A new pulsation policy in disc and doughnut pulsed column applied to the solid-liquid extraction of andrographolide from plants

Léna Brunet (1) , Laurent Prat (1) , Rutchadaporn Wongkittipong (2) , Christophe Gourdon (1) , Gilbert Casamatta (1) , Somsak Damronglerd (2)

1 LGC - Laboratoire de Génie Chimique
2 Chulalongkorn University [Bangkok]

Classically, sinusoidal oscillations are imposed to enhance mixing and mass transfer between two phases contacted. But, in any case of solid/liquid contact, it was noticed that this pulsation mode was not efficient enough to allow a controlled behaviour of the solid phase. The problem is particularly met for the treatment of raw plants or polydispersed populations with complex physical properties. The objective of this study is to demonstrate the viability of using a non-sinusoidal pulsation in a continuous contactor to replace a traditional batch sinusoidal mode. A review of the different pulsation techniques is firstly presented. The example of solid-liquid extraction of Andrographolide from plants has then been choosen to bring out the advantages of the new pulsation mode. The development of this application as a continuous process in a column has indeed encountered difficulties due to the important heterogeneity of the matter : one of these classes tends to float and the other to sink, which always leads to a definitive flooding in classical operations. Typically, the proposed signal is composed of two different periods : in one hand, a classical sinusoidal pulsation step used to mix the liquid and solid phases in the active part of the column and allow an optimal mass transfer and, in a second hand, an impulsion phase, used generally for the transport of solid. The extraction is carried out in a disc and doughnut column of 54 mm in diameter, and 3.5 m in height. Liquid and solid are flowing cocurrently and downwardly. Experiments have been performed to know the global characteristics of the process in steady state and to suggest some elements for industrial design. The results showed that an optimal tuning of the geometric characteristics of the column, the level of interface and the parameters of the pulsation, could increase the operated domain where flooding is avoided.

Mots clés: Solid-liquid extraction; Separation; Pulsed column; Non sinusoidal pulsation; Andrographolide

Domaines: Génie chimique

Léna Brunet, Laurent Prat, Rutchadaporn Wongkittipong, Christophe Gourdon, Gilbert Casamatta, et al.. A new pulsation policy in disc and doughnut pulsed column applied to the solid-liquid extraction of andrographolide from plants. Chemical Engineering and Technology, 2005, 2 (1), pp.110-118. ⟨10.1002/ceat.200402138⟩. ⟨hal-03482826⟩