npj Clean Water最新文献

In this contribution, we report the synthesis of a poly(4-vinylpyridine)-reduced graphene oxide-magnetite (P4VP-rGO-Fe₃O₄) organo-magnetogel (OMG), designed for high-performance pollutant adsorption. In the OMG, rGO and Fe₃O₄ nanoparticles are in situ encapsulated during the chemical cross-linking of the 4-vinylpyridine polymer. The adsorption performance of OMG was evaluated using three model water pollutants, viz., organic dyes, heavy metal ions, and waterborne pathogens. The equilibrium adsorption capacity exceeded 400 mg/g for the organic dyes. Beyond dye removal, the OMG also adsorbed heavy metal ions, such as AsO₂⁻, Pb²⁺, Cr₂O₇^2−, and Cd²⁺ ions, with removal efficiencies exceeding 60% and adsorption capacities exceeding 200 mg/g. The OMG also exhibited remarkable antibacterial activity against E. coli and S. Typhi, with almost zero viability for S. Typhi. The OMG promises a broad-spectrum applicability in wastewater treatment, offering a sustainable and efficient solution for water decontamination.

In this study, the composite photocatalyst UiO-66-NH₂@TiO₂ and a polysulfone membrane modified with it were evaluated for removing humic acid (HA) under visible light in a photocatalytic membrane reactor (PMR). The photocatalyst and membrane were analyzed using FTIR, XRD, FESEM, PL, DRS, AFM, BET, contact angle, and porosity tests to assess pollutant removal, water flux, and membrane resistance. Synthesis was confirmed by FTIR and XRD, while DRS showed a 2.87 eV bandgap, indicating visible light activity. PL results revealed reduced electron-hole recombination. FTIR and SEM confirmed photocatalyst presence and uniform dispersion in the membrane, improving hydrophilicity by decreasing the contact angle by 8°. In suspension, the photocatalyst removed 93% of HA under visible light. Among modified membranes, PS-UNT6% performed best, showing a 26% increase in pure water flux and 12% higher HA removal (total 95.2%) compared to the unmodified membrane. Fouling was significantly reduced, with only a 14% flux drop after 12 h under light, versus 19% without modification. Pore-blocking resistance decreased by over 98%, along with reductions in intrinsic, fouling, and cake resistances, demonstrating enhanced membrane performance through photocatalytic modification.

Surface patterning is a promising anti-fouling strategy, yet its integration with conductive polymers remains underexplored. This study investigates electrically conductive, surface-patterned membranes with integrated porous feed spacers using polyaniline (PANI) as a conductive additive in polyethersulfone (PES) membranes. Among tested concentrations (0.25–2.00 wt.%), 1.00 wt.% PANI membrane (PN1) showed the best performance, with electrical conductivity of ≈130.5 ± 2.87 mS·m⁻¹ and pure water flux of 107.2 ± 15.5 L·m⁻²·h⁻¹ which is around five times that of pristine PES membrane. Under a 4 V electric field, PN1 exhibited lower flux decline (60.6%) and higher flux recovery (FRR 90.1 ± 2.15%). Surface-patterned PN1 membrane (PN1_Patterned) further enhanced performance, achieving a flux of 168.2 ± 20.7 L·m⁻²·h⁻¹ and reduced fouling (51.6% flux decline) compared to surface-patterned PES membrane (66.7%). PN1_Patterned membrane also showed higher FRR (95.4 ± 1.68%) and stable natural organic matter (NOM) rejection ( > 92.9 ± 1.65%). These results highlight the synergistic benefits of combining conductivity with surface patterning, offering a potential approach for improved membrane performance.

Membrane technology is crucial for water treatment as it effectively separates and rejects pollutants. However, its industrial application is often limited by membrane scaling and fouling issues, which degrade membrane performance and affect the efficiency and longevity of membrane systems. Our previous study demonstrated that a 3D-printed carbon nanotube (CNT) spacer improved membrane performance by increasing the membrane flux and controlling scaling in membrane distillation. Here, we present a detailed mechanism by which a CNT spacer mitigates membrane scaling by inducing cooling crystallisation. The CNT spacer delayed crystallisation and reduced crystal adhesion on both the membrane and spacer surfaces. Additionally, the presence of the CNT spacer resulted in the formation of larger crystals that are less likely to adhere to surfaces. The nanoscale roughness and nanochannels created by the exposed CNT in the spacer appeared to strengthen hydrogen bonding within the solution, further delaying crystallisation and reducing crystal adhesion. These findings were corroborated by comparing the experimental observations with theoretical predictions derived from our mechanistic model, providing a comprehensive understanding of the scaling mitigation process. Our approach addresses several limitations of membrane technology, enhancing performance and reducing scaling and fouling risks, paving the way for broader application in water treatment.

High levels of nitrates and nitrites not only threaten aquatic ecosystems and drinking water safety but also impair the biodegradation efficiency of industrial wastewater. In this study, micro-nano-MoS₂-1013 (0.04 g/L) enhanced denitrification by 56.9% and 29.6% in steel pickling and meat processing wastewaters, respectively, and improved chemical oxygen demand (COD) removal by 136.7% in refinery cooling wastewater under continuous-flow conditions using a 3.5 L upflow anaerobic sludge blanket (UASB) reactor. The catalytic effect of micro-nano-MoS₂ on denitrification was achieved by stimulating an increase in the abundance of denitrification genes and the transcript levels of narL (93.82 times), narG (16.34 times), and nirK (12.27 times) within the bacterial cells, which led to an increase in the expression levels of denitrifying enzymes. These findings have significant implications for the design and optimization of biodegradation processes and bio-denitrification systems, particularly for the treatment of high-concentration nitrate wastewater.

Membrane distillation (MD) faces critical challenges at the industrial scale, including poor permeate flux and membrane fouling. To address these issues and efficiently treat highly saline water, this study presents a nature-inspired approach to fabricating a robust multilayer Janus membrane using a gecko-inspired adhesion mechanism. The proposed membrane was fabricated using a layer-by-layer co-deposition method, combining a surface-roughened PVDF flat-sheet membrane prepared via phase inversion with an electrosprayed hydrophobic PVDF-HFP interfacial layer modified with CuO nanoparticles and an electrospun hydrophilic PEI fiber bottom layer. The hydrophobic top layer exhibited a water contact angle of 131.5°, followed by a superhydrophobic interfacial layer and the bottom/support layer with a contact angle of 41.4°, enabling superior directional wettability. The Janus membrane achieved an impressive water gap membrane distillation (WGMD) flux of 37.16 kg m⁻² h⁻¹ with a high salt rejection rate of 99.99% over 24 h. Furthermore, the membrane demonstrated long-term stability and excellent resistance to fouling and delamination in harsh saline environments, maintaining performance over 60 h of continuous MD operation. This work highlights the potential of bio-inspired engineering in developing efficient and durable membranes, offering a promising pathway for advancing MD technology for industrial-scale desalination.

The current study evaluated the innovative application of membrane distillation crystallization (MDCr) for dual treatment and resource recovery from acid mine drainage (AMD), a persistent environmental crisis in South African. This AMD was characterized by exorbitant concentrations of Ca²⁺ (2622 mg·L⁻¹), Fe²⁺ (1421 mg·L⁻¹), SO₄²⁻(9790 mg·L⁻¹) and Cl⁻ (1113 mg·L⁻¹). The current study evaluated the performance of hollow fibre polypropylene membrane in processing both acidic (pH 3.58) and neutralized (pH 6.47) feedwaters. The permeate was 3.3 kg·m⁻²·h⁻¹, 2.2 kg·m⁻²·h⁻¹ and 1.3 kg·m⁻²·h⁻¹ at 70, 60 and 50 °C respectively, which remained relatively stable at high recovery factors ( >80%). Acidic AMD promoted formation of large metal-rich ettringite and halite crystals while neutralized AMD produced small and dense ettringite, hexahydrite and jarosite crystals. This study highlighted the dual functionality of MDCr in water treatment and mineral resource recovery, offering a sustainable solution to address the AMD pollution crisis in South Africa.

In this study, graphene quantum dots/titanium dioxide (GQDs/TiO₂) fiber membranes with engineered oxygen vacancies were fabricated using a combination of electrospinning and solvothermal techniques. Oxygen vacancies, as key active sites, enabled spin polarization during the photocatalytic reaction, and the material’s spin polarization was verified by X-ray Absorption Spectroscopy (XAS) and Density Functional Theory (DFT). For the first time, the effects of high magnetic fields (1000–5000 mT) on photocatalytic performance were systematically explored. The findings reveal that the magnetic field markedly enhances spin polarization, facilitating synergistic interactions between oxygen vacancies and photogenerated electrons while significantly suppressing carrier recombination. Under these conditions, the GQDs/TiO₂ fiber membranes achieved a remarkable 52.44% increase in the degradation rate of methylene blue compared to zero-field conditions. Additionally, the study introduces the concept of magnetic field-induced progressive energy level modulation, wherein defect state energy levels undergo gradual adjustment before stabilization under magnetic influence. This work provides critical insights into radical generation mechanisms driven by the interplay between magnetic fields and oxygen vacancies, offering a novel pathway for designing advanced photocatalysts with broad applications in water pollution treatment and sustainable energy solutions.

Solving three-dimensional (3D) multi-physics forward and inverse problems is indispensable for fundamental understanding and optimal design of membrane-based desalination systems. Unfortunately, it is computationally expensive when applying traditional numerical methods. Herein, a modified Fourier neural operator (FNO)-based method is proposed to efficiently solve complex 3D multi-physics problems. The intelligent solver solves the 3D forward problems in seconds, which is approximately 10⁵-10⁶ times faster than traditional finite-element based method with a comparable solution quality. The average prediction accuracy is more than 96%. Moreover, the proposed FNO-based method is mesh-independent and has zero-shot super-resolution ability. It can be used to provide a fast solution for the optimal design of membrane module to mitigate concentration polarization and membrane fouling for next-generation ultrapermeable membrane system.

To overcome the short retention time in small-scale wastewater treatment plants, it is necessary to develop processes with fast reaction rates. The microwave-Fenton-like reaction (MW-Fenton-like reaction), which combines external energy and catalysts, provides a solution with rapid reaction rate and high degradation efficiency. In this reaction, catalysts significantly influence decomposition efficiency. Developing magnetic catalysts can simplify the separation process. In this study, the superiority of copper-based metal oxides for the MW-Fenton-like reaction was confirmed through comparative experiments of various metal oxides. Based on these findings, highly active CuFe₂O₄/Cu particles were developed. The synthesized particles, with rough-surfaced solid-sphere morphology, exhibited ferromagnetic properties and were completely separated using a laboratory-scale magnet. CuFe₂O₄/Cu also showed high degradation over a wide pH range and achieved the highest degradation rate at pH 7. Furthermore, comparison of 4-nitrophenol (4-NP) degradation using MW and conventional heating demonstrated MW was superior in reaction rate, efficiency, and reusability.