Effects of mixing, seeding, material of baffles and final temperature on solution crystallization of l-glutamic acid in an oscillatory baffled crystallizer

In this paper, we report the effects of mixing intensity, seeding, composition of baffle material and final temperature on meta-stable zone width (MSZW) and crystal polymorph in solution crystallization of an industrially important compound, l-glutamic acid, in an oscillatory baffled crystallizer (OBC). The results show that the MSZW decreases with increasing of mixing; meta-stable α crystals are transformed into stable β crystals with enhanced mixing intensity. Seeding meta-stable α crystals in operational conditions that promote β crystals leads to the formation of α crystals allowing co-existence of both forms; while seeding stable β crystals in conditions that favour α form allow β crystals prevailing in all conditions. Smoother surface of baffle material in OBC exhibits larger MSZW and favours meta-stable crystals, while rougher surface has smaller MSZW with stable crystals dominating. The meta-stable crystals gradually change into the stable form when final cooling temperature is closer to its nucleation temperature. The outcomes from this work indicate that by controlling process parameters desirable crystal polymorph can be obtained in the OBC.