Enhance organic pollutants removal of wastewater by a PVDF/PDA-TiO2 composite membrane with photocatalytic property

It is a great challenge to develop a low cost, high efficiency and environmentally friendly method to treat organic wastewater. In this study, synergistic modification of polyvinylidene difluoride (PVDF) membrane with polydopamine and titanium dioxide (TiO2) nanoparticles is developed to construct a PVDF composite membrane for the organic wastewater treatment. This composite membrane was prepared by firstly forming a membrane with dopamine modified PVDF powder, and then depositing TiO2 nanoparticles by a liquid deposition method. The preexisting polydopamine induced TiO2 to be well dispersed in the membrane pores and on the membrane surface and their synergy endowed the composite membrane with excellent treatment ability for organic wastewater. After the composite membrane was irradiated by UV light for 60 min, its water flux could be three times greater than that of the corresponding PVDF membrane. Meanwhile, the composite membrane showed very high rejection ability for filtering wastewater with organic pollutants, could remove about 99.0% of Congo red and Coomassie brilliant blue G250, 98.2% of humic acid and 86.7% of bovine serum albumin from organic wastewater. Furthermore, after a humic acid solution filtration and a followed 60-min UV irradiation, the composite membrane could recover above 87.2% of the water flux. Due to the good wetting properties and underwater low oil droplets adhesion, this membrane also exhibited high rejection and excellent anti-fouling properties for filtering oil-water emulsion. Undoubtedly, the constructed membrane is a good generalist for the separation and wastewater treatment applications.