EARTH

[1801-09-05] Formation and stability of biogenic tooeleite during Fe(II) oxidation by Acidithiobacillus ferrooxidans

○Mengxue Zhang¹, Liyuan Chai^1,2, Qingzhu Li ^1,2, Jinqin Yang¹, Qianwen Liu¹, Mengqing Yue¹, Qingwei Wang^1,2, Hui Liu^1,2, Guanshi Zhang¹ (1. Central South University, 2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution)

Chairman：Mayumi Ito（Hokkaido University)

Keywords:arsenic, biogenic tooeleite, Acidithiobacillus ferrooxidans, ferrous oxidation, stability

Tooeleite (Fe₆(AsO₃)₄(SO₄)(OH)₄·4H₂O) is the only known ferric arsenite sulfate mineral and has environmental significance for arsenic remediation. In order to improve both arsenic removal and stability of the final residues, the formation of biogenic tooeleite was investigated in this study. Owing to the microbial oxidation of Fe(II) to Fe(III), Acidithiobacillus ferrooxidans facilitated the formation of tooeleite in Fe(II)-As(III)-SO₄^2- system. The suitable initial Fe(II) concentration and pH value did not affect mineral phase but controlled bacteria growth and As(III) removal. Specifically, the higher removal of As(III) by tooeleite formation can be achieved under pH of 2-3 and Fe(II) concentration of 8.978-1.86 g/L. In addition, the obtained biogenic minerals have better stability than chemical one, it can pass the TCLP and are considered safe for disposal in nonhazardous. This study yields a better understanding of biogenic and natural tooeleite formation, and an assessment of potential application in arsenic remediation of As(III)-rich acid mine drainage.