Experimental investigations of adipic acid agglomeration behavior under different operating conditions using image analysis technique QICPIC software

Abstract

The agglomeration behavior in adipic acid crystallization from aqueous solution was experimentally studied under different crystallization conditions. The QICPIC software, which uses image analysis technique, was implemented to evaluate the agglomeration behavior of adipic acid crystals. Primary experimental investigations indicated an important role of cooling rate on the agglomeration and crystal size distribution (CSD) of adipic acid. At slower cooling rates of 17.5 K/h and 6 K/h, larger size particles (80% agglomerates) with bimodal and wide CSD were produced while at a higher cooling rate of 30 K/h a narrower unimodal PSD and smaller size particles with the ratio of agglomerated particles of about 80% were produced. The influence of pH was found to be an important factor when studying the agglomeration behavior of adipic acid. A larger size of the product was measured in the strong acidic medium, indicating enhanced agglomeration. Changing the solvent composition and its effect on the agglomeration of adipic acid were studied. A bimodal and larger size agglomerates are obtained in a pure water solvent while adding ethanol will change the CSD to unimodal shape (no nucleation) with smaller sized agglomerates.

Keywords:

• Adipic acid
• agglomeration
• metastable
• CSD
• QICPIC
• image analysis
• pH supersaturation
• cooling rate
• solvent

Acknowledgments

This work was carried out at the Department of Biochemical and Chemical Engineering of the TU Dortmund, Germany. The author would like to thank Prof. G. Schembecker and Dr. K. Wohlgemuth for providing the lab facilities and their valuable discussions and guidance.

Additional information

Funding

The financial support provided by the Deutsche Forschungsgemeinschaft (DFG) is gratefully acknowledged.