Copper(II)-induced alginate fouling in forward osmosis: a novel water-state perspective using low-field nuclear magnetic resonance (NMR)

In-situ growth of layer double hydroxides on TFC membranes to improve forward osmosis performance

Synergistic integration of forward osmosis coupled with tannic acid/Fe3+ black polyurethane sponge solar evaporators for high-efficiency municipal wastewater reclamation

ABSTRACT The acidic nature of mine water results in elevated concentrations of heavy metals, implying significant pressures on aquatic ecosystems. Mine water treatment consists of objectives: reducing environmental harm by removing contaminants and providing alternative water sources and enabling metal recovery. This study employed forward osmosis to evaluate the treatment of simulated mine water, investigating the effects of draw solution concentration (0.5 and 1 M EDTA), pH levels (4, 7, and 9), ultrasonic parameters (frequencies of 28 kHz and 40 kHz with continuous and pulsed operation modes), and membrane orientation. The research specifically investigated the effect of time as a key factor in evaluating retention changes of heavy metals (Pb, Zn, Fe). The overall trend in metal retention efficiency exhibited a gradual decline over time, primarily influenced by various operational factors. Continuous ultrasonication enhanced performance when the support layer faced the feed solution, whereas pulsed mode was more effective with the active layer, yielding rejection efficiencies in the order Fe < Pb < Zn. Differential Scanning Calorimetry (DSC) revealed that ultrasonic vibrations during FO led to the highest glass transition temperature (Tg = 62.75°C), confirming a greater average water flow (AWF) in US-FO-28 compared to the baseline. Ultrasonication increased the crystallinity index (CI) of the membrane by 42% relative to the pristine membrane. Atomic Force Microscopy (AFM) further supported these improvements, showing a decrease in root mean square roughness (Rq) at 28 kHz.

Forward osmosis (FO) technology for desalination and wastewater treatment has been widely researched because of its significant advantages over traditional pressure-driven membrane processes. However, this process encounters several challenges like low water flux, high reverse solute flux, and inadequate fouling resistance, which necessitate careful consideration in membrane design. This research focuses on improving the desalination, antifouling, and heavy metal rejection efficiency of thin-film nanocomposite (TFN) FO membranes by integrating a CuAl LDH-zeolite X (LDH-Z) into the polyamide active layer. To synergistically exploit the structural characteristics of both LDH and zeolite, the LDH-Z composite was synthesized via a simple in situ coprecipitation method, enabling LDH growth on the external surface and within the pores of zeolite. The intrapore growth of LDH modulated Z internal pore size and enhanced its ion rejection abilities, while the formation of textural mesoporous nanochannels facilitated water transport. FO performance evaluations revealed that the optimized TFN-LZ2 membrane achieved a 64.3% increase in water flux relative to the unmodified TFC membrane. Meanwhile, it maintains reverse solute flux comparable to that of the TFC membrane while exhibiting a 1.35-fold higher selectivity. Moreover, antifouling tests show that water flux decline decreased from 41.9% (TFC) to 26.3% for the optimized membrane due to enhanced surface hydrophilicity and smoothness imparted by LDH-Z. The TFN-LZ2 membrane also performs more effectively at rejecting Cd2+ and Cu2+ heavy metal ions (>97%). These results underscore the capability of LDH-Z-modified membranes to improve FO performance, presenting a promising avenue for FO membrane modification using 2D/3D structured materials.

This study presents a deep learning-based surrogate model for the rapid and accurate prediction of forward osmosis (FO) performance under diverse operating conditions. To assess the applicability of data-driven approaches, several machine learning models - decision tree, random forest, support vector machine, and deep neural network (DNN) - were developed and compared systematically using datasets of varying sizes. Model performance depended strongly on dataset size. The DNN-based surrogate achieved superior accuracy when trained with more than 1563 data points, whereas the random forest model performed better with smaller datasets (<1563). Shapley additive explanation (SHAP) analysis showed that the DNN model captured the physical relationships between input parameters and FO performance effectively. The DNN-based surrogate predicted experimental water flux with a normalized root mean square error (NRMSE) of 0.082, which was comparable with that of the numerical simulation model of 0.083. The proposed DNN-based surrogate model maintains high predictive accuracy while substantially reducing computational time compared with the numerical simulation approach, enabling rapid and efficient process optimization in food manufacturing. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The potential of forward osmosis in reducing water consumption in hemodialysis.

Forward osmosis using a nanoparticle slurry draw solution with DC-field-driven separation

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

Concentration and recovery of nitrogen from municipal solid waste leachate by means of forward osmosis and membrane contactor

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.

Performance evaluation of single and mixed draw solutes in the forward osmosis membrane

Interfacial Engineering of Thin-Film Composite Membranes with Polyoxometalates as Salt Additives for High-Efficiency Forward Osmosis

Zirconium-based metal-organic frameworks (Zr-MOFs) have emerged as promising desalination membrane materials owing to their exceptional chemical and hydrothermal stability, tunable nanoporous architectures, and versatile surface functionality. This review summarizes recent advances in Zr-MOF membranes for desalination, focusing on representative systems such as UiO-66 and its derivatives, MOF-801, MOF-808, and PCN-224. It highlights how framework chemistry, pore architecture, defect engineering, and membrane configuration collectively govern water transport and ion selectivity. Fabrication strategies are systematically discussed, covering both pure Zr-MOF membranes and mixed-matrix membranes (MMMs). Desalination performance is evaluated across various separation processes, including pressure-driven filtration, forward osmosis, and pervaporation. Finally, we discuss the molecular-level sieving mechanisms and outline future research directions toward the development next-generation materials for sustainable water desalination.

Heavy metal contamination of drinking water remains a persistent global challenge, exacerbated by salinity, industrial discharge, and the limitations of existing membrane technologies that are constrained by permeability-selectivity trade-offs. In this study, we develop a hybrid thin film nanocomposite (TFN) forward osmosis (FO) membrane by incorporating a zirconium-based metal-organic framework (UiO-66) and its conductive polymer-functionalized analogue (PANI@UiO-66) into the polyamide active layer via interfacial polymerization. The incorporation of UiO-66 enhances water transport through the introduction of hydrophilic microporous domains, while the polyaniline coating modulates nanoscale transport pathways and interfacial interactions. Systematic variation in filler type and loading reveals distinct functional roles of the two fillers. Membranes incorporating bare UiO-66 exhibit increased water flux, attributed to facilitated transport through MOF-derived nanochannels, but show a moderate increase in reverse solute flux. In contrast, PANI@UiO-66 incorporation results in reduced water flux but significantly suppresses reverse solute flux and enhances chromium rejection, indicating improved control over selective transport. At an optimal loading of 0.15 wt% (TFN-PU3), the membrane demonstrates an improved balance between water permeability and solute selectivity compared to the pristine thin film composite (TFC) membrane under FO conditions. The observed performance is attributed to the combined effects of modified transport pathways and interfacial interactions introduced by the hybrid filler system. The results highlight the potential of conductive polymer-MOF hybridization as a strategy for tuning membrane performance. This work provides a practical framework for designing TFN membranes for selective heavy-metal removal in saline and complex water environments.

Slaughterhouse wastewater (SW) contains high organic matter and nutrients, requiring sustainable treatment methods like forward osmosis (FO). This study evaluates the performance of four membranes: M1 (cellulose triacetate), M2 (M1 with carbon nanotubes), M3 (cellulose triacetate/diacetate), and M4 (M3 with carbon nanotubes) for treating SW. It reports the first-time use of CNTs in a hybrid membrane (CTA/CDA) for FO applications. Characterization showed that CNTs improved the mechanical and structural properties of M1, increasing the contact angle from 68 to 75°C and roughness from 499.59 to 542.57nm. However, for M3, the addition of CNTs in M4 decreased the contact angle from 88 to 77° and roughness from 773.088 to 620.001nm. While CNTs enhanced hydrophilicity, they reduced permeability and fouling resistance due to fewer water transport channels. FTIR analysis revealed distinct stretching patterns correlating with variations in contact angles and membrane performance. The evaluation of membranes in forward osmosis (FO) comprised four phases. In Phase 1, membrane M3 excelled with 91.6% water removal and 0.32 LMH flux using 0.5M MgCl₂, outperforming M4 at 80.84% and 0.28 LMH due to Mg²⁺ ion accumulation in M4. Phase 2 confirmed M3's superiority with MgCl₂ among the four 0.5M draw solutions. In Phase 3, M3 demonstrated an enhancement of 93.76% and 0.33 LMH with a 1M solution., while M4's performance reached 90.91% with 1M NH₄HCO₃. Overall, low water flux was attributed to the lower circulation rates of feed and draw solutions. Phase 4 showed that M3's water flux supported the growth of Dunaliella salina, while M4's lower-salinity flux hindered it. This study explores the potential of hybrid membranes reinforced with carbon nanotubes (CNTs) for forward osmosis in treating slaughterhouse wastewater. It reveals a gap in data regarding CTA and CDA blends with CNTs, marking this as a new research area. The findings indicate that CNTs do not enhance the performance of hybrid membranes for this application; therefore, cost-effective membrane (M3) using recyclable solutes like NH₄HCO₃ present a promising solution for sustainable wastewater treatment.

Interpenetrating polymer networks (IPNs) consist of two interconnected networks that provide distinct physical and mechanical properties. When one of these networks is thermo-responsive, the volume phase transition temperature (VPTT) remains largely unaffected by the hydrophilicity of the second network. This makes IPNs an ideal candidate for modifying properties of hydrogels without altering VPTT. In this study, we explore the use of IPNs, based on poly(N-isopropyl acrylamide) (PNiPAAm) and sodium alginate (SAlg), as draw agents in forward osmosis (FO) desalination. The charged repeating units of SAlg increase the osmotic pressure, enabling water draw, and form crosslinks in the presence of calcium ions. Moreover, PNiPAAm is thermo-responsive and shrinks above VPTT, releasing the absorbed water. Additionally, incorporating graphene oxide (GO) as a light-absorbing agent further enhances the process efficiency by increasing temperature upon exposure to light. The results show that the swelling capacity, shrinkage behavior, and mechanical properties of the hydrogels are influenced by the content of SAlg and GO. However, the VPTT of the IPN hydrogels remains similar to that of the single PNiPAAm network. In FO desalination tests, the IPN hydrogel with 10 wt% SAlg and 0.2 wt% GO demonstrates the best balance between water flux and thermo-responsivity. • IPN hydrogels combine PNIPAAm, sodium alginate, and graphene oxide for desalination. • The VPTT of PNIPAAm remains stable in the presence of charged second network. • GO enables light-triggered water release by enabling photothermal response. • IPN with 10 wt% SAlg and 0.2 wt% GO achieves optimal water flux and responsivity. • Dual light and heat responsiveness enables low-energy, efficient FO osmosis.

Performance and energy balance of an anaerobic dynamic membrane bioreactor treating concentrated municipal wastewater.

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

Enhancement of thin-film composite membrane properties and performance by using modified silicon dioxide for forward osmosis process