Precious metal separations

Narita, Hirokazu*; Kasuya, Ryo*; Suzuki, Tomoya*; Motokawa, Ryuhei; Tanaka, Mikiya*

Encyclopedia of Inorganic and Bioinorganic Chemistry (Internet), 28 Pages, 2020/12

https://doi.org/10.1002/9781119951438.eibc2756

Anomalous small-angle X-ray scattering (ASAXS) study of irradiation-induced nanostructure change in Fe-ion beam irradiated oxide dispersion-strengthened (ODS) steel

Kumada, Takayuki; Oba, Yojiro; Motokawa, Ryuhei; Morooka, Satoshi; Tominaga, Aki; Tanida, Hajime; Shobu, Takahisa; Konno, Azusa; Owada, Kenji*; Ono, Naoko*; et al.

Journal of Nuclear Materials, 528, p.151890_1 - 151890_7, 2020/01

https://doi.org/10.1016/j.jnucmat.2019.151890

We have developed an anomalous small-angle X-ray scattering (ASAXS) diffractometer in SPring-8 to investigate irradiation-induced nanostructural change in ion-beam irradiated stainless steel. A thermally-aged MA956 stainless steel sample displays power-law scattering that follows the Porod law at the magnitude of scattering vector, Q, below 0.5 nm and an overlapped shoulder around 0.7 nm. After the ion-beam irradiation, the intensity of the shoulder remained unchanged, whereas that of the power-law scattering nearly doubled. This result indicates that none of the structural parameters of the Cr-rich nanoprecipitates, such as the number density, size, and interface roughness, were changed by the irradiation.

Extraction performance of a fluorous phosphate for Zr(IV) from HNO solution; Comparison with tri--butyl phosphate

Ueda, Yuki; Kikuchi, Kei; Sugita, Tsuyoshi; Motokawa, Ryuhei

Solvent Extraction and Ion Exchange, 37(5), p.347 - 359, 2019/07

https://doi.org/10.1080/07366299.2019.1638015

We have newly-designed fluorous phosphate(TFP) for the effective Zr(IV) ion extractant as an alternative extractant against the conventional organic phosphate, tri--butyl phosphate(TBP). Zr(IV) ion extraction system using the TBP has many problems such as the formation of the third phase during liquid-liquid extraction. Here, we develop the fluorous extraction system based on the TFP-perfluorohexane for the Zr(IV) ion extraction to improve the Zr(IV) ion extraction system with an effective extractability and without the third phase formation. Our main findings were that the significant high extraction performance of the TFP for Zr(IV) ion as compared with TBP, and the origins of the high extraction performance of the TFP are related to the water and HNO contents in the fluorous phase and the stability of the complex, Zr(No)(TFP).

A Telescoping view of solute architectures in a complex fluid system

Motokawa, Ryuhei; Kobayashi, Toru; Endo, Hitoshi; Mu, J.*; Williams, C. D.*; Masters, A. J.*; Antonio, M. R.*; Heller, W. T.*; Nagao, Michihiro*

ACS Central Science, 5(1), p.85 - 96, 2019/01

https://doi.org/10.1021/acscentsci.8b00669

Comparison of the extractabilities of tetrachloro- and tetrabromopalladate(II) ions with a thiodiglycolamide compound

Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi

Analytical Sciences, 33(11), p.1305 - 1309, 2017/11

https://doi.org/10.2116/analsci.33.1305

Calcium-deficient hydroxyapatite as a potential sorbent for strontium

Sekine, Yurina; Motokawa, Ryuhei; Kozai, Naofumi; Onuki, Toshihiko; Matsumura, Daiju; Tsuji, Takuya; Kawasaki, Riku*; Akiyoshi, Kazunari*

Scientific Reports (Internet), 7(1), p.2064_1 - 2064_8, 2017/05

https://doi.org/10.1038/s41598-017-02269-z

A calcium (Ca)-deficient hydroxyapatite was investigated for its potential to remove Sr from environmentally relevant water. We conducted sorption tests on solutions having Mg and Ca as competing cations at the Sr concentration of 0.05 mmol/L. The Ca-deficient hydroxyapatite maintained its high Sr sorption ratio: the sorption ratio was above 80% in the presence of Mg and Ca in the concentrations between 0.1 to 1.0 mmol/L, whereas stoichiometric hydroxyapatite showed a lower ratio even in the presence of small amounts of Mg and Ca. The bonding states of Sr onto the Ca-deficient hydroxyapatite were evaluated by extended X-ray absorption fine structure measurements. The results indicated that there are specific sorption sites in Ca-deficient hydroxyapatite where Sr could be stably and preferentially immobilized.

Selective extraction of Pt(IV) over Fe(III) from HCl with an amide-containing tertiary amine compound

Maeda, Motoki*; Narita, Hirokazu*; Tokoro, Chiharu*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi

Separation and Purification Technology, 177, p.176 - 181, 2017/04

https://doi.org/10.1016/j.seppur.2017.01.002

Photonic crystals fabricated by block copolymerization-induced microphase separation

Motokawa, Ryuhei; Taniguchi, Tatsuo*; Kumada, Takayuki; Iida, You*; Aoyagi, Shota*; Sasaki, Yusuke*; Kori, Michinari*; Kishikawa, Keiki*

Macromolecules, 49(16), p.6041 - 6049, 2016/08

https://doi.org/10.1021/acs.macromol.6b01190

Comparative molecular dynamics study on tri--butyl phosphate in organic and aqueous environments and its relevance to nuclear extraction processes

Mu, J.*; Motokawa, Ryuhei; Williams, C. D.*; Akutsu, Kazuhiro*; Nishitsuji, Shotaro*; Masters, A. J.*

Journal of Physical Chemistry B, 120(23), p.5183 - 5193, 2016/06

https://doi.org/10.1021/acs.jpcb.6b00781

Mesoporous silica particles as topologically crosslinking fillers for poly(-isopropylacrylamide) hydrogels

Miyamoto, Nobuyoshi*; Shimasaki, Kotaro*; Yamamoto, Kosuke*; Shintate, Morio*; Kamachi, Yuichiro*; Bastakoti, B. P.*; Suzuki, Norihiro*; Motokawa, Ryuhei; Yamauchi, Yusuke*

Chemistry; A European Journal, 20(46), p.14955 - 14958, 2014/11

https://doi.org/10.1002/chem.201403762