Estimating the Potential Release of Thallium from Fly Ash Under Different Environmental Scenarios
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Date
2013-05
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The Ohio State University
Abstract
To date, minimal research has been conducted to determine the intrinsic characteristics of fly ash that control the leaching of thallium. The liquid-solid (L/S) partitioning of thallium leached from Cardinal fly ash as a function of pH was examined under laboratory conditions using parallel batch extraction. The aqueous phase concentration of thallium decreased with decreasing pH. The results suggest that the following three mechanisms facilitate thallium leaching from fly ash:(1) dissolution of thallium salts attached to fly ash surface sites, (2) desorption of thallium from fly ash surface sites, and (3) thallium release due to underlying surface dissolution. X-ray absorption spectroscopy (XAS) was used in order to determine the dominant mechanism facilitating the leaching of thallium. The XAS results were inconclusive and the dominant mechanism could not be determined. The L/S partitioning of thallium as a function of time was also examined under 1-D mass-transfer controlled leaching. The results suggest that the leaching of thallium from fly ash is not a simple diffusion process.
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Keywords
Thallium, Leaching Environmental Assessment Framework, X-Ray Absorption Spectroscopy, Fly Ash, environmental scenarios