Southern, Daniel;
(2024)
Influence of biodiesel molecular structure on exhaust particulate-bound PAHs and toxicity to normal human airway epithelia.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Various feedstocks may contribute to biofuel production to reduce greenhouse gas emissions, however, the toxicity of pollutants produced by combustion of current biofuels for diesel engines (i.e., fatty acid methyl esters, FAMEs) are poorly understood. Furthermore, the fatty acid profile of biodiesels varies in the average chain length and unsaturation. An understanding of the fuel structure effect on particulate toxicity may provide valuable insight for regulators and fuel researchers. A series of experiments investigated FAME biodiesel effects on combustion (in a naturally aspirated single-cylinder direct-injection diesel engine), particulatephase polycyclic aromatic hydrocarbon (PAH) emissions and toxicity to normal human primary bronchial epithelial cells (HPBEC). FAME biodiesels from six feedstocks were chosen because of commercial utilisation (methyl esters of soybean oil, SME; palm oil, PME; rapeseed oil, RME, and waste cooking oil, WCOME) or contrasting constituent methyl ester profiles (methyl esters of coconut oil and linseed oil). The commercial FAMEs were also blended with fossil diesel (B10, B20 and B50) to investigate whether biodiesel blends affect PAH emissions. In addition, six single-component fuels (including decene, decane, undecane, dodecane, methyl dodecanoate and 30/70 v/v% methyl acetate/decene blend) were investigated for further insight into the effect of molecular structure on PAH emissions. HPBEC were cultured at the air-liquid interface (>28d) to achieve sufficient cellular differentiation. Fuel effects on particulate-phase PAH emissions and the mRNA levels of investigated genes were observed and attributed to an increase in FAME unsaturation. For example, measures of PAH content (e.g., B[a]P-equivalence, FPC1) correlated with NQO1, ALDH3A1 and IL19 expression, and significant increases of CYP1A1 expression were observed after neat FAME particulate extract exposure. Additionally, WCOME10, RME10 and SME10 blends emitted higher total particulate-phase PAH emissions compared to fossil diesel, whereas a contrasting trend was observed for PME10. Overall, these results support higher particulate toxicity associated with unsaturated FAMEs.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Influence of biodiesel molecular structure on exhaust particulate-bound PAHs and toxicity to normal human airway epithelia |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10188594 |
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