(164d) Endoscopy and External Bulk Video Imaging Based Nucleation Detection, Metastable Zone Identification and Crystallization Monitoring for Caffeine and Palm Oil Crystallization

This work describes the newly introduced external bulk video imaging (eBVI) method and presents the comparison with existing process analytical technologies (PAT) such as focused beam reflectance measurement (FBRM) and attenuated total reflectance (ATR) ultra violet/visible (UV/Vis) spectroscopy. While the latter two sample the system in small volumes closely to the probe, the BVI approach monitors the entire or large parts of the crystallizer volume using an external video camera. The BVI method is proposed as a complementary noninvasive PAT tool and it is shown that it is able to detect the nucleation onset with comparable or better performance than the FBRM and ATR-UV/Vis probes [1].

The second part of the contribution describes the endoscopy based in-situ bulk video monitoring (iBVI) approach. The video data is processed using the mean gray intensity method and by a digital image processing technique which detects the first crystals during nucleation. The experiments have been carried out in a small scale calorimeter CRCv4, during which the compensation heater and infrared spectroscopy signals were monitored [2]. It is concluded that monitoring the onset of the apparent nucleation, formation of particles with detectable size, using the MGI trend delivers similar performance to the calorimetric and IR spectroscopy signal, whereas the crystal recognition method is the fastest nucleation detection method [3].

The endoscopy based nucleation monitoring technique provides an in-situ, low-cost, robust, probe based method for metastable zone identification which can be easily integrated and automated with existing laboratory hardware and software.

The efficiency of the endoscopy and bulk video imaging methods is proved for caffeine and palm oil crystallization systems.

(1) Simon, L. L.; Nagy, Z. K.; Hungerbuhler, K., Comparison of external bulk video imaging with focused beam reflectance and ultra violet-visible spectroscopy for crystallization nucleation detection and metastable zone identification. Chem. Eng. Sci. 2009, In press.

(2) Billeter, J.; Neuhold, Y. M.; Simon, L.; Puxty, G.; Hungerbuhler, K., Uncertainties and error propagation in kinetic hard-modelling of spectroscopic data. Chemom. Intell. Lab. Syst. 2008, 93, (2), 120.

(3) Simon, L. L.; Nagy, Z. K.; Hungerbuhler, K., Endoscopy based in-situ bulk video imaging of batch crystallization processes. Organic Chemistry Research & Development, special issue on Crystallization & Polymorphism 2009, In press.