Molybdenum speciation in asphaltite bottom ash (Seguruk, SE Anatolia, Turkey)

Asphaltites derive from petroleum origin. The combustion of asphaltites produces fly and bottom ashes that are characterized by a high content of valuable elements such as vanadium, nickel, molybdenum, uranium, thorium, sulfur and unburnt carbon. This study presents the concentration and speciation of molybdenum in bottom ash of asphaltite (Seguruk, SE Anatolia, Turkey). Determination of total molybdenum in asphaltite bottom ash was performed in two stage microwave-acid digestion followed by inductively coupled plasma optical emission spectrometer. A seven step sequential extraction process to speciation of molybdenum from asphaltite bottom ash was investigated. The most abundant form of molybdenum in samples is sulfide fraction of molybdenum. Relative abundances of the remaining fractions follow the order: residual > reducible > oxidizable > exchangeable > carbonate > water soluble. Molybdenum speciation scheme allows quantitative knowledge of molybdenum distribution in asphaltite bottom ash and their toxicity, mobility, leachability, bioaccumulation and bioavailability.