A semi-automatic analysis tool for the determination of primary particle size, overlap coefficient and specific surface area of nanoparticles aggregates

Abstract

The high reactivity of nanostructured materials makes their use very attractive for various industrial applications. However, these materials may also have an important impact on health / environment / climate and on the performances of protective devices (i.e. high efficiency particulate air filters, electrostatic precipitators). Those properties are mainly due to their high specific surface area, which is directly related to the size of the non-porous primary nanoparticles and to the nature of the bridging between them (from point contact for agglomerates to partial fusion for aggregates).In this paper, a straightforward image processing has been developed to measure, assuming a log-normal size distribution, the primary particle diameter (Dpp), the geometric standard deviation GSD (or σg), the projected overlap coefficient (Cov, p) and the specific surface area (SS) directly from TEM images according to the approach introduced by Bau, Witschger, Gensdarmes, Rastoix, and Thomas (2010). Measurements have been performed from TEM images obtained for 22 different kinds of nanoparticles, from simple spheres to soot particles and virtual aggregates. The results show a good agreement (within ± 20%) between automatic and manual analysis of Dpp, σg and SS while the overlap coefficient has been compared to the manual analysis showing a reasonable agreement (within ± 40%).