AA Elhameed, AE Pillay, R Nunn and S Stephen
Keywords: ICP-MS, asphaltenes, crude oil, heavy metals.
Abstract: Environmental sustainability depends on various factors, one of them being the suppression of potential metal contaminants from fossil fuel sources. According to the documented literature, research associated with the retention of toxic and heavy metals in the asphaltene residuum is limited. The aim of this study, therefore, was to explore the phenomena that govern metal retention in asphaltenes and examine the potential environmental outcomes. Asphaltene fractions were isolated from virgin crude oil, purified, digested and analysed for metal and toxic components using ICPMS. The instrument was standardised with certified materials and adjusted for background and matrix effects according to standard protocol. A range of selected toxic elements were determined, including: Be, Al, Se, Ag, Cd, Sb, Pb and Bi. The elemental levels ranged between 2-1500 ppm in the asphaltene phase; and 1-100 ppm in crude oil. These concentrations are elevated and clearly represent a potential environmental hazard. Wide differences existed in metal levels between asphaltene and crude oil samples and suggested metal transfer to the asphaltene phase at the point of precipitation. The experimental data are discussed in terms of environmental impact and the prospect of remediation. Our work contributes to environmental sustainability and fuels research.
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