Monograph
Aerodynamic property and filtration evaluation of airborne graphene nanoplatelets with plate-like shape and folded structure

https://doi.org/10.1016/j.seppur.2020.117293Get rights and content
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Highlights

  • Equivalent diameters were derived to account for plate-like shape effect of GNPs.

  • GNPs had higher filtration efficiency than spheres due to larger interception length.

  • Capture filtration for folded GNPs decreased by 20–30 % compared to planar GNPs.

  • Optimizing membrane structure contributed to the improvement of quality factor.

Abstract

With the wide applications of graphene nanoplatelets (GNPs) in the industries, more concerns are raised about the effectiveness of filtration technology to control GNPs release during manufacturing and handling processes. Accurate prediction of the capture efficiency of airborne GNPs is significant to avoid occupational exposure. Herein, the aerodynamic property and filtration mechanisms of airborne GNPs with plate-like shape and folded structure were studied. Different equivalent diameters of GNPs (aerodynamic diameter da, mobility diameter dm) were derived and used to describe diverse mechanisms in the filtration model. The capture efficiency of plate-like GNPs and sphere-like NaCl particles was measured with Nuclepore membranes and nanofibrous membranes to assess the particle shape effect during filtration. The plate-like GNPs showed higher capture efficiency due to the larger interception length. SEM measurement showed that not only planar GNPs, GNPs with folded structure also occurred due to the large lateral size to thickness ratio and strong mechanical stimulation in the atomization process. For GNPs with aerodynamic diameter of 0.5 – 0.9 μm, the capture efficiency for folded GNPs decreased by 20 – 30% according to the analytical calculation. In addition, the effects of membrane structural parameters (Nuclepore membrane pore radius, fiber diameter, solidity) on the quality factor (Qf) were systematically analyzed to evaluate the overall filtration performance. This study not only elucidates the effect of plate-like shape and folded structure on the aerodynamics of airborne GNPs, but also contributes to better design of Nuclepore and nanofibrous membranes to improve the filtration performance of plate-like particles.

Keywords

Graphene nanoplatelets
Folded structure
Aerodynamic property
Filtration efficiency
Quality factor

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