Experimental And Quantum Chemistry Theoretical Study On The Fluorescence Spectra Of Polycyclic Aromatic Hydrocarbons Of Crude Oil

There has been seriously harm of spilled oils to the marine environment and humanhealth and wildlife. Fluorescence spectroscopy is one of the major spilled oil fingerprintidentification technology. Polycyclic aromatic hydrocarbons are the main components ofcrude oils and have the different compositions of different crude oils. PAHs will fluoresce bythe light irradiation, so that they play an important role in the fluorescence identification. It is avery important subject whether experimental or theoretical study to PAHs.This thesis research and analysis the fluorescence spectra of PAHs in the crude oils fromboth experimental and theoretical to provide some support for spilled oils fluorescentfingerprint identification technology.Experimentally, on the basis of the previous fluorescence spectra experiments of PAHsand crude oils, this thesis study the synchronous fluorescence spectra of PAHs. The studyobtained the structure and concentration impact on the fluorescence properties of PAHs. Anew method is developed to differentiate the spill oil samples. The synchronous fluorescencespectra in the lower nonlinear concentration range of0.01g·L-1~0.10g·L-1were collected toget training data base. Radial basis function neural network is used to identify the samples setswith principal component analysis as the feature extraction method and the recognition rate ofthe closely-related oil source samples is92%. All the results demonstrated that the proposedmethod could identify the crude oil samples effectively by just one synchronous spectrum ofthe spill oil sample and was supposed to be very suitable to the real-time spilled oilidentification.Theoretically, the fluorescence spectra of PAHs are studied to select the Hartree-Fockmethod and6-31+g (d, p) basis set by Gaussian03quantum chemistry program. This thesiscalculate the absorption and emission spectra of PAHs by the Configuration InteractionSingles, and obtained the absorption and emission spectra of PAHs have a relation with its structure, frontier orbital energy and dipole moments. The ring number and arrangement andthe substituent affect on the spectra characteristic of PAHs. According to the characteristicwavelengths and peaks of the different PAHs can identify the aromatic hydrocarbon. Theexperimental and theoretical results are consistent, and the theoretical results compared withthe experimental results are accurate relatively, which avoid the onerous and wasteful of theexperiment. Taking into account the solvent effect, the calculated and experimental results arecloser on the fluorescence spectra of PAHs. The location and intensity of the fluorescencespectrum may be difference of the same substance in different solvents, and the fluorescencewavelength has increased and the transition intensity has significantly strengthened of PAHs inthe same solvent. But the same aromatic hydrocarbon’s spectrum change a little in differentsolvents. The polycyclic aromatic hydrocarbons fluorescence spectral characteristics has littleeffect in the cyclohexane and water, therefore they don’t influence the experimental results.The results lay a good foundation for the spilled oil identification.