TY - JOUR
T1 - Chemical state of Fe3+ in a Fe3+-type cation exchange resin for the removal and recovery of phosphate ions and the adsorption mechanism of phosphate ion to the resin
AU - Juntarasakul, Onchanok
AU - Yonezu, Kotaro
AU - Kawamoto, Daisuke
AU - Ohashi, Hironori
AU - Kobayashi, Yasuhiro
AU - Sugiyama, Takeharu
AU - Watanabe, Koichiro
AU - Yokoyama, Takushi
N1 - Funding Information:
This work was supported by JSPS Core-to-Core Program , “Establishment of Partnership among Mineral and Geothermal Resources in Asia and Africa Region by Near Future Generation Geoscientists” as well as JSPS KAKENHI Grants Number 18H01927. The XA spectra measurements were conducted at BL06 in SAGA-LS as a selected joint work (Project number: 2018IIK015 and 2019IIK009). The 31 P MAS NMR spectra were measured at the Advanced and Chemical Material Research Institute of Kyushu University. The authors thank Dr. Keiko Ideta for helping measurement of NMR spectra. We would like to thank Editage ( www.editage.com ) for English language editing.
Funding Information:
This work was supported by JSPS Core-to-Core Program, ?Establishment of Partnership among Mineral and Geothermal Resources in Asia and Africa Region by Near Future Generation Geoscientists? as well as JSPS KAKENHI Grants Number 18H01927. The XA spectra measurements were conducted at BL06 in SAGA-LS as a selected joint work (Project number: 2018IIK015 and 2019IIK009). The 31P MAS NMR spectra were measured at the Advanced and Chemical Material Research Institute of Kyushu University. The authors thank Dr. Keiko Ideta for helping measurement of NMR spectra. We would like to thank Editage (www.editage.com) for English language editing.
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/11/20
Y1 - 2020/11/20
N2 - To apply the Fe3+-type cation exchange resin, Fe3+-type UBK 10, which is an effective adsorbent of selenite ions, for the removal and recovery of phosphate ions (PO43−), the adsorption mechanism of PO43− to the Fe3+-type UBK 10 resin was investigated. To elucidate the aforementioned mechanism, the chemical state of Fe3+ in the Fe3+-type UBK 10 resin and the adsorption mode of PO43− into the adsorbent were examined via 57Fe Mössbauer spectroscopy and Fe and P K-edge X-ray absorption spectroscopy. The optimum pH for the adsorption of PO43− was found to be approximately 6 and the adsorbed PO43− was rapidly desorbed using 6 mol dm-3 hydrochloric acid (HCl) through the conversion of Fe3+ to FeCl4-, which is practical for the removal and recovery of PO43−. The Fe K-edge X-ray absorption near-edge structure (XANES) spectra showed, through the appearance of three isobestic points, that Fe3+ in the Fe3+-type UBK 10 resin exists as the following four species in equilibrium, depending on the pH: two monomeric hydrolytic species of ferric ions, (-S)2FeOH and (-S)Fe(OH)2, a μ-oxo dimer with corner sharing structure, (-S)2Fe-O-Fe(S-)2, and a dihydroxo dimer with edge sharing structure, (-S)2Fe-(OH)2-Fe(S-)2 (S: SO3 group in UBK 10). It should be emphasized that a PO43− can combine with a (-S)2Fe-(OH)2-Fe(S-)2 site at pH of 6, which is an optimum pH for adsorption of PO43−, forming a bidentate-binuclear configuration, (-S)2Fe-(OH)2(OPO2O)-Fe(S-)2, through the formation of Fe-O-P bonds.
AB - To apply the Fe3+-type cation exchange resin, Fe3+-type UBK 10, which is an effective adsorbent of selenite ions, for the removal and recovery of phosphate ions (PO43−), the adsorption mechanism of PO43− to the Fe3+-type UBK 10 resin was investigated. To elucidate the aforementioned mechanism, the chemical state of Fe3+ in the Fe3+-type UBK 10 resin and the adsorption mode of PO43− into the adsorbent were examined via 57Fe Mössbauer spectroscopy and Fe and P K-edge X-ray absorption spectroscopy. The optimum pH for the adsorption of PO43− was found to be approximately 6 and the adsorbed PO43− was rapidly desorbed using 6 mol dm-3 hydrochloric acid (HCl) through the conversion of Fe3+ to FeCl4-, which is practical for the removal and recovery of PO43−. The Fe K-edge X-ray absorption near-edge structure (XANES) spectra showed, through the appearance of three isobestic points, that Fe3+ in the Fe3+-type UBK 10 resin exists as the following four species in equilibrium, depending on the pH: two monomeric hydrolytic species of ferric ions, (-S)2FeOH and (-S)Fe(OH)2, a μ-oxo dimer with corner sharing structure, (-S)2Fe-O-Fe(S-)2, and a dihydroxo dimer with edge sharing structure, (-S)2Fe-(OH)2-Fe(S-)2 (S: SO3 group in UBK 10). It should be emphasized that a PO43− can combine with a (-S)2Fe-(OH)2-Fe(S-)2 site at pH of 6, which is an optimum pH for adsorption of PO43−, forming a bidentate-binuclear configuration, (-S)2Fe-(OH)2(OPO2O)-Fe(S-)2, through the formation of Fe-O-P bonds.
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U2 - 10.1016/j.colsurfa.2020.125314
DO - 10.1016/j.colsurfa.2020.125314
M3 - Article
AN - SCOPUS:85088896736
SN - 0927-7757
VL - 605
JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects
JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects
M1 - 125314
ER -