Needle-punched electret air filters (NEAFs) with high filtration efficiency, low filtration resistance, and superior dust holding capacity

One-Step Fast Fabrication of Electrospun Fiber Membranes for Efficient Particulate Matter Removal

Rapid social and industrial development has resulted in an increasing demand for fossil fuel energy, which increases particulate matter (PM) pollution. In this study, we employed a simple one-step electrospinning technique to fabricate polysulfone (PSF) fiber membranes for PM filtration. A 0.3 g/mL polymer solution with an N,N-dimethylformamide:tetrahydrofuran volume ratio of 3:1 yielded uniform and bead-free PSF fibers with a diameter of approximately 1.17 μm. The PSF fiber membrane exhibited excellent hydrophobicity and mechanical properties, including a tensile strength of 1.14 MPa and an elongation at break of 116.6%. Finally, the PM filtration performance of the PSF fiber membrane was evaluated. The filtration efficiencies of the membrane for PM2.5 and PM1.0 were approximately 99.6% and 99.2%, respectively. The pressure drops were 65.0 and 65.2 Pa, which were significantly lower than those of commercial air filters. Using this technique, PSF fiber membrane filters can be easily fabricated over a large area, which is promising for numerous air filtration systems.

Preparation of Self-Curling Melt-Blown Fibers with Crimped Masterbatch (CM) and Its Application for Low-Pressure Air Filtration

Particulate matter (PM) and airborne viruses pose significant threats to both the environment and public health. As the most viable solution to prevent the inhalation of these pollutants, there is an urgent demand for face masks with excellent filtration efficiency and low-pressure drop. In this study, a crimped masterbatch (CM) is added to polypropylene feedstocks to produce curling fibers through melt-blown spinning. These curled fibers exhibit low filtration resistance and effective dust-holding performances when used for air filtration. The effect of adding CM on fiber diameter, pore size, crimp, porosity, roughness, and surface potential was studied. The filtration performance of the materials, including the PM filtration capabilities, recirculation filtration, and loading test performance, were also investigated. The results demonstrate that the degree of fiber crimp can be adjusted by incorporating varying amounts of CM. This curling was caused by the uneven shrinkage that occurred due to variations in thermal contraction between these polymers. The curled fibers created a fluffy structure in the fiber network and modified the distribution of pore sizes within it. Under the same filtration conditions as sodium chloride aerogel, CM-2 (PP:CM 8:2) exhibited similar filtration efficiency (95.54% vs. 94.74%), lower filtration resistance (88.68 Pa vs. 108.88 Pa), higher quality factor (0.035 Pa-1 vs. 0.028 Pa-1) and better dust holding capacity (10.39 g/m2 vs. 9.20 g/m2) compared to CM-0 (PP:CM 10:0). After 30 days of indoor storage, the filtration efficiency of CM-2 remained above 94%. The self-curling melt-blown filtration material developed here could potentially be applied in the field of protective masks.

Bioelectret poly(lactic acid) membranes with simultaneously enhanced physical interception and electrostatic adsorption of airborne PM0.3

Traditional polymeric fibrous membranes have been extensively used to reduce the health risks caused by airborne particulate matter (PM), leading to the dramatically increasing pollution of plastics and microplastics. Although great efforts have been made to develop poly(lactic acid) (PLA)-based membrane filters, they are frequently dwarfed by their relatively poor electret properties and electrostatic adsorptive mechanisms. To resolve this dilemma, a bioelectret approach was proposed in this work, strategically involving the bioinspired adhesion of dielectric hydroxyapatite nanowhiskers as a biodegradable electret to promote the polarization properties of PLA microfibrous membranes. In addition to significant improvements in tensile properties, the incorporation of hydroxyapatite bioelectret (HABE) enabled remarkable increase in the removal efficiencies of ultrafine PM_0.3 in a high-voltage electrostatic field (10 and 25 kV). This was exemplified by the largely increased filtering performance (69.75%, 23.1 Pa) for PLA membranes loaded with 10 wt% HABE at the normal airflow rate (32 L/min) compared to the pristine PLA counterpart (32.89%, 7.2 Pa). Although the filtration efficiency of PM_0.3 for the counterpart dramatically decreased to 21.6% at 85 L/min, the increment was maintained at nearly 196% for the bioelectret PLA, while an ultralow pressure drop (74.5 Pa) and high humidity resistance (RH 80%) were achieved. The unusual property combination were ascribed to the HABE-enabled realization of multiple filtration mechanisms, including the simultaneous enhancement of physical interception and electrostatic adsorption. The significant filtration applications, unattainable with conventional electret membranes, demonstrate the bioelectret PLA as a promising biodegradable platform that allows high filtration properties and humidity resistance.

Multilevel structured PASS nanofiber filter with outstanding thermal stability and excellent mechanical property for high-efficiency particulate matter removal

Particulate matter (PM) pollution from industrialization poses a great threat to people's health. Although fiber-based filters are used effectively to capture PM, the traditional filters with large diameter suffer from low filtration efficiency, high pressure drop and low temperature resistance. In this study, multilayer poly arylene sulfide sulfone (M-PASS) composite filter was designed and fabricated via electrospinning technology. The M-PASS composite filter is sandwich-structure. Due to the unique structure and composition, the M-PASS filter exhibited outstanding removal efficiency of 99.97 ± 0.0050%, extremely low air resistance of 44.3 ± 0.7 Pa, excellent quality factor (QF) of 0.19 ± 0.0019 Pa^-1, and desirable mechanical strength of 7.0 ± 0.2 MPa. Furthermore, the as-prepared M-PASS filter can remain outstanding filtration performance at 200.0 ℃ due to the high thermal stability of PASS and the removal efficiency was still above 95.2 ± 0.4% after long-term filtration test. These results demonstrate that the structure of filter is the important one for air filtration and the M-PASS nanofiber filters have great potential in PM removal, especially under high temperature conditions.