Physicochemical and heavy metals values of Nigerian crude oil samples

Abstract

Crude oil samples collected from Nigerian Petroleum Development Company (NPDC) Benin City representing three different oil wells each for Onshore and Offshore and labeled A, B, C for Onshore and D, E, F for offshore were analyzed for their ash content, volatile matter, pH, relative density and metal content. The results showed that manganese recorded the highest concentration, while copper had the least. The mean values of the ash in both the Onshore and Offshore crude oil are in the order C>A>B for the Onshore and E>F>D for the Offshore oil samples analyzed, and the overall ash content for all the samples analyzed are in the order C>E>B>F>D>A. The values of the volatile matter in both the onshore and off shore crude oil samples obeyed the order B>A>C for the onshore and D>F>E for offshore crude oil samples, while the general trend was in the order C<E<B<F<D<A. The mean pH values of both the onshore and offshore samples were (7.89) for A, (7.62) for B, (7.93) for C, and (8.03) for D, (8.23) for E, (8.11) for F. The relative density of crude oil samples determined at temperature 34^oC were of the order C<E<B<F<D>A, The concentration of the heavy metals ranged from 2.20 – 3.5 ppm for Mn, 1.42-1.62 ppm for Ni, 1.04 – 1.44 ppm for Fe, 0.68 – 0.74 ppm for Cr, 0.48 – 0.54 ppm for Zn, 0.28 – 1.12 ppm for Co, 0.31-0.34 ppm for Cd, 017 – 0.19 ppm for Pb and 0.08-0.12 for Cu. It was obvious from these studies and previous ones that Nigerian crude have low metal content. However, the low concentrations could pose an intrinsic health hazard considering their cumulative effect in the environment.

Keywords: Heavy metals, crude oil, petroleum, Nigeria

International Journal of Natural and Applied Sciences, 6(1): 10-15, 2010