Caracterización de nanopartículas de black carbon presentes en el aire de Bogotá mediante espectroscopía Raman y SEM

Abstract

Black Carbon Nanoparticles (BCN) generate a significant impact on climate change. Furthermore, they are correlated with the origin of serious respiratory problems to such an extent that they cause a decrease in human life expectancy. Among the environmental effects they generate, the alteration of radiative forcing and the decrease in albedo stand out, which are related to the atmosphere-land surface temperature and the increase and/or decrease in rainfall, respectively. Due to the above, it is necessary to structurally analyze the BCN in order to better understand its composition and structural organization, which can contribute to the understanding of the effects that this nanoparticulate material generates. This work aims to physically characterize Black Carbon nanoparticles (BCN) present in the air of the city of Bogotá using Raman spectroscopy and Scanning Electron Microscopy (SEM). The analysis was done from BCN samples collected on a quartz fiber tape from an aethalometer of the District Environment Secretariat of Bogotá. It was identified that BCN are made up of crystalline graphitic carbon, they can present the morphology of cables whose diameter ranges from 8 µm to 0.4 µm, they can also be amorphous. Then, a complementary EDX analysis was carried out on which the elemental O/C ratio was calculated, in order to identify the possible emission source of the analyzed BCN. Finally, a Monte Carlo simulation was carried out to predict the trajectories that the photo-electrons possibly took, as well as to demonstrate the beam-sample interaction volume.