Xiong Huixin, Peng Suning, Zhang Bailin
College of Environmental Science and Engineering, Yangzhou University, Yangzhou, Jiangsu, 225127, People's Republic of China.
Environ Sci Pollut Res Int. 2022 Oct;29(50):75566-75574. doi: 10.1007/s11356-022-21084-2. Epub 2022 Jun 3.
Akaganéite (β-FeOOH) with a tunnel structure typically occupied by chloride can undergo anion-exchange reactions in aqueous solutions for pollutant removal. In this work, we studied bioformation of akaganéite in FeCl solutions with Acidithiobacillus ferrooxidans cells at pH 2.9, during 36-h incubation. The obtained products were analyzed and characterized by XRD, FTIR, EDS, FETEM, and HRTEM. Results showed that in acidic media with pH 2.9, the cells facilitated ferrous biooxidation and ferric precipitation. The resulting ferric precipitates were identified as polycrystalline akaganéite powders and had a morphology of nanospindles with a length of less 100 nm. The correlatively chemical formula for akaganéite collected at 1 h was reckoned as FeO(OH)(Cl) with 6.6% Cl. It was observed that ferric precipitates along exterior structures of cells or their extruded organic polymers grew and assembled into cellular shape. The evolved cell-shape akaganéite assemblages were twice of cells (about 2 µm) in size. These results could contribute to understanding of laboratorial bioformation of akaganéite and its biomineralization in acidic environments and promoting its practical applications.
具有隧道结构且通常被氯离子占据的针铁矿（β-FeOOH）可在水溶液中发生阴离子交换反应以去除污染物。在本研究中，我们研究了在pH 2.9的条件下，嗜酸氧化亚铁硫杆菌细胞在FeCl溶液中培养36小时过程中针铁矿的生物形成。通过X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、能谱分析（EDS）、场发射透射电子显微镜（FETEM）和高分辨率透射电子显微镜（HRTEM）对所得产物进行了分析和表征。结果表明，在pH 2.9的酸性介质中，细胞促进了亚铁的生物氧化和铁的沉淀。所得的铁沉淀物被鉴定为多晶针铁矿粉末，其形态为长度小于100 nm的纳米纺锤体。在1小时时收集的针铁矿的相关化学式估计为FeO(OH)(Cl)，含氯量为6.6%。观察到沿细胞外部结构或其分泌的有机聚合物的铁沉淀物生长并组装成细胞形状。演化形成的细胞形状的针铁矿聚集体大小是细胞（约2 µm）的两倍。这些结果有助于理解针铁矿在实验室中的生物形成及其在酸性环境中的生物矿化作用，并促进其实际应用。
