Extraction of trace elements in coal fly ash and subsequent speciation by high-performance liquid chromatography with inductively coupled plasma mass spectrometry. Plenary lecture

Abstract

The speciation of arsenic in coal fly ash is reported. The amounts of As^III and As^V were found and these values, released into water from coal fly ash, are dependent on the pH of extracted solution and the type of coal fly ash (e.g., location collected, type of coal and combustion conditions). A small amount of arsenic conversion from As^III to As^V was found, especially from the lower pH extractions. The arsenic conversion may be caused by co-existing high oxidation states elements in the extracted solution, and may be promoted by the grinding process. Oxygen from the atmosphere was found to be an unlikely source for the arsenic conversion. A preliminary investigation for speciation of vanadium and nickel in coal fly ash shows that V^V, V^IV and Ni^II exist in the extracted solutions. This extraction–speciation approach can provide some basic information for predicting the hydrolytic behaviour of trace elements in the coal fly ash–water systems and can be extended to the speciation of other elements.