The efficient treatment of landfill leachate using a novel osmotic microbial fuel cell system employing forward osmosis membrane featuring proton-conducting medium.

Internal concentration polarization (ICP) in the support layer significantly decreases the water flux performance of forward osmosis (FO) membranes. To overcome this, we developed a novel method for creating a highly porous support layer using ZIF-67 nanoparticles as a sacrificial template. The ZIF-67 nanoparticles were synthesized in a polymer casting solution at different precursor concentrations, including Co2+ and 2-methylimidazole. This method enhances nanoparticle dispersion in the support layer and enables scalable membrane fabrication. ZIF-67 nanoparticles are incorporated into the support layer matrix during phase inversion, then removed by immersing the ZIF-67-incorporated support layer in water, yielding a porous support layer. The modified support layer exhibited a porosity of 83%, which is 15% higher than that of the unmodified membrane, attributed to the templating effect of ZIF-67 nanoparticles. The performance of TFC-FO membranes was evaluated in a FO setup to correlate improved support layer characteristics with FO separation performance. The TFC-2 membrane (fabricated with 3.0 wt.% ZIF-67 precursors) exhibited water fluxes of 29.5 LMH (in FO mode) and 56.4 LMH (in PRO mode), representing a 2.3-fold increase compared to that of the control TFC membrane (13.2/24.6 LMH in FO/PRO modes, respectively). Additionally, the structural parameter decreased from 593µm in TFC to 242µm in TFC-2 membranes, indicating a substantial reduction in ICP. These results demonstrate that the in-situ synthesis of ZIF-67 as a sacrificial template is a simple and effective strategy for preparing high-porosity support layers with reduced ICP.

Modification of thin-film nanocomposite forward osmosis membranes with an antimicrobial carboxymethyl starch-ZnO@MOF-199 nanocomposite for heavy metals and dyes pollutants removal.

Fabrication of NH2-MIL-125(Ti) modified photocatalytic forward osmosis membrane for treating tetracycline hydrochloride and ibuprofen solution

Thin-film composite forward osmosis membranes with a sulfonated polypropylene support for enhanced performance

Catalyzed in-situ amination of support layer for thermally stable forward osmosis membranes in industrial dyeing wastewater concentration

The Smackover Formation brines in southern Arkansas contain a large quantity of lithium, a critical resource for electric vehicle batteries and the global energy transition. To extract the lithium, efficient downstream enrichment technologies are urgently needed. Methods for direct lithium extraction are being explored, followed by further purification and concentration of the lithium salt solution, such as using reverse osmosis, which is energy intensive. Here we use reduced graphene oxide (RGO) membrane-based forward osmosis (FO) as an environment-friendly and near zero-energy input method to concentrate lithium brine. In the FO tests, a saturated NaCl solution serves as a draw solution and either a dilute lithium nitrate (LiNO3) solution (50.4 mM) or an artificial lithium brine (1.00 M NaCl + 12.0 mM LiNO3) as a feed solution, where LiNO3 is selected to mimics the typical LiCl component in lithium brine. Because nitrates have a unique absorption feature at ∼300 nm, their concentrations in both the feed and draw solutions can be monitored by a facile ultraviolet-visible (UV-Vis) absorption spectral method. For the dilute LiNO3 solution, a rejection rate is determined to be 97.9 ± 0.1%, with a water flux of 6.2 ± 0.2 L/hm2. For the artificial brine, a rejection rate of 88.4 ± 0.1% and a water flux of 5.0 ± 0.2 L/hm2 are observed. With further optimization, this forward osmosis approach could provide a more energy-efficient method for lithium salt enrichment, supporting sustainable lithium extraction from Smackover brines.

Abstract The detection of trace antibiotics in aquatic environments poses a critical global challenge, threatening both ecological safety and public health. Forward osmosis (FO) membrane separation technology has emerged as a highly efficient approach for purification of trace antibiotics, characterized by high treatment efficiency and low energy consumption. However, challenges inherent to the recycling of draw solutions restrict the development of FO technology. Herein, we report the synthesis and application of a novel CO 2 -responsive SiO 2 @PDEA nanocomposite as a highly recyclable particulate draw solution. This system leverages CO 2 /heat-triggered reversible switching between hydrophilicity and hydrophobicity to enable facile recovery. The 6 wt% SiO 2 @PDEA solution leads to a significantly enhanced water flux ( J w ) to 5.31 LMH (PRO mode), a threefold increase over bare SiO 2 . Crucially, the ratio of reverse solute flux ( J s ) to J w was minimized to 0.015 g/L, providing a substantial cost advantage over inorganic salts. The efficiency of this approach enabled a threefold concentration of tetracycline. Furthermore, the solution demonstrated outstanding cyclic stability with a solute recovery rate consistently exceeding 99% via mild thermal stimulation. These findings demonstrate that SiO 2 @PDEA is an exceptionally efficient, sustainable, and cost-effective draw solution with substantial potential for the practical remediation of trace antibiotic-containing wastewater.

Forward osmosis (FO) membranes face challenges in balancing high water permeability, low reverse salt flux (RSF), and mechanical durability. Although nanopores in graphene have great theoretical potential, the existing methods make it difficult to independently optimize the nanopores of the graphene layer and the microstructure of the substrate without damaging each other. Here, we propose a defect engineering strategy based on oxygen plasma etching to address this collaborative optimization challenge. Monolayer porous graphene (PG) was integrated with polysulfone (Psf) substrates, followed by oxygen plasma etching to introduce nanopores and oxygen-containing functional groups (e.g., carboxyl, hydroxyl). By controlling the etching time to 10 s, the resulting membrane (S-PG10) exhibited a water flux of 0.24 LMH in 0.5 M NaCl, representing an order-of-magnitude increase compared to the pristine graphene membrane (S-G). Remarkably, S-PG10 maintained a high salt rejection (>96%) and a low Js/Jw (<0.35 g·L-1). Substrate modification via short-term plasma etching (5 min) further doubled the water flux of S*5-PG10 (0.47 LMH in 0.5 M NaCl) by increasing porosity (81.8%→85.6%) and hydrophilicity. However, prolonged etching (>15 min) degraded mechanical strength and increased RSF due to pore structure disruption. To enhance robustness, Poly(D,L-lactic acid) (PDLLA)-doped substrates (S#-PG) were engineered, with 0.1 wt.% PDLLA optimizing mechanical properties while maintaining low RSF and high flux. Excessive PDLLA (10 wt.%) induced hydrophobicity and crystalline structures, reducing permeability. The study demonstrates that synergistic optimization of plasma etching duration on the graphene selective layer (5~10 s) and substrates (5 min) as well as PDLLA doping (0.1 wt.%) balances pore architecture, surface chemistry, and substrate integrity, achieving FO membranes with superior water-salt selectivity and mechanical stability. These findings provide critical insights into designing high-performance graphene-based membranes for sustainable desalination and water purification.

Membrane technology has garnered considerable attention for applications in wastewater treatment and resource recovery. Nevertheless, membrane fouling remains a major barrier, yet the lack of high-resolution non-destructive characterization techniques limits mechanistic understanding and model validation. Here, nanoscale secondary ion mass spectrometry (Nano SIMS) is introduced as a powerful analytical tool to visualize and quantify the fouling layers on forward osmosis (FO) membranes. Using sodium alginate as a model foulant and Ca2 + as a representative multivalent cation, Nano SIMS enabled simultaneous mapping of organic matter (1 2C-, 1 6O-) and Ca-associated matter (4 0Ca1 6O-), revealing the formation and structural evolution of Ca2 +-organic networks within the fouling layer. A binarization-based image analysis method was developed to quantify the polymer volume fraction (φ2), which increased markedly with Ca2 + concentration and correlated strongly with flux decline, providing direct experimental support for the application of Flory-Huggins thermodynamic theory to the interpretation of membrane fouling. Application to real landfill leachate further demonstrated that Nano SIMS retains strong ion-recognition specificity and is capable of resolving fouling structures in complex matrices. This work establishes Nano SIMS as a versatile and robust non-destructive characterization technique for membrane fouling research, offering new opportunities for mechanistic investigation and model development in water treatment technologies.

• Textile wastewater was treated by simultaneous forward osmosis and reverse osmosis. • FO draw solution was continuously concentrated by RO. • Chemical oxygen demand and total organic carbon were rejected above 99%. • Simultaneously, clean water was obtained as the reverse osmosis permeate. The concerning and abundant textile wastewater can be treated by forward osmosis (FO) in order to reduce its volume and simultaneously recover clean water. However, the productivity of FO depends on the concentration of the draw solution that is used. In this work, a simultaneous application of FO and reverse osmosis (RO) is proposed. The HFFO14® FO membrane (Aquaporin, Denmark) was employed to concentrate a real textile wastewater, whereas the SW30-2540 (DuPont, USA) RO membrane was employed to simultaneously regenerate the draw solution, which consisted in a 0.7 M NaCl solution, and to obtain a clean water stream. The concentration of the textile wastewater increased until 90% water recovery was achieved. The rejection values obtained for the chemical oxygen demand and total organic carbon were in the range 99 – 100%. Afterwards, the previously concentrated textile wastewater was again processed until a volume concentration factor of 16.5 was reached. Stable values of permeate flux (around 4 L/h·m 2 ) were obtained in the FO process, whereas the reverse osmosis step permitted the maintenance of a stable conductivity in the draw solution and provided clean water as permeate.

Fouling dynamics of forward osmosis membrane during multi-cycle concentration of hydrolysed and stabilized real human urine

Repurposing usage of oil refinery wastewater with retrofitted desalination technology necessitates the optimization of a forward osmosis (FO) technology. Herein, factors such as draw solution concentration (DS-C) and feed and draw solution flow rates (FS-FR, DS-FR) play significant roles. In this study, the individualistic and interaction effects of these factors were explored to ascertain the FO performance. The effects of these operating factors, DS-C (20-50 g/L), DS-FR (7.5-9.4 L/h), and FS-FR (7.5-9.4 L/h), and their interactive effects on the permeation flux and rejection of Cl-, SO42- and CO32- from oil refinery effluent, were studied using the Box-Behnken design (BBD) of response surface methodology (RSM). Statistical models were developed to optimize the operating conditions. The analysis of variance and the developed response models were used to evaluate the data at a 95% confidence level. Three confirmatory runs were conducted based on the optimum conditions (FS-FR: 9.2 L/h; DS-FR: 9.4 L/h; DS-C: 32.6 g/L). At a desirability of 81%, average rejections of 94.59 ± 0.32% for CO32- and 100% for SO42- were obtained. Average Cl- enrichment was 35.5 ± 5.15% and average permeation flux of 3.64 ± 0.13 L/m2 h were achieved, suggesting that RSM was a suitable tool for optimizing FO for desalinating the effluent. In addition, the average recovered permeation flux of 86.01 ± 2.66% demonstrated the effectiveness of the FO membrane after cleaning.

Reduced graphene oxide (RGO) forward osmosis (FO) membranes have emerged as promising candidates for efficient wastewater management and osmotic energy harvesting, due to their enhanced chemical stability and superior FO performance for low-energy waste brine treatments, such as volume reduction in oxidative chromium brine for cost-effective disposal. This study examines the oxidation resistance of RGO forward osmosis membranes against chromate Cr(VI). Our findings reveal that both the water flux and the reverse salt flux of RGO membranes are suppressed, accompanying an enhanced reverse flux selectivity after exposure to an acidic or neutral medium of Cr(VI) (pH 2.0–7.0). After exposure to a basic Cr(VI) medium of pH 10.0, an increase in reverse salt flux and a reduction in reverse flux selectivity are observed, which could be due to the synergistic effect of both pH and ionic solutes on the RGO membranes, not due to Cr(VI) oxidation. Remarkably, after the removal of chromate with a full rinse, the RGO membranes show a nearly complete recovery of their FO performance.

A thin, porous, and hydrophilic sublayer is essential in the forward osmosis (FO) process to minimize the structural parameter (S), thereby reducing internal concentration polarization (ICP). In this study, the polysulfone (PSf) sublayer of the FO membrane is modified with an amphiphilic graft copolymer, poly(sulfone)- graft -poly(2-hydroxyethyl methacrylate) (PSf-g-PHEMA). The PHEMA with terminal alkyne functional groups is synthesized via atom transfer radical polymerization (ATRP) and subsequently grafted onto azide-functionalized PSf using click reaction. Sublayers are prepared through the phase inversion process by adding different concentrations of the PSf-g-PHEMA copolymer to the PSf casting solution. Different analyses reveal substantial enhancements in the properties of the copolymer-blended sublayer, including improved hydrophilicity, porosity, pure water permeability, and optimized morphology. These improvements are attributed to the hydrophilic segments of the graft copolymer, which influence the phase inversion rate. The membrane containing 10 wt.% PSf-g-PHEMA exhibited the highest water flux in both pressure-retarded osmosis (PRO, 34.5 LMH) and FO (19.4 LMH) modes, compared to the unmodified thin-film composite (TFC) membrane (5.9 LMH). This performance is associated with a significantly reduced structural parameter (S, 478 μm), indicating effective mitigation of ICP. Overall, these findings highlight the significant potential of amphiphilic graft copolymers to enhance the performance of TFC-FO membranes. • Poly(sulfone)- graft -poly(2-hydroxyethyl methacrylate) (PSf-g-PHEMA) established as functional additive • Integration of PSf-g-PHEMA yields optimized PSf-based sublayers for polyamide thin-film composite forward osmosis (FO) membranes • Amphiphilic PSf-g-PHEMA as membrane modifier enhances FO performance by reducing the structural parameter

Data-driven modeling and explainable optimization of organic micropollutant removal in forward osmosis membranes

Nanoplastics-mediated interfacial processes controlling perfluorooctanoic acid transport in forward osmosis.

In-situ confinement growth of PEI-CaCO3@UiO-66 Nanohybrids for high-performance forward osmosis membranes with superior organic pollutant rejection and long-term stability

Investigation of forward osmosis membrane fouling mechanisms based on collision attachment theory: modeling and validation

Zwitterionic membranes are emerging as promising candidates for water treatment due to their highly hydrated surface layer. While common zwitterionic structures are well-established, there is a growing interest in incorporating varieties of cationic moieties without requiring an interfacial layer and while avoiding ester hydrolysis-prone bonds. However, few studies have investigated how the cationic moiety influences membrane performance. In this work, three polysulfone-based zwitterionic membranes were synthesized by varying the alkyl chain length, C4, C8, and C12 of the amine, while maintaining a constant sulfonate (SO3–) group. This set of membranes is analogous to that of polybetaines. Polymer modification was achieved via a surface ring-opening reaction between the 1,3-propane sultone (1,3 PS) and the amine-functionalized polysulfone (PSF-N). The fabricated membranes follow this labeling: PSF-zdiethylsulfonate (PSF-N+R4), PSF-zdibutylsulfonate (PSF-N+R8), and PSF-zdihexylsulfonate (PSF-N+R12). Structural characterization using 1H NMR and FTIR confirmed the successful completion of the zwitterion formation. Moreover, chain-length-dependent effects were observed in hydration behavior, surface charge, and morphology. All the modified membranes showed an enhancement in the surface hydrophilicity, with water contact angle values below 65°. In forward osmosis (FO), PSF-N+R4 had a 4-fold higher flux (57.2 ± 0.4) LMH over pristine PSF (9.3 ± 0.4) LMH. These water flux values are comparable to other works in the cited literature. Overall, these findings demonstrate the impact of cation design on the membrane performance and present a scalable approach for tuning zwitterionic materials. This work provides insight into the zwitterionic structure–function and another molecular view for the development of the next-generation FO membranes.