Modeling the Precipitation of l-Glutamic Acid via Acidification of Monosodium Glutamate

Abstract

A new insight for quantitative determination of the complex interaction of kinetics of reactive crystallization is gained by a study of the acidification of monosodium glutamate with hydrochloric acid in a semibatch reactor. The dynamic equilibrium of the L-glutamic acid ions, their simultaneous presence in the solution, and the effect on the crystal size and size distribution are simulated using a mathematical model based on integration of the population balance equation with the crystallization kinetics and thermodynamics of the process. The model includes equations of chemical reactions, pH, nucleation, size-independent growth, and population balance. This allows a precise determination of the driving force for the reactive crystallization and the parameters of the nucleation and crystal growth rate expressions. The model considers the effect of the controlling parameters such as the rate of addition of the acid and the initial concentrations of ionic species and can be used to predict the concentrations in the solution, the pH, and the crystal mass. The effect of process conditions on the crystal size, crystal size distribution, and morphology is studied.

Process control and monitoring of reactive crystallization of L‐glutamic acid

“…Preliminary preparations included preparing thermostated solutions for the initial batch (T ¼ 25 C) and feed reagent (T % 8 C). The feed acid was cooled to about 17 C below the temperature of the crystallized solution to minimize temperature increase caused by dilution enthalpy and reaction enthalpies.…”

“…16(p. 250) In the present study, glutamic acid is precipitated from a mono sodium glutamate solution by the addition of sulfuric acid in a reactive semi-batch crystallization process. Borissova et al 17 and Schöll et al 6 have studied acidification of monosodium glutamate with HCl in semi-batch crystallizers. Borissova et al have developed a kinetic simulation model for reactive crystallization and have detected the beginning of nucleation with turbidity measurement and the extent of the reaction with pH measurement.…”

Modeling and Bayesian parameter estimation for semibatch pH‐shift reactive crystallization of l‐glutamic acid

“…For the model compound of L-glutamic acid, the dissolution of monosodium glutamate (MSG) in pure water due to protonation and deprotonation mechanism can be represented by 6 …”

“…6 For the various species in solution, only the zwitterion glutamic acid precipitates because of its lowest intrinsic solubility. Either or both of two polymorphic forms of glutamic acid, namely, metastable a-form and stable b-form, can nucleate or grow competitively in solution depending on the solution concentration.…”

“…Although pH-shift reactive crystallization is commonly used in industrial practice for producing amphoteric compounds, such as amino acids, mathematical modeling of this process remains largely open in the literature. 4,5 The most sophisticated mathematical model for a pH-shift reactive crystallization that has been published is that of Borissova et al, 6 which used L-glutamic acid as a model compound. Their model assumed ideal solution properties and a simple empirical power-law kinetic mechanism and did not include polymorphic crystallization phenomena and mixing effects.…”