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Massey, D.*; Williams, C. D.*; Mu, J.*; Masters, A. J.*; Motokawa, Ryuhei; Aoyagi, Noboru; Ueda, Yuki; Antonio, M. R.*
Journal of Physical Chemistry B, 127(9), p.2052 - 2065, 2023/03
Times Cited Count：1 Percentile：0.00(Chemistry, Physical)Narita, Hirokazu*; Nicolson, R. M.*; Motokawa, Ryuhei; Ito, Fumiyuki*; Morisaku, Kazuko*; Goto, Midori*; Tanaka, Mikiya*; Heller, W. T.*; Shiwaku, Hideaki; Yaita, Tsuyoshi; et al.
Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07
Times Cited Count：19 Percentile：78.57(Chemistry, Inorganic & Nuclear)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
Times Cited Count：51 Percentile：85.82(Chemistry, Multidisciplinary)
-butyl phosphate/-octane mixtures by X-ray and neutron scattering in a wide 
rangeMotokawa, Ryuhei; Suzuki, Shinichi; Ogawa, Hiroki*; Antonio, M. R.*; Yaita, Tsuyoshi
Journal of Physical Chemistry B, 116(4), p.1319 - 1327, 2012/02
Times Cited Count：38 Percentile：66.22(Chemistry, Physical)Okamura, Hiroyuki; Ueda, Yuki; Motokawa, Ryuhei; Mu, J.*; Masters, A. J.*; Antonio, M. R.*
no journal, ,
Under practical liquid-liquid extraction conditions with high solute concentrations, clusters of metal-extractant complexes can form in the organic phase. In these conditions, application of the slope analysis method for determining metal-extractant stoichiometry becomes difficult, and the deviations from ideal appear as non-linear responses and non-integer slopes. In this study, we developed novel extraction equilibrium analysis for practical liquid-liquid systems with consideration of the cluster formation and investigated the extension of the classical equilibrium analysis. Molecular dynamics (MD) simulation snapshots indicate the formation of aggregated clusters of 1 to 9 Zr(NO
)
(TBP)
complexes in 
-octane, leading to the determination of composition and molar fraction of each cluster. Considering the extraction equilibrium of clusters composed of 
Zr(NO)(TBP) complexes, the extraction equilibrium constants K
( = 1-9) were calculated from the distribution ratio and the molar fraction for each cluster obtained by the MD analysis. The distribution curve calculated from the obtained K values agrees well with the experimental values. Therefore, MD simulation can accurately reproduce the experimental values in the clustering/aggregation liquid-liquid extraction system, which enabled us to extend the classical equilibrium analysis.
Okamura, Hiroyuki; Ueda, Yuki; Motokawa, Ryuhei; Mu, J.*; Masters, A. J.*; Antonio, M. R.*
no journal, ,
Recently, cluster formation of metal-extractant complexes in organic solvents has been shown to play important roles in liquid-liquid extraction. Although a number of reaction mechanisms have been proposed for liquid-liquid extraction, application of slope analysis method for evaluating metal-extractant stoichiometry fails when the solute concentrations are high. In this study, we performed the analysis of solvent extraction equilibria for practical liquid-liquid systems with consideration of the formation of cluster aggregates in the organic phase during the extraction process. Molecular dynamics (MD) simulation indicates the formation of aggregated clusters of 1 to 9 Zr(NO)(TBP) complexes in -octane, leading to the determination of composition and molar fraction of each cluster. Furthermore, the extraction equilibrium reactions were studied, and the extraction equilibrium constant K ( = 1-9) for each cluster could be determined from the parameters obtained by the MD analysis. The distribution curve calculated from K agrees well with the experimental values. Therefore, one MD simulation can accurately reproduce the distribution curve in the clustering/aggregation liquid-liquid extraction system, which enabled us to overcome the limitations of slope analysis method.
