Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO 65409, United States.
Chemosphere. 2011 Nov;85(8):1368-74. doi: 10.1016/j.chemosphere.2011.08.002. Epub 2011 Aug 30.
Correctly predicting the leaching potential of arsenic (As) and selenium (Se) is critical for assessing the environmental impact of coal fly ash. This study investigated the impacts of several key environmental factors, including pH, leaching time, and ash washing on the batch leaching behavior of As and Se from bituminous coal fly ashes. The experimental results demonstrated that As and Se leaching from fly ash increased beyond the minimal leaching pH ranges. Increasing leaching time increased As leaching but decreased Se leaching in the alkaline pH condition. A speciation-based adsorption model was used to quantify the batch leaching data, and determine the intrinsic leaching parameters including the total batch leachable mass and the adsorption constant of As or Se. The modeling approach was validated by correctly predicting the independent batch leaching data in a broad pH range and a different L/S condition. Experimental and modeling results also demonstrated that ash washing and ash aging (longer leaching time) did not change the adsorption constants of As and Se on the ash surface. However, ash washing could increase the availability of As and Se for leaching.
正确预测砷（As）和硒（Se）的浸出潜力对于评估粉煤灰的环境影响至关重要。本研究探讨了几个关键环境因素的影响，包括 pH 值、浸出时间和粉煤灰洗涤对烟煤粉煤灰中 As 和 Se 的批量浸出行为的影响。实验结果表明，粉煤灰中的 As 和 Se 浸出量超过了最小浸出 pH 值范围。随着浸出时间的增加，碱性 pH 条件下的 As 浸出量增加，但 Se 浸出量减少。基于形态的吸附模型用于定量批量浸出数据，并确定内在浸出参数，包括总批量可浸出质量和 As 或 Se 的吸附常数。该建模方法通过正确预测宽 pH 范围和不同 L/S 条件下的独立批量浸出数据得到验证。实验和建模结果还表明，粉煤灰洗涤和粉煤灰老化（更长的浸出时间）不会改变粉煤灰表面对 As 和 Se 的吸附常数。然而，粉煤灰洗涤可以增加 As 和 Se 的浸出可利用性。
