Speciation of arsenic, chromium, and vanadium in red mud samples from the Ajka spill site, Hungary.
Results are presented from X-ray absorption spectroscopy based analysis of As, Cr, and V speciation within samples of bauxite ore processing residue (red mud) collected from the spill site at Ajka, Western Hungary. Cr K-edge XANES analysis found that Cr is present as Cr(3+) substituted into hematite, consistent with TEM analysis. V K-edge XANES spectra have E(1/2) position and pre-edge features consistent with the presence of V(5+) species, possibly associated with Ca-aluminosilicate phases. As K-edge XANES spectra identified As present as As(5+). EXAFS analysis reveals arsenate phases in red mud samples. When alkaline leachate from the spill site is neutralized with HCl, 94% As and 71% V are removed from solution during the formation of amorphous Al-oxyhydroxide. EXAFS analysis of As in this precipitate reveals the presence of arsenate Al-oxyhydroxide surface complexes. These results suggest that in the circumneutral pH, oxic conditions found in the Torna and Upper Marcal catchments, incorporation and sorption, respectively, will restrict the environmental mobility of Cr and As. V is inefficiently removed from solution by neutralization, therefore, the red mud may act as a source of mobile V(5+) where the red mud deposits are not removed from affected land.
Earth Surface Science Institute, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK. i.burke@see.leeds.ac.uk
Ian T
IT
Burke
William M
WM
Mayes
Caroline L
CL
Peacock
Andrew P
AP
Brown
Adam P
AP
Jarvis
Katalin
K
Gruiz
D000537:Aluminum Oxide / Q000737:chemistry; D001151:Arsenic / Q000032:analysis*; D002857:Chromium / Q000032:analysis*; D004784:Environmental Monitoring; D019652:Extraction and Processing Industry; D006814:Hungary; D007220:Industrial Waste / Q000032:analysis*; D046529:Microscopy, Electron, Transmission; D012989:Soil Pollutants / Q000032:analysis*; D014639:Vanadium / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
D007220:Industrial Waste; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D014639:Vanadium; D002857:Chromium; D000537:Aluminum Oxide; D001151:Arsenic