Aqueous Behavior of Chromium in Coal Fly Ash
- Dhanpat Rai * and
- Roger W. Szelmeczka
Studies were conducted to determine the dominant reactions controlling aqueous Cr concentrations in four coal fly ashes. The fly ashes were adjusted to a range of pH values between 2 and 10. Chromium was found to be present in these aqueous and solid phases as Cr(III). Because of the amorphous character of the important Cr(III) compounds [(Fe,Cr)(OH)3 and Cr(OH)3] and because of the very low total Cr content (<0.025%) of the fly ashes, it was not possible to identify directly the Cr-containing compounds. However, an indirect technique for identifying Cr compounds, comparison of observed activities with those in equilibrium with known solid phases, and with those obtained after spiking the coal ash suspensions with Cr(III), suggest that Cr concentrations are controlled by (Fe,Cr)(OH)3(am) at low pH and by (Fe,Cr)(OH)3(am) and/or Cr(OH)3(am) at pH values greater than ∼5.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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