期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 384, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.jhazmat.2019.121342
关键词
Fe-modified biochar; Confocal micro-X-ray fluorescence imaging; X-ray absorption near-edge structure; Extended X-ray absorption fine structure; Environmental removal
资金
- Major Science and Technology Program for Water Pollution Control and Treatment [2018ZX07110]
- National Natural Science Foundation of China [41521001, 41877478]
- 111 Program [B18049]
- Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) [CUGGC06]
- Program of Geological Processes, Resources and Environment in the Yangtze Basin [CUGCJ1702]
Characterization of the spatial distribution and speciation of iron (Fe) in Fe-modified biochars is critical for understanding the mechanisms of contaminant removal. Here, synchrotron-based techniques were applied to characterize the spatial distribution and speciation of Fe in biochars modified by FeCl3 or FeSO4 and pyrolyzed at 300, 600, and 900 degrees C, respectively. Confocal micro-X-ray fluorescence imaging (CMXRFI) results indicated Fe, sulfur (S), and chlorine (Cl) diffused into the basic porous structure of the biochars and aggregated to the surface as pyrolysis temperature increased. Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra revealed maghemite (gamma-Fe2O3) as the primary Fe species in the modified biochars and Fe(0) was observed when pyrolyzed at 600 or 900 degrees C. Unmodified and FeCl3-modified biochars pyrolyzed at 900 degrees C were evaluated in the removal of arsenate (As(V)), arsenite (As(III)), hexavalent chromium (Cr(VI)) and Hg(II) from aqueous solution and Fe-modification enhanced the removal efficiency from 42.0%, 62.5%, 19.6%, and 97.0%, respectively, to all 99.9%. X-ray absorption spectroscopy results indicate both adsorption and redox reaction contributed to the removal mechanisms. The present study provides a prospective and sustainable material and offers information relevant to tailoring Fe-modified biochars to specific environmental applications.
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