Membranes最新文献

The recycling of a planar composite Pd membrane over a porous stainless-steel support modified with a CeO₂ interlayer (Pd/CeO₂/PSS) was investigated using a leaching-based recycling strategy to recover palladium while maintaining the support's structural integrity. The membrane was prepared by a continuous flowing electroless pore-plating method (cf-ELP-PP) previously developed by our group. A series of experiments was conducted to evaluate the effect of leaching conditions-temperature, acid concentration, and duration-on Pd extraction and support preservation. Nitric acid (HNO₃) was used as the leaching agent, and the condition of 30 vol.% HNO₃ at 35 °C for 24 h was found to enable complete Pd recovery with limited dissolution of metals from the support. The regenerated supports exhibited an Fe-Cr oxide layer and part of the CeO₂ interface, allowing the elimination of cleaning and calcination steps in the membrane reprocessing workflow. A new Pd-CeO₂ interfacial layer was applied, followed by Pd redeposition via cf-ELP-PP. The resulting recycled membrane exhibited a homogeneous and defect-free Pd layer, with hydrogen permeation performance comparable to that of membranes fabricated on fresh supports. These results demonstrate that Pd membranes can be successfully fabricated on recycled 316L stainless-steel substrates, supporting the viability of this approach for material reuse in membrane technology.

Reverse electrodialysis (RED) enables the efficient conversion of the chemical potential difference between seawater and freshwater into electricity while simultaneously facilitating hydrogen production for integrated energy utilization. Nevertheless, the widespread deployment of RED remains constrained by the reliance on ruthenium-iridium-coated electrodes, which are expensive and resource-limited. This study proposes the adoption of titanium-based redox electrodes as a replacement for traditional precious metal electrodes and employs a novel spike structure to accelerate hydrogen bubble detachment. The electrochemical performance of titanium electrodes in an RED hydrogen production system was systematically evaluated experimentally. The influences of several parameters on the RED system performance were systematically examined under these operating conditions, including the ruthenium-iridium catalytic layer, operating temperature (15 to 45 °C), electrode rinse solution (ERS) concentration (0.1 to 0.7 M), and flow rate (50 to 130 mL·min^-1). Experimental results demonstrate that optimized titanium redox electrodes maintain high electrocatalytic activity while significantly reducing system costs. Under optimal conditions, the hydrogen yield of the Ti redox electrode reached 89.7% of that achieved with the mesh titanium plate coated oxide iridium and oxide ruthenium as electrodes, while the electrode cost was reduced by more than 60%. This is also one of the cost-cutting solutions adopted by RED for its development.

Building on our previous study on batch pervaporation membrane reactors for isoamyl acetate synthesis, this work evaluates a two-step continuous process integrating a slurry reactor and a commercial pervaporator module based on a hybrid silica membrane. The system combines catalytic esterification of acetic acid with isoamyl alcohol with simultaneous water removal to enhance conversion and product selectivity. Operating conditions were defined using experimentally validated thermodynamic, kinetic, and mass-transport models. A hydrodynamic assessment confirmed turbulent flow within the membrane module, and model predictions were compared with experimental data for validation. The results confirmed the occurrence of reactive pervaporation and demonstrated that both the membrane area-to-reactor volume ratio and catalyst loading significantly influence the equilibrium shift. Although conversion remained limited by the available membrane area, the commercial pervaporation unit exhibited stable operation, consistent flux behavior, and effective water selectivity. These findings demonstrate the technical feasibility of the continuous slurry reactor-pervaporator configuration and establish a framework for further optimization and scale-up of isoamyl acetate production via reactive pervaporation.

The ongoing expansion of industrial operations has resulted in the generation of a large amount of high-salinity wastewater with complex compositions. The direct discharge of this wastewater poses significant threats to ecosystems and leads to the loss of valuable salt resources, for example, triggering freshwater salinization syndrome and mobilizing heavy metals to form toxic "chemical cocktails", leading to the loss of valuable salt resources. Desalination of high-salinity wastewater primarily involves two key processes: concentration and crystallization, whereby a concentrated brine is first obtained through membrane-based or thermal methods, followed by salt recovery via crystallization. This review begins by employing a bibliometric analysis to map the knowledge structure and trace the evolution of research trends, revealing that "membrane-thermal integration" has become a dominant research hotspot since 2020. It then provides a systematic examination of advanced treatment technologies, chronicling the progression from early biological methods to contemporary membrane-based and thermal desalination approaches. A specific analysis of the influence of salinity on membrane scaling is also included. Consequently, this paper critically assesses the prospects and challenges of several alternative desalination technologies and proposes that integrated processes, combining membrane-based and thermal desalination, represent a highly promising pathway for achieving zero liquid discharge (ZLD). Finally, we suggest that future research should prioritize the development of key functional materials, explore efficient hybrid physiochemical-biochemical processes, and advance emerging technologies, aimed at enhancing treatment efficiency and reducing operational costs.

Seawater has attracted increasing attention as a promising resource for hydrogen production via electrolysis. However, multivalent ions present in seawater can reduce the efficiency of direct seawater electrolysis (DSWE) by forming inorganic precipitates at the cathode. Bipolar membranes (BPMs) can mitigate precipitate formation by regulating local pH, thereby enhancing DSWE efficiency. Accordingly, this study focuses on the fabrication of a high-performance BPM for DSWE applications. The water-splitting performance of BPMs is strongly dependent on the properties of the catalyst at the bipolar junction. Herein, iron oxide (Fe₃O₄) nanoparticles were coated with cross-linked chitosan to improve solvent dispersibility and catalytic activity. The resulting core-shell catalyst exhibited excellent dispersibility, facilitating uniform incorporation into the BPM. Water-splitting flux measurements identified an optimal catalyst loading of approximately 3 μg cm^-2. The BPM containing Fe₃O₄-chitosan nanoparticles achieved a water-splitting flux of 26.2 μmol cm^-2 min^-1, which is 18.6% higher than that of a commercial BPM (BP-1E, Astom Corp., Tokyo, Japan). DSWE tests using artificial seawater as the catholyte and NaOH as the anolyte demonstrated lower cell voltage and stable catholyte acidification over 100 h compared to the commercial membrane.

The study investigates the performance of polyethersulfone (PES) ultrafiltration (UF) membranes modified with a coating of polymerizable bicontinuous microemulsion (PBM) for membrane bioreactor (MBR) applications. Two types of PBM-modified PES membranes-casting-coated and spray-coated-were compared with a commercial PES membrane. A laboratory side-stream MBR (ssMBR) was employed to treat model wastewater (MW) with activated sludge under aerobic conditions. The fouling propensity of the membranes in ssMBR was evaluated through the implementation of two protocols: (i) flux-step test to treat low-strength domestic model wastewater (DMW) and (ii) constant flux test to treat high-strength olive mill model wastewater (OMW). The findings indicated that both the commercial PES and PBM spray-coated PES membranes started to critically foul at 36 L m^-2 h^-1. The PBM spray-coated membranes showed enhanced fouling resistance in comparison to the PBM casting-coated membranes. The deposition of the biofouling layer was the thinnest on PBM spray-coated membranes, which can be attributed to the low surface charge and high hydrophilicity of the modified membrane surface. In contrast, deposition of a thicker fouling layer was found on the commercial PES membrane, which can be attributed to the relatively higher surface charge promoting organic adsorption. A comparison of the fouling trends exhibited by commercial PES and PBM spray-coated membranes in OMW treatment revealed that they have similar fouling tendencies. However, a notable distinction emerged when the PBM spray-coated membrane was observed to demonstrate a lower fouling propensity accompanied by comparatively thinner fouling layers. The results demonstrate that the PBM spray-coated membranes have enhanced fouling resistance and filtration efficacy in MBRs treating wastewater with diverse strengths, thereby affirming their potential for application in wastewater treatment systems.

Reducing the specific energy consumption of reverse osmosis (RO) processes motivates the development of new membrane materials that have enhanced water permeability while maintaining low salt permeability (high rejection). Nanocomposite membranes have shown great promise in achieving these goals, particularly those using nanotubes as fillers. Here, we report on the relationships between the orientations and surface functionalities of imogolite nanotubes (INTs) with water and salt permeabilities for polyamide nanocomposite membranes. An external electric field was used to manipulate the INT orientation within the polyamide active layer. The INT interior and exterior chemistries, respectively, were made hydrophobic using methyl triethoxysilane as a precursor during INT synthesis and post-synthesis modification with alkali-phosphate groups. Irrespective of nanotube orientation or surface chemistry, membrane permeance increased from 0.3 to ≥1.0 L m^-2 h^-1 bar^-1. A salt permeability comparable to the conventional polyamide membrane was maintained by making the INT pore throat hydrophobic. These findings indicated that salt rejection could be tailored by manipulating the INT interior surface chemistry without sacrificing water permeability.

Solvent differences in perfluorinated sulfonic acid ionomer (PFSI) dispersions confound comparisons of catalyst-layer (CL) binders for PEM water electrolysis. We use a propylene-glycol (PG) single-solvent platform to isolate effects of ionomer structure, i.e., side-chain architecture and equivalent weight (EW), across five PFSIs (Nafion D2021, Nafion D2020, Aquivion D98-25BS, Aquivion D72-25BS, and 3M E-22397B) as hydrogen evolution reaction-CL binders. PG collapses ionomer aggregates from microns to sub-100 nm and reduces catalyst-ionomer agglomerates without a systematic EW trend, indicating that performance differences originate during film formation. PG makes CLs more hydrophobic (higher θ_R), yet aerophobicity (θ_Air) still increases with decreasing EW, consistent with higher sulfonic-acid density. Under PG, current density at 1.9 V rises with decreasing EW, with thicker short-side chain/mid-side chain (SSC/MSC) films (≥140 nm) and lower ohmic overpotentials than long-side-chain (LSC) Nafion. Durability under Accelerated Stress Test-2 (AST-2; 0.3/3.0 A cm^-2, 48 h) splits by class: LSC Nafion shows the largest degradation slopes, whereas SSC/MSC are lower; transmission electron microscope images show Pt growth with Nafion D2020-PG but minimal growth with Aquivion D98-25BS-PG. With solvent effects removed, ionomer structure governs CL performance and stability; SSC (EW ≈ 980) is recommended, and MSC maximizes current with moderate stability.

Neuronal development relies on cell-surface glycoconjugates that function as complex bioinformational codes. Recently, altered glycosylation has emerged as a central mechanistic theme in the pathophysiology of autism spectrum disorder (ASD). Critically, the brain maintains a distinctively restricted glycan profile through strict biosynthetic regulation, creating a specialized landscape highly susceptible to homeostatic perturbation. This "membrane-centric vulnerability" spans both glycoproteins and glycolipids; however, evidence remains fragmented, obscuring their pathogenic interplay. To bridge this gap, this review synthesizes evidence for these two primary classes of membrane glycoconjugates into a unified framework. We examine how defects in key glycoproteins (such as NCAM1 and neuroligins) directly impair synaptic signaling, trafficking, and plasticity. We then demonstrate how these defects are functionally coupled to the glycolipid (ganglioside) environment, which organizes the lipid raft platforms essential for glycoprotein function. We propose that these two systems are not independent but represent a final common pathway for diverse etiological drivers. Genetic variants (e.g., MAN2A2), environmental factors (e.g., valproic acid), and epigenetic dysregulation (e.g., miRNAs) all converge on this mechanism of impaired glycan maturation. This model elucidates how distinct upstream causes can produce a common downstream synaptic pathology by compromising the integrity of the membrane signaling platform.

Fouling is a major challenge in membrane-based filtration processes, leading to higher operating and capital costs. Developing new membranes with better fouling resistance has always been a research focus in the membrane field. In particular, designing functional surfaces which mitigate fouling is an effective approach. We successfully fabricated membranes with a graphene functional layer using a single-step laser irradiation known as laser-induced graphene (LIG) on the membrane surface. The LIG ultrafiltration (UF) membranes were prepared by directly lasing poly(ether sulfone) (PES) membrane substrates. Scanning electron microscopy demonstrated the successful ablation of the PES membranes with controlled thickness. Water filtration tests confirmed that the permeance increased by 240% as the laser power increased from 2.4 to 3.2 W; the membrane lased with the highest ablation power (LIG-P8) displayed a high water permeance of ~400 L m^-2 h^-1 bar^-1 and a corresponding bovine serum albumin (BSA) rejection of 92.5%. Fouling experiments using BSA, humic acid (HA), and sodium alginate showed better permeance recovery ratios (78-90%) with LIG membranes compared to the neat PES membrane (65-68%). LIG membranes were also evaluated for antibioufouling filtration tests, which showed exceptional biofilm resistance and potent antibacterial killing effects when treated with Staphylococcus aureus. Applied external voltage and contact time were the key variables to optimize the antibiofouling properties of the LIG UF membranes.