EVALUATION OF THERMAL TREATMENT IN DECONTAMINATING SOILS POLLUTED WITH CRUDE OIL

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-14-8 / ISSN 1314-2704, June 19-25, 2014, Book 3, Vol. 2, 123-130 pp

ABSTRACT
The effectiveness of thermal decontamination of a soil sample polluted with crude oil was assessed using optical methods (absorbance and fluorescence spectroscopy) and the standard high performance liquid chromatography method (HPLC). The sample was divided in aliquots and subjected to pyrolysis for 1 h, at three operating temperatures: 300, 400 and 500°C. Ten common PAHs were found in all samples: anthracene, naphthalene, phenanthrene, pyrene, chrysene, fluoranthene, benzo(a)anthracene, benzo(k)fluoranthene, benzo(b)fluoranthene and benzo(ghi)perylene. Fluorescence spectroscopy proved to be suitable for evidencing the low and high molecular weight PAHs and their evolution after exposure to the various treatment temperatures. It showed similar decontamination degrees as compared with the high performance liquid chromatography, for the low molecular weight hydrocarbons, but overestimated the decontamination efficiency for the heavier ones. The most satisfactory decontamination rate was evidenced for 400°C. The further increase of the temperature did not improve the treatment outcome, due to the formation of by-products, such as benzo(alfa)pyrene and indeno(1,2,3-c,d)pyrene. Results showed that fluorescence measurements were useful in evaluating the efficiency of the pyrolysis process.

Keywords: fluorescence spectroscopy, polycyclic aromatic hydrocarbons, contaminated soil, thermal decontamination, crude oil