Pitzer parameters for the pertechnetate ion in the system Na+/K+/Mg2+/Ca2+/Cl-/SO42-/TcO4-/H2O at 25 degrees C

摘要

Isopiestic vapor pressure experiments are performed at 25 degrees C with aqueous Mg(TcO4)(2) solutions and with ternary mixtures containing various combinations of NaTcO4, Mg(TcO4)(2), NaCl, MgCl2, Na2SO4, and MgSO4. The osmotic coefficients of the binary solutions are used to evaluate the binary Pitzer parameters beta((O)), beta((1)), and C-phi for Mg(TcO4)(2). We previously reported these parameters for NaTcO,. The binary parameters for KTcO4 and Ca(TcO4)(2) are evaluated from solubilities of KTcO4 in KCl and CaCl2 solutions, respectively. The mixing parameters theta(TcO4-/Cl-), psi(MTcO4-/Cl-), theta(TcO4-/SO42-), psi(M/TcO4-/SO42), and psi(Na+/Mg2+/TcO4-) are calculated from either osmotic coefficients or solubilities in the corresponding ternary mixtures. The evaluated set of Fitter parameters predicts well the activity coefficients and solubilities of KTcO4 in multicomponent systems. [References: 14]