天然褐铁矿的光电化学响应及对嗜酸性氧化亚铁硫杆菌生长的影响

通过对比实验研究了天然褐铁矿对嗜酸性氧化亚铁硫杆菌(A.f.)生长的影响.利用X射线衍射分析(XRD)确定实验中所用天然褐铁矿样品的主要物相为针铁矿和赤铁矿,紫外-可见漫反射光谱(UV-Vis DRS)和不同光照条件下的时间电流曲线表明天然褐铁矿在可见光下具有良好的光电化学响应.采用"H"型装置进行双室体系反应,设置了3组对比实验,结果显示A.f.在有光催化电子传入情况下生长较好,在96 h内细胞浓度增加了12倍,3组实验中Fe2+浓度的变化规律与A.f.的生长趋势相对应.由此揭示了天然褐铁矿促进A.f.生长的机制为:在光照作用下天然褐铁矿能产生光生电子-空穴对,光生空穴被电子供体(抗坏血酸)捕获,分离出的光生电子传入阴极室能够将Fe3+还原为Fe2+,实现Fe2+的电化学再生,提供充足的电子能量来源,促进细菌生长.

Photoelectrochemical response of natural limonite and its effect on the growth of Acidithiobacillus ferrooxidans

The effect of natural limonite on the growth of Acidithiabacillus ferrooxidans was studied through control experiments. The main phases of the natural limonite sample used in the experiments were identified as the mixture of goethite and hematite by X-ray diffraction analysis (XRD). UV-vis diffuse reflectance spectra and time-current curve under different irradiation conditions indicate that natural limonite has a good photoelectrochemical response. Dual-chambered system reactions were carried out with an "H"-type device. The results of three sets of control experiments show that A. f. grows better when external electrons are supplied by the photocatalysis of semiconductor minerals. Within 96 h, the cell density increases by 12 times. The variation of Fe~(2+) concentration is consistent with the growth curve of A. f. in control experiments, which reveals that natural limonite indirectly improves the growth of A. f. The mechanism can be interpreted as follows: Natural limonite can produce photo-generated electron-hole pairs under the visible light. The photo-generated hole is captured by the electron donor of ascorbic acid, while the separated photo-generated electrons transfer into cathode chamber to reduce Fe~(3+) to Fe~(2+) . The process achieves the electrochemical regeneration of Fe~(2+), which provides adequate electron energy for the growth of A.f.