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Modeling batch leaching behavior of arsenic and selenium from bituminous coal fly ashes
1Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO 65409, United States.
Chemosphere
|September 2, 2011
Summary
Predicting arsenic (As) and selenium (Se) leaching from coal fly ash is crucial. Environmental factors like pH and ash washing significantly impact As and Se release, influencing environmental risk assessment.
Area of Science:
- Environmental Science
- Geochemistry
- Materials Science
Background:
- Assessing the environmental impact of coal fly ash requires accurate prediction of arsenic (As) and selenium (Se) leaching.
- Coal fly ash utilization can lead to the release of potentially toxic elements into the environment.
Purpose of the Study:
- To investigate the influence of pH, leaching time, and ash washing on the batch leaching behavior of As and Se from bituminous coal fly ashes.
- To develop and validate a speciation-based adsorption model for quantifying As and Se leaching parameters.
Main Methods:
- Batch leaching experiments were conducted under varying pH, leaching time, and liquid-to-solid (L/S) ratios.
- A speciation-based adsorption model was employed to analyze leaching data and determine intrinsic parameters like leachable mass and adsorption constants.
- Model predictions were validated against independent experimental data across different conditions.
Main Results:
- As and Se leaching increased with pH beyond minimal ranges.
- Extended leaching time enhanced As release but reduced Se release under alkaline conditions.
- Ash washing increased the availability of As and Se for leaching, while ash aging did not alter adsorption constants.
Conclusions:
- Environmental factors significantly control As and Se leaching from coal fly ash.
- The developed speciation-based adsorption model accurately predicts leaching behavior and quantifies key parameters.
- Understanding these factors is vital for managing the environmental risks associated with coal fly ash disposal and reuse.
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