Modification of porous alumina membranes with n-alkanoic acids and their application in protein adsorption

In this study, porous alumina membranes were modified with two kinds of n-alkanoic acids (octanoic acid and octadecanoic acid) at different concentrations and reaction times for the preparation of hydrophobic membranes. The properties of the modified membranes were characterized by contact angle, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and electron spectroscopy for chemical analysis (ESCA), and the better modification condition was determined as reaction time of 20 min and concentration of 10 mM for both n-alkanoic acids. Furthermore, adsorption and desorption performances of bovine serum albumin (BSA) onto the modified membranes in the batch and flow processes were investigated. The saturation capacity was 0.003 μmol/cm2 for the octanoic acid-modified membrane and 0.004 μmol/cm2 for the octadecanoic acid-modified membrane, under the better modification condition. Liquid chromatography and fluorescence measurement were subsequently conducted to analyze the BSA properties during the adsorption and desorption stages. Finally, the flow performance of BSA was found to be limited by its slow adsorption and desorption rates.