Camacho Lucy Mar, Munson-McGee Stuart H
Department of Chemical Engineering, New Mexico State University, Las Cruces, NM 88003, USA.
J Hazard Mater. 2006 Sep 1;137(1):144-51. doi: 10.1016/j.jhazmat.2005.12.055. Epub 2006 Mar 28.
This study presents observations on the transient leaching behavior of chromium, cadmium, and aluminum that were solidified/stabilized by pozzolanic fly ash. These three metals were selected since they were present in a simulated waste stream generated by an evaporator during plutonium purification and also because the minimum solubility of these metals occurs at significantly different pHs. The transient pH behavior of the toxicity characteristic leaching procedure (TCLP) leachate showed a monotonic increase for all cases, but the equilibrium value was affected by process conditions. The transient leachate concentration behavior showed curves with one or two local maxima for some cases and curves with a monotonic increase for other cases. Data from the leaching experiments was compared to the solubility curves for the hydroxides of each metal since it was assumed that the highly alkaline conditions inside the fly ash waste would cause the metals to precipitate as hydroxides after initially dissolving in the acidic leaching solution. It was found that of the three metals, only cadmium followed the solubility curve for pure hydroxide solutions or for fly ash systems currently reported in the literature.
本研究展示了对由火山灰飞灰固化/稳定化的铬、镉和铝的瞬态浸出行为的观察结果。选择这三种金属是因为它们存在于钚纯化过程中蒸发器产生的模拟废物流中，还因为这些金属的最低溶解度出现在显著不同的pH值下。毒性特性浸出程序（TCLP）渗滤液的瞬态pH行为在所有情况下均呈单调增加，但平衡值受工艺条件影响。瞬态渗滤液浓度行为在某些情况下显示出具有一个或两个局部最大值的曲线，而在其他情况下则显示出单调增加的曲线。由于假定飞灰废物内部的高碱性条件会导致金属在最初溶解于酸性浸出溶液后以氢氧化物形式沉淀，因此将浸出实验数据与每种金属氢氧化物的溶解度曲线进行了比较。结果发现，在这三种金属中，只有镉遵循目前文献中报道的纯氢氧化物溶液或飞灰系统的溶解度曲线。
