Adsorption Isotherm and Kinetic Modelling of β-Galactosidase Immobilization onto a Basic Resin (Duolite A568)

Abstract

This study aimed to determine adsorption characteristics of Aspergillus oryzae β-galactosidase onto a basic resin Duolite A568. The experimental data were analyzed by the Langmuir and Freundlich isotherm to describe the adsorption equilibrium. The equilibrium data fitted well with the Langmuir model which confirmed that the Duolite A568 was favourable for adsorption of β-galactosidase enzyme under conditions studied. The maximum adsorption capacity was found to be (5.1 ± 0.49) × 10^-2 mg/g at 35 ºC. The kinetic data were fitted to pseudo-secondorder kinetic model of Ho by linear and non-linear regression methods. The enthalpy change (ΔHº), the entropy change (ΔSº) and the Gibb's free energy change (ΔGº) for the sorption processes were calculated to be 15.5 kJ/mol, 30.4 J/mol K and -9.4 kJ/mol, respectively. The positive ΔHº value indicated that the adsorption process was endothermic. ΔGº and ΔSº values showed that adsorption process occurred by physical mechanism and spontaneously.