Abstract：
Immobilization and stabilization of heavy metals (HMs) in sulfidic and metallic tailings are critical to long-term pollution control and sustainable ecological rehabilitation. This study aims to unravel immobilization mechanisms of Pb (Ⅱ) in the neoformed hardpan structure resulting from Acidithiobacillus spp. accelerated bioweathering of sulfides in the presence of silicates. It was found that the bioweathered mineral composite exhibited an elevated Pb (Ⅱ) adsorption capacity compared to that of natural weathered mineral composite. A suit of microspectroscopic techniques such as synchrotron-based X-ray Absorption Spectroscopy (XAS), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and Field-Emission Scanning Electron Microscope (FE-SEM) indicated that secondary Fe-bearing minerals, functional groups, and surface properties in the neoformed hardpan were key factors contributing to Pb (Ⅱ) adsorption and immobilization in ferric-silica microstructures. The underlying mechanisms might involve surface adsorption-complexation, dissolution-precipitation, electrostatic attraction, and ion exchange. Microbial communities within the muscovite groups undergoing bioweathering processes demonstrated distinctive survival strategies and community composition under the prevailing geochemical conditions. This proof of concept regarding Pb (Ⅱ) immobilization in microbial transformed mineral composite would provide the basis for scaling up trials for developing field-feasible methodology to management HMs pollution in sulfidic and metallic tailings in near future.
摘要：
硫化物和金属尾矿中重金属的固定和稳定对于长期污染控制和可持续的生态恢复至关重要。本研究旨在揭示由嗜酸硫杆菌产生的新形成的硬膜结构中Pb（Ⅱ）的固定机制。在硅酸盐存在下加速硫化物的生化作用。结果表明，与自然风化矿物复合材料相比，生化矿物复合材料具有更高的Pb（Ⅱ）吸附能力。一套显微光谱技术，如基于同步加速器的X射线吸收光谱(XAS)，X射线光电子能谱(XPS),傅里叶变换红外光谱(FTIR)和场发射扫描电子显微镜(FE-SEM)表明次生含铁矿物,功能组，新形成的硬盘体的表面性质是影响Pb（Ⅱ）在铁-二氧化硅微结构中吸附和固定的关键因素。潜在的机制可能涉及表面吸附-络合，溶解-沉淀，静电吸引,和离子交换。在当前的地球化学条件下，经历生物化过程的白云母群中的微生物群落表现出独特的生存策略和群落组成。关于在微生物转化的矿物复合材料中固定Pb（Ⅱ）的概念的证明将为扩大试验提供基础，以开发在不久的将来管理硫化物和金属尾矿中HMs污染的现场可行方法。
