Speciation of chromium in swarf wastes pyrolyzed at 673-873 K has been studied by X-ray absorption spectroscopy in the present work. The least-square fitted X-ray absorption near edge structural (XANES) spectrum shows that Cr 3C 2 (84%) was the main chromium species in the untreated swarf. A small amount of CrO 3 and Cr 2O 3 was also found. During pyrolysis at 673-873 K, Cr (35%) and FeCr 2O 4 (24%) were formed with disappearance of about 43% of Cr 3C 2 in the swarf. By extended X-ray absorption fine structural (EXAFS) spectroscopy, we found that metallic Cr (with Cr{single bond}Cr bond distances of 2.56-2.59 ?) was formed during pyrolysis. At least two reaction paths might be involved during pyrolysis at 673-873 K: (1) reduction of Cr 3C 2 to metallic Cr and (2) formation of FeCr 2O 4 via reactions of chromium oxides and iron oxides. ? 2006 Elsevier Ltd. All rights reserved.
Relation:
Radiation Physics and Chemistry 75 (11 SPEC. ISS.) , pp. 2039-2041
