Michel Guiliano

Changes in the chemical structure of low rank coal after low temperature oxidation or demineralization by acid treatment: Analysis by FT-i.r. and u.v. fluorescence☆

The studies have been conducted on low rank coal: Flambant de Provence, France, PRV=0.44 FTIR and UV synchronous fluorescence spectroscopy are used to study structural changes in low rank coal after natural oxidation or acid (HCl/HF) demineralization. The observed variations deal mainly with a decrease in aliphatic structures and an increase in the oxygenated species. A quantitative oxidation study of the effect of temperature, time, mineral matter and oxygen concentrations has been conducted by FTIR. An attempt to describe the oxygenated species by FTIR and to compare their evolution has been conducted. Various oxidation mechanisms are proposed according to the results.

Subfractionation, characterization and photooxidation of crude oil resins

Resins of five crude oils were obtained using SARA fractionation. The maltenic fraction of Blend Arabian Light, was further separated into six polar fractions. These fractions which are the constituents of the resins were analysed by FTIR spectroscopy. They appeared to be more oxidized, more aliphatic and less aromatic than asphaltenes. Photooxidation of resins showed that they are easily oxidizable and much more influenced by photooxidation than asphaltenes. The principal effect of photooxidation are: (i) increase of carbonyl group amounts and particularly formation of carboxylic groups, (ii) oxidation of sulfoxide in sulfone group, (iii) oxidation of alkyl chains and of aromatic rings (quinone structures).

The origins of hydrocarbons trapped in the lake of berre sediments

Abstract For decades, the Lake of Berre (France) - a heavily contaminated ecosystem - has received hudge amounts of hydrocarbons from refineries, petrochemical plants, transportation systems, in addition to those originating from marine and terrestrial biogenic inputs. The purpose of this work was to identify the sources of hydrocarbons trapped in the sediment, using characterization indices, based on n-alkane and isoprenoid abundance ratios obtained from GC/MS analysis. The upper sediment was sampled from 5 widely-separated stations. In each station, the subsurface (0–10 cm) and the underlaying (10–20 cm) sediment were separately analyzed by gravimetry, GC/FID and GC/MS. Total hydrocarbon contents ranged from 63 to more than 6100 mg.kg −1 1 of dry sediment. Qualitative analysis of the saturated hydrocarbon fraction demonstrated the presence of weathered petroleum residues of mixed geochemical origins, as evidenced by the presence of different cyclic alkanes known as biomarkers. Total polyaromatic hydrocarbon contents ranged from 29 to more than 2300 mg.kg −1 1 of dry sediment, associated with molecular indexes suggesting the occurence of combustion processes prior to sedimentation. Petrogenic, pyrolitic, and biogenic sources were discriminated, with reference to previous surveys of the same area or of adjacent areas. With regard to biogenic hydrocarbons, terrestrial sources seem generally predominate, except in the Northwestern area where n-alkane and isoprenoid abundance ratios are more characteristical of organic matter from a marine origin.

In vitro photooxidation of crude oil maltenic fractions : Evolution of fossil biomarkers and polycyclic aromatic hydrocarbons

Abstract Photooxidation is an important transformation pathway for petroleum spilled in the marine environment. The maltenic fraction of ten crude oils was exposed to sunlight. Acidic and non-acidic photoproducts were analysed by FTIR spectroscopy and by GC/MS. A formation of carboxylic acids, straight-chain ketones and alcohols was observed. The GC/MS analyses of residual alkanes showed a preferential alteration of branched alkanes. The analyses of biomarkers such as drimanes, hopanes and steranes indicated that the GC/MS indices widely used in geochemistry, presented a great stability after photooxidation except for the Tm (Tm+Ts) ratio. Concerning the polycyclic aromatic hydrocarbons (PAHs), naphthalene and its derivatives were severely altered by photooxidation whereas, phenanthrene, dibenzothiophene and their derivatives were more recalcitrant. Methyl derivatives were more degraded than their parent molecules and in the case of methyl phenanthrenes, the 2-methyl phenanthrene had a great stability. The following sequence of increasing photodegradability of mono methylated phenanthrenes (MP) can be proposed: 2-MP

APPROCHE METHODOLOGIQUE DIRECTE ET CONTINUE DU PROCESSUS D'OXYDATION DES BITUMES PAR SPECTROSCOPIE INFRAROUGE A TRANSFORMEE DE FOURIER

Abstract (Direct continuous method for studying oxidation of bitumens by Fourier-transform infrared spectrometry). The method is based on the standard rolling thin-film oven test with oxidation in air at 163°C. A specially designed infrared cell is used. FTIR spectrometry provides spectral fingerprints which are characteristic for each bitumen.

Analysis and evolution of coals: UV fluorescence spectroscopy study (demineralized coals-oxidized coals)

Abstract A structural analysis of the organic part of 2 coals of different rank (Gardanne coal and Freyming coal) was performed by UV fluorescence spectroscopy (synchronous excitation-emission technique). The spectral study was made on different extracts (hexane, toluene, tetrahydrofuran and pyridine extracts) obtained by ultrasonic multiple step extraction. On a spectroscopic basis it is thus possible to clearly show the differences between coals of different rank and bring out the notion of “fingerprint” characteristic of a given coal. UV fluorescence spectroscopy also makes it possible to detect structural changes occurring in the aromatic part of coals after demineralization or oxidation.

Biodegradation of the (aliphatic + aromatic) fraction of Oural crude oil. Biomarker identification using GC/MS SIM and GC/MS/MS.

A simplified fraction of the Oural crude oil (aliphatic and aromatic hydrocarbons) was incubated in the presence of an hydrocarbonoclastic bacterial community isolated from a marine sediment highly contaminated by petroleum residue. The biodegradation has been carried out under aerobic conditions for 5 weeks and followed by FTIR, UV synchronous luminescence and GC/FID. Disappearance of the n-alkanes (2nd week), an important attack of the isoprenoïd compounds (5th week) and preferential alteration of monomethylated polyaromatics were observed. Concerning the biomarkers, the bicyclic alkanes and pentacyclic terpanes have been comparatively elucidated using GC/MS data. The identification of C(26) to C(29) steranes has required a most selective method, namely GC/MS/MS. Many molecular ratios based on GC/MS abundances were calculated, which showed good stability. Consequently, they can be used to determine the origin of a petroleum even one altered by biodegradation.

New approach to study of spilled crude oils using high resolution GC-MS (SIM) and metastable reaction monitoring GC-MS-MS

Polycyclic aromatic hydrocarbons (PAHs) and geochemical biomarkers are good environmental markers to study the origin and evolution of an oil spill. To have access to the greatest number of molecular ratios, no fractionation of oil into aliphatic and aromatic compounds is made. Three analytical MS approaches are tested to analyze markers in this total hydrocarbon fraction: classical quadrupole GC-MS, high resolution GC-MS (HR GC-MS) and metastable reaction monitoring GC-MS-MS (MRM GC-MS-MS). This analytical approach is used to follow the evolution of PAHs in petroleum polluted mangrove soils over 8 years by using molecular ratios between polycyclic aromatic hydrocarbons and tri- and tetracyclic terpanes.

Polychlorobiphenyls differentiation and identification by gas chromatography/fourier transform infrared spectroscopy

Reference infrared vapour phase spectra of 20 polychlorobiphenyls (PCBs) have been obtained by gas chromatography/Fourier transform infrared spectroscopy (GC/FTIR). These spectra are consistent with those of PCB obtained by diffuse reflectance IR spectroscopy (DRIFT) and with those of more simple molecular structures (iodochlorobenzenes, 1-bromodichlorobenzenes). The IR frequencies of the GC/FTIR spectra of PCB are assigned in terms of substitution patterns. This work shows that GC/FTIR can be a good approach for differentiation and identification of PCB in complex mixtures.

Classification of Sediment Samples from Brittany Coast 14 Years after Tanio Oil Spill Based on GC/MS Analysis of PAHs and Principal Component Analysis

Abstract Fourteen years after the wreck of the tanker Tanio, 38 samples of marine sediment were taken at different sites of the Pink Granite Coast of Brittany (France). Indexes based on GC/MS SIM abundance ratios were determined for tracking pyrolytic, petrogenic and biogenic origines On the basis of these data, multivariate classification and comparison using Principal Component Analysis (PCA) has been made on the data matrix. These results permitted characterization of anthropogenic, biogenic, pyrolytic and petrogenic origins of hydrocarbon pollution.