Multi-elemental analysis of free water obtained from water in oil emulsions from Niger Delta Region using ICP-OES

Abstract

Disposal of produced water obtained from crude oil could be challenging and tough because of the effect it has on the environment. Produced water contains high levels of salt and toxic substances which must be treated before re-use or disposal to reduce their impact on the environment, people and assets. Hence, the characterization of produced water for its chemical composition is essential. This study presents the determination of heavy metals (Co, Cu, Pb, Fe, Zn, Ni, and Cd) in produced water obtained from crude oil emulsion samples via inductively coupled plasma optical emission spectrometry (ICP-OES). The samples were subjected to treatment prior to analysis. The analytical curve obtained from the calibration gave excellent correlation coefficients ranging from 0.9995- 1.000 and the recovery values obtained were very good (95% - 105%). The result of the heavy metal analysis in μg/l (Co: <DL to 14.3, Cu: 114.1 to 1553.2, Fe: 492.1 to 1576.4, Ni: 52.3 to 174.5, Pb: <DL to 15.1, Zn: 92.4 to 432.9, Cd: 2.3 to 4.4) indicates that the concentrations of the metals evaluated in the produced water samples were above the recommended discharge limit ( Zn - 1.0 mg/L, Co - 0.02 mg/L, Fe - 1.0 mg/L, Cu - 0.02 mg/L, Cd - 0.01 mg/L, Ni - 0.03 mg/L and Pb - 0.05 mg/L).