TY - JOUR
T1 - Mechanism analysis of selenium (VI) immobilization using alkaline-earth metal oxides and ferrous salt
AU - Tian, Quanzhi
AU - Guo, Binglin
AU - Chuaicham, Chitiphon
AU - Sasaki, Keiko
N1 - Funding Information:
This research was supported to KS by the Japan Society for the Promotion of Science (JSPS) KAKENHI (No. JP19H00883 ) and to TQ by the China Scholarship Council (No. 201706420068 ).
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/6
Y1 - 2020/6
N2 - The immobilization of selenate (SeO42–) using metal oxides (CaO and MgO) and ferrous salt as the immobilization reagents were examined by the leaching test and solid-phase analysis via XRD, XAFS, TGA, and XPS. The results indicated that nearly all of SeO42– was reduced to SeO32– in the CaO-based reaction within 7 days. Then, the generated SeO32– was mainly sorbed onto the iron-based minerals (Fe2O3 and FeOOH) through the formation of both bidentate mononuclear edge-sharing (1E) and monodentate mononuclear corner-sharing (1V) inner-sphere surface complexes, suggested by PHREEQC simulation and EXAFS analysis. Differently, less amount of SeO42– (approximately 45.50%) was reduced to SeO32– for the MgO-based reaction. However, if the curing time increases to a longer time (more than 7 days), the further reduction could occur because there are still Fe(II) species in the matrix. As for the associations of Se in the solid residue, most of the selenium (SeO32– and SeO42–) was preferentially distributed onto the Mg(OH)2 through outer-sphere adsorption. Definitely, this research can provide a deep understanding of the immobilization of selenium using alkaline-earth metal oxide related materials and ferrous substances.
AB - The immobilization of selenate (SeO42–) using metal oxides (CaO and MgO) and ferrous salt as the immobilization reagents were examined by the leaching test and solid-phase analysis via XRD, XAFS, TGA, and XPS. The results indicated that nearly all of SeO42– was reduced to SeO32– in the CaO-based reaction within 7 days. Then, the generated SeO32– was mainly sorbed onto the iron-based minerals (Fe2O3 and FeOOH) through the formation of both bidentate mononuclear edge-sharing (1E) and monodentate mononuclear corner-sharing (1V) inner-sphere surface complexes, suggested by PHREEQC simulation and EXAFS analysis. Differently, less amount of SeO42– (approximately 45.50%) was reduced to SeO32– for the MgO-based reaction. However, if the curing time increases to a longer time (more than 7 days), the further reduction could occur because there are still Fe(II) species in the matrix. As for the associations of Se in the solid residue, most of the selenium (SeO32– and SeO42–) was preferentially distributed onto the Mg(OH)2 through outer-sphere adsorption. Definitely, this research can provide a deep understanding of the immobilization of selenium using alkaline-earth metal oxide related materials and ferrous substances.
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U2 - 10.1016/j.chemosphere.2020.126123
DO - 10.1016/j.chemosphere.2020.126123
M3 - Article
C2 - 32059334
AN - SCOPUS:85079066020
VL - 248
JO - Chemosphere
JF - Chemosphere
SN - 0045-6535
M1 - 126123
ER -