Adsorption of Bovine Serum Albumin onto Metal Oxides: Adsorption Equilibrium and Kinetics onto Alumina and Zirconia

In this study, the equilibrium and the kinetics of Bovine Serum Albumin (BSA) adsorption onto metal oxides such as alumina (Al(2)O(3)) and zirconia (ZrO(2)) were investigated in a batch reactor. The effects of pH and temperature to adsorption rate and the equilibrium were studied. The equilibrium process was described by the Langmuir or the Freundlich isotherm models. The maximum adsorption capacity (Q(0)) was found as 81.6 mg/g at pH 5 and 20 degrees C for Al(2)O(3) and 26 mg/g at pH 4 and 40 degrees C for ZrO(2), respectively. The protein adsorption capacity for ZrO(2) increased with increasing pH and temperature, while the protein adsorption capacity of Al(2)O(3) increased with increasing pH and decreasing temperature. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The rate kinetics of BSA adsorption onto Al(2)O(3) and ZrO(2) at all pH and temperatures were best fitted with the pseudo-first-order kinetic model. The electrostatic interactions of BSA with the metal oxide surface were found to be higher at pH 5 for Al(2)O(3) and pH 4 for ZrO(2).