Crystallization of Monohydrate Citric Acid. 2. Modeling through Population Balance Equations

• Published in: Crystal growth & design Vol. 7; no. 10; pp. 2088 - 2095
• Main Authors: Caillet, Alexandre, Sheibat-Othman, Nida, Fevotte, Gilles
• Format: Journal Article
• Language: English
• Published: Washington,DC American Chemical Society 01-10-2007
• Subjects: Chemical and Process Engineering; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Engineering Sciences; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; General studies of phase transitions; Materials science; Methods of crystal growth; physics of crystal growth; Nucleation; Physics; Solid-solid transitions; Specific phase transitions; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Experimental data; Nucleation; Crystallization; Theoretical study; Crystal seeds; Secondary nucleation; Raman spectroscopy; Dissolution; Citric acid; Optimization; Operating conditions; Experimental result; Anhydrous compound; Growth mechanism; Modelling; CONTACT NUCLEATION; SOLUTION-MEDIATED TRANSFORMATION; SCALE-UP; L-GLUTAMIC ACID; KINETICS; GROWTH; CRYSTALS; SECONDARY NUCLEATION; PHASE-TRANSFORMATIONS; IN-SITU
• DOI: 10.1021/cg0606343
• EISSN: 1528-7505
• ISSN: 1528-7483

Experimental data about both the liquid and the solid phases during seeded batch crystallizations of citric acid (CA) in water were obtained using in situ Raman spectroscopy and image acquisition. These experimental results were reported in a previous paper in this issue (Caillet, A., et al. Cryst. Growth Des. 2007, 7, 2080−2087). The present paper is now focused on the mathematical modeling of the desupersaturation process during the crystallization of monohydrate citric acid (MCA), which is the stable form at 15 °C. Both the crystallization of MCA (monohydrate) and the dissolution of the anhydrous (ACA) form were investigated. The model is based upon population balance equations (PBEs) describing the evolution of the crystal size distribution (CSD) during batch seeded operations. The estimation of the kinetic parameters of MCA nucleation and growth, and of the dissolution of ACA, was performed using nonlinear optimization techniques. For various operating conditions (modifications of the initial supersaturation and of the seed amount), the two PBE models represent satisfactorily the experimental behavior of the process. In particular, activated secondary nucleation is shown to explain particular features of the solute/solvent system that were observed previously.