DESIGNING CRYSTAL MORPHOLOGY BY A SIMPLE APPROACH

In separation processes containing solids, mostly crystals, the intere st in shape modifications of the solids has increased. The idea in it is the necessity to save energy, to achieve specific product requireme nts, e.g. purities, or to provide downstream processes with better fee d material. For an organic-crystal a simple way to select a growth inh ibitor is presented here, in contrast to the concept of ''tailor-made additives''. The additive selected is structurally different from the host molecule and modifies the habit in a desired manner. The procedur e of additive selection involves the analysis of the molecular structu re of the crystal to be modified and the orientation of the molecules at the surfaces of the morphological most important faces. Furthermore the problem is discussed if the chosen additive is incorporated into the crystal or not. Results are shown for the system caprolactam/ethan ol.