Crystallisation of Ionic Liquid by Using Avrami Kinetic Theory

Ionic liquids have received an immense increase in interest in the fields of
engineering during the last decade due to their distinctive properties. Ionic liquids
(ILs) are molten salts having by definition melting points below 100DC and a very
important newclassof non-volatile environmentally friendly solvents as compared to
traditional organic solvents. This study is focused on crystallisation of ionic liquid
which is one of the possible techniques to purify ionic liquids. Different factors that
influencing will be explored such as: effects of temperature variations, effects of
coolingrate, effectsof seedingprocedure(additionof crystals as solid) and effects of
ionic liquid content. Analyses will be conducted to evaluate and characterize the
ionic liquid crystallisation are: the percentage of ionic liquid crystallisation (S,
wt.%); the Avrami exponent (n) which correspond to the type of crystals; and the
half time of crystallisation (tm) which is associated with the rate of crystallisation.
On the study of the effect of temperature deviations, it was found that increasing the
initial temperature (7*i) reduced the overall crystallisation; increase of the initial
temperature (T{) altered the type of ionic liquid crystal from needle type to clustered
plate-like shapes; and decreased the rates of crystallisation. On the effect of cooling
rate, it was observed that decreasing the cooling rate reduced the crystallisation,
increased n and tm values hence reduced the crystallisation rates. The study on the
effect of seeding procedure revealed that crystallisation increased with seeding
procedure, increased n value, decreased tin and caused lower crystallisation rate.
Lastly in the effect of ionic liquid content, it was found that the higher the ionic
liquid content, the longer times were taken to produce ionic liquid crystals, increased
n and tm. Since the use of ionic liquid in industrial applications is relatively a new
technology, perhaps the results of this study will provide useful information for
understanding ofthe crystallisation behaviour of this new class of materials.