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Mixing effects on the protonation of polyacrylate in LiCl/KCl aqueous solutions at different ionic strengths,I = 1 to 3.5 mol L− 1, atT = 298.15 K

Authors
Journal
Journal of Molecular Liquids
0167-7322
Publisher
Elsevier
Publication Date
Volume
143
Identifiers
DOI: 10.1016/j.molliq.2008.07.001
Keywords
  • Protonation Of Polyacrylate 2 Kda
  • Protonation In Mixed Electrolytes
  • Mixing Free Energy
  • Models For The Protonation Of Polyelectrolytes

Abstract

Abstract Protonation constants of polyacrylate (MW = 2 kDa) were determined in several mixed LiCl/KCl aqueous mixtures and mole ratios from y = 0 to 1 y = [Li +] / ([Li +] + [K +]) and I = 1 to 3.5 mol L − 1 . Different models were tested in calculating protonation constants from ISE-H + potentiometric data (namely: Henderson–Hasselbalch, Högfeldt and Dicarboxylic-like models). The function log K H vs. y does not follow an ideal behaviour (Young's rule) but can be expressed by a three parameter equation derived by the zeroth Guggenheim approximation. From this equation it is possible to calculate the free energy of mixing. The dependence on ionic strength of protonation constants was modelled by the SIT (Specific ion Interaction Theory) approach.

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