中度嗜热微生物作用下黄铜矿表面改性

Surface modification of chalcopyrite in presence of moderately thermophilic bacteria

通过分析黄铜矿表面接触角、Zeta电位和表面形貌变化,研究嗜热硫氧化硫杆菌(Sulfobacillus thermosulfidooxidans,S.t菌)和氧化亚铁钩端螺旋菌(Leptospirillum ferrooxidans,L.f菌)对黄铜矿表面性质的影响。结果表明,细菌培养基(9K培养基)对黄铜矿表面性质无明显影响,接触角稳定在黄铜矿表面接触角48°左右。两种细菌对黄铜矿表面性质影响规律相似,采用细菌摇瓶浸出时,振动条件下,矿物表面的亲水性随浸出过程逐渐增强;而在静置细菌浸出过程中,浸出初期黄铜矿表面疏水性变强,之后随浸出时间的延长黄铜矿表面的亲水性增强,推测可能是由于浸出前期黄铜矿表面生成疏水硫化物和元素硫,后期被进一步氧化分解。不同细菌作用后,黄铜矿的等电点接近细菌的等电点,说明两种细菌均能有效地吸附在黄铜矿表面。通过原子力显微镜(AFM)观察发现,黄铜矿经细菌浸出后,表面不同程度地被腐蚀,并且随着浸出时间的延长,表面腐蚀程度加剧,其中S.t菌对黄铜矿的腐蚀作用较L.f菌更强。

The effects of Sulfobacillus thermosulfidooxidans and Leptospirillum ferrooxidans on the surface properties of chalcopyrite were investigated by analyzing the contact angle, Zeta-potential and surface morphology changes. The results show that the culture medium （9K medium） has no distinct effect on the chalcopyrite surface properties, the contact angles keep at about 48°. The hydrophilcity of chalcopyrite surface increases during bioleaching in shake flask under vibration condition, while in bioleaching under stationary condition, the surface hydrophobicity of chalcopyrite increases in the initial stage as the formation of hydrophobic substances like elemental sulphur and secondary Cu-Fe-S intermediate species, and then decreases as further oxidation. The isoelectric point of chalcopyrite in the presence of bacterium shifts towards the bacteria’s isoelectric point correspondingly, indicating that bacteria adsorb on the surface of chalcopyrite effectively. The erosion degree of chalcopyrite surface increases with bioleaching through observing atomic force microscope （AFM） images, and the corrosion rate in the presence of Sulfobacillus thermosulfidooxidans is higher than that in the presence of Leptospirillum ferrooxidans.