Development of andrographolide extraction process from andrographis paniculata nees in pulsed column

Abstract

This work deals with the solid liquid extraction from the vegetal material. The characteristics (density, particle size, porosity and shape) of the Andrographis paniculata Nee which is a traditional plant in Thailand have been obtained. The extraction of andrographolide is first studied in a batch reactor. The influences of the operating conditions (initial mass, solvent concentration, particle size, temperature etc) on the kinetics of extraction have been investigated. An extraction yield of 70% to 90% has been reached at 20 to 60 min. The mass transfer model based on the two-shape model is proposed. The diffusion coefficient of the andrographolide in the ethanol solution at the room temperature is 8.43 x 10-14 cm[superscript 2].s[superscript -1]. It can be 52.1 x 10-14 cm[superscript 2].s[superscript -1] at 60 ํC. Preliminary experiments with an air pulsing system have been performed in a continuous column in order to avoid the flooding due to floating particles at the top of the column. The coupling of diffusion model with the mean residence time allows the design of the continuous process: Finally a twin screw extruder is used in order to compare the extraction yields with the batch experiments.