TY - JOUR
T1 - Sorption behavior of the Pt(II) complex anion on manganese dioxide (δ-MnO2)
T2 - a model reaction to elucidate the mechanism by which Pt is concentrated into a marine ferromanganese crust
AU - Maeno, Mamiko Yamashita
AU - Ohashi, Hironori
AU - Yonezu, Kotaro
AU - Miyazaki, Akane
AU - Okaue, Yoshihiro
AU - Watanabe, Koichiro
AU - Ishida, Tamao
AU - Tokunaga, Makoto
AU - Yokoyama, Takushi
N1 - Funding Information:
The authors thank Professor Yoshio Takahashi (Hiroshima University) for helping in the measurements of XAFS and the analysis of the EXAFS spectra. Mr. Taniguchi contributed this study in the early stage. XPS was measured at the Center of Advanced Instrumental Analysis, Kyushu University, Fukuoka, Japan. This study was financially supported by The Japan Mining Promotive Foundation (2008~2010). This work was also financially supported by JST-CREST, JST Research for Promoting Technological Seeds.
Publisher Copyright:
© 2015, Springer-Verlag Berlin Heidelberg.
PY - 2016/2/1
Y1 - 2016/2/1
N2 - It is difficult to directly investigate the chemical state of Pt in marine ferromanganese crusts (a mixture of hydrous iron(III) oxide and manganese dioxide (δ-MnO2)) because it is present at extremely low concentration levels. This paper attempts to elucidate the mechanism by which Pt is concentrated into marine ferromanganese crust from the Earth’s continental crust through ocean water. In this investigation, the sorption behavior of the Pt(II) complex ions on the surface of the δ-MnO2 that is a host of Pt was examined as a model reaction. The δ-MnO2 sorbing Pt was characterized by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) to determine the chemical state of the Pt. Hydrolytic Pt(II) complex ions were specifically sorbed above pH 6 by the formation of a Mn-O-Pt bond. XPS spectra and XANES spectra for δ-MnO2 sorbing Pt showed that the sorbed Pt(II) was oxidized to Pt(IV) on δ-MnO2. The extended X-ray absorption fine structure (EXAFS) analysis showed that the coordination structure of Pt sorbed on δ-MnO2 is almost the same as that of the [Pt(OH)6]2− complex ion used as a standard. Therefore, the mechanism for the concentration of Pt in marine ferromanganese crust may be an oxidative substitution (penetration of Pt(IV) into structure of δ-MnO2) by a reduction-oxidation reaction between Pt(II) in [PtCl4-n(OH)n]2− and Mn(IV) in δ-MnO2 through a Mn-O-Pt bond.
AB - It is difficult to directly investigate the chemical state of Pt in marine ferromanganese crusts (a mixture of hydrous iron(III) oxide and manganese dioxide (δ-MnO2)) because it is present at extremely low concentration levels. This paper attempts to elucidate the mechanism by which Pt is concentrated into marine ferromanganese crust from the Earth’s continental crust through ocean water. In this investigation, the sorption behavior of the Pt(II) complex ions on the surface of the δ-MnO2 that is a host of Pt was examined as a model reaction. The δ-MnO2 sorbing Pt was characterized by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) to determine the chemical state of the Pt. Hydrolytic Pt(II) complex ions were specifically sorbed above pH 6 by the formation of a Mn-O-Pt bond. XPS spectra and XANES spectra for δ-MnO2 sorbing Pt showed that the sorbed Pt(II) was oxidized to Pt(IV) on δ-MnO2. The extended X-ray absorption fine structure (EXAFS) analysis showed that the coordination structure of Pt sorbed on δ-MnO2 is almost the same as that of the [Pt(OH)6]2− complex ion used as a standard. Therefore, the mechanism for the concentration of Pt in marine ferromanganese crust may be an oxidative substitution (penetration of Pt(IV) into structure of δ-MnO2) by a reduction-oxidation reaction between Pt(II) in [PtCl4-n(OH)n]2− and Mn(IV) in δ-MnO2 through a Mn-O-Pt bond.
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U2 - 10.1007/s00126-015-0599-7
DO - 10.1007/s00126-015-0599-7
M3 - Article
AN - SCOPUS:84956610308
SN - 0026-4598
VL - 51
SP - 211
EP - 218
JO - Mineralium Deposita
JF - Mineralium Deposita
IS - 2
ER -
