The formation of biogenic jarosite by AcidithiobacUlus ferrooxidans in the presence of crystal seed and potassium | 晶种和钾离子促进生物成因黄铁矾形成的作用机制

Chinese. 采用摇瓶试验，研究了晶种（先前合成的黄铁矾）和钾离子在生物成因黄铁矾合成中的作用及其影响机制。结果表明：2种材料均能明显促进Fe3＋水解形成黄铁矾沉淀。在起始Fe2＋浓度为160mmol・L. 1，晶种和K＋最大添加量分别为10g和80mmol・L. 1时，经过72h反应后，溶液中的总铁（TFe）分别比对照多沉淀了23和33mmol・L. 1。K＋在黄铁矾形成中起阳离子诱导作用，品种起晶核刺激作用。K＋的促进作用主要发生在24～48h，但在低Fe3＋浓度下作用有限；而晶种可以减少低Fe3＋浓度对黄铁矾形成的不利影响。结论：品种和K＋共同作用不仅能够明显促进Fe2＋的水解沉淀，而且绝大部分反应发生在0―24h．极大地缩短了反应时间。

English. The effects of crystal seed, i. e. , already-formed jarosite, and K＋ on the formation of fresh jarosite facilitated by Acidithiobacillus ferrooxidans in 160 mmol・L. 1 FeSO4 solutions were investigated through batch experiments. Results showed that both the rate and extent of Fe3＋ precipitation increased with the increase of the amount of the two materials added. Compared to the control without addition of crystal seed and K＋,the treatments with 10 g seed and 80 mmol・L . 1 K＋ increased the removal of total iron by 23 and 33 mmol・ L. 1 , respectively. The seed contributed to the precipitation of Fe3＋ by providing a solid surface for the growth of fresh jarosite as well as eliminating the inhibition effect of low Fe3＋ concentration, while K＋ acted as a jarosite-directing cation which improved the formation of jarosite mainly at 24-48 h when there was a high Fe3＋ concentration. The combined application of already- formed jarosite seed and K＋ not only increased the extent of the precipitation reaction, but also accelerated the initial iron precipitation rate. A significant amount of jarosite formed at 0-24 h in the simultaneous presence of jarosite seed and K＋.