Preparation and properties of composite membranes composed of non-conductive membranes and polypyrrole

Conductive composite membrane was prepared by oxidation of pyrrole in the commercial microfiltration membrane support using ferric ions and ascorbic acid as polymerization and oxidation agents, respectively. The concentrations for pyrrole and ferric chloride solutions were optimized as 0.745 and 2 molar, respectively. An acceptable conductivity resistivity equals to 42.1 Kohm.cm was obtained in these conditions. Filtration of BSA (bovine serum albumin-charged protein) solution was carried out to investigate the properties of prepared membrane. Higher fluxes were obtained for conductive membrane, exhibiting the effect of the membrane conductivity. Both BSA and membrane are negatively charged. This results in the partial repulsion of BSA from the membrane surface or membrane matrix due to the electrostatic barrier. Repulsion means less concentration polarization and fouling i.e. lower resistivity against the passage through the membrane or higher flux. For conductive membrane higher rejection was obtained compared to non-conductive membrane. This effect is attributed to the conductivity of the membrane. The negatively charged membrane surface acts as a barrier against BSA. A part of the protein is pushed back due to the electrostatic effect. This results in higher rejection.