Polymeric membranes modified via plasma for nanofiltration of aqueous solution containing organic compounds

Polymeric nanofiltration membranes were prepared modifying via low temperature plasma treatment flat membranes based on a modified poly(ether ether ketone) (PEEKWC). PEEKWC membranes, prepared using wet phase inversion using methanol (M2m) and 1-butanol (M2b) as internal non-solvent, were further plasma surface modified (RF 13.56 MHz) introducing amino groups on the membrane using two different pre-treatment gases, Ar (M2bpsm/Ar/NH3 and M2mpsm/Ar/NH3) and H2 (M2bpsm/H2/NH3 and M2mpsm/H2/NH3). The performances of unmodified and plasma modified membranes M2b and M2m and of a commercial nanofiltration membrane (NFTFC50) were tested in treatment of aqueous solution containing two dyes, characterized by similar molecular weight (≈320 g/mol) and opposite charge, methylene blue and methyl orange, positively and negatively charged, respectively. The observed rejections resulted optimized in terms of fouling for the plasma modified membranes with respect to unmodified and commercial NFTFC50 membranes. In particular, methylene blue was retained for 100% by M2mpsm/Ar/NH3 with a relative flux of 100% compared to 100% and 95% rejections and 85% and 90% relative fluxes observed for unmodified PEEKWC M2b membrane and commercial NFTFC50, respectively.