Characterization of Crude Oil, Asphaltenes Based on Bismuth (Bi), Thorium (Th) and Uranium (U) Levels: Potential Environmental Impact

Abstract

The actinides (Th, U) and bismuth exist at ultra-trace levels in petroleum and have rarely been reported to characterize combustible fuels. However, high-performance mass spectrometry coupled with plasma technology has succeeded in reaching detectable limits in the ng/L range, and has thus made such characterization possible. Crude oil is used as sludge for certain agricultural purposes; and asphaltenes are converted to by-products for constructing car parks, pavements, roofing material and thoroughfares. Our study uncovers an area that has not been previously explored and we examine the potential ecotoxicology of bismuth, thorium and uranium in this context. Asphaltene derivatives were separated from crude oil samples via multiple-stage soxhlet extraction. The virgin crude oil and isolated asphaltenes were investigated for Bi, Th and U content using a high-powered hyphenated facility. A Perkin Elmer SCIEX DRC-e ICP coupled to a quadrupole mass spectrometer was employed to detect the elements of interest. The levels of these elements occurred in the mg/L (ppm) and μg/L (ppb) ranges and were compared for crude oil and asphaltenes. The data showed higher levels of the detected elements in the asphaltene phase. The feasibility of applying the experimental results as a fingerprinting tool for provenancing crude oil and asphaltenes was examined. The results are discussed from the perspective of bismuth and actinide pollution and its long-term impact on sustainable development.