On-line monitoring and analysis of membrane-assisted internal seeding for cooling crystallization of ammonium persulfate

Effective seeding is crucial for the accurate control of cooling crystallization. Herein, the supercooled solution near the membrane interface underwent nucleation, and the membrane-assisted seeding (MAS) was performed for the nucleation and growth control of ammonium persulfate cooling crystallization. Process analytical technologies (PAT) were introduced to obtain on-line nucleation and growth information for the evaluation of the developed MAS process. Experimental comparisons between MAS and conventional seeding crystallization indicated that an appropriate MAS condition could provide a moderate seeding condition. By controlling two key operating parameters, the optimized membrane-involved temperature (18 °C) and duration (30 min), the terminal products possessed narrow crystal size distribution (mean size, 1181 μm; coefficient of variation, 0.162), desired morphology, and high purity (>99.0 wt%). Overall, the results have verified the feasibility of MAS to crystalize products with high quality.