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 (D pp), the geometric standard deviation GSD (or σ g), the projected overlap coefficient (C ov, p) and the specific surface area (SS) directly from TEM images according to the approach introduced by Bau et al. (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 D pp , σ g and SS while the overlap coefficient has been compared to the manual analysis showing a reasonable agreement (within +/-40 %).

Accounting for the effects of nonideal minor structures on the optical properties of black carbon aerosols

“…For practical applications, the detailed parameters of fractal aggregates as well as the minor structures should be known, and such knowledge can be obtained via the analysis of aggregate images (Brasil et al, 2000;Chakrabarty et al, 2006). Among the minor structures, the monomer size polydispersity and overlapping have been most widely considered (Bescond et al, 2014;De Temmerman et al, 2014;Bourrous et al, 2018). However, with the proposed empirical relationship, only simple estimations of the volume or mass variation are sufficient to account for the change in optical properties.…”

Accounting for the effects of non-ideal minor structures on the optical properties of black carbon aerosols

“…For practical applications, the detailed parameters of fractal aggregate as well as the minor structures should be known, and such knowledge can be obtained by the analysis of aggregate images (Brasil et al, 2000;Chakrabarty et al, 2006). Among the minor structures, the monomer size polydispersity and overlapping have been most widely considered (Bescond et al, 2014;De Temmerman et al, 2014;Bourrous et al, 2018). However, with the proposed empirical relationship, only simple estimations of the volume or mass variation are sufficient to account for the change in optical properties.…”

“…Among them, the polydispersity of monomer size is the most well studied (Chakrabarty et al, 2006(Chakrabarty et al, , 2007Bescond et al, 2014;Wu et al, 2015b), and a complete set of methods have been established to characterize monomer size distribution. Bourrous et al (2018) developed a semi-automatic analysis to obtain Atmos. Chem.…”

Quantification and prediction of water uptake by soot deposited on ventilation filters during fire events

“…Soot micrographs were recorded with a Jeol 100CXII microscope equipped with a CCD camera (Gatan® Erlangshein Dualvision 300 W, 780 model). A hundred of TEM images were analysed for each sample, both manually and automatically using ImageJ software and a semi-automatic software ( Bourrous et al, 2018 ), respectively. Measurements of nitrogen sorption at 77 K using a manometric analyser (ASAP 2020, Micromeritics) provided the specific surface area of each sample from the conventional BET analysis ( Gregg and Sing, 1982 ) and for relative pressure of nitrogen (p/p0) ranging from 0 to 0.30 (0 to nearly 300 mbars).…”

“…Soot was collected on polycarbonate membranes in order to perform physico-chemical analysis and sorption measurements. Transmission Electron Microscopy (TEM) image analysis ( Bourrous et al, 2018 ), nitrogen sorption measurements ( Sing, 1985 ), elementary and X-ray Photoemission Spectroscopy (XPS) analysis ( Parent et al, 2016 ) have been used to determine the diameters of the soot primary particles, the Brunauer-Emmett-Teller (BET) specific surface area and the bulk and surface oxygen contents, respectively. Water sorption measurements were carried out for soot compacted into pellets and in powder form, using a gravimetric microbalance and a manometric analyser, respectively.…”