Identification and Quantification of Chemical Forms of Cu and Zn in MSWI Ashes Using XANES

Abstract

Incineration is in many countries a common treatment method for municipal solid waste, and utilization of the ash residues has attracted significant interest. The bottom ash is best suited as a secondary construction material, whereas the fly ash is being investigated as a secondary raw material for recovery of, for example, Zn, Cu, and salts. For both types of application, knowledge about the chemical speciation of Zn and Cu in the ashes is valuable. The present work focuses on identifying and quantifying the chemical species of Zn and Cu in 12 samples of fly ash and bottom ash from three waste-to-energy plants using X-ray absorption near edge structure (XANES). The XANES spectra of the ash samples showed similar distinctive features, and both in the bottom and fly ash samples, the same chemical forms were identified but in various ratios. Cu and Zn occurred in several chemical forms, with typically 5−7 forms present in the same sample. For Cu, the XANES spectra of the fly ash samples were nearly identical, indicating very similar chemical speciation (same chemical forms and similar ratios). Cu was found to exist in various oxide, hydroxide, chloride, silicate, and metallic forms. The most commonly occurring Zn compounds were the aluminate, ferrite, silicate, and oxide along with chloride, basic carbonate (hydrozincite), and occasionally metallic forms, probably alloyed with Cu in brass. Cu occurred in different oxidation states from zero to +II, with a higher prevalence of the lower oxidation states in bottom ash than in fly ash. Zn occurred mainly in oxidation state +II in all ashes analyzed. Finally, we showed that during outdoor storage of bottom ash, levels of Cu and Zn hydroxycarbonates were increased compared to fresh bottom ash. This carbonate formation aims to make Cu and Zn less leachable.

Charge Storage Mechanism in Electrospun Spinel‐Structured High‐Entropy (Mn0.2Fe0.2Co0.2Ni0.2Zn0.2)3O4 Oxide Nanofibers as Anode Material for Li‐Ion Batteries

“…Finally, the Zn K‐edge in the fresh electrode (Figure S4e, Supporting Information) resembles the Zn K‐edge spectrum of ZnFe 2 O 4 , [ 87 ] which belongs to the class of normal spinels. Hence, oxidation state of zinc is 2+ and Zn 2+ cations are expected to occupy tetrahedral 8 a sites.…”

Distribution of Copper States, Phases, and Defects across the Depth of a Cu-Doped CdTe Solar Cell

“…*The data of experimental reference spectra were extracted from the literature and replotted: Cu 2 Te is from ref . ; CuCl and CuCl 2 are from ref . ; CuO is from ref .…”

“…To acquire experimental reference spectra, high-purity powders (metallic Cu, Cu 2 O, Cu 2 S, and CuS) were measured using a 200 μm diameter X-ray beam at end station 2-ID-D at the Advanced Photon Source at Argonne National Laboratory. Some of the spectra were taken from literature (i.e., the Cu 2 Te experimental reference spectrum was taken from ref ., while CuCl and CuCl 2 experimental reference spectra were taken from ref , and CuO experimental spectrum was take from ref .). All other reference spectra were simulated using the structural models provided in Section 2 of the Supporting Information.…”

Microinteraction Analysis between Heavy Metals and Coexisting Phases in Heavy Metal Containing Solid Wastes

“…The linear combination fitting (LCF) result from XANES spectra is regarded as a power tool to obtain complex chemical speciation of heavy metals. Rissler et al 66 investigated municipal solid waste incineration bottom ashes (BA). They found Cu K-edge XANES spectra include one distinct but relatively broad peak at 8997 eV.…”