Investigation of the Extraction of Natural Alkaloids in Karr Reciprocating Plate Columns: Mass Transfer Study

ABSTRACT Solvent extraction plays a vital role in manufacturing high purity alkaloids from natural poppies. Cyanex® 923, which has been widely used in hydrometallurgical processes, is shown to be an effective extractant for natural alkaloid extraction. In this work, 0.2 M Cyanex® 923 in xylene (dispersed phase) was used to investigate the equilibrium isotherm of morphine at pH 9 and morphine extraction in two different reciprocating Karr columns. Two sources of morphine solution (continuous phase), including technical morphine with few impurities and industrial upstream morphine rich extract containing more impurities and other alkaloids, were studied to investigate morphine mass transfer efficiencies in the Karr columns based on different dispersed phase velocities and reciprocating frequencies. The mass transfer coefficients of technical morphine solution were calculated using a backflow model associated with axial dispersion, and the mass transfer coefficients were further used to regress a mass transfer correlation. The regressed correlation was further validated, and the process model was shown to be reliable to predict the extraction efficiency, and outlet morphine concentration of both aqueous phase and organic phase. This work provides insights to scale-up the process design in a short time, bridging the gap between bench scale research and pilot industry scale testing using a simple correlation method.