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Article
Coprecipitated arsenate inhibits thermal transformation of 2-line ferrihydrite: Implications for long-term stability of ferrihydrite
Chemosphere
  • Zhaohui Wang, Southern Cross University
  • Dongxue Xiao, Donghua University, Shanghai
  • Richard T Bush, Southern Cross University
  • Jianshe Liu, Donghua University, Shanghai
Document Type
Article
Publication Date
1-1-2015
Peer Reviewed
Peer-Reviewed
Abstract
2-line ferrihydrite, a ubiquitous iron oxy-hydroxide found in natural and engineered systems, is an efficient sink for the toxic metalloids such as arsenic. While much is known of the excellent capacity of ferrihydrite to coprecipitate arsenate, there is little information concerning the long-term stability of arsenate-accumulated ferrihydrite. By thermal treatment methodology, the expedited transformation of ferrihydrite in the presence of coprecipitated arsenate was studied at varying As/Fe ratios (0–0.5) and different heating temperature (40, 300, 450, 600 °C). Pure and transformed minerals were characterized by thermogravimetry (TG), X-ray diffraction (XRD), Electron Spin Resonance (ESR), Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (SEM–EDX) and Fourier Transform Infrared Spectroscopy (FTIR). Arsenate was found to retard the thermal transformation of ferrihydrite. The extents of ferrihydrite transformation to hematite decreased with increasing As/Fe ratios, but increased at a higher heating temperature. It is predicted that the coprecipitated arsenate can stabilize the amorphous iron oxides against the transformation to more crystalline solids. Arsenate concentration appears to play an important role in this predicted long-term stability.
Disciplines
Citation Information

Wang, Z, Xiao, D, Bush, RT & Liu, J 2015, 'Coprecipitated arsenate inhibits thermal transformation of 2-line ferrihydrite: Implications for long-term stability of ferrihydrite', Chemosphere, vol. 122, pp. 88-93.

Published version available from:

http://dx.doi.org/10.1016/j.chemosphere.2014.11.017