Multielement analysis of Nigerian bitumen by TXRF spectrometry and the physical constants characterization of its hydrocarbon component

Abstract

The Total reflection X-ray fluorescence (TXRF) Spectrometry analytical technique was used for the elemental characterization of bitumen extracted from Nigerian Oil sands. Twelve elements—K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As and Pb were detected and their concentrations, the enrichment factors and correlation determined. Very high enrichment factors were obtained for V, Cr, Ni, Cu, Zn, As and Pb. This has implication for environmental degradation during exploration, refining, transportation and/or marketing of the bitumen. The correlation matrix result indicated that some of the trace elements detected have common sources or similar chemical properties. Samples of the extracted bitumen were also subjected to solvent deasphaltened using n-pentane to obtain maltene and asphaltene. Oil (Hydrocarbon) component was eluted from maltene using n-pentane in a glass chromatographic column, which has been packed with activated neutral alumina of grade Brock Mann 1, type 507 C. The physical characteristics (API gravity, refractive index, viscosity, surface tension and melting point) of the oil eluted from the bitumen were determined. The percentage oil composition (36.98%) was comparable to equivalent values obtained for oil from Athabasca (48.10%) and Venezuela (40.30%) oil sands indicating that Nigerian oil sand is a rich source of petrochemicals. The results of physical characteristics also show that oil could be useful for lubrication purpose.