Zinc speciation in fly ash from MSWI using XAS - novel insights and implications
Journal article, 2024

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.

XANES

Waste incineration

Waste-to-Energy

Chemical form of zinc

Author

Jenny Rissler

Lund University

RISE Research Institutes of Sweden

Karin Karlfeldt Fedje

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Renova

Konstantin Klementiev

MAX IV Laboratory

Burcak Ebin

Chalmers, Chemistry and Chemical Engineering, Energy and Material

Charlotte Nilsson

Fortum Waste Solutions AB

Haakon M. Rui

NOAH AS

Tone M. Klufthaugen

NOAH AS

Simone Sala

RISE Research Institutes of Sweden

Inge Johansson

NOAH AS

Journal of Hazardous Materials

0304-3894 (ISSN) 18733336 (eISSN)

Vol. 477 135203

Unlocking the potential of fly ash as a secondary raw material through the use of LSRI

VINNOVA (2021-03814), 2021-11-15 -- 2023-11-14.

Subject Categories

Other Environmental Engineering

Environmental Sciences

DOI

10.1016/j.jhazmat.2024.135203

More information

Latest update

8/9/2024 8