Study of the Sorption Behavior of Hibiscus sabdariffa Anthocyanins on a Macroporous Resin

Abstract

AbstractThe adsorption of Hibiscus sabdariffa sp. anthocyanins onto a macroporous resin was studied in laboratory experiments. The anthocyanin aqueous extracts obtained from the calyces were used in agitated batch experiments with a macroporous resin. The adsorption kinetics and isotherms of H. sabdariffa anthocyanins on a selected macroporous resin was studied to determine the parameters that have to be optimized to recover the anthocyanins from aqueous extracts of the calyces. The adsorption kinetic experimental data were fit into a pseudo second order kinetic model, which was then used to determine several parameters such as the contact time necessary to reach equilibrium as well as the maximum adsorption capacity. The best fit for the equilibrium adsorption isotherm experimental data was obtained with the Langmuir isotherm model. Based on qualitative and quantitative interpretation of the experimental data, the resin that was tested here appeared to have good adsorption capacity for the anthocyanins even though the necessary time to reach equilibrium was particularly long.Three aspects of the desorption of anthocyanins from the resin were studied: the speed of release of the anthocyanins (desorption kinetics), the extent of the anthocyanin desorption depending on the adsorption contact time and finally, the influence of the mobile phase's characteristics.Practical ApplicationsThe purpose of this work is to facilitate the industrial production of a natural food colorant anthocyanin from H. sabdariffa calyces using a macroporous resin. To attain this, goal values from adsorption experimental data were computed and fit to theoretical adsorption models.The maximum adsorption capacity and the time necessary to reach equilibrium were determined. Qualitative and quantitative interpretation of the experimental data proved that the adsorbent/adsorbate system in study is a favorable process.The desorption of anthocyanins was also studied in order to determine the time necessary to achieve a satisfactory recovery rate, as well as the values of parameters that have a marked influence on the desorption efficiency.The obtained results and the calculated parameters will subsequently be used to plan colorant extraction at a bigger scale.