Hydrophobic sandwich-like PVDF/rGO/PDMS composite membrane with fast electrothermal/photothermal response for crude oil removal

Functional membranes with electrothermal/photothermal effects are considered an effective method for separating water/viscous crude oil mixtures. However, the loading of photothermal and electrothermal particles in polymeric membranes with poor compatibility will deteriorate the membrane performance, leading to the unstable photothermal/electrothermal effects. Therefore, we prepared a hydrophobic sandwich structure polyvinylidene fluoride/reduced graphene oxide/polydimethylsiloxane (PVDF/rGO/PDMS) composite membrane using a two-step electrospinning process, which improved the binding force between the photothermal/electrothermal particles and the matrix with the composite membrane exhibiting super fast electric heating and photothermal effect. The temperature of the composite membrane surface rapidly reached to 162.5 °C within 30 s at 25 V. In addition, the addition of graphene (GO) improved the mechanical properties of the composite membrane. Meantime, the composite membrane possessed stable hydrophobicity and lipophilicity, which was beneficial for separating water/viscous crude oil mixtures. Owing to the controllable pore structure and special wetting behavior, the water-in-oil emulsion was successfully separated. Importantly, the separation rates of the water/crude oil mixtures under the electrothermal effect was 2340 kg·m−2·h−1·bar−1. Thus, this study provides a new method for preparing hydrophobic sandwich-like PVDF/rGO/PDMS composite membrane with electrothermal/photothermal effects, which has significant potential for engineering applications in high-viscosity crude oil removal and water-in-oil emulsion separation.