By-products of biofuel combustion have gained through years increased attention due to their unknown toxicity. In particular, while small compounds are relatively easily detected with traditional GC technique a much smaller database exist for the quantification of larger compounds as PAHs. Among these latters, the presence of oxy-PAHs, intended both as PAH with alcoholic groups and as etero-cyclic compound including oxygen, represents the class of compound less studied. In fact, due to the relative small amount of these PAHs in combustion exhausts, a reliable detection and quantification result quite hard. Consequently, modelling of reaction pathways that lead from the fuel oxidation/pyrolysis to the formation of PAHs and oxy-PAHs is almost absent. Unfortunately, beside of the small amount of these compounds in the exhausts, their impact both on final particulate emission features as well directly on human health has to be considered. In order to obtain more information on oxy-PAH formation and evolution a new approach is here proposed to detect these compounds. The approach is based on thermophoretic sampling of material from gas phase on a substrate. The substrate is a glass plate previously covered by soot, then annealed and washed in organic solvent (DCM) to remove the absorbed fraction. In fact, once rapidly inserted in the flame the substrate treated in this way will act as trap and absorb the gas phase PAHs present in combustion environment. After the insertion (repeated many times to collect enough material) the substrate will be washed again in organic solvent, to allow to perform GC measurements for the identification of the single compounds. The cover and the treatment of the surface will enhance the absorption efficiency with respect to the glass and can be calibrated with traditional probe measurement of PAHs. The method has the advantage with respect to traditional sampling to be easy to setup and operate. The preliminary results obtained for test case biofuel premixed flames are promising in the possibility to apply this sampling/measurement approach also to detect and track traces compounds such as oxy-PAHs.
Workshop on Gas-phase reaction kinetics of biofuels oxygenated molecules
A Ciajolo;C Russo
2018
Abstract
By-products of biofuel combustion have gained through years increased attention due to their unknown toxicity. In particular, while small compounds are relatively easily detected with traditional GC technique a much smaller database exist for the quantification of larger compounds as PAHs. Among these latters, the presence of oxy-PAHs, intended both as PAH with alcoholic groups and as etero-cyclic compound including oxygen, represents the class of compound less studied. In fact, due to the relative small amount of these PAHs in combustion exhausts, a reliable detection and quantification result quite hard. Consequently, modelling of reaction pathways that lead from the fuel oxidation/pyrolysis to the formation of PAHs and oxy-PAHs is almost absent. Unfortunately, beside of the small amount of these compounds in the exhausts, their impact both on final particulate emission features as well directly on human health has to be considered. In order to obtain more information on oxy-PAH formation and evolution a new approach is here proposed to detect these compounds. The approach is based on thermophoretic sampling of material from gas phase on a substrate. The substrate is a glass plate previously covered by soot, then annealed and washed in organic solvent (DCM) to remove the absorbed fraction. In fact, once rapidly inserted in the flame the substrate treated in this way will act as trap and absorb the gas phase PAHs present in combustion environment. After the insertion (repeated many times to collect enough material) the substrate will be washed again in organic solvent, to allow to perform GC measurements for the identification of the single compounds. The cover and the treatment of the surface will enhance the absorption efficiency with respect to the glass and can be calibrated with traditional probe measurement of PAHs. The method has the advantage with respect to traditional sampling to be easy to setup and operate. The preliminary results obtained for test case biofuel premixed flames are promising in the possibility to apply this sampling/measurement approach also to detect and track traces compounds such as oxy-PAHs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
