A study on fabrication of PVDF-HFP/PTFE blend membranes with controllable and bicontinuous structure for highly effective water-in-oil emulsion separation

In this study, poly(vinylidene fluoride-co-hexafluropropylene) (PVDF-HFP)/polytetrafluoroethylene (PTFE) blend membranes for water-in-oil emulsion separation were prepared via a thermally induced phase separation (TIPS) method using dibutyl phthalate (DBP) and dioctyl phthalate (DOP) as a mixed diluent. The effects of PTFE content on the obtained membranes' structure and properties were studied. The results showed that the surface structure of the obtained membranes without addition of PTFE particles was denser and the surface pores got smaller. The porosity, pore size and hydrophobicity obviously increased with the increase in PTFE content. However, the breaking elongation and breaking strength decreased with the increase of PTFE content. When the PTFE content was 10 wt%, the obtained membrane showed the highest separation efficiency for different kinds of water-in-oil emulsions. In addition, the antifouling performance of the obtained membranes was also studied for many times of reuse. This paper introduces an effective and facile method to prepare hydrophobic–oleophilic membranes for water-in-oil emulsion separation.