矿物表面诱导重金属沉淀的分子地球化学机制及环境修复价值

项目名称： 矿物表面诱导重金属沉淀的分子地球化学机制及环境修复价值

项目编号： No.41473084

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 地质学

项目作者： 李伟

作者单位： 南京大学

项目金额： 88万元

中文摘要： 重金属在与环境矿物表面接触时发生的诱导沉淀效应是天然多介质环境中普遍存在的一种地球化学反应。这一过程对于锁定土壤有毒重金属，降低重金属活性和生物可利用性具有重要意义，但是这一反应的地球化学机制研究中存在若干尚待查明的问题：1）反应产物的快速鉴别与化学表征；2）沉淀产生的动力学过程；3）沉淀反应与矿物表面属性的内在耦合关系。为了深入研究这一基础地球化学反应，本项目将采用先进的同步辐射技术手段，并辅以固体核磁共振、高分辨电子显微镜和原子力显微镜等手段表征表面沉淀的物理、化学属性及其与矿物表面活性之间的耦合关系；拟开发时间分辨X射线吸收精细光谱技术（Quick-EXAFS）来研究重金属在矿物-水溶解界面的原位反应动力学过程；探索粘土矿物填埋技术在修复重金属污染土壤的可行性以及阐明其该过程中的重金属锁定机制。

中文关键词： 重金属污染；矿物表面；X射线吸收光谱；反应动力学

英文摘要： Mineral surface induced metal precipitation is a prevalent geochemical reaction occurring at mineral-water interface. This reaction also has strong environmental implications, because it is a major pathway for heavy metals to be sequestered (or removed) from contaminated environment, which significantly reduces heavy metals activity and bioavailability. But a number of important issues in terms of the reaction mechanism remain unclear: 1) rapid identification and chemical characterization of the reaction product; 2) formation kinetics of the metal precipitates; 3) relationship between the precipitation reaction and the intrinsic properties of the mineral surface. In order to fundamentally understand the basis of geochemical reactions, we proposed an experimental program, which will employ advanced synchrotron radiation techniques, supplemented by solid state NMR, high-resolution transmission electron microscopy, and atomic force microscopy, to address these issues. A very novel idea in this proposed research is that we plan to develop time-resolved X -ray absorption fine spectroscopy (Quick-EXAFS) to in situ monitor the reaction kinetic of heavy metals sorption mechanism at mineral-water interface. Additionally, we plan to explore the feasibility of amending clay minerals to remediate heavy metal contaminated soil and address the underlying metal sequestration mechanisms.

英文关键词： heavy metals;mineral surface chemistry;EXAFS;reaction kinetics