Adsorption isotherm and kinetic modelling of ?-galactosidase immobilization onto a basic resin (Duolite A568)
This study aimed to determine adsorption characteristics of Aspergillus oryzae ?-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 ?-galactosidase enzyme under conditions studied. The maximum adsorption capacity was found to be (5.1 ± 0.49) × 10-2 mg/g at 35 °C. The kinetic data were fitted to pseudo-second-order kinetic model of Ho by linear and non-linear regression methods. The enthalpy change (?H°), the entropy change (?S°) and the Gibb's free energy change (?G°) 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 ?H° value indicated that the adsorption process was endothermic. ?G° and ?S° values showed that adsorption process occurred by physical mechanism and spontaneously.