AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Carbon Nanotube Penetration through Different Respirator and Nuclepore Filters: Models and Experiments
SHENG-CHIEH CHEN, Jing Wang, Yeon Kyoung Bahk, Heinz Fissan, David Y. H. Pui, University of Minnesota
Abstract Number: 148 Working Group: Engineered Nanoparticles: Emissions, Transformation and Exposure
Abstract Animal studies have shown asbestos-type pathology associated with exposure to longer and straighter CNTs. Respirators are usually used as the final personal protective equipments to mitigate the exposure of workers who are manufacturing and handling CNTs. However, the performances of respirators were usually obtained by challenging spherical particles; therefore the penetration curves may not be accurate and suitable for CNTs. It has been found that CNTs had a much lower penetration through screen filters at 5 cm/s face velocity than the same mobility diameter spherical particles due to a much longer interception length of CNTs. This result indicates the performance data are applicable for the CNTs. However, the penetration of open Ag agglomerates, which have a similar high length-to-diameter ratio, was found to be close to spherical particles in Nuclepore filter at face velocities higher than 10 cm/s (close to the face velocity for N-95 certification) due to the effect of alignment. This finding attracts our attentions to study whether the penetration could be higher for CNTs than the same mobility diameter spherical particles at face velocity around 10 cm/s and higher velocities. In this study, three different respirator filters (two electrets and one glassfiber) were challenged with different mobility diameter, 30-500 nm, monodisperse CNTs at 5.3 and 10.6 cm/s face velocities. The CNTs were functionalized by the nitric acid refluxing method. The penetration data were compared with that of NaCl particles obtained earlier by us. Results showed that the penetrations of CNTs were mostly lower than NaCl at the same mobility diameter at both face velocities for all three filters. However, it was found the CNTs had higher penetrations than NaCl for sizes larger than 300 nm at 10.6 cm/s face velocity. Finally, the collection mechanisms of CNTs were studied experimentally and theoretically by using Nuclepore filters and capillary tube models, which is a potential method to assess the CNT exposure of workers.