镁离子对氧化亚铁硫杆菌生物合成次生铁矿物的影响

通过摇瓶实验,在Mg2+分别为48,4.8mg/L,其他元素组成与9K液体培养基一致的体系中,采用氧化亚铁硫杆菌A. ferrooxidans催化合成次生铁矿物.考察了Mg2+含量对生物合成次生铁矿物体系pH值、氧化还原电位(ORP)、Fe2+氧化率、总Fe沉淀率、次生铁矿物矿相及矿物晶体尺寸的影响.结果表明,经过48h培养,Mg2+浓度为48,4.8mg/L生物成矿体系pH值分别从原来的2.50降低至2.30,2.19,ORP分别从初始259mV增加至269mV,276mV.两体系Fe2+氧化率培养至第48h均达到100%,然而两体系总Fe沉淀率及矿物形态及却不尽相同.Mg2+浓度为48mg/L生物成矿体系,总Fe沉淀率为23.7%,次生矿物紧密粘附于三角瓶底部.而Mg2+浓度为4.8mg/L生物成矿体系,总Fe沉淀率达到32.2%,次生矿物却均匀分散于溶液中.两体系合成次生铁矿物均为黄铁矾与施氏矿物共存的混合物,Mg2+含量4.8mg/L体系合成黄铁矾单个晶体长度(~1.60μm)约为Mg2+含量48mg/L体系的1.2倍.

Effect of magnesium ions on the formation of secondary iron minerals facilitated by Acidithiobacillus ferrooxidans

In this study, secondary iron minerals was synthesized by A. ferrooxidans in the solution with 48 or 4.8mg/L magnesium ions and other elements in consistent with 9K liquid medium. pH, oxidation reduction potential, Fe2+ oxidation rate, total Fe precipitation rate, secondary iron minerals phase and mineral crystal size in two systems were investigated. pH in the treatment with 48or 4.8mg/L of magnesium ion decreased from 2.50at 0h to 2.30or 2.19at 48h, whereas ORP increased from 259mV to 269mV or 276mV, respectively. Ferrous ions could be completely oxidized by A. ferrooxidans within 48h, secondary iron minerals morphology and total Fe precipitation rate, however, were different in two systems. With 48mg/L of magnesium ion, the total Fe precipitation rate was 23.7% after 48h reaction, while it rose to 32.2% in the presence of 4.8mg/L of magnesium ion. The precipitates formed in the two treatments were a mixture of jarosite and schwertmannite. However, unlike the precipitates closely adhered to the flask bottom in the treatment with 48mg/L of magnesium ion, the precipitates formed in the presence of 4.8mg/L of magnesium ion uniformly dispersed in the solution, and the crystal length (~1.60μm) of jarosite was 1.2times larger than it in the former.