Influence of conductive surface on adsorption behavior of ultrafiltration membrane

In this research the influence of conductivity on adsorptive behavior of PM30 ultrafiltration membrane was investigated using BSA solution as the feed. The conductive membrane was prepared from the originally nonconductive membrane by chemical polymerization of pyrrole as the conducting media on the membrane surface. Both Langmuir and Redlich-Peterson isotherms properly describe the quasi-equilibrium adsorption data which are produced using experimental results of flux and rejection. Higher capacity of protein adsorption was achieved using nonconductive in comparison with conductive membrane. Using nonconductive membrane, an excessive feasibility and spontaneity of BSA adsorption was observed based on the greater negative value of Gibbs free energy change () which is a criterion for spontaneity of adsorption. Determination of filtration mechanism was conducted for elucidation the dominant adsorption region within the membranes i.e. membrane surface or internal pores. The filtration mechanisms for BSA solution using nonconductive and conductive membranes were surface cake deposition and intermediate (partial) blocking, respectively. First-order-kinetic model versus second-order-kinetic model indicated a superior interpretation of adsorption kinetics for both membranes; however, the required time to reach to the equilibrium for nonconductive membrane was slightly higher. All the distinctions in adsorption behavior of the conductive membrane originate from the repulsive potential field appears on the surface of the membrane during preparation. This electrostatic field acts as a barrier against the passage of the negatively charged proteins. Moreover, the partial coverage of membrane surface and internal pores with poly(pyrrole) may reduce the quantity of the active adsorptive sites on the membrane surface and matrix or presumably deactivates a part of the sites.