Adsorption of cellulase Aspergillus niger on a commercial activated carbon: Kinetics and equilibrium studies

The adsorption kinetics of cellulase Aspergillus niger on a commercial activated carbon has been performed using a batch-adsorption technique The effect of various experimental parameters such as initial enzyme concentration, contact lime and temperature were investigated The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data which shows that the adsorption of the enzyme followed the pseudo-second-order rate expression and the rate constants were evaluated The Langmuir and Freundlich adsorption isotherm models were applied to describe the equilibrium isotherms, and the isotherm constants were determined It was found that Langmuir model was mole suitable for our data The activation energy of adsorption was also evaluated for the adsorption of enzyme onto activated carbon. It was found 11 37 kJ mol(-1) Thermodynamic parameters Delta G(0), Delta H-0 and Delta S-0 were calculated, indicating that this process can be spontaneous and endothermic The adsorption enthalpy and entropy were found 11.12 kJ mol(-1) and 0 084 kJ mol(-1) K-1. respectively At 30 degrees C and at pH 48, 1 g activated carbon adsorbed about 1565 mg of cellulase, with a retention of 70% of the native enzyme activity up to five cycles of repeated batch enzyme reactions (C) 2009 Elsevier B.V. All rights reserved