Ultrasound-Assisted Slug-Flow Tubular Crystallization for Preparation of Fine Ibuprofen Crystals

Ibuprofen fine crystals prepared by commonly used methods have some problems such as low-crystallinity product and uneven distributed particle size. An ultrasonic-assisted tubular crystallization system was developed. The effects of tubular crystallization temperature, supersaturation, residence time, surfactant, and flow pattern on the crystal size distribution and average particle size were studied. It was found that ultrasound promotes nucleation and reduces crystal aggregation. Ibuprofen crystals with an average particle size of 6.23 mu m were formed owing to the high degree of continuous supersaturation and promoted micromixing. Finally, a possible mechanism of enhancement of micromixing under ultrasonic and slug flow on tubular crystallization was proposed.