Determination of Geometrical Length of Airborne Carbon Nanotubes by Electron Microscopy, Model Calculation, and Filtration Method

The geometrical length of carbon nanotubes (CNTs) is of significant importance and this study aims at its fast determination.We evaluated a method to determine the geometrical length of CNTs by electricalmobility classification and developed a filtration based method. The measurement was carried out in air and the suitable generation method for airborne CNTs fromliquid suspensions was investigated followed by a proper control of the CNT dispersion degree by changing the CNT concentration in the liquid suspension. Airborne CNTs were generated by an atomizer classified by a differential mobility analyzer and characterized by electron microscopy. The CNT geometrical lengths measured by electron microscopy served as the basis for comparison with other methods. Two theoretical models (Lall and Friedlander 2006; Li et al. 2012) for elongated particles were investigated and the comparison showed good agreement. This demonstrated the validity of the approach to determine the CNT length by the combination of mobility measurement and model calculation. The newly developed method which employed a filtration model with uniform screens showed comparable results with the CNT lengths as obtained from the electron microscopy. Copyright © American Association for Aerosol Research.