TY - JOUR
T1 - Investigations on Adsorption of Inorganic Ions in Aqueous Solution to Some Metal Oxides, Hydroxides and a Carbonate by the X-Ray Spectroscopic Method
AU - Ohashi, Hironori
AU - Yonezu, Kotaro
AU - Kawamoto, Daisuke
AU - Yokoyama, Takushi
N1 - Funding Information:
The authors would like to thank Dr. Yasuhiro Kobayashi for help with the measurements of the Mössbauer spectra at the Institute for Integrated Radiation and Nuclear Science, Kyoto University. We also thank Dr. Tetsuo Honma and Dr. Takeharu Sugiyama for help in the measurement of XAS data at SPring-8 and SAGA-LS.
Publisher Copyright:
© 2021. The Japan Society for Analytical Chemistry
PY - 2021
Y1 - 2021
N2 - Why does the adsorption and concentration of inorganic chemical species proceed at aqueous–solid interfaces? In this review paper, we discuss the use of X-ray chemical state analysis to elucidate the intrinsic adsorption mechanism. Based on the chemical states of the species adsorbed to solids as determined by X-ray chemical state analysis, possible adsorption mechanisms are discussed. The driving forces of adsorption are represented by the Gibbs free energy change (ΔGchem = ΔGchem,1 + ΔGchem,2) resulting from the formation of covalent bonds between metal ions (M) in metal oxides or hydroxides and adsorbed species (X) (M–O–X bond, ΔGchem,1) and the formation of new phases consisting of M and X (ΔGchem,2). The concept of ΔGchem,2 is proposed based on the experimental results from chemical state analyses. As examples, the following investigations are discussed in this review paper: the formation of mullite precursors by the adsorption of monosilicic acid to Al(OH)3, the spontaneous reduction of Au(III) to Au(0) by adsorption of Au(III) to Al(OH)3, MnO2 and Ni(OH)2 and the mechanism of concentration of Co2+, Tl+, Pb2+, Pt2+, Au+, and Pd2+ in marine ferromanganese crusts.
AB - Why does the adsorption and concentration of inorganic chemical species proceed at aqueous–solid interfaces? In this review paper, we discuss the use of X-ray chemical state analysis to elucidate the intrinsic adsorption mechanism. Based on the chemical states of the species adsorbed to solids as determined by X-ray chemical state analysis, possible adsorption mechanisms are discussed. The driving forces of adsorption are represented by the Gibbs free energy change (ΔGchem = ΔGchem,1 + ΔGchem,2) resulting from the formation of covalent bonds between metal ions (M) in metal oxides or hydroxides and adsorbed species (X) (M–O–X bond, ΔGchem,1) and the formation of new phases consisting of M and X (ΔGchem,2). The concept of ΔGchem,2 is proposed based on the experimental results from chemical state analyses. As examples, the following investigations are discussed in this review paper: the formation of mullite precursors by the adsorption of monosilicic acid to Al(OH)3, the spontaneous reduction of Au(III) to Au(0) by adsorption of Au(III) to Al(OH)3, MnO2 and Ni(OH)2 and the mechanism of concentration of Co2+, Tl+, Pb2+, Pt2+, Au+, and Pd2+ in marine ferromanganese crusts.
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U2 - 10.2116/analsci.20SAR20
DO - 10.2116/analsci.20SAR20
M3 - Article
C2 - 34629358
AN - SCOPUS:85117286046
SN - 0910-6340
VL - 37
SP - 1321
EP - 1330
JO - Analytical Sciences
JF - Analytical Sciences
IS - 10
ER -
