粘土矿物-铁（铝）（氢）氧化物复合体协同吸附及含重金属复合体解吸附重金属离子的机制研究

A large percent of farmland was contaminated by heavy metals in China, and the contamination has threatened the local ecological environment. The application aims to study mineralogical components of the laterite, krasnozem, yellow soil and dark brown soils etc. by X-Ray diffractometry, Visible-light diffused reflection spectroscopy etc. Based on the careful mineralogical work, we prepare different "Clay mineral-Iron (Aluminum) (Hydrogen) oxide composites" according to the quantitative calculation of mineral phases using the combination of Vis-DRS and XRD techniques. Then the prepared composites are used to adsorb heavy metals, such as As, Cd, Cu, Pb, Zn etc. in different concentration, different pH and different Eh solutions. The mechanism and kinetics are studied by means the change of the concentration in the relict solution. The adsorption site on the mineral is studied by means ESR and XPS etc. Then, the heavy metal contained composited was leached by different solution with different pH, Eh etc. to explore the easy accessible site relate to which mineral. Finally, the solution of how to delay the release of heavy metals is reached. The study starts from the synthetic "soil", and it is easy controlled and carried out. It is of vitally importance to understand the mechanism of adsorption and desorption of heavy metals from contaminated soils, thus the study has both theoretical and economical significance.

我国存在大面积受重金属离子污染的农田，已经严重威胁到当地生态环境的安全。本申请拟针对我国砖红壤、红壤、黄壤和暗棕壤等几种典型的土壤，利用X射线衍射、可见光漫反射光谱术等进行详细的矿物学工作，并在基于Rietveld技术的全谱拟合技术和漫反射光谱定量技术进行矿物的定量计算；在此基础上配制模拟土壤---“粘土-铁（铝）（氢）氧化物复合体”，然后在针对As、Cd、Cu、Pb、Zn等不同离子进行不同条件下（包括浓度、pH、Eh、温度等）的重金属离子的吸附和解吸附研究。利用包括XPS和ESR等技术探索重金属离子在复合体中的矿物吸附专属性差异、吸附位置和吸附机制等，并探索易于被解吸附的重金属离子的在矿物晶格中的位置进行研究，从而进一步探索延缓重金属离子解吸附的措施。该研究针对模拟土壤进行研究，研究的可操作性和可控性强，对于深刻理解土壤重金属离子的吸附和解吸附机制具有重要理论意义，同时也有一定的经济意义

申请人针对Cr3+、Ni2+、Cd2+等重金属离子在黏土、（氢）氧化物及二者复合系统中的吸附和解吸附行为进行了系统的研究。研究结果表明Cr3+、Ni2+、Cd2+等重金属离子在上述系统中的吸附和解吸附行为总体上相似，也略有差异。在室温条件下，Cr3+、和Ni2+以与水分子形成[Me(H2O)6]n+的形式存在于蒙脱石的层间或黏粒的表面，而在受热的过程中重金属离子向蒙脱石晶格中转移，甚至形成新的矿物相。吸附了上述重金属离子的黏土矿物在酸性-中性-碱性条件下的解吸附表明，解吸附的难易程度由酸性-碱性逐渐变难。吸附时重金属离子由表面向结构中迁移的能力受阴阳离子半径比决定，Cr3+和Ni2+离子可以通过置换八面体位置的阳离子而进入八面体位，形成新的黏土矿物。蒙脱石在适当的条件下也发生相转变，可转变为海绿石、伊利石和绿泥石等。其中铁离子的作用尤其显著，它可以促进蒙脱石转变为海绿石或伊利石。