Department of Environmental Engineering, School of Information and Safety Engineering, Zhongnan University of Economics and Law, Wuhan, People's Republic of China.
Department of Environmental Engineering, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, People's Republic of China.
Environ Technol. 2021 Jun;42(15):2325-2334. doi: 10.1080/09593330.2019.1701564. Epub 2019 Dec 18.
The oxidation of Fe by () in acid mine drainage (AMD) is often accompanied by formation of iron hydroxysulfate minerals, such as schwertmannite and jarosite. This study reported that 80 mmol L of Fe could be completely oxidized by LX5 within 48 h, but only 27.7% of the resultant Fe precipitated to form schwertmannite. However, the conversion efficiency to jarosite was much higher (54.5%). The formation of jarosite lasted 120 h, while only 24 h when conversed to schwertmannite. By constructing a cyclic process of 'Cu-reducing coupled with bio-oxidization', the total Fe in AMD could be fully converted into mineral precipitates. The resultant mineral specie could be regulated simply by control the K concentration. Thermodynamically, Fe cannot hydrolyze spontaneously to form schwertmannite due to the positive Gibbs free energy ( = 6.63 kJ mol) of the reaction. However, if Fe were biologically oxidized by , the resultant Fe could spontaneously form schwertmannite because the aforementioned coupling reaction has a negative Gibbs free energy ( = -34.12 kJ mol). Even though Fe itself could hydrolyze to form jarosite spontaneously with = -22.20 kJ mol, the coupling reaction of Fe bio-oxidation followed by Fe hydrolysis in the presence of K could easily promote the formation of jarosite, which exhibited a great negative Gibbs energy ( = -67.45 kJ mol).
在酸性矿山排水 (AMD) 中，（）氧化 Fe 通常伴随着铁羟基硫酸盐矿物的形成，如纤铁矿和黄钾铁矾。本研究表明，在 48 小时内，LX5 可以完全氧化 80mmol/L 的 Fe，但只有 27.7%的生成的 Fe 沉淀形成纤铁矿。然而，转化为黄钾铁矾的效率要高得多（54.5%）。黄钾铁矾的形成持续 120 小时，而转化为纤铁矿仅需 24 小时。通过构建“Cu 还原与生物氧化偶联”的循环过程，可以将 AMD 中的总 Fe 完全转化为矿物沉淀物。通过控制 K 浓度，可以简单地调节生成的矿物种类。从热力学角度来看，由于反应的吉布斯自由能（ = 6.63 kJ/mol）为正值，Fe 不能自发水解形成纤铁矿。然而，如果 Fe 被生物氧化为 ，则生成的 Fe 可以自发形成纤铁矿，因为上述偶联反应具有负吉布斯自由能（ = -34.12 kJ/mol）。尽管 Fe 本身可以自发水解形成黄钾铁矾，其吉布斯自由能（ = -22.20 kJ/mol）为负值，但在 K 存在下，Fe 生物氧化随后进行 Fe 水解的偶联反应很容易促进黄钾铁矾的形成，其吉布斯自由能（ = -67.45 kJ/mol）为负值。
