氧化亚铁硫杆菌对黄铁矿的氧化作用初探

PRELIMINARY STUDY ON BIO-OXIDATION OF PYRITE BY Acidithiobacillus ferrooxidans

利用自行分离培养的氧化亚铁硫杆菌(A.f菌)为实验菌株,比较了黄铁矿化学氧化和生物氧化过程中溶液铁离子浓度的变化。研究发现,Fe3+对黄铁矿的氧化速率较低,而在细菌的作用下可以不断将Fe2+氧化成Fe3+使得黄铁矿的氧化速率明显加快,因此生物氧化具有更高的效率。经过44 d的氧化之后,利用扫描电镜对氧化后的黄铁矿表面进行了显微观察,发现Fe3+的化学氧化主要集中在化学键较弱的晶棱部位,而在生物氧化的情况下矿物表面充满了密集的溶蚀坑,溶蚀坑的形状与A.f菌的外形非常相近,且规则排列。这说明A.f菌能够吸附到黄铁矿表面,并且这种吸附具有定向排列的特点。

The strain of Acidithiobacillus ferrooxidans was used to study the bio-oxidation mechanism of pyrite in laboratory. A series of experiments were designed to compare differences between chemical oxidation and bio-oxidation of pyrite. Changes in concentrations of total iron in the solution during the experiment were monitored and the change of the pyrite surface was also investigated by means of a scanning electron microscope （SEM）. The results showed that the chemical oxidation velocity of pyrite was very low and the presence of bacteria obviously quickened the leaching of pyrite. The SEM image showed that the chemical oxidation focused on the edge of pyrite crystal. However, a large number of erosion pits with certain orientations appeared on the crystal face of pyrite in the bio-oxidation environment. These erosion pits or microperforations which were arranged regularly are similar to the bacterium in shape and length, indicating that the adherence of cells to mineral surfaces existed during bio-oxidation of pyrite and cell adherence is not randomin direction.