Characterization of carbonaceous particles generated from three flame modes using a single burner to enable properties-based exposure studies

Carbonaceous particles exhibit wide variation in their physicochemical properties; understanding the relationship between these properties and health effects remains challenging due to the heterogeneity of real-world emissions. This study presents the design and operation of a laboratory-scale laminar flame ethylene burner. The burner can generate soot with a wide range of physical and chemical properties through three distinct flames: Premixed Flame (PF), Inverse Diffusion Flame (IDF), and Normal Diffusion Flame (NDF). Results are compared to other custom-built and commercial burners for soot generation. PF soot is generated by varying two burner parameters: the equivalence ratio and the adiabatic flame temperature, whereas IDF and NDF soot are produced by varying the molar fuel to oxygen ratio. The mobility size distribution of the generated soot is measured using SMPS, while the organic and elemental carbon fractions are analyzed using thermal-optical analysis. The fluorescence response of cyclohexane-extractable PAH-like organic compounds is normalized by soot mass to assess relative variations in fluorescent organic content. Excitation Emission Matrix (EEM) fluorescence spectroscopy coupled with Parallel Factor Analysis (PARAFAC) is applied to resolve fluorescent components and characterize their relative contributions among soot samples from different flame modes. The results show that the design and operation of the burner, by changing the flame type and conditions, can produce carbonaceous particles with select tunable properties, which may help in systematic studies linking exposure to toxicity.