Membranes最新文献

Reverse electrodialysis (RED) is a relatively recent technology for renewable energy harvesting from the interaction of river and seawater. This paper revisits the thermodynamic equilibrium governing the ionic transport processes through ion-exchange membranes (IEMs) under RED conditions and theoretically derives approximate analytical expressions for the ionic concentrations at the inner boundaries of a permeable membrane with well-stirred baths. The equation for the Donnan ion partitioning at the membrane-solution interface, which is based on the equality of the electrochemical potential in the two phases, is analysed for binary salts with symmetric (1:1) and asymmetric (2:1) electrolytes, by considering bathing solutions with the equivalent concentrations 0.02 M in the dilute bath, and 0.5, 1, and 1.5 M in the concentrate one. Simple approximate analytical expressions exhibiting the evolution with the membrane fixed-charge concentration of the counter-ionic concentrations at the inner boundaries of the membrane, the concentration gradients inside the membrane, the total Donnan electric potential, and the ionic partitioning coefficients have been derived. The approximate generalised expressions for a general z₁:z₂ binary electrolyte are also presented for the first time.

A techno-economic and environmental evaluation of dehydrating five industrially relevant solvents (isopropanol, acetonitrile, tetrahydrofuran, acetic acid, and n-methyl-2-pyrrolidone) using pervaporation-based processes was performed and compared to their respective traditional distillation processes. A standalone pervaporation and two hybrid processes (i.e., distillation-pervaporation and distillation-pervaporation-distillation) employing HybSi^® AR membranes were simulated in Aspen Plus, where the pervaporation module was modeled as a separator block that followed the experimental data. The experiments were performed at a vacuum pressure of 20 mbar and a temperature of 130 °C. The performance was compared based on several technical, economic, and environmental measures, of which key metrics are the levelized cost of separation (LCOS) and CO₂ footprint reduction. From the economic perspective, the pervaporation-based processes are much more economical than the distillation processes for isopropanol (up to 42% reduction in LCOS) and acetonitrile (up to 39% reduction in LCOS), while their economic performance is similar to the benchmark process in the case of tetrahydrofuran (only up to 4% reduction in LCOS). For acetic acid (9% higher LCOS) and n-methyl-2-pyrrolidone (124% higher LCOS), the pervaporation-based processes do not perform better than the distillation processes under the current technical and economic considerations. However, a sensitivity analysis showed the potential to make the pervaporation-based processes more economical by improving the permeate flux and membrane module cost. On the other hand, the pervaporation-based processes are much more environmentally friendly for all the solvents studied compared to their respective benchmark processes. The reduction in CO₂ footprint is in the order of 86%, 82%, 73%, 82%, and 65%, respectively, for the aforementioned solvents.

The ultimate objective of this research is to concentrate nutrients-nitrogen (N), phosphorus (P), and potassium (K)-and produce process water from a chemically pretreated liquid digestate using an FO-RO hybrid process. However, in this manuscript, we assessed the suitability of (NH₄)₂SO₄ and NaCl as draw solutes in a series of FO experiments employing a commercial CTA membrane and DI water as the feed solution. We also examined the regeneration of (NH₄)₂SO₄ in a series of RO experiments at various feed concentrations and pressures using a commercial polyamide (PA) thin-film composite (TFC) membrane, ACM4. Additionally, the RO experiments enabled the experimental determination of the osmotic pressure of (NH₄)₂SO₄ at various feed concentrations, which is crucial for designing the FO part of the hybrid process. The CTA membrane exhibited a significantly greater selectivity for (NH₄)₂SO₄ than for NaCl at any osmotic pressure. The RO experiments demonstrated the possibility of reconcentrating (NH₄)₂SO₄ to 0.5 mol/L, with a corresponding water flux of 60 L h^-1 m^-2 at 40 bars. The experimentally determined osmotic pressures were lower than those predicted by van't Hoff's equation but were consistent with those reported in the literature using an indirect hygrometric method.

MXenes, members of two-dimensional materials, were discovered in 2011 for the first time. MXenes are famous nowadays for their attractive and unique properties such as hydrophilicity, surface area, and catalytic activity for various industrial applications. This review comprehensively focused on composite membranes with MXenes that can be directly deployed for water purification. Moreover, this review will also give significant insight into new synthetic approaches for MXene-based composite membranes. A review of the utilization of MXene-based composite membranes in modern separation techniques such as nanofiltration, ultrafiltration, and forward osmosis has also been summarized. Finally, the current issues and future perspectives on applying two-dimensional materials for water treatment are elaborately discussed.

A commercial anion-exchange membrane was modified via the electrodeposition of different water-soluble polymers to study the effects of surface modification on electrodialysis performance. X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy analyses showed that the different polymers were successfully electrodeposited on the membrane surface. The surface morphology and electrical resistance of the modified AEMs were almost unchanged. Contact angle and zeta potential measurements indicated differences in the surface hydrophilicity and surface charge density of the modified AEMs. The electrodialysis performance of the pristine AEM declined significantly in the presence of the foulant. In contrast, the electrodialysis performance of the AEMs modified with poly (vinylsulfonic acid, sodium salt) showed almost no decline and exhibited the best antifouling property in the presence of the foulant, followed by those modified with poly (sodium acrylate) and poly (vinyl alcohol). The results indicated that an increase in surface negative charge density and surface hydrophilicity increased the resistance of the modified AEMs to the foulant and improved their electrodialysis performance.

Efficient management for electrochemical reactions within Pt/C electrodes, specifically the oxygen reduction reaction (ORR) and methanol oxidation reactions (MOR), is critical to the performance and long-life stability of direct methanol fuel cells (DMFCs). Optimizing the hierarchical macro/mesoscale structures of Pt/C electrodes plays a decisive role in regulating the mass transport pathways and electrochemical reactions. In this work, bead-like Pt/C-ionomer hybrid porous nanofibrous networks are constructed via electrospinning. Ascribing to the hierarchical architecture consisting of continuous nanofibers and bead-like Pt/C-ionomer fibrous networks, the hybrid porous nanofibrous electrode exhibits a 55% increase in maximum mass power density in comparison to the conventional Pt/C electrode. Such enhancement is attributed to excellent ORR activity enabled by efficient triple-phase reaction regions, coupled with superior MOR tolerance resulting from restricted methanol transport from the hybrid porous nanofibrous electrode to triple-phase reaction regions.

This study reports the development of an optimized tight ultrafiltration (UF) membrane prepared from recycled acrylic fiber (polyacrylonitrile, PAN) waste for the efficient removal of organic pollutants from water. Membranes were fabricated using different concentrations of acrylic fiber waste to examine the influence of polymer content on their morphology and performance. The prepared membranes were characterized using scanning electron microscopy (SEM), porosity measurements, contact angle analysis, and mechanical strength testing to evaluate their structural and physicochemical properties. Among the tested formulations, membrane M4, containing 22.5 wt.% acrylic fiber waste, shows the most balanced performance, high mechanical integrity, and good surface hydrophilicity, with a contact angle of about 52° and porosity of 27%. The optimized M4 membrane demonstrates excellent pure water flux of 65 LMH. M4 achieves a flux recovery ratio (FRR) above 80%. Its performance was further evaluated for the removal of humic acid (HA) and paracetamol as a model of organic contaminants. The results also demonstrate strong chemical stability under acidic and basic conditions, highlighting the potential of recycled acrylic fiber waste as a sustainable polymer source for high-performance tight UF membranes. This approach offers an environmentally friendly and cost-effective solution for water purification and pharmaceutical contaminant removal.

The separator is a key component of lithium-ion batteries, and its properties play a crucial role in the performance of such batteries. However, the most widely used polyolefin separators are not only made from non-renewable resources such as petroleum, but also have poor wettability to electrolytes, and their low melting points may cause short circuits or even explosions. Therefore, advanced separators that meet the increasing requirements of such batteries are urgently needed. Compared to polyolefin separators, renewable biomass fiber-based separators have better compatibility with electrolytes, higher thermal stability, and are naturally abundant. Their use is not only in line with sustainable development, but it also lowers their material cost. Therefore, biomass fiber-based separators are considered a promising candidate for replacing polyolefin separators for lithium-ion batteries in the future. In this article, studies on the preparation and application of biomass fiber-based separators in lithium-ion batteries in recent years are reviewed, looking forward to their future development, with the aim of providing a reference for researchers.

Polysulfone (PSF), despite its excellent thermal and mechanical stability, exhibits moderate gas separation performance and poor compatibility with inorganic fillers, resulting in interfacial voids and structural defects. This study addressed these limitations by incorporating vinyltrimethoxysilane (VTMS)-functionalized TiO₂ nanoparticles into PSF matrix to develop mixed matrix membranes (MMMs) for selective CO₂/N₂ separation. Membranes with 1-5 wt.% VTMS@TiO₂ loadings were fabricated via solution casting, and their gas separation performance was systematically evaluated. VTMS modification enhanced the dispersion and interfacial adhesion of TiO₂ within the PSF matrix, as confirmed by SEM, FTIR, XRD, and TGA analyses. The 4 wt.% VTMS@TiO₂ loaded membrane showed optimal performance, with a CO₂ permeability of 8.48 barrer and a CO₂/N₂ selectivity of 26.50 due to stronger polymer-filler interactions and enhanced CO₂ affinity by VTMS functional groups. This membrane has shown stable transport behavior and favorable CO₂ selectivity as confirmed by pressure- and temperature-dependent permeation studies. Robeson plot analysis showed that the optimized membrane approached the upper bound, demonstrating a significant improvement over pure PSF. The study confirmed that VTMS-functionalized TiO₂ enhanced both permeability and selectivity through improved filler dispersion, interfacial integrity, and CO₂ affinity.

Pharmaceutically active compounds (PhACs), pesticides, and poly- and perfluoroalkyl substances (PFAS) are increasingly detected in surface waters at trace concentrations, raising concerns for both aquatic systems and, consequently, human health. Conventional solutions are insufficient to achieve complete removal at trace compound concentrations, highlighting the need for advanced separation technologies. This study aims to comprehensively analyze rejection and removal mechanisms of selected PhACs, pesticides, and PFAS present in water solutions at reported environmentally relevant concentrations (300 ng L^-1), using two nanofiltration (NF) and one reverse osmosis (RO) polyamide membrane. PhACs, pesticides, and PFAS were selected to cover a broad range of physicochemical properties, specifically molecular mass (MM), dissociation constant (pKa), and octanol-water partition coefficient (logK_o/w). Rejection values ranged from 42.1% (acetaminophen) to apparent 100% (for multiple compounds), depending on water pH, solute properties, and membrane characteristics. Size exclusion and electrostatic interactions were identified as the primary removal mechanisms, with hydrophobic interactions having a lower impact, particularly for carbamazepine, bezafibrate, and perfluorooctane sulfonic acid (PFOS). Addition of sodium chloride (3 g L^-1) decreased rejection of most negatively charged compounds due to suppression of membrane surface charge, although clarithromycin and ofloxacin exhibited improved rejection. Presented results provide fundamental insight into compound-specific membrane rejection and highlight the importance of membrane-solute interactions under environmentally realistic conditions. The results support further optimization of NF and RO for targeted compound rejection and provide a baseline for data-driven membrane process modeling.