The effect of agitation on the nucleation of α-lactose monohydrate

Nucleation in an industrial crystallisation process determines how many crystals are formed and defines the final particle size distribution. This parameter plays a critical role in determining the success of an industrial lactose crystallisation, impacting yield, throughput and product quality. Previous studies on lactose crystallisation have reported that mixing can influence the nucleation kinetics of α-lactose monohydrate. This work looked to authenticate this by measuring the induction time required for nucleation of supersaturated lactose solutions across a range of agitation rates. Increasing agitation increased the rate of nucleation at a given supersaturation. The results show that this is a result of an increase in the frequency of activated molecular collisions and not a change in the critical nucleus size, which remains constant at a defined supersaturation.