Electrospun Cyclodextrin/Poly(L-lactic acid) Nanofibers for Efficient Air Filter: Their PM and VOC Removal Efficiency and Triboelectric Outputs

Abstract

In this work, PLLA and CD/PLLA nanofibers were fabricated using electrospinning and utilized as a particulate matter (PM) and volatile organic compounds (VOCs) filter. The electrospun PLLA and CD/PLLA were characterized with various techniques, including SEM, BET, FTIR, XRD, XPS, WCA, DSC, tensile strength testing, PM and VOCs removal efficiency, and triboelectric performance. The results demonstrated that the best air filter was 2.5 wt%CD/PLLA, which performed the highest filtration efficiencies of 96.84 ± 1.51% and 99.38 ± 0.43% for capturing PM_2.5 and PM₁₀, respectively. Its PM_2.5 removal efficiency was 16% higher than that of pure PLLA, which were contributed by their higher surface area and porosity. These 2.5 wt%CD/PLLA nanofibers also exhibited the highest and the fastest VOC entrapment. For triboelectric outputs, the 2.5 wt%CD/PLLA-based triboelectric nanogenerator provided the highest electrical outputs as 245 V and 84.70 μA. These give rise to a three-fold enhancement of electrical outputs. These results indicated that the 2.5 wt%CD/PLLA can improve surface charge density that could capture more PM via electrostatic interaction under surrounding vibration. Therefore, this study suggested that 2.5 wt%CD/PLLA is a good candidate for a multifunction nanofibrous air filter that offers efficient PM and VOC removal.

Keywords: PM; VOC; air filter; cyclodextrin; eco-friendly; electrospinning; nanogenerator; poly(L-lactic acid); triboelectric performance.

Figure 1

SEM images of (a) PLLA nanofiber, (b) 2.5 wt% CD/PLLA, (c) 5 wt% CD/PLLA, and (d) 10 wt% CD/PLLA nanofibers. The third column represents the histograms of size diameter distribution of the corresponding sample.

Figure 2

(a) FTIR spectra of electrospun PLLA, 2.5 wt % CD/PLLA, 5 wt% CD/PLLA, and 10 wt% CD/PLLA and (b) Expanded FTIR spectra.

Figure 3

XRD pattern of PLLA and CD/PLLA nanofibers.

Figure 4

C1s XPS spectra of (a) PLLA and (b) 2.5 wt% CD/PLLA and O 1s XPS spectra of (c) PLLA, (d) 2.5 wt% CD/PLLA electrospun nanofibers. (e) the schematic illustration of the interaction between CD and PLLA.

Figure 5

Contact angle of electrospun PLLA compared with 2.5, 5, and 10 wt% CD/PLLA.

Figure 6

DSC thermograms of PLLA and CD/PLLA nanofibers.

Figure 7

Stress-strain curves of PLLA and CD/PLLA nanofibers.

Figure 8

(a) PM_2.5 and PM₁₀ removal efficiency and (b) quality factor of PLLA and CD/PLLA nanofibers.

Figure 9

VOC removal efficiency of PLLA and CD/PLLA nanofibers.

Figure 10

(a) Configuration and (b) photograph of CD/PLLA nanofiber-based TENG, (c) photograph of CD/PLLA nanofiber-based TENG can a charge capacitor to light, and LED, (d) output voltage and (e) output voltage of PLLA and 2.5 wt% CD/PLLA nanofibers based TENG, (f) output voltage/current and output power density when connected with external load resistance, (g) charging curves of a capacitor (2.2 μF) and the schematic illustration of charging circuit (inset), and (h) the average calculated surface charge.