High-Efficiency PLA Nano-Microfibrous Filters Enabled by Bimodal Structure and Corona Discharge

Air pollution is a pressing issue for environmental sustainability and human health, with air filters playing a pivotal role in mitigating its effects. However, conventional polymer-based air filters pose environmental challenges. This study focuses on developing biodegradable poly(lactic acid) fibrous unimodal and bimodal filter webs using electro-blowing (EB) and solution-blowing (SB) techniques. Fiber diameters were controlled by adjusting solution concentrations (10% and 20% w/w) and applying an electric field during production. EB with low-concentration solutions produced nanofibers (Y) averaging 0.14 μm, while SB with high-concentration solutions yielded fibers (X) around 1.60 μm. Bimodal fibrous webs exhibited a dual-peak distribution with diameters centered at 0.17 and 1.56 μm. Filtration tests at a 95 L/min air flow rate for PM_0.3 particles revealed that the EB sample had the highest filtration efficiency (96.562%) and airflow resistance (177 Pa). Among bimodal configurations, X + Y, with nano/microfibers collected simultaneously, demonstrated the best quality factor (98.604% efficiency and 146 Pa ΔP). Corona discharge treatment further enhanced filtration efficiency, with the X + Y sample achieving 99.997% efficiency. After a week of repetitive testing, X + Y maintained high performance with 99.972% efficiency and a 192 Pa ΔP. These findings highlight PLA filters' potential as sustainable and efficient air filtration solutions.