Determination of policyclic aromatic compounds, (PAH, nitro-PAH and oxy-PAH) in soot collected from a diesel engine operating with different fuels

S Lara; F Villanueva; B Cabañas; S Sagrario; I Aranda; J A Soriano; P Martin

doi:10.1016/j.scitotenv.2023.165755

Determination of policyclic aromatic compounds, (PAH, nitro-PAH and oxy-PAH) in soot collected from a diesel engine operating with different fuels

Sci Total Environ. 2023 Nov 20:900:165755. doi: 10.1016/j.scitotenv.2023.165755. Epub 2023 Jul 25.

Authors

S Lara¹, F Villanueva², B Cabañas³, S Sagrario³, I Aranda¹, J A Soriano⁴, P Martin⁵

Affiliations

¹ Universidad de Castilla-La Mancha, Instituto de Investigación en Combustión y Contaminación Atmosférica, Camino de Moledores s/n, 13071 Ciudad Real, Spain.
² Universidad de Castilla-La Mancha, Instituto de Investigación en Combustión y Contaminación Atmosférica, Camino de Moledores s/n, 13071 Ciudad Real, Spain; Parque Científico y Tecnológico de Castilla-La Mancha, Paseo de la Innovación 1, 02006 Albacete, Spain.
³ Universidad de Castilla-La Mancha, Instituto de Investigación en Combustión y Contaminación Atmosférica, Camino de Moledores s/n, 13071 Ciudad Real, Spain; Universidad de Castilla-La Mancha, Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Avenida Camilo José Cela s/n, 13071 Ciudad Real, Spain.
⁴ Universidad de Castilla-La Mancha, Campus de Excelencia Internacional en Energía y Medioambiente, Instituto de Investigación Aplicada a la Industria Aeronáutica INAIA, Escuela de Ingeniería Industrial y Aeroespacial de Toledo. Real Fábrica de Armas, Edif. Sabatini, Av. Carlos III s/n, 45071, Toledo, Spain.
⁵ Universidad de Castilla-La Mancha, Instituto de Investigación en Combustión y Contaminación Atmosférica, Camino de Moledores s/n, 13071 Ciudad Real, Spain. Electronic address: Mariapilar.martin@uclm.es.

PMID: 37499818
DOI: 10.1016/j.scitotenv.2023.165755

Abstract

A qualitative and quantitative analysis of polycyclic aromatic compounds (PACs; polycyclic aromatic hydrocarbons (PAHs), oxygenated and nitrated polycyclic aromatic hydrocarbons (OPAHs and NPAHs)) present in the soluble organic fraction (SOF) of different soot samples has been carried out to determine the effect of soot-generation conditions on their composition and health effects. The soot samples were generated using a diesel engine bench powered by diesel (DS) and biodiesel (BS) fuels under different combustion conditions. To optimize the procedure, a surrogate soot (Printex-U) and a certified reference material (SRM1650b) were also tested. Different extraction methods were used to extract the PAHs, OPAHs and NPAHs, and the Soxhlet technique using pyridine:acetic acid 1 % was found to be the most suitable procedure to extract the highest concentration (ng mg^-1) and more types of PAHs and OPAHs from the soot. The results show that the PACs identified, and their concentrations, depend on the formation and collection conditions. The predominant compounds in all soot samples studied were fluorene (Flo), phenanthrene (Phe), fluoranthene (Fla), pyrene (Pyr), 9-fluorenone (9Flo) and 9,10-anthraquinone (9,10Anq). As such, the presence of these PACs in the atmosphere of urban and rural areas can mainly be attributed to the emissions from diesel vehicles. The percentage of OPAHs with respect to total PACs was highest in the soot generated from a biofuel. These oxidized compounds favor regeneration of the diesel particulate filter (DPF). The results also indicate that the carcinogenicity of the soot depends on the combustion conditions and type of fuel.

Keywords: Cancer risk; Diesel engine; Nitro-PAHs; Oxygenated-PAHs; PAHs; Soot.