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Zinc speciation in fly ash from MSWI using XAS - novel insights and implications

Rissler, Jenny LU ; Fedje, Karin Karlfeldt ; Klementiev, Konstantin LU ; Ebin, Burçak ; Nilsson, Charlotte ; Rui, Haakon M. ; Klufthaugen, Tone M. ; Sala, Simone LU and Johansson, Inge (2024) In Journal of Hazardous Materials 477.
Abstract

The chemical forms of zinc in fly ash from municipal solid waste incineration (MSWI) crucially affect ash management, influencing both material recovery options and the risk of unwanted leaching into ecosystems. The zinc speciation was investigated in fly ash samples sourced from full-scale MSWI plants, including four grate fired boilers (GB) and one fluidized bed boiler (FB). We applied X-ray Absorption Spectroscopy (XAS), and the spectra were analyzed against a unique library of over 30 relevant compounds, tailored to the nuances of zinc chemistry of fly ash. Nano-XANES and sequential leaching were employed as complementary analytical methods. Multiple chemical forms of zinc were found in the ash, whereof potassium zinc chloride salts... (More)

The chemical forms of zinc in fly ash from municipal solid waste incineration (MSWI) crucially affect ash management, influencing both material recovery options and the risk of unwanted leaching into ecosystems. The zinc speciation was investigated in fly ash samples sourced from full-scale MSWI plants, including four grate fired boilers (GB) and one fluidized bed boiler (FB). We applied X-ray Absorption Spectroscopy (XAS), and the spectra were analyzed against a unique library of over 30 relevant compounds, tailored to the nuances of zinc chemistry of fly ash. Nano-XANES and sequential leaching were employed as complementary analytical methods. Multiple chemical forms of zinc were found in the ash, whereof potassium zinc chloride salts (K2ZnCl4) emerged as the predominant form in GB fly ash representing 41–64 % of the zinc content, while less for FB fly ash (19 %). The mere exposure to humidity in the air during storage resulted in hydroxylation of the alkali zinc chlorides into Zn5(OH)8Cl2·H2O. Other forms of zinc in the ash were Zn4Si2O7(OH)2·H2O, ZnFe2O4, ZnAl2O4, surface adsorbed zinc, and Zn5(CO3)2(OH)6. Notably, the proportion of zinc in spinel forms (ZnFe2O4 and ZnAl2O4) increased threefold in FB ash compared to GB ash, representing ∼60 % and ∼10–20 % of the zinc, respectively.

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Chemical form of zinc, Waste incineration, Waste-to-Energy, XANES
in
Journal of Hazardous Materials
volume
477
article number
135203
publisher
Elsevier
external identifiers
  • pmid:39047558
  • scopus:85199255850
ISSN
0304-3894
DOI
10.1016/j.jhazmat.2024.135203
language
English
LU publication?
yes
id
7c3d140c-3d91-4346-833e-ca0458eaf6f7
date added to LUP
2024-09-03 16:24:27
date last changed
2024-09-03 16:25:49
@article{7c3d140c-3d91-4346-833e-ca0458eaf6f7,
  abstract     = {{<p>The chemical forms of zinc in fly ash from municipal solid waste incineration (MSWI) crucially affect ash management, influencing both material recovery options and the risk of unwanted leaching into ecosystems. The zinc speciation was investigated in fly ash samples sourced from full-scale MSWI plants, including four grate fired boilers (GB) and one fluidized bed boiler (FB). We applied X-ray Absorption Spectroscopy (XAS), and the spectra were analyzed against a unique library of over 30 relevant compounds, tailored to the nuances of zinc chemistry of fly ash. Nano-XANES and sequential leaching were employed as complementary analytical methods. Multiple chemical forms of zinc were found in the ash, whereof potassium zinc chloride salts (K<sub>2</sub>ZnCl<sub>4</sub>) emerged as the predominant form in GB fly ash representing 41–64 % of the zinc content, while less for FB fly ash (19 %). The mere exposure to humidity in the air during storage resulted in hydroxylation of the alkali zinc chlorides into Zn<sub>5</sub>(OH)<sub>8</sub>Cl<sub>2</sub>·H<sub>2</sub>O. Other forms of zinc in the ash were Zn<sub>4</sub>Si<sub>2</sub>O<sub>7</sub>(OH)<sub>2</sub>·H<sub>2</sub>O, ZnFe<sub>2</sub>O<sub>4</sub>, ZnAl<sub>2</sub>O<sub>4</sub>, surface adsorbed zinc, and Zn<sub>5</sub>(CO<sub>3</sub>)<sub>2</sub>(OH)<sub>6</sub>. Notably, the proportion of zinc in spinel forms (ZnFe<sub>2</sub>O<sub>4</sub> and ZnAl<sub>2</sub>O<sub>4</sub>) increased threefold in FB ash compared to GB ash, representing ∼60 % and ∼10–20 % of the zinc, respectively.</p>}},
  author       = {{Rissler, Jenny and Fedje, Karin Karlfeldt and Klementiev, Konstantin and Ebin, Burçak and Nilsson, Charlotte and Rui, Haakon M. and Klufthaugen, Tone M. and Sala, Simone and Johansson, Inge}},
  issn         = {{0304-3894}},
  keywords     = {{Chemical form of zinc; Waste incineration; Waste-to-Energy; XANES}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Hazardous Materials}},
  title        = {{Zinc speciation in fly ash from MSWI using XAS - novel insights and implications}},
  url          = {{http://dx.doi.org/10.1016/j.jhazmat.2024.135203}},
  doi          = {{10.1016/j.jhazmat.2024.135203}},
  volume       = {{477}},
  year         = {{2024}},
}