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Thin-film nanocomposite (TFN) forward osmosis (FO) membranes have attracted significant attention due to their potential for solving global water scarcity problems. In this study, we investigate the impact of titanium oxide (TiO 2 ) and titanium oxide/reduced graphene (TiO 2 /rGO) additions on the performance of TFN-FO membranes, specifically focusing on water flux and reverse salt diffusion. Membranes with varying concentrations of TiO 2 and TiO 2 /rGO were fabricated as interfacial polymerizing M-phenylenediamine (MPD) and benzenetricarbonyl tricholoride (TMC) monomers with TiO 2 and its reduced graphene composites (TiO 2 /rGO). The TMC solution was supplemented with TiO 2 and its reduced graphene composites (TiO 2 /rGO) to enhance FO performance and reverse solute flux. All MPD/TMC polyamide membranes are characterized using various techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. The results demonstrate that incorporating TiO 2 /rGO into the membrane thin layer improves water flux and reduces reverse salt diffusion. In contrast to the TFC membrane (10.24 L m −2 h −1 and 6.53 g/m 2 h), higher water flux and higher reverse solute flux were detected in the case of TiO 2 and TiO 2 /rGO-merged TFC skin membranes (18.81 and 24.52 L m −2 h −1 and 2.74 and 2.15 g/m 2 h, respectively). The effects of TiO 2 and TiO 2 /rGO stacking on the skin membrane and the performance of TiO 2 and TiO 2 /rGO skin membranes have been thoroughly studied. Additionally, being investigated is the impact of draw solution concentration. Graphical Abstract

In this study, L-histidine zwitterionic carbon dots (HZCDs) were synthesized using the hydrothermal method. The synthesized HZCDs were used to modify polyethersulfone (PES) membranes. Additionally, the HZCDs-modified membranes were activated using the protease enzyme to prepare protease-activated composite membranes. The prepared materials underwent extensive characterization and validation using various techniques, including Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) analyses. The blending or activation of HZCDs by the protease enzyme reduced the contact angle of the prepared membranes. The contact angle decreased from 78.75° to 50.12° and 40.02° for 2.0 wt.% HZCDs-PES and PES/Protease-HZCDs membranes, respectively. As the contact angle decreased, the hydrophilic nature of the prepared membranes increased, reflecting a strong affinity for water and efficient wettability. In this context, the pure water flux (PWF) values of PES membranes increased from 140.5 ± 5.3 to 248.7 ± 8.4 L/m 2 .h with rising HZCDs amount from 0 to 2 wt.% HZCDs-PES. Additionally, PWF values for protease-activated composite membranes increased from 140.5 ± 5.3 to 321.1 ± 9.2 L/m 2 . h. BSA flux values of PES membranes increased from 56.4 ± 2.4 to 82.9 ± 0.9 L/m 2 .h with increasing HZCDs amount from 0 to 2.0 wt.% HZCDs-PES. Besides, BSA values for protease-activated composite membranes increased from 56.4 ± 2.4 to 89.8 ± 2.2 L/m 2 .h. The purpose of this modification was to impart hydrophilic properties to the PES membrane and address the issue of membrane fouling, which is a common problem in filtration processes. 2.0 wt.% HZCDs-PES and enzyme-activated membranes PES membranes demonstrated 100% BSA removal efficiency. Also, 2.0 wt.% HZCDs-blended membranes and 2.0 wt.% protease-HZCDs-blended membranes demonstrated remarkable antifouling properties up to 87.7% and 88.8% flux recovery ratio (FRR), respectively. In contrast, BSA flux recovery reached only 67.8% for the pristine PES. When compared to pristine PES membranes, enzyme-activated membranes demonstrated superior filtration and protein rejection efficiencies.

In this research work, silver nanoparticles/polyethylene glycol/cellulose acetate ultrafiltration (Ag-NPs/PEG/CA UF) composite membranes were synthesized and characterized. The Ag-NPs were embedded in the polymer matrix by two methods: in situ and ex situ; varying the type of solvent used (dimethylformamide, DMF; or N -methyl-2-pyrrolidone, NMP). The Ag-NPs used in the ex situ method were synthesized by a green chemistry reduction method. The composite membranes were characterized by Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis-derivative thermogravimetric analysis (TGA-DTG); the molecular weight cut-off and permeability were also determined. Moreover, the antibacterial efficiency of the composite membranes was measured against bacteria like Escherichia coli and Staphylococcus aureus . By FTIR-ATR analysis it was possible to observe that the Ag-NPs embedded in membranes changed the membrane morphology. The SEM-EDS analysis showed that the in situ composite membranes have good dispersity of Ag-NPs, DMF FB being the most densely populated obtained. By another hand, the ex situ DMF NP composite membrane presented the highest amount of silver signals per unit area (µm 2 ). The permeability of the membrane was affected by the presence of the Ag-NPs; the DMF NP composite membrane had the highest permeate flow, while DMF FB had the highest antibacterial activity.

Adhesion after tendon injury is a common complication in clinical practice. The lack of effective prevention mechanisms seriously affects the functional rehabilitation of patients. This research aimed to optimise the amniotic membrane and explain the mechanism of tendon-amniotic membrane by imitating the tendon sheath to construct a multilayer electrospun polycaprolactone (PCL) nanofibre membrane. Fresh amnions were subjected to freezing and vacuum drying. The two surfaces of freeze-dried amnions were coated with PCL nanofibres by electrospinning, thereby forming a multilayer composite membrane and constructing a growth factor-sustained release system conforming to the tendon-healing cycle. The new materials were characterised, and the biological effects on tenocytes and fibroblasts were evaluated. The tendon injury model of New Zealand rabbits was constructed to observe the effects on tendon adhesion and healing. After freezing and vacuum drying, fresh amnions were found to effectively remove most of the cell components but retained the active components TGF-β1, bFGF, VEGF, and PDGF, as well as the fibrous reticular structure of the basement membrane. After coating with PCL nanofibres, a composite membrane mimicking the structure of the tendon sheath was constructed, thereby strengthening the tensile strength of the amnion. By up-regulating the phosphorylation of ERK1/2 and SMAD2/3, the adhesion and proliferation of tenocytes and fibroblasts were promoted, and collagen synthesis was enhanced. In the rabbit tendon repair model, the composite membrane effectively isolated the exogenous adhesion tissue and promoted endogenous tendon healing. The composite membrane mimicking the structure of tendon sheath effectively isolated the exogenous adhesion tissue and achieved good tendon slip. By slowly releasing the growth factors TGF-β1, bFGF, VEGF and PDGF, the ERK1/2 and SMAD2/3 pathways were regulated. Consequently, endogenous tendon healing was promoted. This strategy can alternatively address the clinical problem of tendon adhesion.

Water desalination and recycling of wastewater is a key challenge to meet water shortage issues. Thin film composite polyamide membranes are widely used for desalination; however, their low permeability due to a poor hydrophilicity is a major drawback. Here, we designed novel thin film composite membranes having good hydrophilicity, permeability, and stability without compromising solute rejection. We improved the membrane hydrophilicity by incorporation of hydrophilic additives, such as glycine and l-glutamine, into the polyamide layer. Hence polyamide-based flat sheet membranes were fabricated via interfacial polymerization of m-phenylenediamine and trimesoyl chloride and then were coated over a polysulfone/sulfonated polyphenylsulfone (85:15) support. Polyamide membranes were then characterized and tested for desalination. Results show that the ridge and valley structure observed by scanning electron microscopy confirms the formation of the polyamide layer on membrane surface. The performance reached the highest pure water flux of 36.23 Lm−2 h−1 and flux recovery ratio of 89.18% for membranes with 2 wt% of l-glutamine. Incorporation of 2 wt% l-glutamine induced a high permeate flux and a maximum rejection of 87.87% for MgSO4, 83.50% for Na2SO4 and 60.77% for NaCl solutions. Overall, the polyamide nanofiltration membrane with hydrophilic groups displayed superior antifouling property and can be used as a potential candidate for desalination.

The double-layer PVDF-PVC (D-PP/PP) super-hydrophobic composite membrane was prepared by the coating immersion phase separation method to enhance the mechanical properties of the composite membrane. The D-PP/PP super-hydrophobic membrane was prepared using the casting solution concentration of 12 wt% PVDF-PVC composite membrane as basement and 4% casting of PVDF-PVC coating. The contact angle of the D-PP/PP membrane was 150.4 ± 0.3°, and the scanning electron microscope showed that the surface of the D-PP/PP membrane was covered by a cross-linked micro–nano microsphere. The mechanical properties showed that the maximum tensile force of the D-PP/PP composite membrane was 2.34 N, which was 19.4% higher than that of PVDF-PVC (1.96 N). Nano-graphite was added to the coating layer in the experiment. The prepared double-layer PVDF-PVC-nano-graphite/PVDF-PVC (D-PPG/PP) composite membrane reached 153.7 ± 0.5°, the contact angle increasing by 3.3°. The SEM comparison showed that the D-PPG/PP composite membrane had a more obvious micro–nano level microsphere layer. The mechanical properties are also superior. By preparing the D-PP/PP membrane, the mechanical properties of the membrane were improved, and the super-hydrophobic property of the coating was also obtained. At the same time, it was found that adding nano-graphite to the coating layer can better improve the hydrophobic, mechanical, and self-cleaning properties of the D-PP/PP composite membrane.

Considering the high potential of hydrogen (H2) as a clean energy carrier, the implementation of high performance and cost-effective biohydrogen (bioH2) purification techniques is of vital importance, particularly in fuel cell applications. As membrane technology is a potentially energy-saving solution to obtain high-quality biohydrogen, the most promising poly(ionic liquid) (PIL)–ionic liquid (IL) composite membranes that had previously been studied by our group for CO2/N2 separation, containing pyrrolidinium-based PILs with fluorinated or cyano-functionalized anions, were chosen as the starting point to explore the potential of PIL–IL membranes for CO2/H2 separation. The CO2 and H2 permeation properties at the typical conditions of biohydrogen production (T = 308 K and 100 kPa of feed pressure) were measured and discussed. PIL–IL composites prepared with the [C(CN)3]− anion showed higher CO2/H2 selectivity than those containing the [NTf2]− anion. All the membranes revealed CO2/H2 separation performances above the upper bound for this specific separation, highlighting the composite incorporating 60 wt % of [C2mim][C(CN)3] IL.

The use of poly(vinylidene fluoride) (PVDF) microfiltration (MF) membranes to purify oily water has received much attention. However, it is challenging to obtain high-performance PVDF microfiltration membranes due to severe surface fouling and rapid decline of permeability. This study explored a new approach to fabricate high-performance PVDF/silica (SiO2) composite membrane via the use of a polymer solution featuring lower critical solution temperature (LCST) characteristics and the non-solvent thermally induced phase separation method (NTIPS). Coupling with morphological observations, the membrane formation kinetics were analyzed in depth to understand the synergistic effect between the LCST solution properties and fabrication conditions in NTIPS. Utilizing such a synergistic effect, the transition from finger-like macrovoid pores to bi-continuous highly connected pores could be flexibly tuned by increasing the PVDF concentration and the weight ratio of SiO2/PVDF in the dope solution and by raising the coagulation temperature to above the LCST of the solution. The filtration experiments with surfactant-stabilized oil-water emulsion showed that the permeation flux of the PVDF/SiO2 composite membranes was higher than 318 L·m−2·h−1·bar−1 and the rejection above 99.2%. It was also shown that the PVDF/SiO2 composite membranes, especially those fabricated above the LCST, demonstrated better hydrophilicity, which resulted in significant enhancement in the anti-fouling properties for oil/water emulsion separation. Compared to the benchmark pure PVDF membrane in oily water purification, the optimal composite membrane T70 was demonstrated via the 3-cycle filtration experiments with a significantly improved flux recovery ratio (Frr) and minimal reduced irreversible fouling (Rir). Overall, with the developed method in this work, facile procedure to tune the membrane morphology and pore structure was demonstrated, resulting in high performance composite membranes suitable for oil/water emulsion separation.

The study investigated the use of thin film composite membrane (TFC) as a potential candidate for hydroquinone removal from water. Thin film composite membranes were prepared by polyamide coating on Polysulfone asymmetric membrane. FTIR study was performed to verify the Polysulfone as well as polyamide functionality. TFC membrane was characterized by contact angle, zeta potential, scanning electron microscopy studies. The salt rejection trend was seen from 500 to 1000 mg/L. The membrane is marked by permeability co-efficient B based on solution diffusion studies. The value is 0.98 × 10 −6  m/s for NaCl solution at 1.4 MPa. The separation performance was 88.87% for 5 mg/L hydroquinone at 1.4 MPa. The separation was little bit lowered in acid medium because of the nature of the membrane and feed solute chemistry. The ‘pore swelling’ and ‘salting out’ influenced hydroquinone separation in the presence of NaCl. The hydroquinone separation was 80.63% in 1000 mg/L NaCl solution. In acidic pH, NaCl separation was influenced much more compared to hydroquinone. The separation is influenced by field water matrix.

Salination of solutions of salinity gradient releases large‐scale clean and renewable energy, which can be directly and efficiently transformed into electrical energy using ion‐selective nanofluidic channel membranes. However, conventional ion‐selective membranes are typically either cation‐ or anion‐selective. A pH‐switchable system capable of dual cation and anion transport along with salt gradient energy harvesting properties has not been demonstrated in ion‐selective membranes. Here, we constructed an amphoteric heterolayer metal–organic framework (MOF) membrane with subnanochannels modified with carboxylic and amino functional groups. The amphoteric MOF‐composite membrane, AAO/aUiO‐66‐(COOH)2/UiO‐66‐NH2, exhibits pH‐tuneable ion conduction and achieves osmotic energy conversion of 7.4 and 5.7 W/m2 in acidic and alkaline conditions, respectively, using a 50‐fold salt gradient. For different anions but the same cation diffusion transport, the amphoteric membrane produces an outstanding I−/CO32− selectivity of ~4160 and an osmotic energy conversion of ~133.5 W/m2. The amphoteric membrane concept introduces a new pathway to explore the development of ion transport and separation technologies and their application in osmotic energy‐conversion devices and flow batteries. Osmotic energy generator with an amphoteric MOF‐on‐MOF membrane with carboxylic and amino functional groups that are pH‐switchable to mediate ion conduction and osmotic energy conversion of 7.4 and 5.7 Wm−2 in acidic and alkaline media, respectively, using a 50‐fold salinity gradient of NaCl and 9.8 Wm−2 from the interface of actual seawater and river water.