Fabrication of fully degradable branched poly (lactic acid) nanofiber membranes for high‐efficiency filter paper materials

Abstract

Air pollution caused by particulate matter (PM) poses an imminent threat to the global environment and public health. However, balancing the removal efficiency and pressure drop of most filter materials is difficult. Moreover, filter materials are non-degradable and non-recyclable, causing serious harm to the environment. Herein, a strategy to create fully degradable branched poly (lactic acid) (PLA) nanofibers based on electrospinning by adjusting the spinning solution properties was reported and branched PLA nanofibers were applied as nanofiber filter paper for air filtration materials. When the PLA and tetrabutylammonium chloride concentrations were 8 and 5 wt%, respectively, PLA nanofibers with branched structures were obtained. The obtained nanofibers possessed a small pore size (0.70 μm), high porosity (92.3%), appropriate mechanical properties, resulting in high PM 0.3 removal efficiency (99.95%), low air resistance (79.67 Pa), and promising long-term PM 2.5 purification. Notably, branched T-PLA-5 nanofibers exhibited excellent filtration performance when applied to cellulose wood pulp paper. The filtration efficiency of the nanofiber filter paper remained stable above 85% for PM 0.3 (32 L min À1 ) after 5000 backflushings. Thus, the preparation of such nanomaterials may provide new insights into the design and development of high-performance degradable filtration materials for various applications.

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

“…8, it can be seen that the PLA 8/2–12% (porous) filtration composites exhibited excellent filtration efficiencies (97.8246%, 99.8806%, and 99.9989%) for the different spinning times and lowest pressure drops (39.85 Pa, 72.07 Pa, and 90.35 Pa) among the three samples. Therefore, the filtration efficiency (>99.5%) and pressure drop (<100 Pa) of the PLA 8/2–12% (porous) filtration composites were well balanced compared to those in previous studies (>100 Pa) 7,14,38 due to the porous structure of the PLA nanofibers. This was attributed to having the largest specific surface area, surface energy and surface tension among the three samples due to the porous structure in the PLA nanofibers (Fig.…”

“…This was attributed to having the largest specic surface area, surface energy and surface tension among the three samples due to the porous structure in the PLA nanobers (Fig. 6), 13,14,38,43 which could increase the deposition, direct interception and Brownian diffusion effect of the surface of the nanobers on airborne particulates (PM 0.3 ) and consequently improve the ltration efficiency without increasing the pressure drop. Moreover, the appearance of the nanopores could enhance the surface roughness of the PLA nanobers, which may increase the friction coefficient between the nanobers and particles, beneting particle capture.…”

“…Li et al reported a bead-on-string PLA/chitosan composite fibrous membrane fabricated via electrospinning; it exhibited a filtration efficiency of 98.99% for 260 nm particles with a pressure drop of 147.6 Pa. 7 Sun et al prepared a branched PLA nanofiber material by electrospinning, which achieved a high PM 0.3 removal efficiency (99.95%) and low air resistance (79.67 Pa). 38 Wang et al reported hierarchical structured nano-sized/porous PLA composite fibrous membranes for air filtration, which exhibited a filtration efficiency of 99.999% for 260 nm particles with a relatively low pressure drop (93.3 Pa) at a low face velocity of 5.3 cm s −1 . 14 As mentioned above, the shape of the PLA nanofibers could significantly influence the filtration performance of filters.…”

“…Hence, changing the surface shape (such as the pore structure) of the PLA nanobers may be an effective way to improve the air ltration performance. 39 However, charge elimination of electrospun PLA nanobers was not performed in previous studies; 7,8,14,31,38 this could improve the test results of ltration performance due to the electret effect of electrospinning. Thus, the effect of the nanober shape on ltration performance has rarely been accurately reported.…”

Electrospun Membrane for Media Filters: A Review

“…The work by Sun et al (2022) used branched PLA nanofibers for producing fully degradable air filters, as shown in image on Figure 3E. The asobtained product possesses filtration efficiency higher than 99% for PM0.3; and even after 5,000 washes, the filter still maintained this filtration efficiency [27].…”