Enhanced Water Flux Research Articles

Comparative study of PS and PES and their sulfonated forms in antifouling behavior and rejection efficiency

In this study, novel hybrid ultrafiltration (UF) membranes were developed using polyethersulfone (PES), polysulfone (PS), and their sulfonated counterparts (SPES and SPS) to enhance water flux and antifouling properties. FTIR and XRD analyses validated the successful incorporation of sulfonate groups and structural changes, while SEM images revealed more porous and uniform membrane structures. Thermogravimetric analysis (TGA) showed enhanced thermal stability for the sulfonated membranes. Mechanical property evaluations demonstrated that the sulfonated membranes maintained good tensile strength and flexibility. Water uptake and porosity measurements indicated increased hydrophilicity and porosity for SPES and SPS membranes compared to their pristine forms. The pure water flux of SPES (130 L/m2·h) is significantly higher compared to PES (110 L/m2·h). The sulfonated membranes (SPS and SPES) exhibit significantly enhanced antifouling properties, as demonstrated by the improved flux recovery ratios (FRR) for SA, BSA, and HA compared to their non-sulfonated counterparts (PS and PES), reaching up to 75 % for SPES. The rejection performance for BSA, HA, and SA solutions showed that SPES membranes achieved 95 %, 90 %, and 92 % rejection rates, respectively, compared to 80 %, 75 %, and 70 % for PS membranes. Fouling resistance tests using BSA, HA, and SA solutions showed that SPES and SPS membranes had significantly higher flux and lower fouling tendencies.

Efficient Lithium Recovery from Water Using Polyamide Thin-Film Nanocomposite (TFN) Membrane Modified with Positively Charged Silica Nanoparticles.

The separation of Li+ from Mg2+ in salt-lake brines using nanofiltration (NF) has become the most popular solution to meet the rising demand for lithium, particularly driven by the extensive use of lithium-ion batteries. This study presents the fabrication of a uniquely designed polyamide (PA) thin-film nanocomposite (TFN) membranes with ultrahigh Li+/Mg2+ selectivity and enhanced water flux by covalently incorporating mixed ligands functionalized silica nanoparticles (F-SiO2NPs) into the selective PA layer and covalently bonding them to the membrane surface. In this strategy, bare silica nanoparticles (SiO2NPs) were functionalized with mixed superhydrophilic ligands, including primary amine and quaternary ammonium groups, resulting in a highly positive surface charge primarily from the quaternary ammonium groups and enabling covalent conjugation via amine groups. Among the F-SiO2NP-incorporated membranes, M500 containing 500 ppm of F-SiO2NPs exhibited the best performance. In a solution with 2000 ppm salt concentration (Li+/Mg2+ ratio of 1:20), the M500 membrane showed an improved Li+/Mg2+ selectivity of 7.41 compared to the nonmodified TFC membrane, which had a selectivity of 5.05. Further surface conjugation of the M500 sample with 1500 ppm of F-SiO2NPs resulted in the C1500 membrane, demonstrating the best performance among all of the surface-modified membranes. C1500 showed an outstanding Li+/Mg2+ selectivity of 37.95, with a Mg2+ rejection of 95.7% and a Li+ rejection of -63.2%, and a water flux of 56.0 L m-2 h-1 at 70 psi. Notably, a 7.5-fold improvement in Li+/Mg2+ selectivity over the TFC membrane was achieved without compromising the water flux. This is evident from the nearly identical water flux values of the TFC, M500, and C1500 membranes, which were 57.1, 54.8, and 56.0 L m-2 h-1, respectively. Considering key factors for large-scale applications, such as cost-effectiveness, environmental impact, the abundance of synthetic precursors, and the maturity of synthesis and tailoring technologies, SiO2NP-based modifications outperform all other reported approaches to date.

Robust and efficient oil-water separation using candle soot deposited stainless steel mesh

In recent years, the rising concerns regarding oil pollution and the emissions of organic pollutants from industrial activities have posed significant environmental and public health challenges. The treatment of oily wastewater and organic pollutants has emerged as pressing issue, necessitating the development of efficient solutions. Oil-water separation stands out as a promising approach to address these challenges. However, the effictiveness and robustness of the separating membranes have been identified as key limitations hindering the advancement of oil–water separation technologiess. This paper introduces a novel superhydrophilic/underwater superoleophobic membrane tailored specifically for oil–water separation with enhanced water flux. This film is prepared by depositing candle soot on a stainless steel mesh and then polymerizing phytic acid (CSM-PA). The contact angle of CSM-PA membranes underwater for a wide range of oils is above 140°, reaching a maximum of 152.73°. The CSM-PA membrane demonstrates excellent separation performance for various oils, achieving separation efficiencies flux surpassing 99.990 %, achieving separation efficiencies flux surpassing 18950.360 L·m−2·h−1. Notably, the membrane exhibits contact angles under water exceeding 142° for all oils tested. After conducting immersion, sand impact, and water impact tests, the underwater contact angle for both light and heavy oils was found to exceed 139°. The surface roughness of the CSM-PA film on the initial stainless steel mesh improved significantly, increasing from 106 nm to 452 nm. Impressively, even after 70 cycles, the CSM-PA membrane maintains an oil (n-hexane) water separation efficiency exceeding 99.997 % and a remarkable flux rate of 21055.956 L·m−2·h−1, the maximum separation flux is even 29154.400 L·m−2·h−1. Furthermore, the CSM-PA membrane shows significant stability and resistance to mechanical abrasion, ensuring long-term and reliable operational performance. The findings of this study hold significant implications for the advancement of oil–water separation technologies, offering a promising avenue for addressing oil pollution and organic pollutant emissions in a sustainable and effective manner.

Step‐wise non‐solvent induced phase separation of polyacrylonitrile/thermoplastic polyurethane self‐supportive filtration membranes

AbstractThis study investigated the fabrication of polyacrylonitrile (PAN) membranes using non‐solvent induced phase separation methods, with the addition of thermoplastic polyurethane (TPU) as an additive. The incorporation of TPU and the utilization of stepwise induced phase separation techniques resulted in notable improvements in membrane structure and water filtration performance. Scanning electron microscopy revealed that membranes with TPU exhibited a denser pore network and finer primary channels, leading to enhanced water flux and protein rejection rates. Mechanical testing indicated that TPU addition improved the membrane's mechanical properties, particularly its elongation at break and tensile strength, especially under wet conditions. Additionally, optimization of the coagulation bath involved methanol spraying followed by water immersion, resulting in membranes with further enhanced flux and rejection properties. Compared with neat PAN membranes, the membranes with TPU exhibited increased water flux from 405 to 539 L/m2 h, as well as improved elongation at break and tensile strength in both dry and wet conditions. Furthermore, the combination of stepwise induced phase separation significantly enhanced the water flux from 342.7 to 483.0 L/m2 h, while also improving the retention rate of ovalbumin from 25.7% to 31.5%.

Scalable and cost-effective ultra-dispersible graphene oxide blended ultrafiltration mixed matrix membrane: Assessment of mechanical, water flux, and anti-biofouling properties

Graphene oxide-modified pressure-driven membranes are attractive due to their enhanced water flux and mechanical properties. However, the large-scale use of membranes such as ultra-filtration (UF) is hindered due to the challenges in bulk production of graphene oxide at an affordable cost. The present work reports the application of ultra-dispersible graphene oxide (UDGO) synthesized through a single-step scalable approach in fabricating UF membranes. Compared to Hummers' graphene oxide, the UDGO is highly dispersed in solvents and is 8-10 times more cost-effective. Various microscopic and macroscopic studies were performed to study the physicochemical properties of UDGO and UDGO-modified UF membranes. The influence of UDGO content on the membrane efficiency and anti-fouling potential was elucidated. The UDGO-modified UF membranes showed ~18% enhancement in flux and ~64% increment in protein rejection compared to pristine membranes. The modified membranes also showed a ~20% greater flux recovery ratio and ~60% lesser bovine serum albumin adsorption, indicating a better level of anti-fouling potential. The higher biofilm inhibition potential of UDGO with an increase in dead biomass makes it a potential candidate for developing anti-biofouling membranes with enhanced water flux.

Cucurbit[6]uril-tuned nanochannels of graphene oxide membrane for enhanced water flux in nanofiltration

Graphene oxide (GO) membranes exhibit promising potential in nanofiltration due to their controllable transport channel size and low transport resistance of water molecules, resulting in exceptional water permeability. However, the trade-off between water flux and rejection ratio stemming from tightly packed interlayers poses a challenge to the application of GO membranes in nanofiltration. To overcome this trade-off, a practical method is urgently needed to regulate the interlayer space of GO membranes. In this study, a macrocyclic molecule with a rigid porous structure, cucurbit[6]uril (CB[6]), has been introduced to enlarge and precisely adjust the interlayer distance of GO membranes, effectively addressing the trade-off dilemma. The interlayer distance can be precisely adjusted within a range of 0.46 to 1.35 nm, making it suitable for the removal of small organic molecules from wastewater. Through the optimization of GO and CB[6] quantities, the GO membrane containing 20 µg GO and 49.9 wt% CB[6] (CB6GO-4) demonstrates a high pure water flux (PWF) exceeding 171.3 L m-2h−1 bar−1, more than 5.9 times higher than a pure GO membrane (28.8 L m-2h−1 bar−1), alongside a dye rejection ratio over 92 %, indicating the promising potential of CB[6]-intercalated GO membranes in removing organics from industrial saline wastewater.

Pore Engineering of MFI Zeolite Membranes: Enhancing Water Flux and Ion Rejection Using Polyacrylamide as a Secondary Template

Pore Engineering of MFI Zeolite Membranes: Enhancing Water Flux and Ion Rejection Using Polyacrylamide as a Secondary Template

Boosting water flux and dye removal: Advanced composite membranes incorporating functionalized AC-PAA for wastewater treatment

This study addresses the challenge of enhancing dye removal and antifouling properties in wastewater treatment by developing a composite membrane incorporating poly(acrylic acid)-functionalized activated carbon (AC-PAA) into a polyethersulfone (PES) matrix. The activated carbon was functionalized using surface-initiated atom transfer radical polymerization (SI-ATRP), followed by hydrolysis to introduce hydrophilic poly(acrylic acid) chains. The AC-PAA composite was characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, and energy-dispersive X-ray analysis, confirming successful grafting and functionalization. Compared to pristine PES, the addition of 0.5 wt% AC-PAA led to significantly enhanced water flux (54 L/m2h vs. 30 L/m2h) and superior dye removal, achieving 63 % for methyl orange and 67 % for methylene blue at alkaline pH. Poly(acrylic acid) was selected for its carboxyl groups, which enhance adsorption capacity and antifouling characteristics. In addition to effective dye removal, the composite membranes were antifouling, with a flux recovery ratio of 72 %. Response surface methodology optimized parameters, confirming highest performance at pH 11 and 6 bar. AC-PAA functionalized membranes are an efficient solution in wastewater treatment, increasing dye removal and antifouling capacity versus current membrane technologies.

Advanced lithium extraction nanofiltration membrane with fast transport channels via competitive diffusion and reaction of rigid electropositive phenylbiguanide molecules

The utilization of nanofiltration membranes for lithium extraction from Salt-Lake holds the potential to address lithium resource scarcity and drive energy transformation. Nevertheless, the trade-off effect between water permeability and Mg2+/Li+ separation selectivity poses a challenge in the application of these membranes. In this work, rigid-flexible interpenetration and competitive diffusion reaction strategies were proposed to regulate the pore structure and charge density of the functional layer, thus enhancing the overall separation performance of nanofiltration membrane. Phenylbiguanide (PBG) possessing rigid structure, high positive charge density, and low energy transfer barrier was embedded into flexible polyethyleneimine-based polyamide network. This integration facilitated the formation of continuous and semi-permanent microcavities with rigid-flexible coupled structure, and meanwhile, elevated the density of positive charges. Consequently, the modification extended the water molecular transport channels within the functional layer, leading to a notable enhancement in pure water flux, from 7.40 to 26.43 L m−2h−1. In addition, due to the faster diffusion of PBG than polyethyleneimine with high molecular weight (70000 Da, as aqueous monomer in this work), it could react with excess 1,3,5-trimesoyl chloride (TMC) on the surface of initial membrane to form a new polyamide layer, which repaired the defects in the functional layer and also enhanced the charge density inside pore channels. Therefore, Mg2+/Li+ separation selectivity factor increased from 3.79 of TFC membrane to 22.98 of PBG membrane, i.e., by about 6 times. This study provided an effective strategy to develop nanofiltration membranes with both good water permeability and Mg2+/Li+ selectivity.

Study in the impact of quaternized graphene oxide (QGO) composition as modifier on the chemical, physical, mechanical, and performance properties of polyvinylidene fluoride (PVDF)-based nanocomposite membrane

Polyvinylidene Fluoride (PVDF) membranes were modified with quaternized graphene oxide (QGO) synthesized from graphene oxide and quaternized ammonium groups. PVDF/QGO membranes were created by blending PVDF and 0.01-0.05 g QGO via phase inversion. FTIR confirmed the successful QGO incorporation. PVDF/QGO membranes exhibited increased mechanical stiffness. Meanwhile, SEM revealed asymmetric morphology with surface and internal pores. AFM showed the membrane with 0.05 g and QGO had the highest surface roughness of 101.2 nm, which increased filtration area and flux. QGO improved hydrophilicity through hydroxyl and quaternary ammonium groups, enhancing water flux up to 1208 Lm?2h?1 for 0.05 g QGO. Cu2+ rejection increased to 75% for 0.05 g QGO membrane due to chelation and adsorption effects. PVDF/QGO membranes displayed bacterial growth inhibition, unlike pristine PVDF. The inhibition zone diameter increased with more QGO, indicating improved antibacterial activity. Overall, this study demonstrated that QGO improved PVDF membranes' hydrophilicity, antibacterial properties, and mechanical strength.

Fouling Reduction and Thermal Efficiency Enhancement in Membrane Distillation Using a Bilayer-Fluorinated Alkyl Silane-Carbon Nanotube Membrane.

In this study, we report the robust hydrophobicity, lower fouling propensity, and high thermal efficiency of the 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS)-coated, carbon nanotube-immobilized membrane (CNIM) when applied to desalination via membrane distillation. Referred to as FAS-CNIM, the membrane was developed through a process that combined the drop-casting of nanotubes flowed by a dip coating of the FAS layer. The membranes were tested for porosity, surface morphology, thermal stability, contact angle, and flux. The static contact angle of the FAS-CNIM was 153 ± 1°, and the modified membrane showed enhancement in water flux by 18% compared to the base PTFE membrane. The flux was tested at different operating conditions and the fouling behavior was investigated under extreme conditions using a CaCO3 as well as a mixture of CaCO3 and CaSO4 solution. The FAS-CNIM showed significantly lower fouling than plain PTFE or the CNIM; the relative flux reduction was 34.4% and 37.6% lower than the control for the CaCO3 and CaCO3/CaSO4 mixed salt solution. The FAS-CNIM exhibited a notable decrease in specific energy consumption (SEC). Specifically, the SEC for the FAS-CNIM measured 311 kwh/m3 compared to 330.5 kwh/m3 for the CNIM and 354 kwh/m3 for PTFE using a mixture of CaCO3/CaSO4. This investigation underscores the significant contribution of the carbon nanotubes' (CNTs) intermediate layer in creating a durable superhydrophobic membrane, highlighting the potential of utilizing carbon nanotubes for tailored interface engineering to tackle fouling for salt mixtures. The innovative design of a superhydrophobic membrane has the potential to alleviate wetting issues resulting from low surface energy contaminants present in the feed of membrane distillation processes.

Forward osmosis membrane substrates with low structure parameter: Modification with PSf‐g‐PMMA graft copolymer

AbstractIn this work, using the combination of atom transfer radical polymerization and click chemistry, the graft copolymer polysulfone‐graft‐poly (methyl methacrylate) (PSf‐g‐PMMA) was synthesized as a modifying agent. The copolymer was embedded in the PSf substrate using a nonsolvent phase inversion method. Then, the modified substrate was used to make thin film composite forward osmosis (TFC‐FO) membranes using the interfacial polymerization method. Also, the effect of PSf‐g‐PMMA copolymer content on the surface properties of the membrane, as well as the filtration performance, was investigated. The increase in hydrophilicity, porosity, and average pore diameter indicated the favorable effect of PSf‐g‐PMMA copolymer on the characteristics of modified substrates. In addition, the improvement in the membrane morphology (an increase in the length and number of finger‐like pores) provided a substrate with low tortuosity and structure parameters. Therefore, the pure water permeability increased from 79.9 LMH/bar for the control membrane to 372.1 LMH/bar for the membrane containing 20 wt.% of PSf‐g‐PMMA copolymer. Investigating the FO separation properties of TFC‐FO membranes showed an increase in water flux and selectivity due to an improvement in the morphology of the modified substrate with low structural parameters. The new TFC‐FO membranes have been optimized, and water flux has significantly improved. Compared with the control membrane, which did not have copolymer blending, the new membranes have a triply enhanced water flux of 17.1 LMH. In addition, the selectivity of these optimized membranes has improved when 1 M NaCl is used as the draw, and DI water is used as the feed in the FO mode.

Superhydrophobic and oleophobic Nylon, PES and PVDF membranes using plasma nanotexturing: Empowering membrane distillation and contributing to PFAS free hydrophobic membranes

As freshwater demand is constantly increasing, water purification via membrane distillation (MD) emerges as a promising water production technology, especially when combined with the use of superhydrophobic membranes. Here, following our previous work [1] we extend our universal, environmentally friendly, plasma nanotexturing and hydrophobization technology for rendering practically any type of membrane superhydrophobic and oleophobic. Thus, we render three commercial porous membranes superhydrophobic, namely, polyvinylidene (PVDF 0.45 μm) (initially hydrophobic), polyethersulfone (PES 1.20 μm) and nylon (NY 1.20 μm) (both initially hydrophilic). We demonstrate superhydrophobic, superoleophobic (down to 40mn/m surface tension) and oleophobic properties (down to 30mN/m surface tension) for PVDF, PES and Nylon membranes thus paving the way for their use with low surface tension waste streams. Moreover, the technology presented herein not only improves existing hydrophobic membranes but may lead to elimination of the use of Teflon-like fluorinated hydrophobic membranes altogether in the future, thereby contributing to the PFAS (Per and Poly Fluoro Alkyl Substances) and Teflon-like membrane use reduction. We subsequently evaluated the performance of the treated membranes in direct contact membrane distillation (DCMD) for desalination of sea-like water (35 g/L NaCl). All membranes showed enhanced water flux with an increase of >13% compared to the pristine hydrophobic PVDF membranes for at least 2 h of continuous operation, with salt rejection exciding 99.99%.

Fe3+-modified polyamide membrane with a porous network structure: Rapid permeation and efficient interception of trace organic compounds

Forward osmosis (FO) is a promising technology in the treatment of trace organic substances. However, the development of this technology is limited by membrane material selection and the long-term chemical stability and durability of the membrane. Whereas ibuprofen, a representative trace organic substances that is hydrophobic and negatively charged, poses potential environmental hazards due to its bioactivity. In this work, polyethersulfone (PES) membranes were modified with iron metal complexes via chelation reactions to achieve high rejection rates for ibuprofen. The Fe3+-modified composite FO membrane increased the ibuprofen rejection rate to 98.3 % compared to less than 80.0 % for the original PES membrane. Additionally, the modified membrane enhanced water flux by at least 25.0 % and reduced reverse solute flux to a maximum of 73.0 % of that of the polyamide composite membrane, while significantly improving anti-fouling capabilities. Membrane characterization results revealed that the significant enhancement in the ibuprofen retention rate was due to the addition of a negative charge by forming complexes with Fe3+, which increased intermolecular interactions. Additionally, the dense network structure developed by the Fe3+-EDTA-2Na modification also contributed to the enhanced membrane performance.

Novel strategy to enhance water flux and stability of low swelling GO/NaY/Nylon membrane to adsorb ciprofloxacin from water

To improve the water flux and stability of GO membrane, GO/NaY/Nylon membrane was prepared, in which zeolite were used to increase the layer spacing of GO nanosheets. And the interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) was employed to improve the stability of membrane. The GO/NaY/Nylon membrane with high content of nanoparticles was first used for antibiotic adsorption. The static thermodynamics, kinetics and isotherm for ciprofloxacin (CIP) were studied. The adsorption mechanism on CIP is chemisorption, conforming to the pseudo-second-order model and Langmuir model, and as the equilibrium concentration (ce) increases, the maximum adsorption capacity of GO/NaY/Nylon membrane first increases rapidly, then reaches a plateau, with a maximum adsorption capacity of 49.2 mg·g−1 at 328 K (ce:45.1 mg·L-1). The GO/NaY/Nylon membrane showed higher water flux and stability than the GO membranes, indicating great promising in removing CIP from aqueous solution.

Optimized preparation route for polyamide top-coated forward osmosis membrane for enhanced water flux using industrial wastewater as feed.

The forward osmosis (FO) process has recently gained significant interest in treating wastewater, brackish/seawater and concentrating feedstocks for various operations, including desalination. The study investigates the effect of different synthesis conditions of the polyamide-based thin-film composite (TFC) FO membranes on the membranes' final performance. Taguchi statistical analyses were used to fabricate and optimize the polyamide TFC FO membrane. The process parameters as factors were the amount of polyethersulfone (PES), polyethylene glycol 400 (PEG-400), polyvinyl pyrrolidone (PVP), m-phenylenediamine (MPD), and trimesoyl chloride (TMC), and TMC reaction-time (RT). The Taguchi method was adopted to investigate the optimal conditions and the significance of individual factors using an L16 (45) orthogonal array. Another Taguchi analysis (Taguchi 2) was adopted to investigate the influence of other important parameters like optimal conditions for MPD, TMC, and TMC reaction-time factors using an L9 (33) orthogonal array. Confirmation tests validated a maximum water flux of 46.4 ± 2.32 L/m2·h with a specific combination of control factors for membrane synthesis: PES/PEG/PVP/MPD/TMC/TMC RT-16/7/0.5/1/0.05/30. These tests demonstrated a high-water flux of 7.05 ± 0.35 L/m2·h when exposed to industrial wastewater (secondary effluent) as the feed solution (FS) and fertilizer as the draw solution (DS) in the FO process. The R2 values were more than 90%. The experimental validation confirmed the models' predictive ability with different FSs, including industrial wastewater.

Solar-enhanced lithium extraction with self-sustaining water recycling from salt-lake brines

Lithium is an emerging strategic resource for modern energy transformation toward electrification and decarbonization. However, current mainstream direct lithium extraction technology via adsorption suffers from sluggish kinetics and intensive water usage, especially in arid/semiarid and cold salt-lake regions (natural land brines). Herein, an efficient proof-of-concept integrated solar microevaporator system is developed to realize synergetic solar-enhanced lithium recovery and water footprint management from hypersaline salt-lake brines. The 98% solar energy harvesting efficiency of the solar microevaporator system, elevating its local temperature, greatly promotes the endothermic Li+ extraction process and solar steam generation. Benefiting from the photothermal effect, enhanced water flux, and enriched local Li+ supply in nanoconfined space, a double-enhanced Li+ recovery capacity was delivered (increase from 12.4 to 28.7 mg g-1) under one sun, and adsorption kinetics rate (saturated within 6 h) also reached twice of that at 280 K (salt-lake temperature). Additionally, the self-assembly rotation feature endows the microevaporator system with distinct self-cleaning desalination ability, achieving near 100% water recovery from hypersaline brines for further self-sufficient Li+ elution. Outdoor comprehensive solar-powered experiment verified the feasibility of basically stable lithium recovery ability (>8 mg g-1) directly from natural hypersaline salt-lake brines with self-sustaining water recycling for Li+ elution (440 m3 water recovery per ton Li2CO3). This work offers an integrated solution for sustainable lithium recovery with near zero water/carbon consumption toward carbon neutrality.

Improving water flux distribution and energy efficiency in reverse osmosis for high-recovery water reuse

Reverse osmosis (RO) is widely accepted for water reuse because it ensures clean water production. However, innovation in the RO process is necessary for water reuse to enhance its recovery while mitigating membrane fouling and reducing the increase in specific energy consumption (SEC). Therefore, circle sequence reverse osmosis (CSRO) adopts a staged design with flow reversal (FR) and a semi-batch design with a jet pump to enhance water flux distribution and energy efficiency for high-recovery water reuse. This study examined the water flux distribution and SEC of CSRO. When the distribution of water flux was compared, CSRO demonstrated a 7.7 % reduction in water flux in the front element compared to semi-batch reverse osmosis (SBRO). This reduction was attributed to advanced designs in SBRO, such as the two-stage design and an FR operation. The SEC of RO systems was also compared under high-recovery conditions. While both SBRO and CSRO achieved SEC reduction of 20–25 % or 9–18 % compared to two-stage RO depending on the feed salinity, CSRO was slightly more energy-efficient for high-saline feed. It is expected that CSRO has excellent potential for high-recovery water reuse, considering the improvement in water flux distribution and energy efficiency.

Electrochemically Enhanced Forward Osmosis Processes Unlocking Efficiency and Versatility

AbstractThe growing interest in forward osmosis (FO) for water reclamation and desalination over the past two decades stems from its potential for lower energy consumption. Despite its promise, FO faces significant challenges, such as the lack of an appropriate draw solute, concentration polarization, membrane fouling, and reverse solute flux (RSF). Recent trends in research have focused on combining various technologies with FO to address these challenges. Notably, the integration of electrochemical technologies with FO offers new possibilities. This review covers FO combined with electrochemical cells (FO‐ECs), categorizing them based on their working principles and applications in improving FO. The review discusses different FO‐EC configurations, including (1) electrodialysis‐combined FO for RSF, (2) electro‐FO for water flux enhancement, and (3) electrochemical oxidation‐combined FO and FO with electro‐conductive membranes for self‐cleaning and fouling mitigation. Additionally, it covers (4) reusable electro‐responsive draw solutes, (5) electrochemical osmosis systems for metal removal and energy production, and (6) osmotic microbial fuel cells for energy recovery and other benefits. The review also assesses the practical applicability and potential for achieving carbon neutrality of the FO‐ECs. It concludes with a forward‐looking perspective, outlining future research directions to optimize and expand the use of electrochemical‐enhanced FO technologies.

Characterization and performance evaluation of in-house ultrafiltration membrane coupled with photocatalysis for 17α-methyltestosterone hormone removal.

17α-methyltestosterone (MT) hormone is a synthetic androgenic steroid hormone utilized to induce Nile tilapia transitioning for enhanced production yield. This study specifically focuses on the removal of MT through the utilization of photocatalytic membrane reactor (PMR), which employs an in-house polyvinylidene fluoride (PVDF) ultrafiltration membrane modified with 1% nanomaterials (either TiO2 or α-Fe2O3). The molecular weight cut-off (MWCO) of the in-house membrane falls within the ultrafiltration range. Under UV95W radiation, the PMR with PVDF/TiO2 and PVDF/α-Fe2O3 membranes achieved 100% MT removal at 140 and 160 min, respectively. The MT removal by the commercial NF03 membrane was only at 50%. In contrast, without light irradiation, the MT removal by all the membranes remained unchanged after 180 min, exhibiting lower performance. The incorporation of TiO2 and α-Fe2O3 enhanced water flux and MT removal of the membrane. Notably, the catalytic activity was limited by the distribution and concentration of the catalyst at the membrane surface. The water contact angle did not correlate with the water flux for the composited membrane. The degradation of MT aligned well with Pseudo-first-order kinetic models. Thus, the in-house ultrafiltration PMR demonstrated superior removal efficiency and lower operational costs than the commercial nanofiltration membrane, attributable to its photocatalytic activities.