Surface modification of PVDF hollow fiber ultrafiltration membranes for biopharmaceutical products, virus, and bacterial phage removal technology

In this study, radicals were chemically formed at the hydroxyl (-OH) sites on the surface of polyvinylidene fluoride (PVDF) hollow fiber membranes, and anionic-hydrophilic and hydrophobic materials were grafted onto the surface through -OH radical reaction to generate anions (−28, −41 mV). These membranes were then used as biomembranes (BMs) and showed excellent properties. We also studied the effects of chemical surface modification and reduction in pore size (60–130 nm) according to molecular weight. After anionic modification, the electrostatic repulsion between the pore surface and the bacteria prevents adsorption when anionic bacteria pass through the pores. Particles do not pass through the asymmetric pores due to agglomeration, resulting in separation. The hydrophilic membrane had a high initial water flux, but the flux gradually decreased due to fouling. In contrast, the hydrophobic modified membrane had a low initial water flux that eventually stabilized due to excellent fouling resistance. The protein recovery ratio (PRR) was 98.8 % for hydrophilic particles and 99.2 % for hydrophobic molecules, showing a higher PRR than the pristine membrane (96.4 %). An evaluation of removal of the gram-negative bacteria Brevundimonas diminuta (Bd) showed that no bacteria in membrane-purified solutions, confirming 100 % removal efficiencies. The developed membrane can be used in biopharmaceutical production and removal of proteins, retro viruses, and bacteria.