A.I.Kravchenko
Received November 11, 1998; in final form January 10, 2000
A method has been proposed to evaluate the efficiency of
different distillation methods based on the efficiency, S,
calculation as the ratio of the substance purification degree using
a specific technique to that attainable by the simple distillation.
The method peculiarities have been discussed associated with the S
dependence on the temperature and impurity concentration. Literature
data have been considered concerning different distillation techniques
(condensation under a temperature gradient, distillation with the
vapor chemical treatment, using of a chemically active admixture or
chemically active filter, etc.). The S values for different
distillation techniques have been found to vary from <<1 to 260 (S<<1
means that the result is worse than at the simple distillation). In
some cases, the efficiency is very high and comparable to that of
rectification; in other ones, the efficiency can be enhanced. The
techniques combining the distillation with a chemical treatment are
of somewhat higher efficiency. The efficiency of most techniques is
better with respect to impurities having the separation coefficient
close to 1. In each technique, S can exceed 1 for some impurities
and be less than 1 for other ones. S can be concentration-dependent
and decrease as the initial impurity concentration decreases.