Chemical speciation of lead in secondary fly ash using X-ray absorption spectroscopy

In this study, fly ash samples were collected from bag houses in a Chinese municipal solid waste incinerator (MSWI) and secondary fly ash (SFA) samples were collected from a high-temperature tubular electric furnace by thermal treatment of MSWI fly ash at 1050, 1100, 1150, 1200, and 1250 °C.We determined the speciation and atomic coordinates of lead in SFA using X-ray absorption spectroscopy (XAS) techniques. The results obtained by X-ray absorption near edge structure (XANES) spectra revealed that the mass fraction of PbO in MSWI fly ash was 57.9% (wt %) while PbCl₂ and PbS were the dominant species in SFA. Extended X-ray absorption fine structure (EXAFS) data analysis indicated the atomic coordinates of Pb were proportional to the weights of PbCl₂ and PbS, in good agreement with the XANES spectra. These findings highlight lead evaporation processes in the MSWI fly ash during heat treatment and provide a method for consistent speciation analysis of environmental samples using XAS.