Liu Ronghui, Tian Zhuang, Cheng Haina, Zhou Hongbo, Wang Yuguang
School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, Hunan, China.
Key Laboratory of Biohydrometallurgy of Ministry of Education, Changsha, 410083, Hunan, China.
Environ Sci Pollut Res Int. 2021 Feb 25. doi: 10.1007/s11356-021-13027-0.
Metal-containing plant incineration ash (MPIA), which was the by-product for metal extraction from soil by phytoextraction process, contains various kinds of heavy metal that have post potential risk to the environment. This study investigated the leaching efficiency and metal redistribution of MPIA using organic acid as leaching agents. The MPIA before and after leaching was characterized using the toxicity characteristic leaching procedure (TCPL) test, X-ray diffraction, scanning electronic microscopy, and Fourier transform infrared spectroscopy. The results showed that all tested organic acids resulted in the dissolution of metals, especially 1 mol L citric acid leaching achieved for the dissolution efficiency of 84% Mn, 87.01% Cd, 66.97% Zn, and 55.83% Pb. During leaching progress, the synergetic of chelation and acid soluble action accelerated the metal release and redistribution, and the dissolution of Mn, Zn, Pb, and Cd fit best to the shrinking core model of chemical control. Meanwhile, the leaching residue reached the regulatory standard. Thus, organic acid leaching may be a feasible strategy for detoxification of MPIA.
含金属植物焚烧灰（MPIA）是植物提取法从土壤中提取金属的副产品，含有多种重金属，对环境具有潜在风险。本研究以有机酸为浸出剂，研究了MPIA的浸出效率和金属再分布情况。采用毒性特性浸出程序（TCLP）试验、X射线衍射、扫描电子显微镜和傅里叶变换红外光谱对浸出前后的MPIA进行了表征。结果表明，所有测试的有机酸都导致了金属的溶解，尤其是1 mol/L柠檬酸浸出时，Mn的溶解效率达到84%，Cd为87.01%，Zn为66.97%，Pb为55.83%。在浸出过程中，螯合作用和酸溶作用的协同作用加速了金属的释放和再分布，Mn、Zn、Pb和Cd的溶解最符合化学控制的收缩核模型。同时，浸出残渣达到了监管标准。因此，有机酸浸出可能是MPIA解毒的一种可行策略。
