Determination of the Cd-bearing phases in municipal solid waste and biomass single fly ash particles using SR-microXRF spectroscopy.
By using an excitation energy of 27.0 keV, synchrotron radiation-induced micro-X-ray fluorescence (SR-microXRF) is employed to extract information regarding the composition and distribution of Cd-bearing phases in municipal solid waste (MSW) and biomass fly ashes. Significance of observation is based on statistics of totally more than 100 individual MSW and biomass fly ash particles from a fluidized bed combustion (FBC) plant. Cd concentrations in the parts-per-million range are determined. In general, although previous leaching studies have indicated Cd to be predominant in the smaller-size ash particles, in the present study Cd is more evenly distributed throughout all the particle sizes. For MSW fly ashes, results indicate the presence of Cd mainly as CdBr2 hot-spots, whereas for biomass fly ashes, which exhibit lower CdX2 concentration, a thin Cd layer on/in the particles is reported. For both ashes, Ca-containing matrixes are found to be the main Cd-bearing phases. Support for this observation is found from independent first-principles periodic density functional theory calculations. The observations are condensed into a schematic mechanism for Cd adsorption on the fly ash particles.
Camerani
Maria Caterina
MC
Chemical Analysis, Eka Chemicals AB, S-445 80 Bohus, Sweden, DiffAbs Beamline, Synchrotron Soleil, BP 48, 91192, Gif-sur-Yvette Cedex, France. caterina.camerani@eka.com
Somogyi
Andrea
A
Vekemans
Bart
B
Ansell
Stuart
S
Simionovici
Alexandre S
AS
Steenari
Britt-Marie
BM
Panas
Itai
I
D000465:Algorithms; D018533:Biomass; D002104:Cadmium / Q000737:chemistry* / Q000302:isolation & purification; D002118:Calcium / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D060729:Coal Ash; D003201:Computers; D010316:Particle Size; D052638:Particulate Matter / Q000737:chemistry*; D012037:Refuse Disposal / Q000379:methods*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D017356:Synchrotrons; D014466:Ultraviolet Rays
D060729:Coal Ash; D052638:Particulate Matter; D002104:Cadmium; D002244:Carbon; D002118:Calcium