KINETIC REGULARITIES OF ADSORPTION OF ANTHOCYANINS FROM EXTRACTS OF CHOCKEBERRY AND ELDERBERRY ON CATIONIC EXCHANGER FIBAN K-1

Abstract

This study describes kinetic regularities of anthocyanin adsorption from chokeberry and elderberry extracts on fibrous strong acid cationic exchanger FIBAN K-1 in a batch mode. Extracts of chokeberry and elderberry were prepared by maceration of crushed berries in 0.1 M HCl. The effect of various parameters like initial anthocyanin concentration (100-250 mg/L), temperature (20-50 oC), pH (2.0-3.5), and cationic exchanger mass (4.5-9.0 g/L) on kinetics of anthocyanin adsorption was investigated. Increasing of the initial anthocyanin concentration from 100 to 250 mg/L increases equilibrium anthocyanin adsorption ~ in 2.5 times from chokeberry extracts and ~ in 2 times from elderberry extracts. Equilibrium adsorption time of both types of the berries decreases from 135 to 75 min with increasing of temperature from 20 to 50 °C. Maximum values of equilibrium anthocyanin adsorption from chokeberry and elderberry extracts was observed at pH=2.0. Equilibrium adsorption of anthocyanins on cationic exchanger FIBAN K-1 decreases with increasing of its mass. Experimental kinetic curves of anthocyanin adsorption were modeled using four kinetic models. The adequacy of kinetic models was estimated using linear correlation coefficients (R2) and standard errors (SE). It was established, that kinetics results are better simulated by the kinetic models in the order: pseudo-second order > Elovich > intra-particle diffuse > pseudo-first order. The experimental kinetic curves are fitted well to the pseudo-second order and Elovich models indicatting that adsorption process is limited by chemical reaction between anthocyanins as flavilium cations with SO3-functional groups of cationic exchanger. The simulation with the diffusion model has shown the adsorption process proceeds in the mixed diffusion regime.

Keywords

• адсорбція
• кінетика
• ФИБАН К-1
• антоціани