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- Title
Immobilization of heavy metals from MSWI fly ash using a novel cementitious material: Long-term leaching behavior and mechanism.
- Authors
Deng, Wei; Fu, Pingfeng; Li, Jia; Wang, Xiaoli; Zhang, Yuliang
- Abstract
Little attention has been paid to the long-term leaching hazard of heavy metals in municipal solid waste incineration (MSWI) fly ashes solidified by phosphate-containing cementitious material. Herein, long-term leaching behaviors of Pb, Zn, and Cd in MSWI fly ashes solidified by a novel cementitious material (MSCM) containing phosphoric acid sludge were investigated. During 120-days acid rain leaching test, cumulative leaching concentrations of Pb, Zn, and Cd in MSCM-solidified fly ash increased to 50.4, 3694.0, and 24.0 μg/L, achieving reductions of 51.5, 27.4, and 23.1%, respectively, compared to those in ordinary Portland cement (OPC) solidified fly ash. During 300-years leaching simulation, leaching concentrations of Pb, Zn, and Cd continuously increased, yet remained lower in MSCM-solidified fly ash compared to OPC-solidified fly ash. Mechanism studies revealed that the MSCM promoted significant formation of R10(PO4)6(OH)2 (R2+: Pb2+, Zn2+, and Cd2+) and resulted in high contents of C–S–H, AFt, and Friedel's salt in fly ashes. In contrast, transformation from R–O–Al–O–R to R–O–Al–O–Si bonds (R: Pb and Zn) resulted in higher release of Pb2+ and Zn2+ in OPC-solidified fly ash. This study demonstrated that the MSWI fly ashes solidified by phosphate-containing material could achieve superior long-term environmental safety owing to its complex leaching control processes.
- Subjects
FLY ash; INCINERATION; HEAVY metals; SOLID waste; ENVIRONMENTAL security; LEACHING; ANALYSIS of heavy metals
- Publication
Journal of Material Cycles & Waste Management, 2024, Vol 26, Issue 3, p1804
- ISSN
1438-4957
- Publication type
Article
- DOI
10.1007/s10163-024-01942-6