5 Control of Crystal Size Distribution and Polymorphs …
91
Fig. 5.8 Size distribution of the alanine crystals on the basis of the long axis length
5.3.4 Control of Polymorph by Changing Mixing Ratio
of Glycine Solution and Poor Solvent Methanol
The experimental results shown above were obtained by poor solvent crystallization where equal volume of the solution and methanol were mixed. The solubility
changes with the composition of solvent and the supersaturation also change with
those mixing ratios. Then, we investigated the effect of mixing ratio of the solution
and poor solvent methanol on the crystallization of l-alanine. The mixing ratio of
methanol was changed by using different size of plastic syringes to 50, 78, and 91%.
The residence time was fixed to 3.3 s. Figure 5.9 presents the SEM images of lalanine crystals. The size of crystals became small with an increase in the methanol
composition. The supersaturation ratio was 3.1 at 50% methanol and 9.8 at 91%
methanol. The high supersaturation resulted in micronization of crystals.
Fig. 5.9 SEM images of the alanine crystals
91
Fig. 5.8 Size distribution of the alanine crystals on the basis of the long axis length
5.3.4 Control of Polymorph by Changing Mixing Ratio
of Glycine Solution and Poor Solvent Methanol
The experimental results shown above were obtained by poor solvent crystallization where equal volume of the solution and methanol were mixed. The solubility
changes with the composition of solvent and the supersaturation also change with
those mixing ratios. Then, we investigated the effect of mixing ratio of the solution
and poor solvent methanol on the crystallization of l-alanine. The mixing ratio of
methanol was changed by using different size of plastic syringes to 50, 78, and 91%.
The residence time was fixed to 3.3 s. Figure 5.9 presents the SEM images of lalanine crystals. The size of crystals became small with an increase in the methanol
composition. The supersaturation ratio was 3.1 at 50% methanol and 9.8 at 91%
methanol. The high supersaturation resulted in micronization of crystals.
Fig. 5.9 SEM images of the alanine crystals