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Kinoshita, Ryoma; Sasaki, Yuji; Kaneko, Masashi; Matsumiya, Masahiko*; Shinoku, Kota*; Shiroishi, Hidenobu*
Hydrometallurgy, 222, p.106159_1 - 106159_12, 2023/10
Times Cited Count：2 Percentile：18.84(Metallurgy & Metallurgical Engineering)Solvent extraction is conducted using a total of 20 metals revealing high stability constants with Cl and hexahexyl-nitrilotriacetamide (NTAamide(C6)) extractant. The metals used here may behave as anions at high Cl concentrations, and NTAamide(C6), which contains a tertiary N atom, is protonated under acidic conditions. Most of the metal ions in this study display higher distribution ratios (D(M)) from HCl than those from HNO
, and exhibit 1:1 stoichiometries with NTAamide. Following the experimental results, the association constants and distribution coefficients of the group 12 elements are calculated via ion-pair extraction modeling using density functional theory calculations, and the simulations of D yield calculated values with the same trend as that of the measured values.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Kinoshita, Ryoma; Matsumiya, Masahiko*; Shinoku, Kota*; Shiroishi, Hidenobu*
Analytical Sciences, 39(9), p.1575 - 1583, 2023/09
Times Cited Count：3 Percentile：29.31(Chemistry, Analytical)Extraction of Rh from HCl can be performed by NTAamide(C6) (hexahexyl-nitrilotriacetamide) and other related compounds into n-dodecane. We use ion-pair extraction of anionic species of Rh-chloride and protonated extractant. Rh behave as anion in hydrochloric acid and the tertiary nitrogen atom in extractant may be protonated to produce the quaternary amine in acidic condition. From the present work, the maximum distribution ratio of Rh(III) is 16. The D(Rh) values are changeable during preparation of the aqueous solutions because different Rh-Cl-H
O complexes are formed in HCl media and show the slow exchange rate between Cl and HO. Using the UV spectrum, Rh-chloride solution having the peak of spectrum at 504 nm can be extracted effectively, where RhCl
(HO)
and RhCl
(H
O)
exist mainly from DFT calculation. Stoichiometry of one-one complex of Rh and NTAamide is obtained from slope analysis, and 85 mM of concentrated Rh ion can be extracted.
Matsumiya, Masahiko*; Kinoshita, Ryoma*; Sasaki, Yuji
Journal of the Electrochemical Society, 169(8), p.082513_1 - 082513_9, 2022/08
Times Cited Count：7 Percentile：37.20(Electrochemistry)Matsumiya, Masahiko*; Tsuchida, Yusuke*; Kinoshita, Ryoma*; Sasaki, Yuji
Journal of the Electrochemical Society, 168(7), p.076508_1 - 076508_6, 2021/07
Times Cited Count：1 Percentile：2.02(Electrochemistry)It is important to develop solvent extraction and electrodeposition processes for platinum group metals in order to reduce the volume of secondary wastes. In this study, the electrodeposition behavior of the extracted Pt(IV) complex in a phosphonium-based ionic liquid (IL) was investigated by using an electrochemical quartz crystal microbalance (EQCM). The charge transfer reaction Pt(IV) + 2e(-) 
Pt(II) was observed at -0.53 V and the electrodeposition reaction Pt(II) + 2e(-) Pt(0) proceeded at -1.65 V in this system. Moreover, consecutive solvent extraction and electrodeposition of Pt metal in Alamine336/IL system were performed at 10 cycles. High extraction percentage (E 
95.1 %) and good current efficiency (
85.8 %) were maintained in the first to sixth cycles. The XPS Pt-4f (7/2) spectrum confirmed that all the electrodeposits were in the metallic state.
Matsumiya, Masahiko*; Kinoshita, Ryoma*; Tsuchida, Yusuke*; Sasaki, Yuji
Journal of the Electrochemical Society, 168(5), p.056501_1 - 056501_6, 2021/05
Times Cited Count：9 Percentile：35.14(Electrochemistry)The extraction behavior of Ir(IV) in a phosphonium-based ionic liquid (IL) system, triethyl-n-pentyl phosphonium bis(trifluoromethyl-sulfonyl)amide ([P
][NTf]), was investigated using an amine extractant. Voltammetry-based electrochemical analysis revealed that the reduction of Ir(IV) proceeded via an intermediate Ir(III) species in two steps, namely, Ir(IV) + e(-) Ir(III) and Ir(III) + 3e(-) Ir(0). Diffusion coefficients of the extracted Ir(IV) species in the IL were determined over the temperature range of 298-373 K using semi-integral and semi-differential analyses, and values obtained from the two analyses were consistent with each other. Furthermore, consecutive solvent extraction and electrodeposition of Ir metal in the IL bath were performed for 10 cycles. The entire Ir electrodeposit was in the metallic state, as is evident from the 4f (7/2) spectrum obtained by XPS.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Kinoshita, Ryoma*; Matsumiya, Masahiko*; Shinoku, Kota*; Shiroishi, Hidenobu*
no journal, ,
We obtained relatively high D(Rh) of approximate 1 by iminodioctamide (IDOA) having tertially amino N atom from concentrated HCl solution. The reason is that IDOA is protonated, behaves as cationic extractant, and extracts anionic RhCl
through ion-pair extraction. Up to now, there is less information on Rh(III) extraction, we investigate the behavior of Rh extraction and discuss with theoretical studies.
Kinoshita, Ryoma; Sasaki, Yuji; Kaneko, Masashi; Matsumiya, Masahiko*; Shinoku, Kota*; Shiroishi, Hidenobu*
no journal, ,
Many metal ions are stable in hydrochloric acid solutions as anionic species; diamidic-extractants containing tertiary amino nitrogen atom, such as NTAamide (hexaalkyl-nitrilotriacetamide), are normally protonated in acidic solutions and become cationic extractants. In this study, the ion-pair extraction reactions of metal chloride anions with cationic NTAamide(C6) extractant were investigated. In addition, we attempted to predict the distribution ratio by combining the stability constants of metal chloride complexes and DFT calculations, and compared the results with experimental values.
