生物浸出系统中Acidithiobacillus ferrooxidans对雄黄表面改性研究

Surface alteration of realgar by Acidithiobacillus ferrooxidans in bioleaching systems

摘要:

【目的】研究Acidithiobacillus ferrooxidans BY-3对雄黄表面改性作用，为进一步研究雄黄的生物炮制技术提供实验基础与理论依据。【方法】在4组生物浸出体系中(每组包含100 mL无亚铁离子的9K培养基和0.500 g雄黄)：第1组无添加；第2组添加4.469 g硫酸亚铁；第3组添加0.100 g硫粉；第4组加入4.469 g硫酸亚铁和0.100 g硫粉。在上述4组中使用A. ferrooxidans BY-3对雄黄进行生物浸出。浸出前后雄黄表面形貌及元素变化，使用扫描电镜(SEM)与能谱仪(EDS)、X-射线衍射(XRD)、拉曼光谱(Raman)、电感耦合等离子体原子发射光谱仪(ICP-AES)进行分析。【结果】4组浸出体系均发现A. ferrooxidans BY-3粘附于雄黄表面以此来产生直接作用。含Fe2+的浸出体系中雄黄表面产生非常明显的变化，含硫的浸出体系中雄黄表面变化不明显；只有Fe2+存在的浸出体系中As/S比率增高，而其余3组浸出体系中As/S比率均明显下降；另外，改性雄黄的表面存在黄钾铁矾、硫、赤铁矿、针铁矿和磁铁矿等，但未检测到砷华(As2O3)与副雄黄(Pararealgar)。【结论】A. ferrooxidans对雄黄改性具有重要作用。Fe2+对雄黄的改性具有促进作用，而硫对雄黄的改性具有抑制作用。雄黄改性前后的物化分析结果证实了生物浸出技术可有效解决传统方法制备雄黄及贮存过程中氧化和光化问题。

Abstract:

[Objective] Surface alteration of realgar by Acidithiobacillus ferrooxidans BY-3 were investigated in this work. The fundamental knowledge derived from this study should provide an experimental and theoretical foundation for further investigation into the biotechnological applications in realgar extraction. [Methods] The bioleaching experiment was divided into four groups (each containing 100 mL of 9K medium without ferrous iron and 0.500 g of realgar): the first group had no additions; the second group had 4.469 g of FeSO4·7H2O added; the third group had 0.100 g of sulfur added; and the fourth group had 4.469 g of FeSO4·7H2O and 0.100 g of sulfur added. A. ferrooxidans BY-3 were used throughout the bioleaching experiments. Before and after bioleaching on the surface alteration and chemical properties of realgar were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy and inductively coupled plasma atomic emission spectroscope (ICP-AES). [Results] All of bioleaching systems shown that A. ferrooxidans BY-3 cells were attached to the surface of the realgar particles. The results suggested that A. ferrooxidans BY-3 cells must be essentially attached so that the direct action occurs. Bioleaching systems in the presence of ferrous iron indicated that surface alteration of realgar was discernible change, whereas bioleaching systems with sulfur was the other way round. Compared to the other three bioleaching systems, there was a higher ratio of As/S by A. ferrooxidans in the medium with ferrous iron as the only substrate. In addition, the mineral composition found in the solid residues after bioleaching comprised jarosite, sulfur, hematite, gothite and magnetit, whereas As2O3 and pararealgar were not observed. [Conclusion] A. ferrooxidans has plays an important role in the alteration of realgar. The effect of ferrous irons could enhance the alteration of realgar by A. ferrooxidans BY-3, while sulfur plays a negative role in the bioleaching of realgar. This study shown that bioleaching technology can effectively solve the problems which oxidation and photochemistry of realgar due to the traditional preparation and the storage of realgar.