Crude barakol extraction from Cassia siamea using packed bed extractor

Abstract

The effects on crude barakol extraction from Cassia siamea leaves in a packed bed extractor, using 15%(V/V) ethanol as solvent, were studied to determine suitable operating conditions as well as determine effective diffusivities. A series of experiments were carried out at various conditions with directions of feed solution both in an upward and downward direction, with particle sizes between 0.42, 0.59 and 0.84 mm and solvent flow rates between 18.44, 29.36 and 37.96 ml/min for the upward direction of feed solution and 14.80, 23.68 and 30.88 ml/min for the downward direction of feed solution. In a first set of experiments lasting 3 hours, the packed bed was was contacted only with fresh solvent. It was found that the reduction of particle size enhanced barakol extraction yield. But, if too fine a particle size is used, the bed behaves as a fluidized bed. An upward direction of feed solution resulted in a barakol extraction yield which was superior than using a downward direction of flow. A set of suitable operating conditions found was a particle size of 0.59 mm, a solvent flow rate of 37.96 ml/min and an upward direction of flow and yielded 71.80 mg of barakol/g of dried Cassia siamea powder. Comparing the yield of barakol extraction in the previous system which did not include a recycle stream with a system with recycle, it was found that the yield of barakol extraction in a system without recycle was superior to the barakol extraction system with recycle however there is a cost associated with recovery of barakol from the solvent. The ratio of solid to solvent (W/V) which gives the highest extracted yield was 1:60. The mass transfer coefficient of crude barakol extraction with 15%(V/V) ethanol as solvent increased with increasing feed flow rate. The average effective diffusivity of crude barakol extraction with 15%(V/V) ethanol as solvent was 8.16*10(-11) m2/s.