Toxic arsenics in an AsH3 scrubber sludge were thermally stabilized in the temperature range of 973–1,373 K. To better understand how the high-temperature treatments can stabilize arsenics in the sludge, their synchrotron X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra of arsenics were determined. It is found that the reduced arsenic leachability may be associated with the formation of As2O5 (51–59%) and embedded As(V) within the Ca3(PO4)2 matrix (41–49%) in the stabilized sludge. In addition, the As-O bond distances in the stabilized As2O5 are much less than that of normal As2O5 by 0.05–0.07 Å. The shorter As-O bond distances accompanied with the higher bonding energy also have a contribution to the thermal stabilization of arsenics.
Design of a high-temperature and high-pressure liquid flow cell for x-ray absorption fine structure measurements under catalytic reaction conditions
