Synthesis and characterization of amino acid-modified adsorption resins and their adsorption properties in the purification of tabersonine from Voacanga africana seeds
A series of macroporous adsorption resins anchoring valine and glycine were synthesized and characterized. The structural characterization indicated that the Brunauer–Emmett–Teller (BET) surface area and pore volume of the resins decreased after functionalization with amino acids. The adsorption kinetics and adsorption isotherm experiments indicated that the pseudo second-order rate equation was more appropriate for characterizing the kinetic data and the Freundlich model was more suitable for fitting the equilibrium data. Moreover, the results also revealed that the maximum adsorption capacity of tabersonine on resins reduced to 14 mg g−1 from 254 mg g−1 after functionalization with valine. Causes for the low adsorption capacity of tabersonine on the modified resins were discussed. The modified resins were applied to purify tabersonine extracted from Voacanga africana seeds. The results showed that the modified resins were good for the adsorption of impurities but poor for the adsorption of tabersonine from the extracts of Voacanga africana seeds. Tabersonine was efficiently purified with purity above 90%. The reusability of the modified resins was also assessed and the modified resins exhibited considerable reusability.