NICKEL SPECIATION OF FLY-ASH BY PHASE EXTRACTION

Chemical speciation of nickel is necessary for risk assessment of foss il fuel fly ash. We have used a standard coal fly ash in sequential ex traction to show reproducibility and mass balance of nickel phase frac tionation, and applied it to two field samples of oil fly ash. Nine di stinct nickel phases were quantitated by voltammetry and characterized by cumulative extraction plots and dissolution kinetics. They are fur ther correlated with SEM/EDX analysis of the fly ash. This nickel spec iation method reflects the difference in the combustion process in gen erating the two oil fly ash and allows comparison of their nickel dist ribution and bioavailablity.