Vanadium fractions determination in asphaltite combustion waste using sequential extraction with ICP-OES

Asphaltite derives from petroleum origin solid fossil fuel. It contains many elements in different forms which may change during combustion process. A true understanding of the dynamics of elements in the natural environment requires an expanded knowledge of its oxidation-reduction cycling. This study presents a sequential extraction method for the fractionation of vanadium (V) from asphaltite combustion waste (ACW) in seven forms (water soluble, exchangeable, carbonate, reducible, oxidizable, sulfide, and residual) and their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The 292.464 nm line was used because it offers better detectability and was free from major spectral interferences. Two-stage microwave acid digestion was used to preparation of samples. Total V concentration in the ACW is 546.15 mg kg(-1) dry weight (d.w). The most abundant vanadium in studied ACW sample was found as sulfide fraction of V(307.50 mg kg(-1)d.w.). Relative abundances of the remaining V fractions in ACW are as follows: Oxidizable (86.19 mg kg(-1)d.w.) > reducible (64.18 mg kg(-1)d.w.)> carbonate (32.79 mg kg(-1)d.w.) > residual (32.18 mg kg(-1)d.w.) > exchangeable (14.25 mg kg(-1)d.w.)> water soluble (9.04 mg kg(-1)d.w.). The results were found to be in good agreement with the certified value. The advantages of the technique include a high degree of automation, good reproducibility, and short analysis time and thus make it the method of choice for the fractionation of V. (c) 2012 Elsevier B.V. All rights reserved.