Polymorphism, morphologies and bulk densities of DL-methionine agglomerate crystals

To explain the experimentally determined operation conditions to produce DL-methionine (DL-Met) crystalline particles having high bulk density from reaction crystallization, the morphologies of DL-Met agglomerated crystals in addition to the crystallographic structures were investigated. The existence of the third polymorph, the gamma-form, was confirmed. Both the observed and predicted morphologies for the elementary particles were plate-like and were strongly affected by the crystal structures. The effect of polymorphism and morphology of resulting particles from reaction crystallization on the bulk density of the product agglomerates was discussed. The bulk density was strongly affected by the agglomeration and the morphology of the constituent elementary crystals. The morphology change with pH of the solution was also experimentally found. Local pH during the reaction crystallization is concluded essential to determine the morphology of the elementary particle, and hence the bulk density of the agglomerates. (C) 1999 Elsevier Science B.V. All rights reserved.