101. The effect of thermal treatment on the transformation and transportation of arsenic and cadmium in soil.
- Author
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Zhou F, Guo M, Zhao N, Xu Q, Zhao T, Zhang W, and Qiu R
- Subjects
- Environmental Restoration and Remediation methods, Hot Temperature, Cadmium chemistry, Cadmium analysis, Soil Pollutants analysis, Soil Pollutants chemistry, Arsenic analysis, Arsenic chemistry, Soil chemistry
- Abstract
Thermal treatment can effectively decontaminate soils but alter their properties. Previous research mainly focused on volatile organic compounds and metals, i.e. Hg, neglecting non-volatile metal(loid)s. This study aimed to investigate Cd and As transformation during aerobic and anaerobic calcination. The results showed that both aerobic and anaerobic calcination increased soil pH by reducing soil organic matter (SOM) content, which also influenced the cation exchange capacity (CEC) and the leaching behavior of Cd and As in the soil. The total concentrations of Cd and As in the calcined soils varied depending on the calcination temperature and atmosphere. When the aerobic calcination temperature exceeded 700 °C, Cd volatilized as CdCl
2 , while anaerobic calcination at relatively low temperatures (600 °C) involved reductive reactions, resulting in the formation of metallic Cd with a lower boiling point. Similarly, As volatilized at 800 °C aerobically and 600 °C anaerobically. The formation of As-based minerals, particularly Ca3 (AsO4 )2 , hindered its gasification, whereas anaerobic calcination promoted volatilization efficiency through the generation of C-As(III) based gaseous components with lower boiling points. Contrasting trends were observed in the TCLP-extractable Cd and As contents of the calcined soils. Over 70% of TCLP-extractable Cd contents were suppressed after thermal treatment, attributed to the elevated pH and reduced CEC of the soil, as well as volatilization. However, TCLP-extractable As contents increased with elevated temperatures, likely due to the desorption of AsO4 3- and re-adsorption of gaseous As2 O3 during cooling. These findings have implications for assessing the environmental impact of thermal treatment and provide insights for remediation strategies concerning Cd and As-contaminated soils., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)- Published
- 2024
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