Reducing protein fouling of a polypropylene microporous membrane by CO2 plasma surface modification

CO2 plasma was used to modify hydrophobic polypropylene microporous membranes to create hydrophilic surfaces. Structural and morphological changes on the membrane surface were characterized by X-ray photoelectron spectroscopy and scanning electron microscope. Membrane performance was tested with water flux measurements as well as protein fouling studies. The relative pure water flux of the modified membranes had a maximal value for the plasma treatment time of 2 min. It was found that the surface modified membranes showed better regeneration behavior. Flux recoveries after water and caustic cleaning were 33.1 and 27.5% higher, while reduction of pure water flux was 9.2% lower for the 30 s CO2 plasma treated polypropylene microporous membranes than those of the virgin membranes. Moreover, the amount of protein adsorption decreased by over 50% for the treated membranes compared to the unmodified membranes. The results demonstrated that the bovine serum albumin fouling was suppressed significantly by plasma surface modification.