Abstract
The influence of strongly polarizing cations Mg2+, Ca2+, Sr2+, and Ba2+ on the charge transfer kinetics of the redox couple Ti(IV)/Ti(III) is studied. The standard rate constants of charge transfer (k s) for the Ti(IV)/Ti(III) redox couple in the (NaCl–KCl)eq–NaF (10 wt %)–K2TiF6 melt upon the addition of the strongly polarizing cations into the starting melt are determined. The dependence of the charge transfer rate constants on the ionic potential of the cations is established. The activation energies of the charge transfer process are calculated for the fluoride complexes of the Ti(IV)/Ti(III) redox couple with the outer-sphere cations Mg2+, Ca2+, Sr2+, and Ba2+.
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References
L. P. Polyakova, P. T. Stangrit, and E. G. Polyakov, “Electrochemical study of titanium in chloride–fluoride melts,” Electrochim. Acta 31, 159–161 (1986).
C. A. Sequeira, “Chronopotentiometric study of titanium in molten NaCl + KCl + K2TiF6,” J. Electroanal. Chem. 239 (1–2), 203–208 (1988).
L. P. Polyakova, P. Taxil, and E. G. Polyakov, “Electrochemical behaviour and codeposition of titanium and niobium in chloride–fluoride melts,” Alloys Compd. 359, 244–255 (2003).
S. A. Kuznetsov and M. Gaune-Escard, “Influence of second coordination sphere on the kinetics of electrode reactions in molten salts,” Z. Naturforsch. 57, 85–88 (2002).
S. A. Kuznetsov and M. Gaune-Escard, “Kinetics of electrode process and thermodynamic properties of europium chlorides dissolved in alkali chloride melts,” J. Electroanal. Chem. 595, 11–12 (2006).
S. A. Kuznetsov and M. Gaune-Escard, “Electrochemical transient techniques for study of the electrochemistry and thermodynamics of nuclear materials in molten salts,” J. Nucl. Mater. 389, 108–114 (2009).
A. V. Popova and S. A. Kuznetsov, “Standard rate constants of charge transfer for the redox couple Nb(V)/Nb(IV) in equimolar NaCl–KCl,” Elektrokhimiya 44 (8), 992–997 (2008).
S. A. Kuznetsov, V. G. Kremenetsky, A. V. Popova, et al., “Unusual influence of the second coordination sphere on the standard rate constants of charge transfer for the redox couple Nb(V)/Nb(IV) in chloride–fluoride melts,” Dokl. Akad. Nauk 428 (6), 770–773 (2009).
A. V. Popova, V. G. Kremenetsky, V. V. Solov’ev, L. A. Chernenko, O. V. Kremenetskaya, A. D. Fofanov, and S. A. Kuznetsov, “Standard rate constants of charge transfer for the the redox couple Nb(V)/Nb(IV) in chloride–fluoride melts: experimental and calculation methods,” Elektrokhimiya 46 (6), 714–722 (2010).
A. V. Popova and S. A. Kuznetsov, “Standard rate constants of charge transfer for the redox couple Nb(V)/Nb(IV) in fluoride melts,” Elektrokhimiya 48 (1–6), 102–107 (2012).
A. V. Popova, V. G. Kremenetsky, and S. A. Kuznetsov, “Charge transfer kinetics for the redox couple Nb(V)/Nb(IV) in melts of alkaline metal chlorides,” Elektrokhimiya 50 (9), 807–809 (2014).
Yu. V. Stulov and S. A. Kuznetsov, “Standard rate constants of charge transfer for the redox couple Cr(III)/Cr(II) in salt melts NaCl–KCl–CrCl3 and NaCl–KCl–K3CrF6,” Rasplavy, No. 6, 26–34 (2010).
Yu. V. Stulov, V. G. Kremenetsky, O. V. Kremenetskaya, et al., Experimental and calculation methods for the investigation of the influence of the second coordination sphere on the standard rate constants of charge transfer for the redox couple Cr(III)/Cr(II) in chloride melts,” Elektrokhimiya 47 (8), 1014–1025 (2011).
Yu. V. Stulov, V. G. Kremenetsky, and S. A. Kuznetsov, “Influence of the second coordination sphere on the electrochemical behavior of chromium complexes in chloride melts: experimental and calculation methods,” Int. J. Electrochem. Sci. 8, 7327–7344 (2013).
Yu. V. Stulov, V. G. Kremenetsky, and S. A. Kuznetsov, “Electrochemical and quantum-chemical studies of the chromium fluoride complexes in molten alkaline metal chlorides,” Elektrokhimiya 50 (9), 907–916 (2014).
D. A. Vetrova, O. S. Kazakova, and S. A. Kuznetsov, “A study of the electrochemical behavior of the redox couple Ti(IV)/Ti(III) in a NaCl–KCl–K2TiF6 melt for the optimization of titanium electrorefining and synthesis of related melts,” Zh. Prikl. Khim. 87 (4), 446–450 (2014).
R. S. Nicholson, “Theory and application of cyclic voltammetry for measurement of electrode reaction kinetics,” Anal. Chem. 37 (11), 1351–1355 (1965).
S. A. Kuznetsov, S. V. Kuznetsova, and P. T. Stangrit, “Cathodic reduction of hafnium tetrachloride in a molten equimolar mixture of sodium and potassium chlorides,” Elektrokhimiya 26, 63–68 (1990).
B. B. Damaskin and O. A. Petrii, Introduction into Electrochemical Kinetics (Vysshaya Shkola, Moscow, 1975).
H. Matsuda and Y. Ayabe, “Theorie der randles-sevcikschen kathodenstrahl-polarographie,” Z. Elekrochem. 59, 494–503 (1955).
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Original Russian Text © D.A. Vetrova, S.A. Kuznetsov, 2016, published in Rasplavy, 2016, No. 6, pp. 524–534.
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Vetrova, D.A., Kuznetsov, S.A. Influence of alkaline earth metal cations on the charge transfer kinetics for the redox couple Ti(IV)/Ti(III) in a chloride–fluoride melt. Russ. Metall. 2017, 100–105 (2017). https://doi.org/10.1134/S0036029517020148
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DOI: https://doi.org/10.1134/S0036029517020148