Adsorption and Enrichment of Alkalids from Areca Nut by Means of Macroporous Resins

Resin adsorption as a means of separating and enriching areca alkalids from areca nut extracts was investigated. The adsorption/desorption properties of areca alkalids on six macroporous adsorption resins and a macroporous cation-exchange resin D151 were evaluated. The results showed that D151, AB-8 and XAD-7 resins presented a higher adsorption capacity, adsorption ratio and desorption ratio than the other resins studied. Equilibrium and kinetic adsorption data for areca alkalids onto these three resins were obtained. Such data were best fitted by the Langmuir isotherm model and the pseudo-first-order kinetic model. The thermodynamic and kinetic parameters showed that D151 resin possessed the greatest adsorption capacity and the highest adsorption rate of the three resins, with the adsorption of areca alkalids being spontaneous and endothermic. To optimize the operating parameters for enriching areca alkalids, dynamic adsorption and desorption tests were undertaken employing a column packed with D151 resin. The optimum parameters for adsorption were an inlet areca alkalid concentration of 2.24 mg/ml, a feed volume of 7 BY and a flow rate of 6 BV/h; for desorption, the corresponding conditions were the use of ethanol as the elution solvent at a feed volume of 8 BV and a flow rate of 1.5 BV/h. After treatment for only one cycle with D151 resin, the content of areca alkalids in the product was increased from 8:28% to 81.78% with an overall recovery of 87.40%. Moreover, D151 resin exhibited excellent re-usability for at least three adsorption/desorption cycles. The results obtained showed that macroporous resin could provide a feasible means for the large-scale preparation of areca alkalids from areca nut extract.