Multiple Feeding Strategy for Phase Transformation of GMP in Continuous Couette–Taylor Crystallizer

A continuous Couette–Taylor (CT) crystallizer with a multiple feed mode was developed to promote the phase transformation of guanosine 5-monophosphate (GMP). In drowning-out crystallization, amorphous GMP is initially precipitated and then transformed into hydrate GMP crystals via the spontaneous nucleation of hydrate crystals and consecutive dissolution of the amorphous GMP and growth of hydrate GMP crystals. Importantly, the multiple feeding strategy had a significant accelerating effect on the phase transformation process, resulting in the complete conversion of the amorphous GMP into hydrate crystals within an overall mean residence time of 2.5 min, even with a high GMP feed concentration of 152.8 g/L and low rotation speed of 300 rpm. Thus, the phase transformation in the continuous CT crystallizer with the multiple feed mode (feeding mode IV) was at least 2 times faster than the phase transformation with the conventional feeding mode (feeding mode I), and 10 times faster when compared to the phase transformation in a continuous MSMPR crystallizer. The effectiveness of the multiple feeding mode for the phase transformation can be explained in terms of independently controlling the supersaturation, mean residence time, seeding effect, and mass transfer rates in each region of CT crystallizer depending on the multiple feeding strategy and feeding distribution ratio.