Mixing effects on the protonation of polycarboxylates. Protonation of Benzenehexacarboxylate in LiCl-KCl, NaCl-KCl, NaCl-LiCl and LiCl-CsCl aqueous solutions at I = 1 mol L-1 and T = 298.15 K.

Protonation constants are reported for 1,2,3,4,5,6-benzenehexacarboxylate in the electrolyte mixtures LiCl-KCl, NaCl-KCl, NaCl-LiCl, and LiCl-CsCl at a total ionic strength of 1 mol · L-1 and T ) 298.15 K, for different molar ratios (y) from 0 to 1. The function log10 KH vs y is not linear and can be expressed by a three-parameter equation derived using the zeroth Guggenheim approximation. Deviation from linearity was interpreted in terms of mixing free energy and mixed-metal complex formation.