Thermal transformations of the optical constants of petroleum products films on the water surface
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EVTODIEV, Silvia, CARAMAN, Iuliana, UNTILA, Dumitru, CARAMAN, Mihail. Thermal transformations of the optical constants of petroleum products films on the water surface. In: Central and Eastern European Conference on Thermal Analysis and Calorimetry, Ed. 4, 28-31 august 2017, Chişinău. Germany: Academica Greifswald, 2017, Editia 4, p. 255. ISBN 978-3-940237-47-7.
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Central and Eastern European Conference on Thermal Analysis and Calorimetry
Editia 4, 2017
Conferința "Central and Eastern European Conference"
4, Chişinău, Moldova, 28-31 august 2017

Thermal transformations of the optical constants of petroleum products films on the water surface


Pag. 255-255

Evtodiev Silvia12, Caraman Iuliana3, Untila Dumitru14, Caraman Mihail1
 
1 Moldova State University,
2 University of European Political and Economic Studies „Constantin Stere”,
3 "Vasile Alecsandri" University of Bacau,
4 Institute of the Electronic Engineering and Nanotechnologies "D. Ghitu" of the Academy of Sciences of Moldova
 
Disponibil în IBN: 3 octombrie 2019


Rezumat

As a result of tehnological accidents, processing, transport and use of oil and its derivatives there are possible both their leaks and infiltration into soil and aquatic systems. In order to determine the nature of the impurities, the composition of the petroleum product and its effects on the environment, it is necessary to know the factors that lead to their degradation, such as solar radiation and temperature. Since petroleum products form thin layers of micro- and submicrometric thicknesses on the water surface, optical and luminescence methods are dominant among the analytical methods for identifying the product and determining the contamination duration. Optical radiation interacts with the environment through so-called optical constants (refractive index, extinction coefficient, and absorption coefficient). Since the molecular composition of the substance determines refraction, and emission (luminescence) and absorption processes are determined by electronic transitions in molecules, the structure of the absorption / emission spectra and the intensity of the molecular electronic bands are investigated for the broad characterization of the substance. In this work the absorption, photoluminescence (PL) and refraction spectra of gasoline films (A92 and A95) and diesel on the water surface, as well as the temperature influence on their structure are investigated. Samples temperature was varied in the range of 15-55°C. Layer absorption was determined from measurements of the transmission and reflection coefficients from the layer-substrate (water) assembly in the 260-1100 nm wavelength range. Samples photoluminescence was excited with the radiation of both Hg lamp (λ = 253.6 nm) and N2 laser (λ = 337.4 nm). The diesel fuel absorption spectrum contains three low intensity bands in the blue-UV spectral region. In this spectral range there are two PL bands. The intensity of both absorption and PL bands depend on the sample temperature. It has been established that the absorption coefficient in blue-violet band tends to saturate at temperatures higher than 50°C, whereas the intensity of the band from the UV region is poorly temperature-dependent in the studied thermal range. These results indicate the thermal dissociation of diesel fuel. In the paper similar studies for gasoline (A92 and A95) are also presented. The results of the study of temperature influence on the optical spectra indicate the composition of the fuel layer on the water surface and the contamination duration.