Nucleation kinetics of paracetamol–ethanol solutions from induction time experiments using Lasentec FBRM®

A study of the nucleation kinetics for cooling crystallisation of paracetamol–ethanol solutions in a batch reactor is described in this paper. Induction time experiments were conducted in order to estimate the nucleation kinetics of the system. Measured induction times can be affected by numerous process parameters, such as concentration, agitation rate and solution hydrodynamics. The theoretical approach of Kubota (2008) [14] was employed to estimate the nucleation kinetics, where the induction time is assumed to correspond to the time required for the number density of grown crystals to reach a fixed value. The induction time was observed to be independent of the solution temperature. This is suggested from Kubota's theory, in agreement with previous work and serves to further validate the induction time theory of Kubota. In this investigation, induction times were observed to decrease significantly with increased levels of agitation. Furthermore, the presence of wall baffles in the reaction vessel was also found to significantly reduce the measured induction times for the solution system.