In situ XANES study of removal of heavy metals from laboratory wasteliquid by the ferrite process

Heavy metals in the laboratory wasteliquid can be recovered as stable and economic ferrite by the ferrite process. The spectrum of X-ray absorption near edge structure (XANES) specifically shows that 92% of Cr(OH)₃ and 8% of CrCl₂ in the original laboratory wasteliquid are converted to 70% of Cr₂O₃ and 30% of CrCl₂ in the precipitates by the ferrite process. The concentrations of total chromium, lead and zinc in the laboratory wasteliquid also dropped from 383,000, 20.9 and 277 ppb, respectively, to lower than the effluent standards of the Environmental Protection Administration (EPA) in Taiwan. The XRD (X-ray diffraction) analysis shows that the chromium ferrite is achieved at pH > 9. On the other hand, the XANES spectra of the in situ experiment show there were 52% of Fe₃O₄ in the precipitates.