Batch cooling crystallization study based on in-line measurement of supersaturation and crystal size distribution

Qu, Haiyan; Pöllänen, Kati; Louhi-Kultanen, Marjatta; Kilpiö, Teuvo; Oinas, Pekka; Kallas, Juha

doi:10.1016/j.jcrysgro.2004.11.278

Cited by 14 publications

(13 citation statements)

References 7 publications

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“…The calibration model of the spectra is usually generated based on spectra collected from a series of undersaturated solutions with known solute concentration [14][15][16][17]. These standard solutions can be prepared easily by dissolving a certain amount of solute and solvent at a given temperature.…”

Section: Atr Ftir Spectramentioning

confidence: 99%

“…Advanced spectroscopy techniques, such as ATR FTIR and Raman spectroscopy, can be considered the most powerful tool currently available to execute in-line monitoring of both solute concentration in the liquid phase and polymorphic composition of the crystals throughout the whole precipitation process. ATR FTIR spectroscopy has been proved to be an accurate tool to measure the concentration of the crystallizing solute in thick solid-liquid suspensions during cooling crystallization, for both open-loop optimization and closed-loop control purpose [14][15][16][17]. However, the application of ATR FTIR spectroscopy in precipitation processes to obtain the whole supersaturation profile is rare.…”

Section: Introductionmentioning

confidence: 99%

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Raman and ATR FTIR spectroscopy in reactive crystallization: Simultaneous monitoring of solute concentration and polymorphic state of the crystals

Alatalo

Hatakka

et al. 2009

Journal of Crystal Growth

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Section: Atr Ftir Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Raman and ATR FTIR spectroscopy in reactive crystallization: Simultaneous monitoring of solute concentration and polymorphic state of the crystals

Alatalo

Hatakka

et al. 2009

Journal of Crystal Growth

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“…It is clearly seen that the spectral data changes on various wave numbers at sample number 15 (time point 15), corresponding to the occurrence of nucleation in the system (see sample 15 in Figures 4 and 5). However, signs of oncoming changes can be seen even before this moment (at time points [12][13][14]. Detailed discussion of the capability and usability of multivariate control charts is beyond the scope of this paper.…”

Section: Results Of Monitoring Of Solidsmentioning

confidence: 99%

In‐line monitoring of reactive crystallization process based on ATR–FTIR and Raman spectroscopy

Alatalo

Kohonen

et al. 2008

Journal of Chemometrics

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aThe paper studies the utilization of attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) and Raman spectroscopy to investigate isothermal semi-batch precipitation of a model compound, L-glutamic acid. ATR-FTIR spectroscopy was mainly used for in-line monitoring of the solution phase and Raman spectroscopy for analysis of the solid phase. L-glutamic acid has two reported polymorphs: a metastable a form and a stable b form. The b form can be obtained at relatively high supersaturation levels at 25 o C. The synthesis consists of a sodium glutamate reaction with sulfuric acid yielding L-glutamic acid crystals and sodium sulfate as a side-product solute. The spectral data were utilized to interpret the crystallization process using multivariate methods. A thermodynamic model taking into account the non-ideal character of the studied compound system and dissociation of different compounds is introduced. The resolution of ATR-FTIR is not sufficient to determine directly the L-glutamic acid concentration in the solution. Therefore, special efforts were made to determine the instantaneous concentration of dissolved glutamic acid based on the mass balance and ATR-FTIR spectra. Calibration concentrations were based on thermodynamic data. Multivariate methods were applied in monitoring the precipitation process and to predict indirectly the concentration of the chemical compounds. In this study, the spectra from ATR-FTIR were utilized to estimate and predict the concentrations from thermodynamic modeling. It was also investigated if the Raman spectra could be used for this purpose.

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“…The concentration was computed with a multivariate model from the ATR-FTIR spectrum [7,8,14,15,19,20,22,27,28]. FTSW-100 spectrometer software of ABB was used www.cet-journal.comwith an OPC server.…”

Section: Crystallizer and Instrumentationmentioning

confidence: 99%

Closed‐Loop Control of Reactive Crystallization. Part I: Supersaturation‐Controlled Crystallization of L‐Glutamic Acid

Alatalo¹,

Hatakka²,

Louhi-Kultanen³

et al. 2010

Chem Eng & Technol

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The feedback control policy of the reactive crystallization process is studied. A concentration of a crystallizing compound is used to compute the feedback in the closed-loop control of semi-batch precipitation. The pH is used as a second feedback value, and the dynamic change of the set value is based on the mass of added acid. The concentration of L-glutamic acid is determined from measured MID-IR attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra based on a multivariate model. The importance of the supersaturation level control at the nucleation moment and the effect of different supersaturation levels on the quality of the product crystals are studied by using a 50-L crystallizer. The studied crystal properties of the product are polymorphism (reported metastable a-and stable b-forms) and crystal size. The results show that the feedback process control system developed in this study makes it possible to control the formation of polymorphs effectively.

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Batch cooling crystallization study based on in-line measurement of supersaturation and crystal size distribution

Cited by 14 publications

References 7 publications

Raman and ATR FTIR spectroscopy in reactive crystallization: Simultaneous monitoring of solute concentration and polymorphic state of the crystals

Raman and ATR FTIR spectroscopy in reactive crystallization: Simultaneous monitoring of solute concentration and polymorphic state of the crystals

In‐line monitoring of reactive crystallization process based on ATR–FTIR and Raman spectroscopy

Closed‐Loop Control of Reactive Crystallization. Part I: Supersaturation‐Controlled Crystallization of L‐Glutamic Acid

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