Steady-state and time-resolved fluorescence measurements are reported for several crude oils and their saturates, aromatics, resins, and asphaltenes (SARA) fractions (saturates, aromatics and resins), isolated from maltene after pentane precipitation of the asphaltenes. There is a clear relationship between the American Petroleum Institute (API) grade of the crude oils and their fluorescence emission intensity and maxima. Dilution of the crude oil samples with cyclohexane results in a significant increase of emission intensity and a blue shift, which is a clear indication of the presence of energy-transfer processes between the emissive chromophores present in the crude oil. Both the fluorescence spectra and the mean fluorescence lifetimes of the three SARA fractions and their mixtures indicate that the aromatics and resins are the major contributors to the emission of crude oils. Total synchronous fluorescence scan (TSFS) spectral maps are preferable to steady-state fluorescence spectra for discriminating between the fractions, making TSFS maps a particularly interesting choice for the development of fluorescence-based methods for the characterization and classification of crude oils. More detailed studies, using a much wider range of excitation and emission wavelengths, are necessary to determine the utility of time-resolved fluorescence (TRF) data for this purpose. Preliminary models constructed using TSFS spectra from 21 crude oil samples show a very good correlation (R 2 > 0.88) between the calculated and measured values of API and the SARA fraction concentrations. The use of models based on a fast fluorescence measurement may thus be an alternative to tedious and time-consuming chemical analysis in refineries. ' INTRODUCTIONOnline remote characterization and real-time classification of crude petroleum are the most important current challenges faced by the petrochemical industry and environmental agencies. A rapid and inexpensive method for the remote analysis and classification of petroleum prior to distillation of the crude would provide chemical information of great importance for real-time adjustment of the critical operational parameters of a refinery, permitting an optimization of the process and resulting in economic and environmental benefits.A variety of spectroscopic techniques have been used over the last few decades for the analysis, characterization, and classification of crude oil in drilling fields, for the analysis of petroleum products, and for the detection of oil spills. The advantages of using such techniques include rapid response, the requirement of minimal sample preparation, and relatively inexpensive equipment costs. Of all of the optical spectroscopic techniques employed, vibrational [infrared (IR) and Raman] 1,2 and electronic [ultravioletÀvisible (UVÀvis) and fluorescence] spectroscopies have shown the highest potential in the field. Fluorescence is a more complex phenomenon than absorption (UVÀvis or IR), and effects such as quenching and energy transfer have to be considered. 3,...

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Fenol puede ser degradado a casi 100 % en pocos minutos vía los procesos Fenton y fotoFenton. Su degradación y la relación entre las concentraciones molares iniciales de oxidante y catalizador utilizadas aumentan en sentidos inversos, y una relación de 38,4 fue óptima para soluciones acuosas contaminadas con 20 ppm de fenol. Asimismo, el uso de luz ultravioleta del tipo A aumentó la degradación comparado a menores longitudes de onda.