Polylactic acid-based composite filter with multi-gradient structure developed for high-efficiency particulate matter filtration and NH3 purification

Particulate matter (PM), ammonia (NH3) 3 ) and other polluted gases emitted from animal feeding operations have emerged as significant risks to workers, surrounding residents, and the regional environment. Therefore, the development of air filters capable of simultaneously filtering PM and adsorbing toxic gases is particularly important. In this study, a three-layer gradient structure nanofiber filter was prepared by electrospinning technology, consisting of fluorinated Polylactic acid (PLA)/SiO2 2 as the outer layer, PLA nanofibers as the middle layer, and PLA/UiO-66-NH2 2 as the inner layer. This gradient structure of composite filter featured gradually decreasing pore sizes, exhibited optimal air filtration performance compared to PLA filter and commercial glass fiber filter. At 5.3 cm/s flow rate, the composite nanofiber filter achieved high filtration efficiency (99.15 % for PM0.5) 0.5 ) and low pressure drop (89.65 Pa). Furthermore, the composite nanofiber filter exhibited highest dust holding capacity, indicating longer service life. It also featured excellent self-cleaning capabilities, allowing for reuse after simple water rinsing. Additionally, the results of ammonia (NH3) 3 ) adsorption tests demonstrated the prepared composite filter's highest adsorption capacity for NH3. 3 . Therefore, this work enhanced the application potential of high-performance air filters in the removal of PM pollution and hazardous gases.