Immobilization of α‐amylase via adsorption onto bentonite/chitosan composite: Determination of equilibrium, kinetics, and thermodynamic parameters

Abstract

Immobilization of α‐amylase onto bentonite/chitosan (BC) composite was studied via adsorption. The composite was characterized by FTIR, SEM, and surface area measurements. The effect of different factors such as, pH, temperature, initial enzyme concentration, and various thermodynamic parameters was determined. The maximum α‐amylase adsorption capacity of the BC composite was determined as 64 mg/g at 0.8 mg/mL enzyme concentration. The activity of the immobilized enzyme was measured under varying experimental conditions. The highest enzyme activity for free and immobilized enzyme was determined at 30 and 35°C in 0.1 M phosphate buffer at pH 7.0. The effect of substrate concentration on enzyme activity of free and immobilized enzymes showed a good fit to the Lineweaver–Burk plots. Michaelis constant, Km, for the immobilized α‐amylase was found to be higher than for the free enzyme. The adsorption isotherm was modeled by the Langmuir equation.