Thermal decomposition of the vivianite arsenates—implications for soil remediation |
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Authors: | Ray L. Frost Matt L. WeierWayde Martens J. Theo KloproggeZhe Ding |
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Affiliation: | Centre for Instrumental and Developmental Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, Qld 4001, Australia |
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Abstract: | The presence of arsenate compounds in soils and mineral dump leachates is common. One potential method for the removal of the arsenates from soils is through thermal treatment. High-resolution thermogravimetric analysis has been used to follow this thermal decomposition of selected vivianite arsenates. This decomposition occurs as a series of steps. The first two steps involve dehydration with 6 mol of water lost in the first step and two in the second. The third major weight loss step occurs in the 750-800 °C temperature range with de-arsenation. The application of infrared emission spectroscopy confirms the loss of water by around 250 °C and the loss of arsenic as arsenic pentoxide is observed by the loss of AsO stretching bands at around 826 cm−1. Thermal activation of arsenic contaminated soils may provide a method of decontamination. |
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Keywords: | Vivianite Iron Phosphate Thermal analysis Infrared emission spectroscopy |
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