Revealing the parameters to design the habit modifiers for rock-salt crystals: empirical to rational approach

Abstract

Morphology of rock-salt crystals can be influenced by internal and external factors like temperature, super saturations, solvent, and impurities. Many impurities and additives have been reported to date for the habit modification of common salt; however, the selection of such impurities is largely empirical. The partition coefficient or log P, which is a measure of hydrophobic hydrophilic property of a material, very aptly signifies the ability of additives to modulate the morphology of sodium chloride crystals. Application of the partition coefficient of additives led to the discovery of two new habit modifiers (cytosine and DMSO) for rock-salt crystals. The predicted results have been verified by experimental studies. Furthermore, the known habit modifiers and also the nonhabit modifiers for sodium chloride crystals corroborate the importance of this parameter to define the morphology of salt crystals. This study is of fundamental importance, which otherwise was rather empirical for the last two centuries.