Transformation of cadmium-associated schwertmannite and subsequent element repartitioning behaviors

TY - JOUR

T1 - Transformation of cadmium-associated schwertmannite and subsequent element repartitioning behaviors

AU - Fan, Cong

AU - Guo, Chuling

AU - Chen, Meiqin

AU - Huang, Weilin

AU - Wan, Jingjing

AU - Reinfelder, John R.

AU - Li, Xiaofei

AU - Zeng, Yufei

AU - Lu, Guining

AU - Dang, Zhi

N1 - Funding Information: 2015BAD05B05), and the Science and Technology Planning Project of Guangdong Province (No. 2016B020242004). Funding Information: Funding information This study was financially supported by the National Natural Science Foundation of China (Nos. 41330639 and 41720104004), the National Key Technology Support Program (No. Publisher Copyright: © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Schwertmannite is an important sink for cadmium (Cd) in acid mine drainage (AMD) environments and is unstable when environmental conditions change. However, the release and redistribution of Cd during schwertmannite transformation with respect to pre-bound Cd are poorly understood. In this work, the transformation of cadmium-associated schwertmannite and subsequent Cd repartitioning behaviors were investigated. The way of schwertmannite associated with Cd was predominant by absorption, and the diffuse layer model (DLM) showed that Cd 2+ existed as monodentate complexes ≡Fe (1) OCd + and ≡Fe (2) OCd + on schwertmannite surfaces. Kinetics of SO 4 2− release and mineralogical characterization both showed that the mineral transformation rates decreased and more lepidocrocite aggregated with increasing adsorbed Cd levels. The shrinking core model revealed that Fe(II)-induced process would affect mineral dissolution by changing surface reaction-controlled step to internal diffusion-controlled step, and significantly promote the dissolution rate of Cd-adsorbed schwertmannite. Adsorbed Cd blocked the surface sites for later Fe(II) adsorption and the Fe(II)-Fe(III) electron transfer, then resulted in the decelerated transformation and the accumulation of intermediate phase lepidocrocite. The maximum release of aqueous Cd occurred after 1 mM Fe 2+ addition, then over 69% of initial added Cd (aq) re-bound to solid-phase accompanying with mineral transformation, and finally, Cd was mainly associated with the secondary minerals by complexation with surficial OH groups. These findings are useful for developing the strategies for treating Cd contamination in AMD affected areas.

AB - Schwertmannite is an important sink for cadmium (Cd) in acid mine drainage (AMD) environments and is unstable when environmental conditions change. However, the release and redistribution of Cd during schwertmannite transformation with respect to pre-bound Cd are poorly understood. In this work, the transformation of cadmium-associated schwertmannite and subsequent Cd repartitioning behaviors were investigated. The way of schwertmannite associated with Cd was predominant by absorption, and the diffuse layer model (DLM) showed that Cd 2+ existed as monodentate complexes ≡Fe (1) OCd + and ≡Fe (2) OCd + on schwertmannite surfaces. Kinetics of SO 4 2− release and mineralogical characterization both showed that the mineral transformation rates decreased and more lepidocrocite aggregated with increasing adsorbed Cd levels. The shrinking core model revealed that Fe(II)-induced process would affect mineral dissolution by changing surface reaction-controlled step to internal diffusion-controlled step, and significantly promote the dissolution rate of Cd-adsorbed schwertmannite. Adsorbed Cd blocked the surface sites for later Fe(II) adsorption and the Fe(II)-Fe(III) electron transfer, then resulted in the decelerated transformation and the accumulation of intermediate phase lepidocrocite. The maximum release of aqueous Cd occurred after 1 mM Fe 2+ addition, then over 69% of initial added Cd (aq) re-bound to solid-phase accompanying with mineral transformation, and finally, Cd was mainly associated with the secondary minerals by complexation with surficial OH groups. These findings are useful for developing the strategies for treating Cd contamination in AMD affected areas.

KW - Acid mine drainage

KW - Cadmium

KW - Cd redistribution

KW - Schwertmannite

KW - Sulfate release kinetics

KW - Transformation

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U2 - https://doi.org/10.1007/s11356-018-3441-9

DO - https://doi.org/10.1007/s11356-018-3441-9

M3 - Article

C2 - 30411291

SN - 0944-1344

VL - 26

SP - 617

EP - 627

JO - Environmental Science and Pollution Research

JF - Environmental Science and Pollution Research

IS - 1

ER -