Polycyclic Aromatic Hydrocarbons in Particulate Matter Emitted by the Combustion of Diesel and Biodiesel

Abstract

Two sets of experiments were performed for collected particulate mass emitted directly from the exhaust of diesel engines burning diesel and biodiesel fuels: First, a diesel truck was used in the field, and in the second test, a similar diesel engine was used in the laboratory. The mass of particles and polycyclic aromatic hydrocarbons (PAH) was determined. No reduction was observed in the mass of particles per min using biodiesel relative to that produced when burning diesel. Pyrene and phenanthrene showed the highest mass concentrations in diesel and biodiesel in both tests. Reductions in these PAHs greater than 80% (in the truck field test) and 35% AE 11% (in the engine laboratory test) were observed when using biodiesel in any mixture thereof, with respect to diesel. The mean AE standard deviation of the ratios of BaA/(BaA þ Chry) and (BbF þ BkF)BghiP for diesel emissions were consistent with the literature. Four ratios amongst PAHs were proposed, with relative standard deviation < 10%, which suggests that these ratios could be used as emission markers for diesel and animal biodiesel blends (<B20).

A Unified Mechanism on the Formation of Acenes, Helicenes, and Phenacenes in the Gas Phase

“…[23] Here,t he hydrogen abstraction-vinylacetylene addition (HAVA )p athway signifies av ersatile reaction mechanism to generate even more complex acenes,helicenes, and phenacenes through barrierless,s tepwise ring expansion via elementary gas phase reactions of an aryl radical, which can be formed inside molecular clouds from the corresponding aromatic precursor via photolysis by the internal ultraviolet field, with vinylacetylene.Incircumstellar envelopes of carbon stars with temperatures of up to afew 1000 Kand even in combustion flames,molecular mass growth processes could also be triggered by hydrogen abstraction from phenanthrene and anthracene followed by formation of tetracene, [ 4]phenacene,a nd/or [4]helicene as identified as products of incomplete combustion of coal, [24] wood, [25] and (bio)diesel. [26] This proposes HAVA as af acile key mechanism propelling molecular mass growth processes of PA Hs via de facto barrier-less,s uccessive ring expansions involving elementary reactions of aryl radical with vinylacetylene as am olecular building block.…”

Effects of fuel composition and vehicle operating temperature on in vitro toxicity of exhaust emissions

“…Similarly, the aromatic content of the fuel has been shown to increase the toxicological responses to the exhaust PM in several studies. [58][59][60][61][62][63] Moreover, the previous study by Hakkarainen et al, 2023 (ref. 24) shows that higher concentrations of PM-bound PAH compounds resulted in an increase in the toxicological potential of diesel exhaust.…”

A Unified Mechanism on the Formation of Acenes, Helicenes, and Phenacenes in the Gas Phase

“…Here, the hydrogen abstraction—vinylacetylene addition (HAVA) pathway signifies a versatile reaction mechanism to generate even more complex acenes, helicenes, and phenacenes through barrierless, stepwise ring expansion via elementary gas phase reactions of an aryl radical, which can be formed inside molecular clouds from the corresponding aromatic precursor via photolysis by the internal ultraviolet field, with vinylacetylene. In circumstellar envelopes of carbon stars with temperatures of up to a few 1000 K and even in combustion flames, molecular mass growth processes could also be triggered by hydrogen abstraction from phenanthrene and anthracene followed by formation of tetracene, [4]phenacene, and/or [4]helicene as identified as products of incomplete combustion of coal, wood, and (bio)diesel . This proposes HAVA as a facile key mechanism propelling molecular mass growth processes of PAHs via de facto barrier‐less, successive ring expansions involving elementary reactions of aryl radical with vinylacetylene as a molecular building block.…”