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With the rapid advancement of global industrialization, air and water pollution caused by ultrafine particulate matter (PM) has become increasingly severe, posing significant threats to ecosystem stability and human health. Traditional fiber filtration materials face structural limitations: in air filtration, they struggle to balance precise capture of ultrafine particles with low air resistance requirements; in water filtration, they cannot simultaneously achieve efficient interception of ultrafine pollutants and high water flux. More critically, most current research focuses on single-scenario applications, making it difficult for advanced filtration materials to achieve cross-domain synergistic applications. Therefore, developing novel multifunctional fiber filtration materials that combine efficient ultrafine particle interception, low pressure drop, and high flux has become key to breaking through pollution control bottlenecks.
Recently, Prof. Lai Yuekun and Prof. Huang Jianying's team at Fuzhou University published their latest research titled "Ultrafine Nanofiber-based Membrane with Rational Hierarchical Networks for Efficient and High-flux Air and Water Purification" in *Advanced Fiber Materials*. Through innovative "jet-branching electrospinning technology," the researchers successfully introduced PQ-10 to effectively optimize the properties of PTT precursor solutions, promoting jet branching and resulting in the formation of multiscale structured fiber membranes based on ultrafine nanofibers. These membranes can simultaneously achieve efficient interception of ultrafine particulate pollutants in both air and water, with advantages including low pressure drop, high flux, and long-term stability. This breakthrough provides a new and efficient solution for environmental pollution control, showing broad application prospects in air purification and water treatment.
Figure 1: Membrane fabrication technology and applications
As shown in Figure 1a, the authors prepared PTT@PQ-10 multiscale fiber membranes via one-step electrospinning. Polyquaternium-10 induced jet branching to form fibers with three-tiered diameter distributions: ultrafine (31±5 nm), medium (89±21 nm), and coarse submicron (314±130 nm). The synergistic effect of the high surface area of ultrafine fibers and hierarchical pore structure enables the membrane to efficiently intercept ultrafine particles like PM0.3 with low air resistance while simultaneously achieving rapid filtration of 100-300 nm pollutants in water, maintaining ultrahigh water flux and combining functionality with practicality (Figures 1b-c).
Figure 2: PQ-10's effects on solution properties and fiber morphology
Figure 2 systematically investigates the regulatory mechanism of polyelectrolyte PQ-10 on PTT electrospinning solution properties and fiber membrane structure. As shown in Figures 2a-c, PQ-10, as a cationic polyelectrolyte, affects surface tension and significantly enhances solution conductivity and viscosity characteristics, thereby promoting jet branching to form multiscale fibers. Experiments demonstrate that optimal balance is achieved at 6 wt% PTT concentration and 0.8 wt% PQ-10 concentration (Figures 2d-g). The material features an ultra-small pore size of 0.603 μm and a specific surface area increased to 14.32 m² g⁻¹ (Figures 2h-i). The study confirms that multiscale fiber membrane preparation not only significantly improves pollutant capture efficiency but also ensures material process controllability, providing new insights for developing high-performance filtration materials.
Figure 3: Air filtration performance and mechanisms
The authors also examined the air filtration performance and primary filtration mechanisms of PTT@PQ-10 multiscale fiber membranes. Experimental results show that when PQ-10 concentration is optimized to 0.8 wt%, the filtration efficiency for the most challenging PM0.3 particles reaches 99.96%, with a pressure drop of only 88 Pa and a quality factor (QF) as high as 0.089 Pa⁻¹, demonstrating excellent filtration performance. By adjusting PTT concentration and basis weight, the membrane structure was further optimized to maintain >99.90% PM0.3 retention while achieving optimal balance with low resistance (Figures 3a-f). The multiscale fiber membrane captures PM0.3 and PM0.5 through Brownian diffusion, while filtering PM1.0 and PM3.0 through physical interception, gravitational settling, and inertial effects (Figure 3h), providing an innovative solution for micro-nano particle separation.
Figure 4: Comprehensive air filtration performance comparison
The authors systematically compared the comprehensive filtration performance of PTT@PQ-10 multiscale fiber membranes. Results show the material maintains stable PM0.3 retention >99.90% across airflow rates of 10-85 L min⁻¹, significantly outperforming commercial filter materials (Figure 4a). After 30 cycle tests, efficiency remains >99.90% with only a 5 Pa pressure drop increase (Figure 4b). The multiscale structure effectively intercepts particles and forms surface deposition layers while maintaining structural integrity (Figure 4c). In 120-minute continuous filtration tests, its performance stability (>99.90% efficiency) proves superior to commercial masks (Figure 4d). This breaks through the technical bottleneck of traditional materials struggling to balance efficiency and resistance, providing innovative solutions for air purification in heavily polluted environments.
Figure 5: Water filtration performance
The authors also investigated the water filtration performance of PTT@PQ-10 multiscale fiber membranes. Figure 5a shows the water filtration process and experimental setup. Results demonstrate that introducing PQ-10 significantly enhances membrane hydrophilicity, with pure water flux far exceeding commercial nylon membranes (CM4) (Figures 5b-c). Optimization of PTT and PQ-10 concentrations and basis weight shows the multiscale fiber membrane maintains >99.5% retention efficiency for 100-300 nm TiO₂ particles across 5-20 kPa driving pressures. Notably, the membrane achieves >4000 L m⁻² h⁻¹ flux under low driving pressures, demonstrating significant energy efficiency advantages (Figures 5d-g). Compared with similar studies, this material simultaneously achieves breakthroughs in high flux and high retention under low-pressure conditions, providing new insights for developing efficient and energy-saving water treatment technologies.
Figure 6: Long-term, recyclable, and practical water filtration performance
Comparative experiments verify the excellent comprehensive water filtration performance of PTT@PQ-10 multiscale fiber membranes. In continuous filtration tests, the membrane maintains stable retention efficiency >99.0%, far exceeding pure PTT fiber membranes while consistently showing higher water flux than commercial nylon membranes (CM4) (Figures 6a-b,d-e). After 10 reuse cycles, retention remains >99.0%, confirming outstanding antifouling properties and reusability. SEM images reveal the hierarchical fiber network effectively forms surface cake layers similar to commercial nylon membranes (Figure 6c). In practical applications, turbid river water becomes nearly zero-absorbance after filtration (Figure 6f).
Paper link: https://doi.org/10.1007/s42765-025-00551-8
