Preparation of porous polylactic acid nanofibers and application in non-electret high-efficiency filtration composites

Abstract

Air pollution caused by fine particulate matter (PM_0.3) has drawn increasing attention as an overwhelming threat to public health. Electret treatment is commonly used to improve the filtration performance of commercial fibrous filter materials by enhancing the electrostatic adsorption effect, but it is greatly affected by environmental factors (especially humidity). Moreover, filter materials are generally non-degradable and non-recyclable, causing serious environmental pollution. Herein, a strategy to manufacture fully degradable polylactic acid (PLA) filtration composites based on porous PLA nanofibers prepared by electrospinning was investigated in this study. Porous, bead-on-string and conventional PLA nanofibers could be obtained by adjusting spinning condition parameters. The porous PLA nanofibers exhibited 9.8 times greater specific surface area (24.01 m² g⁻¹) and 18 times more cumulative pore volume (0.108 cm³ g⁻¹) than conventional PLA nanofibers. More importantly, fibrous filtration composites based on porous PLA nanofibers possessed a high PM_0.3 filtration efficiency (99.9989%), low pressure drop (90.35 Pa) and high air permeability (72.4 Pa⁻¹) at an air flow rate of 32 L min⁻¹ without electret treatment. The fibrous filtration composites based on conventional or bead-on-string PLA nanofibers also exhibited excellent filtration performance (>99.99%), but the associated high pressure drop and low air permeability limited their application.