Volume
VII describes how to make various measurements
related to crystallization, such as the measurement
of solubility, crystal size distribution or derivation
of growth and nucleation rates.
Volume
CR VII Part 1 Solubility measurement and correlation.
This
report provides a general introduction to equilibrium
solubility in solid-liquid systems. Some of the basic
concepts of solubility are described and applied to
electrolytes and non-electrolytes, aqueous and non-aqueous
systems, and to both highly and sparingly soluble systems.
Brief reference
is made to plotting and interpreting phase diagrams,
and some simple methods for recording and correlating
solubility data are described. A number of different
laboratory techniques available for achieving the solid-liquid
equilibrium state and for measuring solubility under
a variety of conditions are critically surveyed. Some
general characteristics of solvents are considered,
such as solvent classes, solvent power and temperature
coefficient of solubility, with particular reference
to the selection of solvents for crystallization processes.
Finally, a brief survey
is made of some proposed methods for predicting solubility
in binary and multicomponent systems, but with the added
cautionary note that a measured value is preferable
to an estimated one.
Volume
CR VII Part 2, 4. 5 Measurement
of crystallization kinetics.
The
determination of the kinetics of crystallization processes
(i.e. the characteristics of growth and nucleation)
is an important step in the design of crystallization
equipment. This report gives practical advice on how
to determine the rates of these processes. The first
step is to collect some basic information on the crystallizing
system, which will indicate the type of technique to
be used to measure the kinetics. A variety of measurement
techniques are available and are reviewed in the report.
The equipment required to measure the kinetics can then
be selected. The experimental data must then be analysed
carefully to obtain the form of the growth and nucleation
rate equations which can form the basis for detailed
design of crystallizers.
When this
report is revised, it will be split into separate parts
in this volume. Currently contains information covering
three areas; concentration and supersaturation, crystal
size and shape, growth and nucleation kinetics.
Volume
CR VII Part 3 Polymorphism
and non-crystalline phases.
This
newly commissioned report will provide practical guidelines
for dealing with polymorphism issues in industrial crystallization
processes, a particular problem area for the pharmaceutical
and fine chemicals sectors.
The report
will begin with a review of the underlying science and
then move onto offer practical guidelines for addressing
phase problems in crystallization problems such as the
isolation of metastable phases, mixtures of phases and
the problem of finding the ground state polymorph early
in process development.
Volume
CR VII Part 4 Determination
of kinetics.
>This
report reviews the various approaches for measuring
the kinetics of the crystallization process. It includes
a practical guide to analysing experimental data to
obtain these kinetics. The report comprises three main
parts:
- Experimental techniques;
a review of various experimental approaches to kinetics
measurement.
- Kinetics derivation;
how to extract kinetics from experimental data.
- Kinetics correlation;
how to correlate kinetics data against common kinetics
expressions.
A strategy
for selection of the most appropriate techniques for
gathering experimental data, extraction of the kinetics
and their correlation with operational variables in
provided. This is based on a scoping experiment which
takes the form of a Recommended Procedure.
