TY - JOUR
T1 - Behavior of sulfate ions during biogenic scorodite crystallization from dilute As(III)-bearing acidic waters
AU - Tanaka, Masahito
AU - Sasaki, Keiko
AU - Okibe, Naoko
N1 - Funding Information:
This work was partly supported by JSPS KAKENHI (Grant Number JP24760689 ). M.T. is grateful for the financial assistance provided by the Kyushu University Advanced Graduate Program in Global Strategy for Green Asia.
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/9
Y1 - 2018/9
N2 - This study revealed the importance of SO4 2− ions during biogenic scorodite crystallization via a two-stage As-removal process, using a combination of liquid and solid analyses (chemical digestion, FT-IR, SEM, TG-DTA, particle distribution). The first-stage As-removal was induced by microbial oxidation of Fe2+ and As(III), precipitating SO4 2−-bearing amorphous precursors composed of basic ferric sulfate (MFex(SO4)y(OH)z) and ferric arsenate (FeAsO4·(2 + n)H2O). This was followed by an induction period (a period of constant concentration), where dissolution-recrystallization of unstable amorphous precursors proceeded: Re-dissolved metal ions became locally concentrated on the surface of precursors, which gave the driving force for the second-stage As-removal as secondary layers of crystalline biogenic scorodite (Fe(AsO4)0.94(SO4)0.08·1.69H2O) out of even more dilute and seeded solution. This phase transformation process was also accompanied by continuous dehydration. This two-stage As-removal via SO4 2−-mediated phase transformation was shown to be key to promote biogenic scorodite formation with greater final As-removal from dilute As(III)-bearing solutions.
AB - This study revealed the importance of SO4 2− ions during biogenic scorodite crystallization via a two-stage As-removal process, using a combination of liquid and solid analyses (chemical digestion, FT-IR, SEM, TG-DTA, particle distribution). The first-stage As-removal was induced by microbial oxidation of Fe2+ and As(III), precipitating SO4 2−-bearing amorphous precursors composed of basic ferric sulfate (MFex(SO4)y(OH)z) and ferric arsenate (FeAsO4·(2 + n)H2O). This was followed by an induction period (a period of constant concentration), where dissolution-recrystallization of unstable amorphous precursors proceeded: Re-dissolved metal ions became locally concentrated on the surface of precursors, which gave the driving force for the second-stage As-removal as secondary layers of crystalline biogenic scorodite (Fe(AsO4)0.94(SO4)0.08·1.69H2O) out of even more dilute and seeded solution. This phase transformation process was also accompanied by continuous dehydration. This two-stage As-removal via SO4 2−-mediated phase transformation was shown to be key to promote biogenic scorodite formation with greater final As-removal from dilute As(III)-bearing solutions.
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U2 - 10.1016/j.hydromet.2018.07.018
DO - 10.1016/j.hydromet.2018.07.018
M3 - Article
AN - SCOPUS:85050684163
SN - 0304-386X
VL - 180
SP - 144
EP - 152
JO - Hydrometallurgy
JF - Hydrometallurgy
ER -