Ca2+对酸性硫酸盐环境中次生铁矿物合成的影响

通过摇瓶培养试验,在富铁酸性硫酸盐环境中,探析0、50、100、200或400mg/L Ca2+加入对嗜酸性氧化亚铁硫杆菌(A. ferrooxidans)生物合成次生铁矿物过程的影响.分析了体系pH值、氧化还原电位(ORP)、Fe2+氧化率、总Fe沉淀率以及次生铁矿物矿相等相关指标的变化情况.结果表明,0~24h培养过程中,各体系pH值、ORP、Fe2+氧化率及总Fe沉淀率变化幅度基本一致.24~108h培养过程中,体系中Ca2+加入量越大,Fe2+氧化越迅速,相应总Fe沉淀率相对较高.400mg/L Ca2+的加入使得体系Fe2+在72h氧化完全,总Fe沉淀率在108h达到39.1%.0、50、100或200mg/L Ca2+ 加入的体系在24~84h培养过程中,体系Fe2+氧化速率随着Ca2+加入量逐渐增加而依次升高,并在84h Fe2+氧化完全,且在108h,相应体系总Fe沉淀率分别为27.0%、29.7%、33.9%或36.9%.不同体系所得次生铁矿物均为施氏矿物与黄铁矾的混合物.本研究结果对明晰富铁酸性硫酸盐环境钙离子调控生物成因次生铁矿物合成的影响机理有一定指导意义.

Effect of calcium ions on secondary iron minerals formation in sulfate-rich acidic environment

Secondary iron minerals were synthesized by A. ferrooxidans in the iron- and sulfate-rich acidic environment through shake flask incubation experiment in this study. The effect of 0, 50, 100, 200, or 400mg/L Ca2+ on pH, oxidation reduction potential (ORP), Fe2+ oxidation efficiency, total Fe precipitation efficiency, and secondary iron minerals phase in A. ferrooxidans incubation systems were investigated. The results showed that variation of pH, ORP, Fe2+ oxidation efficiency, and total Fe precipitation efficiency were similar during 0~24h incubation for all treatments. In the period of 24~108h, the more Ca2+ added in systems, the faster Fe2+ oxidation rate and the higher total Fe precipitation efficiency. When Ca2+ was added at 0, 50, 100, and 200mg/L, Fe2+ oxidation efficiency reached 100% at 84h and the corresponding total Fe precipitation efficiency was 27.0%, 29.7%, 33.9%, and 36.9%, respectively. While a complete oxidation was achieved in the presence of 400mg/L Ca2+ at 72h and total Fe precipitation efficiency reached up to 39.1 % at 108h. In this study, secondary iron minerals harvested from different systems were the mixture of schwertmannite and jarosite. The data obtained from this study will offer constructive meanings for understanding the secondary iron minerals bio-synthesis mechanism in the iron- and sulfate-rich acidic environment with Ca2+ existing.