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Red mud-metakaolin based cementitious material for remediation of arsenic pollution: Stabilization mechanism and leaching behavior of arsenic in lollingite.
- Source :
-
Journal of Environmental Management . Dec2021, Vol. 300, pN.PAG-N.PAG. 1p. - Publication Year :
- 2021
-
Abstract
- The proper treatment of lollingite is of great significance due to its rapid oxidation leading to release of arsenic into the environment. Herein, a green multi-solid waste geopolymer, consisting of red mud, metakaolin, blast furnace slag, and flue gas desulfurization gypsum, was developed. The obtained red mud-metakaolin-based (RMM) geopolymer demonstrated good arsenic retention capability. The results showed that the replacement of SO 4 2− in ettringite with AsO 4 2− via ion exchange, formation of Ca-As and Fe-As precipitates, and physical encapsulation with aluminosilicate gel were the main mechanisms that prevented the release of arsenic. Further dissolution of ettringite in RMM was alleviated by adding a suitable amount of Ca(OH) 2 and controlling the pH of the leachate. TCLP results verified that RMM materials possessed an outstanding ability to stabilize arsenic, with a leaching rate below the permitted value of 5 mg/L for safe disposal. The low leachability of the RMM geopolymers (<0.50 mg/L) is potentially related to the pH buffering capacity of the hydration products at a pH range of 2–5. RMM geopolymers showed a high compressive strength (>15 MPa) and low arsenic leaching concentration (<2.66 mg/L) after 28 days of curing. These results demonstrate the potential of RMM geopolymers to be utilized as an environmentally friendly backfilling cementitious material for sustainable remediation of arsenic pollution. • The evolution pathways of arsenic from lollingite to RMM samples was investigated. • The dissolution of ettringite is correlated with the increase of As leachability. • Arsenic-bearing phases in RMM samples were demonstrated to be stable at pH 2–5. • RMM can be used as environmentally multi-solid waste cementitious material. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 03014797
- Volume :
- 300
- Database :
- Academic Search Index
- Journal :
- Journal of Environmental Management
- Publication Type :
- Academic Journal
- Accession number :
- 152847341
- Full Text :
- https://doi.org/10.1016/j.jenvman.2021.113715