Comparison of the adsorption behaviour of catechin onto cellulose and pectin

Abstract

The adsorption behaviour of catechin onto cellulose and pectin was compared. The adsorption of catechin onto the two fibres involved an initial fast adsorption phase followed by a slower adsorption as the sites became saturated and the systems moved towards equilibrium. The adsorption capacity of pectin for catechin (20.71 ± 2.24 mg/g) was significantly greater than that of cellulose (2.41 ± 0.05 mg/g) after equilibration for 24 h at 37 °C. The Langmuir and Freundlich models were applied to obtain the quantitative information about the adsorption of catechins to pectin and cellulose. Thermodynamic data derived from the isothermal adsorption carried out at the temperatures of 27 °C, 32 °C, 37 °C and 42 °C suggested that the adsorption was spontaneous and the binding was driven predominantly by physisorption. Fluorescence experiments confirmed the adsorption of catechins onto cellulose and pectin. The results showed that catechin adsorption capacity and adsorption mechanism were different for pectin and cellulose.