硫复铁矿固定锑过程中的结构与界面机制研究

China is the world largest antimony producer and reserve country. Recently, antimony pollution in water caused by long-term mining activities brought serious harm to people’s health. It is found that iron sulfides can long-term immobilize Sb in deep reduction environment. However, the research on micro-mechanism of Sb immobilization by iron sulfates are still lacking. In this work, greigite is used as a carrier to study its immobilization mechanism to antimony through adsorption and co-precipitation process. In adsorption pathway, Fe3S4 and Fe3O4 is synthesized via hydrothermal method, and its antimony adsorption ability will be studied. Furthermore, from the perspective of crystal structure and interface interaction, this study is aimed to reveal the enhance mechanism of Sb adsorption ability by spinel mineral after S isomorphism substitution to O. In co-precipitation pathway, the immobilization effect of Sb by greigite was evaluated by the adjusting the ratio of Fe/Sb. The role of structure incorporation in the process of Sb immobilization by greigite was studied by desorption experiments. The structure incorporation mechanism of Sb in greigite were revealed by XRD refinement and XAFS techniques. Finally, by analyzing the redox reaction in the above process, the electron transfer mechanism in the reduction of Sb(V) by Fe2+, structural sulfide and dissolved sulfide is clarified. The research results will provide a theoretical support for the remediation of Sb pollution in water, and provide a better understanding of the Sb migration and transformation process in environment.

我国是世界上最大的锑（Sb）矿储备和生产国，近年来长期的开采活动造成的水体Sb污染严重危及人民群众身体健康。研究发现，铁硫矿物能将Sb长效稳定的固定至深层地质环境中，然而固定过程中的微观机制研究仍相对欠缺。本项目以典型铁硫矿物硫复铁矿（Fe3S4）为载体，通过吸附和共沉淀法研究其对Sb的固定效率及机制。吸附法中，通过水热法合成Fe3S4，并与Fe3O4对比吸附Sb效率，从结构与界面的角度揭示硫同晶取代氧影响尖晶石吸附能力的机制。共沉淀法中，调控Fe/Sb计量比分析Fe3S4对Sb固定效果，结合解吸实验研究此过程中结构因素的贡献；进而通过XRD结构精修和XAFS揭示Sb在Fe3S4结构的掺杂配位机制。分析上述过程中氧化还原机制，研究Fe2+以及晶格态和溶解态的S2⁻还原Sb(V)过程中的电子传递机制。研究成果将为水体Sb污染治理提供理论依据，并有助于加深对于Sb在环境中迁移转化规律的认识。

我国是世界上最大的锑（Sb）矿储备和生产国，近年来长期的开采活动造成的水体Sb污染严重危及人民群众身体健康。研究发现，铁硫矿物能将Sb长效稳定的固定至深层还原环境中，然而固定过程中的微观机制研究仍相对欠缺。本项目以尖晶石结构铁硫矿物硫复铁矿（Fe3S4）为载体，研究了尖晶石结构中阴离子的取代对Fe3S4吸附 Sb性能的影响及其界面机制，并通过氧化还原作用揭示反应过程中的电子传递机制。此外以正反尖晶石结构的ZnFe2O4和CoFe2O4为吸附载体，通过表面羟基调控，研究界面调控对尖晶石吸附Sb性能的影响机制。.通过对比研究Fe3O4和Fe3S4发现，阴离子S(-II)取代O(-II)后，Fe3S4拥有更小的晶粒尺寸和更大的比表面积。XPS分析表明Fe3S4表面存在丰富的羟基基团，为Sb的吸附提供了更多的活性位点。吸附实验的结果表明Fe3S4对Sb(III)和Sb(V)的最大理论吸附容量分别为178.87和163.52mg/g，均高于Fe3O4。DFT理论计算发现阴离子取代后，Sb配位模式发生变化。Sb(III)和Sb(V)吸附在Fe3O4表面的桥键位点上，而在Fe3S4表面则吸附在更具活性的顶部位点上，且Fe3S4对Sb持有更大的吸附能。.阐明了Fe3S4对 Sb 的氧化还原机制。XPS表征和氧化还原实验探究表明Fe3S4与Sb反应时溶解的铁离子形成铁(氢)氧化物以促进对Sb的去除，同时在Fe3S4表面，Fe(III)将S(-II)氧化为单质硫S(0)，该过程诱导了Fe3S4表面的Fe(III)/Fe(II)循环。.探究了界面调控对尖晶石材料吸附Sb能力的影响。结果表明前驱体水含量的变化不会影响正尖晶石ZnFe2O4和反尖晶石CoFe2O4的晶体结构，但对二者的晶粒尺寸和表面羟基数量影响显著。吸附实验结果表明更小的晶粒尺寸和表面羟基数量越多的ZnFe2O4和CoFe2O4对低浓度Sb的吸附能力增强，通过调整前驱体中水的含量提升了材料的性能，强化了正反尖晶石对Sb的吸附。.研究成果有望为尖晶石在水体Sb污染的治理应用中提供理论指导，并有助于加深Sb在环境中迁移转化规律的认识。