Chemical speciation of vanadium in coal bottom ash

Abstract

Chemical speciation of vanadium is important to understand the true nature of this element in the environment as well as its biochemical pathways. Sample pretreatment, preparation, and chemical speciation methods were applied for vanadium in coal bottom ash here. Two-stage microwave acid digestion was used to preparation of samples. Determination of vanadium was performed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Speciation of vanadium was carried out using a seven-step sequential extraction procedure of the coal bottom ash each releasing species of vanadium: Water soluble, exchangeable, carbonate, reducible, oxidizable, sulfide, and residual fractions. Total vanadium concentration in the coal bottom ash is 701?mg?kg-1 d.w. The most abundant form of vanadium in coal bottom ash is residual fraction of vanadium (196?mg?kg-1 d.w.). Relative abundances of the remaining vanadium fractions in coal bottom ash are as follows: Reducible (176?mg?kg-1 d.w.)?>?sulfide (176?mg?kg-1 d.w.)?>?carbonate (85?mg?kg-1 d.w.)?>?oxidizable (50?mg?kg-1 d.w.)?>?water soluble (10.6?mg?kg-1 d.w.)?>?exchangeable (9.0?mg?kg-1 d.w.).