkanesulfonates (abbreviated as [P4444][C n S], n = 6, 8, 10, and 12), where n is the number of carbon atoms in the alkyl group on the 1-alkanesulfonate anion, were prepared by an ion-exchange reaction to investigate their potential ability toward the application of draw solutes in forward osmosis (FO). We systematically studied the recovery properties and FO performance of [P4444][C n S]. This series exhibited lower critical solution temperature (LCST) characteristics, which offer a clear advantage of being energy-efficient for recovering draw solutes; however, [P4444][C6S] was only observed at 20 wt %. The LCSTs of the 20 wt % [P4444][C6S], [P4444][C8S], [P4444][C10S], and [P4444][C12S] draw solutions were approximately 83, 54, 49, and 56 °C, respectively. Moreover, when the orientation of the active layer was heading toward the draw solution (AL-DS mode), the water and reverse solute flux of [P4444][C10S] were about 1.58 LMH and 0.81 gMH, respectively, at 20 wt % aqueous solutions. When the membrane was used in the active layer facing the feed solution (AL-FS) system, the water and reverse solute flux of [P4444][C10S] were approximately 0.71 LMH and 0.38 gMH, respectively, at 20 wt % aqueous solutions. Thus, this study is the first to examine the structural transformations of the bulkier alkyl group on the sulfonate anion moiety and its feasibility as the new draw solute for the FO system.

Fouling limitations of osmotic pressure‐driven processes and its remedial strategies: A review

AbstractThe scarcity of freshwater is one of the major challenges to the civilized community around the World. So, the various engineered processes have been developed for the remediation of this problem such as osmotic pressure‐driven processes (OPDPs). OPDPs includes forward osmosis and pressure retarded osmosis, which have gained enormous attention and becoming a flexible membrane‐based technology for desalination and wastewater treatment. The most significant components of the OPDPs to be efficient are the membranes and the draw solution. Although numerous studies highlighted the membrane fouling and concentration polarization are one of the critical parameters to assess the system efficiency in the OPDPs and other pressure driven membrane processes. This study delivers an up‐to‐date review of the OPDPs in terms of concentration polarization, membrane fouling (organic, inorganic, and biofouling), foulant interactions, remedial strategies, monitoring and characterization techniques, and future directions of research. Numerous foulant interactions are also elaborated for the OPDPs in the field of the membrane separation technique. State of the art in antifouling membrane fabrication methods are critically reviewed along with different remedial strategies for fouled membranes in OPDPs.

Assessment of highly concentrated pear juice production through single-run forward osmosis using sodium lactate as the draw solute

Forward osmosis (FO) is a competitive alternative of thermal process for food liquid concentration. In this work, highly concentrated pear juice (TSS >60 °Bx, concentration factor ∼ 6.5-fold) was successfully produced by a single-run FO process using sodium lactate (NaLA) as the draw solute, and the properties of concentrates were compared with those produced by vacuum evaporation. The evolution of water flux, process resistance as well as the key physicochemical properties of pear juice over time during FO were assessed. The rheological properties of pear juice concentrates and salt accumulation during concentration were also analyzed. The results suggest that NaLA is a powerful draw solute as it can not only provide sufficient driving force to concentrate the pear juice from TSS 9.6 °Bx to 62 °Bx by a single-run treatment without any recharge of draw solute, but also deliver pear juice concentrates of better quality with higher antioxidant capacity, non-browning delightful color and richer aroma and flavor compared to those produced by vacuum evaporation. This work offers a reference of both theoretical and practical aspects for liquid food processing in the future. • Sodium lactate could be a promising draw solute for juice concentration. • Pear juice could be concentrated to 62 °Bx (6.5-fold) by a single-run FO process. • Overall concentrate quality of FO is much better than vacuum evaporation.