Revaluation of equilibrium quotient between titanium ions and metallic titanium in NaCl-KCl equimolar molten salt

In this study, the effect of oxide ion on the equilibrium between titanium ions and metallic titanium was investigated in NaCl-KCl equimolar molten salt. The soluble species containing Ti(3+) and O(2-) was not confirmed in the molten salt by absorption spectroscopy. The result of XRD for the solidified sample containing Ti(3+) and O(2-) implies that O(2-) reacts with Ti(3+) and Cl-to form TiOCl(s). The concentration quotient of the equilibrium between titanium ions (Ti(2+), Ti(3+)) and metallic Ti, K(c), was revaluated at 740 degrees C as follows: 3Ti(2+) -> 2Ti(3+) + Ti, Kc = 8.0 x 10(-2) mol L(1) = 1.2 x 10(-1) mol kg(-1). In addition, the solubility product of TiOCl(s) in NaCl-KCl equimolar molten salt, K(sp), at 700 degrees C was determined using the results of absorption spectra, K(sp) = 1.2 x 10(-2) mol(2) L(-2) = 5.1 x 10(-3) mol(2) kg(-2). (C) 2011 Elsevier B.V. All rights reserved.