Stabilization of heavy metals in MSWI fly ash using silica fume

Xinying Li, Quanyuan Chen, Yasu Zhou, Mark Tyrer, Yang Yu

Research output: Contribution to journalArticlepeer-review

85 Citations (Scopus)


The objective of this work was to investigate the feasibility and effectiveness of silica fume on stabilizing heavy metals in municipal solid waste incineration (MSWI) fly ash. In addition to compressive strength measurements, hydrated pastes were characterized by X-ray diffraction (XRD), thermal-analyses (DTA/TG), and MAS NMR (27Al and 29Si) techniques. It was found that silica fume additions could effectively reduce the leaching of toxic heavy metals. At the addition of 20% silica fume, leaching concentrations for Cu, Pb and Zn of the hydrated paste cured for 7days decreased from 0.32mg/L to 0.05mg/L, 40.99mg/L to 4.40mg/L, and 6.96mg/L to 0.21mg/L compared with the MSWI fly ash. After curing for 135days, Cd and Pb in the leachates were not detected, while Cu and Zn concentrations decreased to 0.02mg/L and 0.03mg/L. The speciation of Pb and Cd by the modified version of the European Community Bureau of Reference (BCR) extractions showed that these metals converted into more stable state in hydrated pastes of MSWI fly ash in the presence of silica fume. Although exchangeable and weak-acid soluble fractions of Cu and Zn increased with hydration time, silica fume addition of 10% can satisfy the requirement of detoxification for heavy metals investigated in terms of the identification standard of hazardous waste of China.

Original languageEnglish
Pages (from-to)2494-2504
Number of pages11
JournalWaste Management
Issue number12
Early online date29 Sep 2014
Publication statusPublished - Dec 2014
Externally publishedYes

Bibliographical note

NOTICE: this is the author’s version of a work that was accepted for publication in Waste Management. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Waste Management, [34,] [12], (2014)]

© 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International


  • Fly ash
  • Municipal solid waste
  • Pozzolanic reaction
  • Silica fume
  • Stabilization

ASJC Scopus subject areas

  • Waste Management and Disposal
  • Medicine(all)


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