Adsorption of Myricetrin, Puerarin, Naringin, Rutin, and Neohesperidin Dihydrochalcone Flavonoids on Macroporous Resins

The adsorption properties (equilibrium, kinetics, and column breakthrough) of five model flavonoids (myricetrin, puerarin, naringin, rutin and neohesperidin dihydrochalcone) on selected macroporous resins were investigated in order to identify a suitable resin adsorbent for effective separation and purification of flavonoids from the extracts of herbal plants. It was observed that the resins with a low polarity and a high specific surface area have high adsorption capacities for all five flavonoids. Both the Langmuir and Freundlich isotherm equations correlate well the adsorption equilibrium data of the five flavonoids on four selected resins, and adsorption enthalpy, entropy, and free energy of the five flavonoids on HPD300 resin were calculated from the adsorption isotherms by the Freundlich equation constants. The pseudo-second-order adsorption rate equation fits the kinetic data on four selected resins better than the pseudo-first-order adsorption rate equation, and the initial adsorption rates were calculated and discussed. The HPD300 resin was selected as the most promising adsorbent for a preliminary separation and purification of flavonoids because of its excellent adsorption/desorption properties including high adsorption rates for all five flavonoids. The adsorption breakthrough experiment with a synthetic flavonoid mixture solution on the HPD300 resin further confirmed that the HPD300 resin can separate the five flavonoids effectively, especially for purifying neohesperidin dihydrochalcone from the flavonoid mixtures.