锑在赤铁矿晶面的吸附与转化机制研究

The micro-interfacial process and transformation are essential steps controlling the environmental geochemical cycling of antimony. The project focuses on the interfacial process of antimony, and hematite facets are used as environmental micro-surface. Multiple complementary techniques including synchrotron-based methods and quantum chemistry based theoretical simulation are employed to explore the reaction dynamic process and molecular mechanism of antimony adsorption and transformation on hematite facets. The project will elucidate the key role of hematite crystal facets in the antimony adsorption and transformation. The mechanism of the transformation of adsorbed antimony mediated by iron reduction with the coupling effect of hematite facets and iron reducing bacteria will be highlighted. The impact of electron shuttle on antimony transformation in the presence of iron reducing bacteria will be investigated. The research should shed light on the molecular-level mechanisms of antimony reaction on hematite facets with iron reducing bacteria. The results should provide the theoretical basis for further understanding of antimony biogeochemical cycling.

锑的微界面过程与转化是控制其环境地球化学循环的重要过程。本项目将围绕锑的环境界面过程，以赤铁矿特性晶面为环境介质界面，利用以同步辐射为主的多种谱学技术结合第一性原理的理论量化计算研究锑在赤铁矿晶面上吸附与转化的动态过程及分子机制；阐明赤铁矿晶面在锑的吸附与转化中所起的关键作用；重点研究赤铁矿晶面和铁还原菌耦合作用介导的晶面铁还原对吸附态锑转化的调控机制；探讨电子梭在铁还原菌参与下对吸附态锑的价态转化及释放的影响。通过揭示锑-赤铁矿晶面-铁还原菌多界面过程作用机制，为深入理解锑的生物地球化学循环提供理论基础。

锑的微界面过程与转化是控制其环境地球化学循环的重要过程。项目利用同步辐射X射线扩展吸收精细结构（EXAFS）结合密度泛函理论（DFT）计算，研究了锑在赤铁矿晶面上的吸附沉淀过程及其分子机制，发现锑的吸附构型同时依赖于晶面和锑浓度，在高浓度锑条件下形成表面沉淀。基于高分辨透射电镜（HR-TEM）和X射线衍射（XRD）表征，明确了锑在赤铁矿晶面的沉淀结构，表明锑沉淀相晶型与赤铁矿表面结构存在晶格匹配关系。在此基础上，研究了赤铁矿晶面和铁还原菌耦合作用介导的晶面铁还原过程及其对吸附态锑转化的调控机制，发现溶解态锑/铁的摩尔比依赖于赤铁矿晶面。基于分子动力学模拟（MD）探讨了赤铁矿晶面与外膜蛋白的相互作用及电子传递链长度，发现不同晶面上电子传递链长度的差异导致铁还原速率不同，促进吸附态锑的释放。项目研究了锑在赤铁矿晶面的吸附沉淀和脱附释放等环境过程，阐明了赤铁矿晶面在锑吸附与转化中所起的关键作用，为深入理解锑的环境生物地球化学循环并开发污染防治对策提供了理论基础及科学依据。