An interpretation of the metastable zone width concerning primary nucleation in anti-solvent crystallization

Metastable zone width, crystal nucleation and growth kinetics measurement in anti-solvent crystallization of β-artemether in the mixture of ethanol and water

“…A max is the maximum excessive anti-solvent composition defined by A max = A − A sat , where A is the anti-solvent composition calculated at the outset of nucleation(t) detected by on-line turbidity probe, A sat is the anti-solvent composition of solution saturated with the solute (Kubota, 2008). In this study, A sat was calculated from the literature (Zhang et al, 2009).…”

Crystallization by Antisolvent Addition and Cooling

“…Analyzing data of benzoic acid crystallization in water-ethanol solution by the water addition, Kubota (2008) concluded that solvent composition has no effect on induction time or primary nucleation rate, which could be modeled considering only the supersaturation imposed to the system as water as added.…”

On the interpretation of metastable zone width in anti‐solvent crystallization

“…Supersaturation for crystallization of solute at a constant temperature is generated by addition of an anti-solvent at a constant rate to a solution prepared in a solvent in which the solute is fairly soluble. Although the effects of parameters such as the type of anti-solvent, feed concentration, solution concentration, anti-solvent addition rate and stirring rate on anti-solvent crystallization have been reported [1], there is sparse literature on the understanding of the metastable zone width in anti-solvent crystallization [2][3][4][5].…”

“…The problem with the above approaches is that they consider nucleation rate on mass basis. To overcome this drawback, Kubota [5] proposed another approach based on the number density of nuclei (i.e. number of nuclei per unit volume) that have reached a certain value for detection.…”

“…(5) the metastable zone width Δx max depends on nucleation parameters k and m, and the antisolvent addition rate R A . 2.2 Kubota's approach [5] Kubota considered the excessive anti-solvent composition Δx in terms of the number density of nuclei (N/V) max , defined as the number of nuclei N per unit volume V, that have reached a certain value for detection. He calculated the value of (N/V) max by integrating the nucleation rate J = d(N/V)/dt with respect to time from 0 to t max :…”