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

•Membrane-assisted seeding process were on-line monitored and analysed.•Appropriate membrane-involved operation route can effectively control seeding.•Membrane-assisted seeding is a promising method for high-quality crystallization. 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.