Seeded Batch Cooling Crystallization of Adipic Acid from Ethanol Solution

Adipic acid was crystallized by cooling in a batch crystallizer. At low seed loadings, the product crystal size distribution (CSD) was bi-modal because of enormous secondary nucleation. However, at high seed loadings, it became uni-modal, where the crystallization was dominated by seed growth with practically no secondary nucleation. Enough seeding was thus effective in suppressing nucleation during batch crystallization. The mean mass size of the product crystals obtained at high seed loadings agreed with that calculated by a simple mass balance assuming growth-dominated crystallization with no change in the number of crystals during operation and no residual supersaturation towards the end of batch. The products obtained, i.e., grown seeds, were not well faceted but rounded, probably because of abrasion caused by mechanical impact induced by agitation.