On the Mechanism of Growth of Lactose Crystals from Supersaturated Solutions

The existence of cavitation zones on the faces of a growing lactose crystal and the driving role of cavitation in the crystal growth have been substantiated. It is shown that the most favorable conditions for the conversion of dissolved lactose into the crystalline state are formed around crystal edges in the phase transition zones. The size of the phase transition zone of the crystallizing substance is calculated and compared with the available data on the sizes of crystalline nuclei. The radii of the cavitation zones were found to be r₂ ~ 7 nm (for a crystal with a size of 60.5 µm, at a temperature of 30°C and supersaturation of 0.55) and r₂ ~ 30 nm (for a 84-µm crystal, at a temperature of 50°C and supersaturation of 1.88). A mathematical model of the growth rate of lactose crystal in a supersaturated solution is proposed. The possibility of studying the crystallization mechanisms and determining the growth rate of lactose crystals based on the theory of dynamic interaction bodies and liquids by A.Y. Milovich is substantiated.