Formation of appropriate sites on nanofiltration membrane surface for binding TiO2 photo-catalyst: Performance, characterization and fouling-resistant capability

Titanium dioxide (TiO2) nanoparticles were assembled on the surface of nanofiltration blend membrane. For settling TiO2 on the membrane surface, two membrane categories were used: (i) unmodified polyethersulfone (PES)/polyimide (PI) blend membrane, and (ii) –OH functionalized PES/PI blend membrane with different concentrations of diethanolamine (DEA). These membranes were radiated by UV light after TiO2 depositing with different concentrations. 15 min immersion in colloidal suspension and 15 min UV irradiation with 160 W lamps were used for modification. The modification resulted in the formation of a photo-catalytic property with enhanced membrane hydrophilicity. The self-assembly of TiO2 nanoparticles was established through coordinance bonds with –OH functional groups on the membrane surface. A comparison between the UV irradiated TiO2 deposited blend membrane and deposited-functionalized blend membranes showed that –OH groups originate excellent adhesion of TiO2 nanoparticles on the membrane surface, increase reversible deposition, and diminish irreversible fouling. The membranes were characterized using SEM, FTIR, EDX, contact angle, cross flow filtration, and antifouling measurements. SEM images show that the presence of –OH groups on the DEA-modified membrane surface is the main parameter for extra uniformly settlement of TiO2 nanoparticles on the membrane surface. This procedure is a superior technique for modification of PES/PI nanofiltration membranes to enhance water flux and minimization membrane fouling.