Meitan xuebao (Apr 2024)
Preparation and long-term filtration performance of PLA-based nanofibrous membrane filters for ultra low-resistance respiratory protection
Abstract
Long-term exposure to high concentrations of fine particulate matter (PM2.5) in the atmosphere has negative impact on the long-term health effect of human beings. Traditional air filtration materials are difficult to take into account the high-efficiency and low-resistance protection, and are non-degradable, which not only aggravates global plastic pollution, but also tends to cause stronger microplastics hazards. To solve the problems above-mentioned, self-powered and biodegradable nanofibrous membranes with air slip effect are developed to achieve a long-term and low-resistance respiratory protection. A two-step hydrothermal method is proposed to prepare the easily dispersed BTO dielectric with an average particle size of 49.6 nm, then the BTO nanoparticles (BTO NPs) are embedded into the PLA nanofibrous membranes by a combined “electrospinning‒electrospray” strategy. The frictional electricity effect and size effect of BTO NPs are utilized to simultaneously regulate the filtration efficiency and resistance of nanofibrous membranes. By controlling the concentration of BTO NPs in spraying suspension, the relationship between it and electroactivity, filtration properties and mechanical properties of PLA/BTO nanofibrous membranes is investigated. Microstructure characterization and performance testing show that the PLA/BTO nanofibrous membranes have excellent electroactivity, filtration properties and mechanical properties. The surface potential of PLA/BTO nanofibrous membranes is up to 5.9 kV, the dielectric constant is up to 1.20 F/m, and the average output voltage is up to 12.4 V. Benefiting from the enhanced slip effect and increased electroactivity, the electrospun-electrosprayed PLA/BTO10 nanofibrous membrane could significantly reduce air resistance (as low as 20 Pa), while improving the filtration efficiency of PM0.3 by 7.78%−9.05% and the filtration efficiency of PM2.5 by 2.90%−13.19%. Even at the high airflow velocity of 85 L/min, the filtration efficiency of PM2.5 still achieves as high as 97.25%. At the same time, the increase of tensile strength of PLA/BTO nanofibrous membranes is up to 60% (22.5 MPa), the increase of elongation at break is up to 68% (25%), and the fracture toughness increases by 1.3 times (3.6 MJ/m3). Therefore, the proposed degradable PLA/BTO nanofibrous membrane filters with long-term and low-resistance filtration properties have some broad application prospects in the field of respiratory protection, and also provide a new approach to alleviate the plastic pollution exacerbated by discarded masks.
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