From tables 1 and 2 and figures 1 and 2, it can be noticed that
equations (1) and (5) can be used to correlate the experimental results
of the solubility of gallic acid in pure water, ethanol and binary
(water + ethanol) mixtures at different temperatures. Based on
obtained results, we can reach the following conclusions: (1) the
solubility of gallic acid in (water + ethanol) mixtures increases
slightly with temperature increasing; (2) at the same temperature,
the solubility of gallic acid in pure ethanol is much larger than in
any other (water + ethanol) mixed solvents; (3) the experimental
data indicate that the solubilities increase from x = 0.0 to 0.5 and
slowly decrease until x = 0.8. From x = 0.8 to 1.0, the solubility
curve of gallic acid rises sharply. The Maxima in the solubility
curves can be explained by the competitive effects of hydrophobic
and hydrophilic hydration of ethanol molecules. The first effect
prevails in the range of binary solvents compositions up to the
point corresponding to the maximum in the solubility. Minima
are due probably to the maximum stabilization of the water structure
by the non electrolyte.