Chemistry Reference
In-Depth Information
10
Solubilities of
Various Solutes in
Multiple Solvents
A Fluctuation Theory
Approach
Ivan L. Shulgin and Eli Ruckenstein
CONTENTS
10.1 Introduction .................................................................................................. 258
10.2 Derivatives of Activity Coefficients via the Kirkwood-Buff Theory of
Solutions ....................................................................................................... 260
10.3 Solubility of Gases in Binary Mixed Solvents ............................................. 262
10.4 Solubility of Drugs and Hydrophobic Organic Pollutants in Binary
Mixed Solvents ............................................................................................. 265
10.5 Solubility of Solutes in Multicomponent Mixed Solvents ............................ 270
10.5.1 Quaternary Mixed Solvent ............................................................... 277
10.5.2 Quinary Mixed Solvent .................................................................... 277
10.6 Solubility of Protein in Mixed Solvents ....................................................... 278
10.7 Conclusions ................................................................................................... 285
Abstract
: As is well known, the methods of classical thermodynamics (activity
coefficient or equation of state approaches) have frequently failed to correctly
predict the solubilities of various solutes in pure or multiple solvents. This
is true for the solubility of gases, large molecules (drugs, biomolecules), and
very large molecules (polymers and proteins) in water and aqueous solutions.
The main reason for this difficulty is that these systems are highly nonideal
and the activity coefficients cannot be predicted using the traditional ther-
modynamic methods. Fortunately, the fluctuation theory of solutions (or the
Kirkwood-Buff [KB] theory of solutions) has proven to be a very effective
tool for predicting the solubility of various solutes, especially in mixed sol-
vents. During the last decade, the KB theory was successfully applied to the
solubility of solid solutes in supercritical solvents, to the solubility of gases in
multiple solvents and polymer solutions, to the solubility of drugs and pollut-
ants in aqueous mixtures and to the solubility of proteins in mixed solvents.
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