Insights into the mechanisms of mercury sorption onto aluminum based drinking water treatment residuals

[Display omitted] •Mercury sorption by Al-WTRs involves electrostatic forces and chemisorption.•Hg forms bonds with oxygen and sulfur atoms of Al-WTR’s organic ligands.•Mercury is incorporated into the residual fraction to form stable complexes.•Mercury binds mainly to SiOx species in the residual f...

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Bibliographic Details
Published in:Journal of hazardous materials 2016-04, Vol.307, p.184-192
Main Authors: Deliz Quiñones, Katherine, Hovsepyan, Anna, Oppong-Anane​, Akua, Bonzongo, Jean-Claude J.
Format: Article
Language:English
Subjects:
Aluminum
Contamination
Drinking water
Immobilization
Mercury
Mercury (metal)
Solid phase analysis
Sorption
Sorption mechanisms
WTR
X-ray photoelectron spectroscopy
X-rays
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Summary:[Display omitted] •Mercury sorption by Al-WTRs involves electrostatic forces and chemisorption.•Hg forms bonds with oxygen and sulfur atoms of Al-WTR’s organic ligands.•Mercury is incorporated into the residual fraction to form stable complexes.•Mercury binds mainly to SiOx species in the residual fraction. Several studies have demonstrated the ability of drinking water treatment residuals (WTRs) to efficiently sorb metal cations from aqueous solutions. Reported results have stimulated interest on the potential use of WTRs as sorbent for metal removal from contaminated aqueous effluents as well as in metal immobilization in contaminated soils. However, knowledge on mechanisms of metal sorption by WTRs remains very limited and data on the long-term stability of formed metal–WTR complexes as a function of changing key environmental parameters are lacking. In this study, chemical selective sequential extraction (SSE), scanning electron microscopy combined with X-ray energy dispersive spectrometer (SEM-EDS), and X-ray photoelectron spectroscopy (XPS) were used to gain insight into the different mechanisms of mercury (Hg) binding to aluminum based WTR (Al-WTRs). Results from sorption studies show that a significant portion of Hg becomes incorporated in the operationally defined residual fraction of Al-WTRs, and therefore, not prone to dissolution and mobility. The results of solid phase analyses suggested that Hg immobilization by Al-WTR occurs largely through its binding to oxygen donor atoms of mineral ligands driven by a combination of electrostatic forces and covalent bonding.
ISSN:0304-3894
1873-3336
DOI:10.1016/j.jhazmat.2016.01.001