Enhanced Capture of Particulate Matter by Molecularly Charged Electrospun Nanofibers

We
introduce molecularly charged electrospun nanofibers obtained
by soft chemical treatment for the capture of particulate matter (PM).
These PMs, along with certain volatile organic compounds (VOCs), pose
a severe threat not only to human health but also to the environment.
As the concentrations of these PMs have been steadily increasing in
the Southeast Asian countries, a dire need for protection against
these particles is warranted. Filtering out the polluted air using
various filtration media, such as face masks and nasal filters, has
been the standard method for minimizing exposure to PM. Here, we demonstrate
the removal of PM and VOCs by utilizing electrospun nanofibers of
polystyrene (PS) and polyacrylonitrile (PAN) with molecular charges
imparted on them via chemical treatment. The chemically treated fibers
were successful in capturing even particles measuring 300 nm, which
are considered to be the most penetrable particles. We report a filtration
efficiency of ∼93% for removing such particles, which is ∼3
± 1.5% enhancement when compared to the untreated fibers. The
fibers have been subjected to extreme haze conditions (∼1413
μg m–3) of PM2.5 for a duration
of 1 h, and the filtration efficiency was measured to be ∼99.01%.
These fibers also possess the capability to capture model VOCs such
as aniline, toluene, tetrahydrofuran, and chloroform. When PAN, PS,
and their chemically treated counterparts were tested for their antibacterial
activity, these filter mats had bactericidal effect on Escherichia coli, Bacillus subtilis, and Enterococcus faecalis. A nasal
plug hosting these filter mats has been designed, which can offer
personal protection from PM. Enhanced removal of residual particles
is extremely important, and this difficult task is made possible with
our approach. The efficiency of our approach is due to the charged
nature of PM, especially of the smaller size regime.

本研究介绍了通过软化学处理制备的分子带电静电纺纳米纤维，用于捕集颗粒物（particulate matter，PM）。此类颗粒物与部分挥发性有机化合物（volatile organic compounds，VOCs）不仅会对人体健康造成严重危害，还会破坏生态环境。鉴于东南亚国家此类颗粒物的浓度持续攀升，对这类颗粒污染物开展防护的需求极为迫切。通过口罩、鼻腔过滤器等各类过滤介质净化污染空气，是降低PM暴露风险的常规手段。本研究通过化学处理为聚苯乙烯（polystyrene，PS）与聚丙烯腈（polyacrylonitrile，PAN）静电纺纳米纤维赋予分子电荷，以此实现对PM与VOCs的去除。经化学处理的纤维甚至可有效捕集尺寸为300 nm的颗粒物——这类颗粒被认为是最易穿透过滤介质的粒径区间。本研究测得此类颗粒物的过滤效率约为93%，较未处理纤维提升约3±1.5个百分点。将该纤维置于PM2.5浓度约1413 μg·m⁻³的极端雾霾环境中处理1小时后，其过滤效率仍可达约99.01%。该纤维同时可捕集苯胺、甲苯、四氢呋喃与三氯甲烷等典型挥发性有机化合物。对PS、PAN及其化学处理产物的抗菌活性测试结果表明，此类过滤毡对大肠杆菌（Escherichia coli）、枯草芽孢杆菌（Bacillus subtilis）与粪肠球菌（Enterococcus faecalis）均具有杀菌效果。本研究还设计了搭载此类过滤毡的鼻腔塞，可为个体提供PM防护。高效去除残留颗粒物极为关键，而本研究提出的方法可实现这一高难度目标。该方法的高效性源于颗粒物尤其是小粒径颗粒物的带电特性。