Search Results (279)

Nanofiltration (NF) is considered a competitive purification method for acidic stream treatments. However, conventional thin-film composite NF membranes degrade under acid exposures, limiting their applications in industrial acid treatment. For example, wet-process phosphoric acid contains impurities of multivalent metal ions, but NF membrane technologies for impurity removal under harsh conditions are still immature. In this work, we develop a novel strategy of acid-resistant nanofiltration membranes based on interfacial polymerization (IP) of polyethyleneimine (PEI) and cyanuric chloride (CC) with the s-triazine ring. The IP process was optimized by orthogonal experiments to obtain positively charged PEI-CC membranes with a molecular weight cut-off (MWCO) of 337 Da. We further applied it to the approximate industrial phosphoric acid purification condition. In the tests using a mixed solution containing 20 wt% P₂O₅, 2 g/L Fe³⁺, 2 g/L Al³⁺, and 2 g/L Mg²⁺ at 0.7 MPa and 25 °C, the NF membrane achieved 56% rejection of Fe, Al, and Mg and over 97% permeation of phosphorus. In addition, the PEI-CC membrane exhibited excellent acid resistance in the 48 h dynamic acid permeation experiment. The simple fabrication procedure of PEI-CC membrane has excellent acid resistance and great potential for industrial applications. Full article

Polymeric composite thin films have emerged as promising antimicrobial materials, particularly in response to rising antibiotic resistance. This review highlights the development and application of such films produced by laser-based deposition techniques, notably pulsed laser deposition and matrix-assisted pulsed laser evaporation. These methods offer precise control over film composition, structure, and thickness, making them ideal for embedding antimicrobial agents such as metal nanoparticles, antibiotics, and natural compounds into polymeric matrices. The resulting composite coatings exhibit enhanced antimicrobial properties against a wide range of pathogens, including antibiotic-resistant strains, by leveraging mechanisms such as ion release, reactive oxygen species generation, and membrane disruption. The review also discusses critical parameters influencing antimicrobial efficacy, including film morphology, composition, and substrate interactions. Applications include biomedical devices, implants, wound dressings, and surfaces in the healthcare and food industries. Full article

Access to clean water is a pressing global concern and membrane technologies play a vital role in addressing this challenge. Thin-film composite membranes prepared via interfacial polymerization (IPol) using meta-phenylenediamine (MPD) and trimesoyl chloride (TMC) exhibit excellent separation performance, but face limitations such as fouling and low hydrophilicity. This study investigated the interaction between MPD and sulfonated zinc phthalocyanine, Zn(SO₂⁻)₄Pc, as a potential strategy for enhancing membrane properties. Using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT), we analyzed the optimized geometries, electronic structures, UV–Vis absorption spectra, FT-IR vibrational spectra, and molecular electrostatic potentials of MPD, Zn(SO₂⁻)₄Pc, and their complexes. The results show that MPD/Zn(SO₂⁻)₄Pc exhibits reduced HOMO-LUMO energy gaps and enhanced charge delocalization, particularly in aqueous environments, indicating improved stability and reactivity. Spectroscopic features confirmed strong interactions via hydrogen bonding and π–π stacking, suggesting that Zn(SO₂⁻)₄Pc can act as a co-monomer or additive during IPol to improve polyamide membrane functionality. A conformational analysis of MPD/Zn(SO₂⁻)₄Pc was conducted using density functional theory (DFT) to evaluate the impact of dihedral rotation on molecular stability. The 120° conformation was identified as the most stable, due to favorable π–π interactions and intramolecular hydrogen bonding. These findings offer computational evidence for the design of high-performance membranes with enhanced antifouling, selectivity, and structural integrity for sustainable water treatment applications. Full article

The inherent hydrophobic nature of PVDF material renders it challenging to establish a stable aqueous hydration layer, thereby limiting its suitability as a substrate for the preparation of nanofiltration (NF) membranes. In this study, we developed a novel modification approach that effectively enhances the hydrophilicity of PVDF substrates through the incorporation of sulfonic acid-doped polyaniline (SPANI) and hyperbranched polyester (HPE) into the PVDF casting solution, followed by cross-linking with trimesoyl chloride (TMC). The introduction of SPANI and HPE, which contain reactive polar amino and hydroxyl groups, improved the hydrophilicity of the substrate, while the subsequent cross-linking with TMC effectively anchored these components within the substrate through the covalent linking between TMC and the reactive sites. Additionally, the hydrolysis of TMC yielded non-reactive carboxyl groups, which further enhanced the hydrophilicity of the substrate. As a result, the modified PVDF substrate exhibited improved hydrophilicity, facilitating the construction of an intact polyamide layer. In addition, the fabricated TFC NF membrane demonstrated excellent performance in the advanced treatment of tap water, achieving a total dissolved solid removal rate of 57.9% and a total organic carbon removal rate of 85.3%. This work provides a facile and effective route to modify PVDF substrates for NF membrane fabrication. Full article

This study examined total ammoniacal nitrogen (TAN) rejection by two reverse osmosis (RO) and two nanofiltration (NF) membranes as a function of pH for three ammonium salts to optimize conditions for a hybrid membrane system that can produce high-purity TAN streams suitable for reuse. The results showed that TAN rejection was significantly influenced by membrane type, feed pH, and the ammonium salt used. This study represents the first attempt to simulate real manure wastewater conditions typically found in pig manure. TAN rejection for (NH₄)₂SO₄ and NH₄HCO₃ reached up to 95% at pH values below 7, with the SW30 membrane showing the highest performance (99.5%), attributed to effective size exclusion and electrostatic repulsion of SO₄²⁻ and HCO₃⁻ ions. In contrast, lower rejection was observed for NH₄Cl, particularly with the MPF-34 membrane, due to its higher molecular weight cut-off (MWCO), which diminishes both exclusion mechanisms. TAN rejection decreased markedly with increasing pH across the BW30, NF90, and MPF-34 membranes as the proportion of uncharged NH₃ increased. The lowest rejection rates (<15%) were recorded at pH 11.5 for both NF membranes. These results reveal a notable shift in separation behavior, where NH₃ permeation under alkaline conditions becomes dominant over the commonly reported NH₄⁺ retention at low pH. This novel insight offers a new perspective for optimizing membrane-based ammonia recovery in systems simulating realistic manure wastewater conditions. TAN recovery was evaluated using a hybrid membrane system, where NF membranes operated at high pH promoted NH₃ permeation, and the SW30 membrane at pH 6.5 enabled TAN rejection as (NH₄)₂SO₄. This hybrid system insight offers a new perspective for optimizing membrane-based ammonia recovery in systems simulating realistic manure wastewater conditions. Based on NH₃ permeation and membrane characteristics, the NF90 membrane was operated at pH 9.5, achieving a TAN recovery of 48.3%, with a TAN concentration of 11.7 g/L, corresponding to 0.9% nitrogen. In contrast, the MPF-34 membrane was operated at pH 11.5. The NF90–SW30 system also achieved a TAN recovery of 48.3%, yielding 11.7 g/L of TAN with a nitrogen content of 1.22%. These nitrogen concentrations indicate that both retentate streams are suitable for use as liquid fertilizers in the form of (NH₄)₂SO₄. A preliminary economic assessment estimated the chemical consumption cost at 0.586 EUR/kg and 0.729 EUR/kg of (NH₄)₂SO₄ produced for the NF90–SW30 and MPF-34–SW30 systems, respectively. Full article

Correlations between conditions of the polyaniline (PANI) interlayer formation on the surface of a polysulfone (PSF) porous membrane substrate and the structure and performance of thin-film composite (TFC) membranes for nanofiltration with a polyamide (PA) selective layer prepared via interfacial polymerization (IP) were studied. It was shown that application of the PANI layer significantly enhanced hydrophilicity (the water contact angle decreased from 55 ± 2° down to 26–49 ± 2°), decreased pore size and porosity, and increased the surface roughness of the selective layer surface of porous PSF/PANI membrane substrates due to the formation of bigger PANI globules, which affect the formation of the PA layer of TFC membranes via IP. It was shown that the application of the PANI intermediate layer yielded the formation of a thinner PA selective layer, a decline in surface roughness, and an increase in hydrophilicity (the water contact angle declined from 28 to <10°) and crosslinking degree of the selective layer of TFC NF membranes. The developed approach allows us to enhance the water permeation up to 45–64 L·m⁻²·h⁻¹ at ΔP = 0.5 MPa and improve membrane selectivity (rejection coefficient of MgSO₄—>99.99%; LiCl—5–25%; sulfadimetoxine—80–95%) and also ensure enhanced long-term operational stability of TFC nanofiltration membranes with a PANI interlayer. Moreover, Mg²⁺/Li⁺ separation factor values were found to increase to 37 and 58 for PANI-modified membranes compared to 9 and 8 for the reference NF-PSF membranes. Full article

The development of sustainable nanofiltration membranes requires alternatives to petroleum-derived polymer substrates. This study demonstrates the successful use of an eco-friendly cellulose acetate/cellulose nitrate (CA/CN) blend substrate for fabricating high-performance modified thin-film composite (mTFC) membranes. A dense, non-porous polyamide (PA) selective layer was formed via the interfacial polymerization method and modified with 0.05–0.1 wt.% HKUST-1 (Cu₃BTC₂, MOF-199). Characterization by FTIR, XPS, SEM, AFM, and contact angle measurements confirmed the CA/CN substrate’s suitability for TFC membrane fabrication. HKUST-1 incorporation created a distinctive ridge-and-valley morphology while significantly altering PA layer hydrophilicity and roughness. The mTFC membrane performance could be fine-tuned by the controlled incorporation of HKUST-1; incorporation through the aqueous phase slowed down the formation of the PA layer and significantly reduced its thickness, while the addition through the organic phase resulted in the formation of a denser layer due to HKUST-1 agglomeration. Thus, either enhanced permeability (123 LMH bar⁻¹ with 0.05 wt.% aqueous-phase incorporation) or rejection (>89% dye removal with 0.05 wt.% organic-phase incorporation) were achieved. Both mTFC membranes also exhibited improved heavy metal ion rejection (>91.7%), confirming their industrial potential. Higher HKUST-1 loading (0.1 wt.%) caused MOF agglomeration, reducing performance. This approach establishes a sustainable fabrication route for tunable TFC membranes targeting specific separation tasks. Full article

This study aims to optimize the application of electrospun nanofibrous substrates in thin-film composite (TFC) nanofiltration (NF) membranes for enhanced liquid separation efficiency by employing a method of effective welding between fibers using latent solvents. Polyacrylonitrile (PAN) nanofiber substrates were fabricated via electrospinning, and a dense polyamide selective layer was formed on their surface through interfacial polymerization (IP). The investigation focused on the effects of different solvent systems, particularly the role of dimethyl sulfoxide (DMSO) as a latent solvent, on the nanostructure and final membrane performance. The results indicate that increasing the DMSO content can enhance the greenness of the fabrication process, the substrate hydrophilicity, and the mechanical strength, while also influencing the thickness and morphology of the polyamide layer. At a DMSO rate of 30%, the composite membrane achieves optimal pure water permeability and high rejection rates; when the DMSO content exceeds 40%, structural inhomogeneity in the substrate membrane leads to an increase in defects, significantly deteriorating membrane performance. These findings provide theoretical insights and technical guidance for the application of electrospinning technology in designing efficient and stable NF membranes. Full article

The large-scale application of aromatic polyamide (PA) thin-film composite (TFC) membranes for reverse osmosis has provided an effective way to address worldwide water scarcity. However, the water permeability and salt rejection capabilities of the PA membrane remain limited. In this work, cyclic micropores based on crown ether were introduced into the PA layer using a layer-by-layer interfacial polymerization (LbL-IP) method. After interfacial polymerization between m-phenylenediamine (MPD) and trimesoyl chloride (TMC), the di(aminobenzo)-18-crown-6 (DAB18C6) solution in methanol was poured on the membrane to react with the residual TMC. The cyclic micropores of DAB18C6 provided the membrane with rapid water transport channels and improved ion rejection due to its hydrophilicity and size sieving effect. The membranes were characterized by FTIR, XPS, SEM, and AFM. Compared to unmodified membranes, the water contact angle decreased from 54.1° to 31.6° indicating better hydrophilicity. Moreover, the crown ether-modified membrane exhibited both higher permeability and enhanced rejection performance. The permeability of the crown ether-modified membrane was more than ten times higher than unmodified membranes with a rejection above 95% for Na₂SO₄, MgSO₄, MgCl_2, and NaCl solution. These results highlight the potential of this straightforward surface grafting strategy and the modified membranes for advanced water treatment technologies, particularly in addressing seawater desalination challenges. Full article

Hydrogen purification is a critical industrial process, and there are ongoing efforts to develop low-cost alternatives to palladium foil membranes. Titanium nitride (TiN) is studied as an interdiffusion barrier to enable hydrogen permeation in composite palladium–vanadium membranes. TiN was deposited via reactive sputtering, and films with the desired (200) orientation were obtained in the metallic regime at 400 °C under a 200 V bias to the substrate. The permeability of thin-film TiN was determined with palladium-based sandwich structures. TiN layers up to 10 nm resulted in a minimal decrease in flux (~20%) relative to a freestanding PdCu foil, which was attributed to the interfacial resistance. At greater thicknesses, the TiN layer was rate-limiting, and it was found that the effective permeability of the sputtered TiN thin films was ~6 × 10⁻¹² mol s⁻¹ m⁻¹ Pa^−0.5. Composite Pd|TiN|V|TiN|Pd membranes exhibited permeability values up to three times greater than pure palladium, exhibiting stability at 450 °C for over 100 h, with the lack of intermetallic diffusion and alloy formation being confirmed with XRD. The membranes were unstable at 500 °C, which was attributed to the instability of the thin Pd layer and loss of catalytic activity. Full article

Reverse osmosis membranes have been predominantly made from aromatic polyamide composite thin-films, although significant research efforts have been dedicated to discovering new materials and synthesis technologies to enhance the water–salt selectivity of membranes in the past decades. The lack of significant breakthroughs is partly attributed to the limited comprehensive understanding of the relationships between membrane features and their performance. Insights into the intrinsic features of reverse osmosis (RO) membranes based on metadata were obtained using explainable artificial intelligence to understand the relationships and unify the research efforts. The features related to the chemistry, membrane structure, modification methods, and membrane performance of RO membranes were derived from the dataset of more than 1000 RO membranes. Seven machine learning (ML) models were constructed to evaluate the membrane performances, and their applicability for the tasks was assessed using the metadata. The contribution of the features to RO performance was analyzed, and the ranking of their importance was revealed. This work holds promise for metadata analysis, evaluating the RO membrane against the state of the art and developing an inverse design strategy for the discovery of high-performance RO membranes. Full article

The global water scarcity crisis requires urgent action to improve wastewater treatment and develop sustainable water resources. This study focuses on producing Thin Film Composite (TFC) membranes based on polyethylene terephthalate track membranes (PET-TM) coated with polytetrafluorethylene-like material (PTFE), named PET-TM/PTFE-like, designed to purify saline water using Air Gap Membrane Distillation (AGMD) technique. The research emphasizes the optimization of these membranes’ chemical composition and surface characteristics by plasma that enhances their hydrophobicity and overall operational efficiency. A systematic investigation was conducted to clarify the relationship between water flux and salt rejection, enabling the customization of membrane properties for better performance. It was shown that salt rejection exceeding 99% is obtained for all the investigated PET-TM/PTFE-like membranes, with values up to 99.63% for the PET-TM(250 nm)/PTFE-like(200 nm) system and condensate flows as high as 1325 g/m²h for the PET-TM(450 nm)/PTFE-like(200 nm) system. This comprehensive analysis identified the most effective TFC configurations for AGMD applications, providing a promising pathway to advance desalination techniques and wastewater treatment solutions. Full article

This study explored the batch membrane filtration of 40% ethanol extracts from spent lavender, containing valuable compounds like rosmarinic acid, caffeic acid, and luteolin, using a polyamide-urea thin film composite X201 membrane. Conducted at room temperature and 20 bar transmembrane pressure, the process demonstrated high efficiency, with rejection rates exceeding 98% for global antioxidant activity and 93–100% for absolute concentrations of the target components. During concentration, the permeate flux declined from 2.43 to 1.24 L·m⁻²·h⁻¹ as the permeate-to-retentate-volume ratio increased from 0 to 1. The process resistance, driven by osmotic pressure and concentration polarization, followed a power–law relationship with a power value of 1.20, consistent with prior nanofiltration studies of rosmarinic acid solutions. Notably, no membrane fouling occurred, confirming the method’s scalability without compromising biological activity. The antioxidant activity, assessed via the DPPH method, revealed that the retentate exhibited double the activity of the feed. Antibacterial assays using broth microdilution showed that the retentate inhibited Escherichia coli by 73–96% and Bacillus subtilis by 97–98%, making it the most active fraction. These findings validate the effectiveness of the X201 membrane for concentrating natural antioxidants and antibacterial agents from lavender extract under sustainable operating conditions. Full article

Access to clean and reliable water has become a critical concern due to the global water crisis. High sulfate levels in drinking water raise health concerns for humans and animals and can cause serious corrosion in industrial systems. Sulfated waters represent a major challenge on the Canadian prairies, leading to many cattle deaths. While reverse osmosis (RO) membranes effectively remove sulfates, they are costly due to high-pressure requirements. Nanofiltration (NF) membranes present a more affordable alternative, outperforming traditional methods like adsorption, desalination, and ion exchange. Developing low-pressure ultrafiltration (UF) and microfiltration (MF) membranes could also reduce costs. This review explores advancements in polymeric materials and membrane technology to enhance sulfate removal, focusing on methods used to reduce fouling and improve permeate flux. Techniques discussed include phase inversion (PI), thin-film composite (TFC), and thin-film nanocomposite (TFN) membranes. The review also highlights recent fabrication methods for pristine and nanomaterial-enhanced membranes, acknowledging both benefits and limitations. Continued innovations in polymer-based membranes are expected to drive further performance and cost-efficiency improvements. This review found that studies in the literature dealt mainly with sulfate concentrations below 2000 mg/L, indicating a need to address higher concentrations in future studies. Full article

In this study, the performance and durability of polymer electrolyte membrane fuel cells (PEMFCs) were improved using a Pt-Pr₆O₁₁ composite electrode fabricated through a co-sputtering technique. Platinum (Pt), widely used as the catalyst material in PEMFCs, often faces stability issues under various electrical load conditions. These issues require greater efforts to enhance PEMFC durability. Various approaches, including replacement of catalyst supports with electrically stable materials (such as metal oxides) or adoption of core-shell and alloy structures to stabilize Pt, have been attempted. In this research, a thin film electrode combining Pr₆O₁₁ and Pt was fabricated. Pr₆O₁₁, a lanthanide oxide, enhances the oxygen reduction reaction (ORR) through strong interactions with Pt, and its multi-valence state contributes to improved durability. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to analyze the composition, morphology, and chemical characteristics of the electrodes. I-V curves and electrochemical impedance spectroscopies (EIS) were measured to evaluate electrochemical properties of fuel cells. A cyclic voltammetry (CV) test was conducted to calculate the electrochemical surface area of the cell. As a result, the incorporation of Pr₆O₁₁ improved the pristine cell performance by 7.6% and increased performance after degradation testing by 121% compared to Pt-only cases. This demonstrates the effectiveness of the Pt-Pr₆O₁₁ composite in enhancing both the initial performance and the durability of PEMFCs. Full article