Natural organic matter removal and flux decline with PEG–TiO2-doped PVDF membranes by integration of ultrafiltration with photocatalysis

Ultrafiltration (UF) has become one of the best alternatives replacing conventional drinking water treatment technologies because of increasing stringent regulations for drinking water quality. However, membrane fouling is an important factor which restricts its widespread application. In this study, the modified PVDF membranes were prepared by adding different amounts of PEG and TiO2 particles. The performances of PVDF–PEG membranes and PVDF–PEG–TiO2 membranes were investigated by discussing NOM removal and flux decline in both dead-end and cross-flow filtration experiments. The effect of photocatalytic degradation on TiO2-doped PVDF membranes was also evaluated. Results indicated that appropriate TiO2-doped modification on PVDF membrane could be an effective way for better removal of NOM and reduction of membrane fouling at the same time. During the ultrafiltration on TiO2-doped PVDF membrane, an equilibrium might be reached between the foulants deposited on the membrane surface and photocatalytic degradation of the foulants during cross-flow UF coupled with photocatalysis. TiO2-doped PVDF membrane also shows good self-cleaning ability. The fouled membrane can be cleaned with irradiation and the foulants’ photocatalytic degradation is most effective in the first 30 min.

► Modified PVDF membrane increases NOM removal rate and decreases the flux decline.
► TiO2-doped PVDF membrane has a good self-cleaning ability.
► Fouling and photocatalytic degradation might reach equilibrium during cross-flow UF.
► Adding TiO2 to PVDF–PEG improves membrane hydrophilicity, smoothness and rejection.