Characterization of polyvinylidene fluoride hollow fiber membrane with titanium dioxide for water treatment

Abstract

Membrane filtration system is one of the effective ways to remove micro-pollutants such as natural organic matter (NOM) in water treatment process. The surface of the membrane is, however, easily fouled by the deposition of NOM, thereby decreasing flux and separation performances. Thus, in this study, a series of polyvinylidene fluoride/titanium dioxide (PVDF/TiO2) hollow fiber membranes with different TiO2 loadings ranging from 0-3 wt.% were prepared via phase inversion method. The result shows that morphology of membrane layer becomes denser and thicker with the addition of TiO2. The increase of TiO2 loadings ranging from 0 to 2 wt.% resulted in the increase of membrane pore size from 142 to 155 nm with increase surface roughness from 20.2 to 23.98 nm. However with further increase of TiO2 loading the pore size and surface roughness decreased to 152 and 19.33 nm respectively. The mechanical strength of membrane showed slight improvement from 3.01 MPa to 3.41 MPa as TiO2 loading increased from 0 to 2 wt.% before reducing to 3.06 MPa with further increase of 3 wt.% TiO2. Water contact angle demonstrated that with increase TiO2 loading from 0 to 2 wt.% the contact angle was lowered slightly from 79o to 74o. At 2 wt.% TiO2 loading, the highest peak values achieved were 37.86 L/m2h for polymer organic solution flux and 39.04 L/m2h for pure water flux. Membrane with 2 wt.% of TiO2 loadings gives the highest rejection for all molecular weights of PVP. 14 % flux reduction were achieved at 2 wt.% TiO2 loadings for pure water flux after organic polymer rejection test from 38.64 L/m2h to 33.11 L/m2h. Based on this study, it was found that membranes with 2 wt.% addition of TiO2 were excellent in mitigating fouling particularly in reducing fouling resistance and increasing the rate of rejection.