Journal of Membrane Science最新文献

The amine functionalized graphene oxide (GO) was prepared via a chemical reaction. This was achieved by reacting GO with a mixture of ethanolamine, N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride, and sodium tripolyphosphate (STTP). The amine-functionalized graphene oxide (EGOS) with varying STTP:GO weight ratios was then used to fabricate cation-exchange membranes (CEMs) based on polyvinylidene fluoride. The characterizations of the modified EGOS samples were investigated using various techniques, such as Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Raman spectroscopy, and energy dispersive spectroscopy (EDS). Furthermore, the influence of the STTP:GO weight ratio in the EGOS samples on the properties of the fabricated CEMs was investigated using different experimental methods. More desirable characteristics were recorded for the EGOS-based CEMs compared to GO-containing membranes. The top-performance membrane comprising EGOS0.5 (STTP: GO weight ratio of 0.5:1) demonstrated a remarkable water content of 45.6 ± 1.3 %, and an ion exchange capacity of 3.6 ± 0.3 meq g⁻¹. The electrochemical impedance spectroscopy results showed that this membrane has the lowest resistance of 1.5 Ω cm², which was considerably (86.96 %) less than the value obtained for the unmodified GO-containing reference membrane (11.5 Ω cm²). The diffusion coefficient of sodium ions through the fabricated CEMs was investigated via electrochemical cyclic voltammetry (CV) and the Randles-Sevceks equation and the highest value was obtained for EGOS0.5-based CEMs.

Hollow fiber membranes (HFMs) are an ideal configuration for industrial applications of pervaporation desalination (PV) membranes. Currently, the efficient fabrication of PV HFMs is restricted by multi-step post-treatment processes on their outer surfaces to form the selective layer. Herein, we utilized the surface segregation strategy to fabricate a hetero-structured HFM in one step, simultaneously forming the hydrophilic dense outer layer and the porous support layer. During hollow fiber spinning process, the amphiphilic copolymer polyvinylpyrrolidone-polyvinyl acetate (PVP-PVAc) in polyether sulfone (PES) dope solution migrated towards water contacting interface in the coagulation bath and formed the hydrophilic layer by extending hydrophilic segment outwards. This fast in-situ hydrophilization well matched the spinning efficiency. The optimal PVP-PVAc content and phase inversion temperature were investigated and the spinning parameters on the structure and performance of HFMs were studied. The HFMs prepared realized a flux of 26.70 kg m⁻² h⁻¹ and the salt rejection of 99.98 %, along with adaptability to solutions with different salinities and excellent anti-organic fouling property. This study may provide a facile method to fabricate HFMs with desirable PV desalination performance and scaling-up potential.

Thin film composite (TFC) membranes are state-of-the-art membranes that are widely applied in water treatment and seawater desalination. However, these membranes are typically prepared using petrochemical-based monomers and toxic solvents. Herein, plant-based monomers, namely priamine (PA), 2,5-furandicarboxaldehyde (FDA) are used to fabricate green PA–FDA TFC membranes via interfacial polymerization. Additionally, PA was also combined with trimesoyl chloride (TMC) to obtain PA–TMC TFC membranes. The reaction conditions were varied to investigate their effects on membrane morphology and performance. The resultant membranes exhibited smooth surfaces with an average roughness ranging from 15 to 30 nm, and increasing the monomer concentration increased the film thickness. The PA–TMC free-standing films had higher thicknesses (130–300 nm) than the PA–FDA films (36–122 nm). Furthermore, PA–TMC and PA–FDA films were hydrophobic due to the long aliphatic chains of PA. Moreover, PA–TMC membranes demonstrated a water permeance of ∼4 L m⁻² h⁻¹ bar⁻¹ with 74% NaCl rejection, while PA–FDA membranes achieved better NaCl rejection (∼80%) but lower water permeance (0.3–4 L m⁻² h⁻¹ bar⁻¹). Applied in brine separation, the membranes demonstrated ∼90% divalent ion rejection and only 70% monovalent ion rejection. The proposed plant-based monomer combination provides a steppingstone toward green TFC membrane manufacturing for water treatment and desalination applications.

This study investigates the effects of various porous supports and the presence of additional gases in the feed on hydrogen permeation using an unsupported Pd₈₂–Ag₁₅–Y₃ membrane. The pore sizes and thicknesses of metallic supports varied from 1 to 270 μm and 50–3000 μm, respectively. The membrane was unsupported, synthesized by cold-rolling, and characterized by a thickness of 38 μm. The tests were performed at 400 °C with pressures ranging from 1.4 to 3 bar. Results showed that the unsupported Pd₈₂–Ag₁₅–Y₃ membrane reached 12 % and 267 % higher hydrogen permeation than the supported membrane by 1 μm pore size and 50 μm thick woven mesh, and 1 μm pore size and 3 mm thick of porous stainless steel (PSS), respectively. The unsupported Pd₈₂–Ag₁₅–Y₃ membrane showed one of the highest hydrogen permeability in the literature (7.5 $\times$ 10⁻⁸ mol m⁻¹ s⁻¹.Pa^−0.5 at 400 °C). However, the presence of porous supports used to enhance the mechanical stability of the membrane negatively affected the hydrogen permeation due to mass transfer limitation. In addition, the presence of supports induced an unreal ‘n’ value for the Pd-based membrane, where the ‘n’ value is the exponent of the driving force in the equation of hydrogen transport, varying between 0.5 and 1. In particular, for the unsupported membrane, the ‘n’ value was 0.6, but it increased to 0.7 and 0.8 when supports with 1 μm pore size and 50 μm thick and 5 μm and 80 μm thick were utilized. Binary hydrogen permeation tests were also performed in the presence of N₂, CH₄, CO₂, and CO at 400 °C by using unsupported and supported membranes to investigate the reduction in hydrogen permeation flux due to the effect of the supports plus the effect of the presence of other gas. The results revealed that CO had the highest inhibition effect for all the unsupported and supported membranes tested due to competitive adsorption on the surface. No superficial adsorption on the membrane was observed for N₂, CH₄, and CO₂ during permeation, and they inhibited hydrogen permeation mainly due to depletion, dilution, and concentration polarization. The PSS_1–3000 indicated the lowest hydrogen permeation between the gas mixture and the porous support, whereas the presence of 40 % of the binary gas mixture had lower hydrogen permeation than porous support except for the PSS.

Inspired by the structure of seal whiskers, this study undertakes a biomimetic design of the spacer in Reverse osmosis (RO) desalination, the performance of biomimetic spacers based on parameters such as elliptical cross-sectional area ratio (SR), twist angle (φ) and Reynolds number (Re) are analysed. Spacer performance ratio on the water production per unit pressure drop (SPR) and energy loss factor (λ) are introduced to better elucidate the structural performance of the spacer. The experimental and simulation studies on the adopted commercial spacer and the improved biomimetic spacer are used to demonstrate the reliability of the simulation. The structure of commercial spacer is further obtained by using micro-CT scanning, then the performance of commercial spacer (S1), circular cross-section spacer (CS), and prototype biomimetic spacer (BS) are numerically compared, and an improved biomimetic spacer (IBS) is obtained. When Re = 50 (Re = 300), the pressure drop of IBS is reduced by approximately 38 % (35 %) compared to the CS, and 39 % (28 %) compared to the S1; SPR is increased by approximately 83 % (57.4 %) compared to the CS, and 60.8 % (37 %) compared to the S1. With a filament angle (γ) of 60°, the IBS exhibits optimal performance. Ultimately, through data and theoretical analysis, theoretical formulas are developed to reflect the energy loss factor (λ) based on the projected area of the spacer along the flow direction, Re, and pressure drop. Through optimization of design, the improved biomimetic spacer can not only significantly reduce the pressure drop, but also obtain the high water flux, which provides new insights and methods for the development of seawater desalination technology.

High permselectivity and antifouling/self-cleaning nanofiltration (NF) membranes are ideal materials for water treatment, and this vision is expected to be reached through the design of multifunctional self-cleaning interfaces. In this study, we employed metal - polyphenol network (MPN) to mediate in situ mineralization of porous substrates, enabling simultaneous modulation of interfacial polymerization (IP) and catalytic self-cleaning. The findings demonstrate that the mineralized layers employ an interlayer modulation strategy to produce a polyamide (PA) layer that is more hydrophilic, thinner, and structurally denser. As a result, the resulting PA-Fe₃O₄-PSF membrane exhibited a 2.5-fold increase in permeance (19.2 L m⁻² h⁻¹ bar⁻¹) and a 7.3-fold enhancement in Cl⁻/SO₄²⁻ selectivity (66.4), compared to the control membrane (PA-PSF). Additionally, its highly polarized membrane surface significantly improved its antifouling performance. Compared to membranes with mineralized layers on the surface (Fe₃O₄-PA-PSF), PA-Fe₃O₄-PSF constructs a confined space that facilitates more efficient regeneration through in situ catalytic self-cleaning and ensures greater stability during multiple fouling-regeneration cycle operations. This study paves the way for fabricating multifunctional NF membranes with sustainable applications in material concentration, wastewater treatment, and environmental remediation.

Carbon mineralization is a promising approach for carbon capture, utilization, and storage (CCUS) but still faces technical and economic challenges. This study reports on CO₂ mineralization using various hollow fiber membrane contactors (HFMCs) to optimize the system and understand the mass transport mechanism. We conducted a quantitative comparative assessment through theoretical and experimental approaches to evaluate the performance of three HFMC types with different morphological and chemical characteristics at various gas and liquid velocities. Results showed that the in-house developed highly porous hollow fiber (HF) membrane exhibited superior CO₂ capture efficiency compared to commercial membranes. In contrast to other HFMCs showing a sharp decline in CO₂ flux due to internal fouling caused by pore wetting and external fouling, the highly porous HF membrane with surface modification maintained stable performance during continuous operation due to its superhydrophobicity and surface roughness. The HF membrane also achieved the highest overall mass transfer coefficients, closely matching the theoretical non-wetted mode due to negligible partial wetting. We expect that this study will provide insights into optimizing HFMCs for enhanced carbon mineralization efficiency.

Three nanofiltration (NF) membranes (positive charge, negative charge and near charge neutrality) were fabricated to investigate the anti-adhesion mechanism. Among them, the NF membrane with positive charge was synthesized through an electrophilic substitution reaction between the amino group of polyethyleneimine (PEI) and the chloromethyl groups of chloromethyl polysulfone (CMPSf) on a supporting polysulfone (PSf)/CMPSf blend membrane. The NF membrane with negative charge was fabricated through polycondensation using 1, 3, 5-benzenetricarbonyl trichloride (TMC) as a reactive monomer on the positive charge NF membrane. Subsequently, the near charge neutral zwitterion NF membrane (ZNF) was prepared by grafting 3-((2-aminoethyl) dimethylammonio) propane-1-sulfonate (sulfobetaine) (ADSS) onto the negative charge NF membrane. The anti-adhesion behaviors of the NF membranes during the dye selective separation were analyzed by Atomic force microscopy (AFM) and quartz crystal microbalance with dissipation (QCM-D). The results demonstrated that the near charge neutral ZNF membrane displayed a higher dyes rejection (>94.4 %) and higher flux recovery rates (>88.1 %) than charged NF membranes. Meanwhile, the near charge neutral ZNF membrane demonstrated the lowest amounts of dye deposition compared with charged NF membranes, such as reactive blue 4 (R4) for 509.9 ng/cm², basic blue 24 (BB 24) for 269.0 ng/cm², rhodamine B (RB) for 197.4 ng/cm²). Additionally, the near charge neutral ZNF membrane with the thicker hydration layer (121.7 nm) displayed weaker interaction forces (−4.8 nN to −7.4 nN) with the dyes than the charged membranes (−10.4 nN to −28.6 nN). Finally, an anti-adhesion mechanism involved charged shielding effect and hydration layer formation was proposed. These observations provide comprehensive insights into the anti-adhesion mechanism of ZNF membrane.

The advancement of aqueous organic redox-flow batteries (AORFBs) is impeded by the lack of efficient, low-resistance, and highly selective ion-conducting membranes (ICMs). Although polybenzimidazole (PBI) is one of the most promising low-cost non-fluorinated ion-conducting membranes, it remains challenging to design stable PBI membranes with fast and selective ion transport channels. Here, we engineer the chemical structure of PBI and regulate the ion transport channels to prepare highly conductive and selective Pd²⁺-coordinated membranes with grafting and crosslinking structures. In this design, the positively charged quaternary ammonium groups on the side chain improve the conductivity of OH⁻, while the continuous cross-linked network formed by ionic bonds between quaternary ammonium groups and deprotonated imidazole groups significantly enhances the membrane's mechanical properties. Furthermore, the coordination of Pd²⁺ with PBI and plasticization of PBI chain by trifluoroacetate anions expand the molecular free volume while inducing local contraction. Consequently, the QPBI-xPBI-Pd membrane enables fast charge carrier transport and suppresses the diffusion of active substances. The AORFBs assembled with the QPBI-10PBI-Pd membranes exhibit high coulombic efficiency (99.6 %) and energy efficiency (77.67 %) at 100 mA cm⁻², maintaining excellent stability for 500 cycles. This study provides an innovative strategy to design high-performance PBI membranes for RFBs, thereby advancing the viability of RFBs in the realm of large-scale energy storage technologies.